Patent Publication Number: US-7722626-B2

Title: Method of manipulating matter in a mammalian body

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. application Ser. No. 10/238,813, filed Sep. 9, 2002, now U.S. Pat. No. 6,986,774, which is a divisional application of U.S. application Ser. No. 08/914,081, filed Aug. 18, 1997, now U.S. Pat. No. 6,447,523, which is a divisional application of U.S. application Ser. No. 08/398,629, filed Mar. 3, 1995, now U.S. Pat. No. 6,004,330, and a continuation-in-part of U.S. application Ser. No. 07/843,775, filed Feb. 28, 1992, now U.S. Pat. No. 5,632,746, and which is a continuation-in-part of U.S. application Ser. No. 07/774,016, filed Oct. 9, 1991, now U.S. Pat. No. 5,486,183, which is a continuation-in-part application of U.S. applications Ser. Nos.: 07/394,463, filed Aug. 16, 1989, now abandoned; 07/594,768, filed Oct. 9, 1990, now abandoned, 07/608,117, filed Nov. 1, 1990, now abandoned; 07/594,769, filed Oct. 9, 1990, now abandoned; Ser. No. 07/594,871, filed Oct. 9, 1990, now abandoned; Ser. No. 07/594,873, filed Oct. 9, 1990, now abandoned; Ser. No. 07/594,874, filed Oct. 9, 1990, now abandoned; Ser. No. 07/594,896, filed Oct. 9, 1990, now abandoned; Ser. No. 07/608,117, filed Nov. 1, 1990, now abandoned; Ser. No. 07/608,121, filed Nov. 1, 1990, now abandoned; 07/594,871, filed Oct. 9, 1990, now abandoned; 07/594,896, filed Oct. 9, 1990, now abandoned; 07/594,874, filed Oct. 9, 1990, now abandoned; 07/594,873, filed Oct. 9, 1990, now abandoned; and 07/656,651, filed Feb. 15, 1991, now abandoned. The entire disclosures of these applications are hereby incorporated by reference for all purposes. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a device or apparatus for manipulating matter within a confined or inaccessible space, especially during surgery in a living body. 
   2. Description of the Prior Art 
   Matter may be manipulated in such circumstances in various ways, for example by application of a ligature, by suturing, by cutting with a knife or scissor action, or by capture and retrieval in devices such as screens, baskets, barriers, pouches, or retractors. Such manipulation may be difficult when operating in the confined space of a very deep wound or through a small arthroscopic or other endoscopic incision or body aperture. 
   Many forms of apparatus for performing surgical operations have been proposed previously using flexible steel wires which spring apart when extended from the distal end of a tube and which can be brought together again on withdrawal back into the tube. Examples of such known devices may be seen in U.S. Pat. Nos. 2,114,695; 2,137,710; 2,670,519; 3,404,677; 4,174,715; 4,190,042; 4,222,380; 4,249,533; 4,347,846; 4,655,219; 4,691,705; 4,741,335, 4,768,505; and 4,909,789. However, these devices may not be completely satisfactory for various reasons, especially after repeated use or long storage which may fatigue the materials used. 
   Attempts have been made to use shape memory metals in surgical apparatus, but these suffer from inconvenience and from the risk of damage to living tissues resulting from the need either to cool the memory metal while positioning it in the body so that body heat thereafter actuates the shape memory effect, or to heat the metal above body temperature to actuate it after positioning. Examples of such attempts are described in U.S. Pat. Nos. 4,509,517; 3,868,956; and 4,425,908. 
   SUMMARY OF THE INVENTION 
   The present invention uses pseudoelastic materials, preferably pseudoelastic shape memory alloys, which bend pseudoelastically to perform manipulations which may be difficult or impossible to achieve reliably with previously known devices. Pseudoelastic alloys have previously been described for non-manipulative devices such as lesion marker probes, bone anchors, heart valves, intrauterine devices, dental arch wire, coil stents and filters, as described in U.S. Pat. No. 4,665,906 (Jervis), U.S. Pat. No. 4,616,656 (Nicholson), U.S. Pat. No. 4,898,156 (Gattuma), U.S. Pat. No. 4,899,753 (Nicholson), and U.S. Pat. No. 4,946,468 (Li). In one case, U.S. Pat. No. 4,926,860 (Stice) describes a straight suturing needle made of such alloy which ensures the needle emerges straight after being inserted through a curved cannula. None of these known uses in any way suggests the present ingenious use of the power of pseudoelastic bending on extending a pseudoelastic manipulator means from a cannula to perform manipulations in difficult locations. 
   The present invention accordingly provides a device or apparatus for manipulating matter in a confined or inaccessible space, comprising:
     (i) manipulator means at least partly constructed of one or more bent or twisted elongate shape memory alloy members having pseudoelasticity at the intended manipulation temperature, and   (ii) a hollow housing (preferably of elongate tubular form) or cannula capable of holding at least the shape memory alloy member(s) in a relatively straightened state, and   (iii) actuating means for extending the shape memory alloy member(s) from the housing to manipulate matter within the said space and for withdrawing the shape memory alloy member(s) into the housing, the arrangement being such that the shape-memory alloy member(s) bend(s) or twist(s) pseudoelastically in a lateral or helical sense to manipulate the matter on extending from the housing at the said manipulation temperature, and become(s) relatively straightened on withdrawal into the housing at the said temperature.   

   Preferably the invention provides such a device or apparatus which is of elongate form for surgical manipulation of matter within a living body, and which has the manipulator means at its distal end with the shape memory alloy member(s) having pseudoelasticity at the temperature to be encountered within that body, and wherein the actuating means is operable from the proximal end of the device. 
   Various forms of device or apparatus will now be described independently, it being understood that all may be inventive in themselves, although all are preferably within the scope of at least the first (more preferably both) of the two immediately preceding paragraphs, Non-surgical uses may be appropriate for some forms. 
   Any elastic material may be used in some of the embodiments of this invention, but it is generally preferred to use a pseudoelastic material. Many different materials exhibit pseudoelasticity and can be used in any embodiment of this invention. It is preferred to use a pseudoelastic shape memory alloy. 
   The term “elastic material” is used herein to mean a material that has spring-like properties, that is, it is capable of being deformed by an applied stress and then springing back, or recovering, to or toward its original unstressed shape or configuration when the stress is removed. The elastic material is preferably highly elastic. The material can be polymeric or metallic, or a combination of both. The use of metals, such as shape memory alloys, is preferred. Shape memory alloys that exhibit pseudoelasticity, in particular superelasticity, are especially preferred. The elastic materials herein exhibit greater than 1% elastic deformation, more generally greater than 2% elastic deformation. Preferably, the elastic materials herein exhibit greater than 4% elastic deformation, more preferably greater than 6% elastic deformation. 
   Preferably, the elastic member is at least partially formed from a pseudoelastic material, such as a shape memory alloy that exhibits pseudoelasticity. Shape memory alloys which exhibit superelasticity (also referred to in the literature as non-linear pseudoelasticity), are especially preferred. 
   U.S. Pat. No. 4,935,068 to Duerig, which is commonly assigned with the present application and incorporated herein by reference, teaches the fundamental principles of shape memory alloys. Some alloys which are capable of transforming between martensitic and austenitic phases are able to exhibit a shape memory effect. The transformation between phases may be caused by a change in temperature. For example, a shape memory alloy in the martensitic phase will begin to transform to the austenitic phase when its temperature rises above A S  and the transformation will be complete when the temperature rises above A f . The forward transformation will begin when the temperature drops below M S  and will be complete when the temperature drops below M f . The temperatures M S , M f , A S , and A f  define the thermal transformation hysteresis loop of the shape memory alloy. 
   Under certain conditions, shape memory alloys exhibit pseudoelasticity, which does not rely on temperature change in order to accomplish shape change. A pseudoelastic alloy is capable of being elastically deformed far beyond the elastic limits of conventional metals. 
   The property of pseudoelasticity of certain shape memory alloys, which preferably is used in the devices of this invention, is the subject of a paper entitled “An Engineer&#39;s Perspective of Pseudoelasticity”, by T. W. Duerig and R. Zadno, published in Engineering Aspects of Shape Memory Alloys, page 380, T. W. Duerig, K Melton, D. Stoeckel, and M. Wayman, editors, Butterworth Publishers,. 1990 (proceedings of a conference entitled “Engineering Aspects of Shape Memory Alloys”, held in Lansing, Mich. in August 1988). As discussed in the paper, the disclosure of which is incorporated herein by reference, certain alloys are capable of exhibiting pseudoelasticity of two types. 
   “Superelasticity” arises in appropriately treated alloys while they are in their austenitic phase at a temperature which is greater than A S  and less than M d  (A S  is the temperature at which, when a shape memory alloy in its martensitic phase is heated, the transformation to the austenitic phase begins, and M d  is the maximum temperature at which the transformation to the martensitic phase can be induced by the application of stress). Superelasticity can be achieved when the alloy is annealed at a temperature which is less than the temperature at which the alloy is fully recrystallized. Alternative methods of creating superelasticity in shape memory alloys, such as solution treating and aging, or alloying, are also discussed in “An Engineer&#39;s Perspective of Pseudoelasticity”, referenced above. An article may be provided with a desired configuration by holding it in that configuration during annealing, or during solution treatment and aging. An article formed from an alloy which exhibits superelasticity can be deformed substantially reversibly by 11% or more. In contrast, “linear pseudoelasticity”, is believed not to be accompanied by a phase change. It is exhibited by shape memory alloys which have been cold worked or irradiated to stabilize the martensite, but have not been annealed in the manner discussed above. An article formed from an alloy which exhibits linear pseudoelasticity can be deformed substantially reversibly by 4% or more. The treatment of shape memory alloys to enhance their pseudoelastic properties is also discussed in above-mentioned U.S. Pat. No. 4,935,068 to Duerig, incorporated herein by reference. 
   While the alloy that is used in the devices of this invention may exhibit either linear pseudoelasticity or superelasticity (which is sometimes referred to as non-linear pseudoelasticity), or pseudoelasticity of an intermediate type, it is generally preferred that it exhibit superelasticity because of the large amount of deformation that is available without the onset of plasticity. U.S. Pat. No. 4,665,906 to Jervis, which is commonly assigned with the present application and is incorporated herein by reference, teaches the use of pseudoelastic shape memory alloys in medical devices. 
   The pseudoelastic material will be selected according to the characteristics desired of the article. When a shape memory alloy is used, it is preferably a nickel titanium based alloy, which may include additional elements which might affect the yield strength that is available from the alloy or the temperature at which particular desired pseudoelastic characteristics are obtained. For example, the alloy may be a binary alloy consisting essentially of nickel and titanium, for example 50.8 atomic percent nickel and 49.2 atomic percent titanium, or it may include a quantity of a third element such as copper, cobalt, vanadium, chromium or iron. Alloys consisting essentially of nickel, titanium and vanadium, such as disclosed in U.S. Pat. No. 4,505,767, the disclosure of which is incorporated herein by reference, are preferred for some applications, particularly since they can also exhibit superelastic properties at or around body temperatures, and because they are stiffer and/or can store more elastic energy. Copper based alloys may also be used, for example alloys consisting essentially of copper, aluminum and nickel; copper, aluminum and zinc; and copper and zinc. 
   An article exhibiting superelasticity can be substantially reversibly deformed, by as much as eleven percent or more. For example, a 1.00 meter length of superelastic wire may be stretched to 1.11 meters in length, wherein its alloy will undergo a phase change to at least a partially more martensitic phase known as stress-induced-martensite. Upon release of the stress, the wire will return substantially to its 1.00 meter length, and its alloy will, correspondingly, return at least substantially toward its more austenitic phase. By way of contrast, a similar wire of spring steel or other conventional metal may only be elastically stretched approximately one percent, or to 1.01 meter in length. Any further stretching of the conventional wire, if not resulting in actual breakage of the wire, will result in a non-elastic (plastic) transformation such that, upon relief of the stress, the wire will not return to its original length. Linear pseudoelastic and superelastic materials may also be bent, twisted, and compressed, rather than stretched, to a far greater degree than conventional metals. 
   It is believed that the superelastic property is achieved by phase transformation within the alloy, rather than by the dislocation movements which occur during the plastic deformation of ordinary metals. A superelastic material may be deformed and released thousands of times, without being subject to breakage due to the metal fatigue which limits the number of deformation cycles which an ordinary metal may undergo without failure. 
   Shape memory alloys have a special feature which is beneficial for certain of the embodiments of this invention. As a superelastic shape memory alloy is increasingly deformed from its unconstrained shape, some of its austenitic phase changes into stress-induced-martensite. The stress/strain curve presents a plateau during this phase change. This means that while the alloy undergoes this phase change, it can deform greatly with only minimal increases in loading. Therefore, elements comprising superelastic shape memory alloys have a built-in safety feature. These elements can be designed (using appropriately treated alloys and appropriate dimensions) such that when they are loaded beyond a certain amount, the elements will tend to deform with a concomitant austenite to stress-induced-martensite phase change, instead of merely presenting a greater resistance or force with limited deformation to the load, which is seen with conventional metals. 
   Just as the stress strain curves of shape memory alloys present a plateau upon loading, they also present a plateau in the stress strain curve upon unloading. Unloading occurs when an element made of superelastic shape memory alloy is permitted to revert from a significantly deformed shape toward its original unstressed shape. Because of the plateau, such an element can maintain an almost constant force during much of the unloading cycle until just before it is completely unloaded. 
   One form of the present invention provides a surgical instrument which enables the passage of a ligature around a bone, blood vessel, or other such body member, or the grasping of such a body member, without requiring the surgical instrument to be swept over a wide angle of motion. The apparatus includes a cannula and, within the cannula, a member which is at least partly constructed of an elastic material, preferably a pseudoelastic material and most preferably a pseudoelastic shape memory alloy, such as those disclosed in U.S. Pat. No. 4,665,906 to Jervis, dated May 19, 1987, and U.S. Pat. No. 4,505,767 to Quin, dated Mar. 19, 1985, which are preferred for all forms of this invention and which are incorporated herein by reference. 
   Although the following detailed description and the accompanying Figures illustrate the cannula as having a straight shape, and the elastic member as being held therein in a straightened configuration, it will be understood that the cannula may advantageously be formed with any desirable shape, such as an arc, and that the elastic member may take on any desirable shape upon extrusion from the cannula. 
   The straight cannula and curved elastic members are used as examples, only, and should not be interpreted to limit the scope of this invention. It will also be understood that although the cannula is discussed as being fairly rigid, it may be formed of a plastically deformable material, which will allow the surgeon to shape the instrument to any required configuration. The instrument may also be flexible to be used within the working channel of a flexible endoscope, the lumen of a catheter or to function as a catheter itself. 
   Furthermore the elastic member may be coated with a suitable material, such as a polymer. 
   The elastic member has a distal end portion with a specific curved shape when not subject to mechanical stress. In a first embodiment, the elastic member is of sufficient strength and rigidity to enable a surgeon to grasp and manipulate a body structure, such as a bone, thereby. In the first embodiment, the elastic member includes a distal end structure which may be a pointed tip or a structure which serves to protect the patient&#39;s body and to prevent complete withdrawal of the elastic member into the cannula. As the elastic member is distally extended from the cannula, it curves around the body structure sufficiently for grasping and manipulating the body structure. 
   In a second embodiment, the elastic member may be of less substantial construction and its distal end portion is adapted to retain a ligature. In order to pass the ligature around a blood vessel or bone, the surgeon need only place the distal end of the apparatus near the vessel or bone, and extend the elastic member from the cannula without any required lateral angular motion of the cannula. The elastic member returns to its specific curved shape as it extends beyond the catheter, wrapping itself around the blood vessel or bone. The ligature may then be attached to the distal end of the elastic member, and the elastic member may be withdrawn into the cannula, to pull the ligature around the vessel or bone. By pre-attaching the ligature to the elastic member, the ligature may be passed around the vessel or bone upon extension rather than retraction of the elastic member. The apparatus may further include a means for automatically attaching the ligature to or unattaching the ligature from the elastic member. 
   The elastic member, if made of pseudoelastic material, will not readily break during repeated use, since metal fatigue does not occur under pseudoelastic use conditions. The instrument operates even though the cannula is not swept over any degree of motion. The instrument is of a simple design, and is of relatively low production cost. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1-1-  to  1 - 3  illustrate a first embodiment of the present invention. 
       FIG. 1-1   a  is a cross-sectional diagram, showing the elastic member disposed within the cannula, in a mode in which the elastic member has a distal end structure. 
       FIG. 1-1   b  is a cross-sectional diagram, showing a mode in which the elastic member has a pointed distal tip. 
       FIGS. 1-2   a - b  illustrates modes of the elastic member, returning toward a curved shape and a corkscrew shape upon extrusion from the cannula, respectively. 
       FIGS. 1-3   a - c  illustrate linear, lateral, and axial manipulation of a bone. 
       FIGS. 1-4-  to  1 - 12  illustrate a second embodiment of the present invention. 
       FIG. 1-4  is a cross-sectional diagram, showing the elastic member fully disposed within the cannula. 
       FIGS. 1-5   a - b  show alternative modes of the ligature retainer. 
       FIG. 1-6  shows extension of the elastic member of  FIG. 1-5   a  around a blood vessel. 
       FIGS. 1-7   a - f  illustrate a means for automatically grasping a ligature which is passed around a blood vessel. 
       FIGS. 1-8   a - d  illustrate an alternative mode of automatically grasping the ligature. 
       FIG. 1-9  illustrates another alternative mode of automatically grasping the ligature. 
       FIGS. 1-10   a - d  illustrate how the apparatus may be used to pass the ligature and automatically tie a half-hitch knot therein. 
       FIG. 1-11  shows a sliding sleeve which aids in tying the half-hitch knot 
       FIGS. 1-12   a - c  illustrate how the apparatus may be used to pass the ligature and automatically tie a logger&#39;s knot therein. 
       FIG. 1-13  shows a prior art apparatus, and illustrates the wide angle of access needed therefore. 
       FIGS. 2-1  to  2 - 6  illustrate the first embodiment of the present invention, which longitudinally extrudes an elastic needle through the distal end of a cannula. 
       FIG. 2-1   a  is a cross-sectional view, showing the elastic needle held inside the cannula in a straightened configuration under mechanical stress. 
       FIG. 2-1   b  shows partial extrusion of the elastic needle from the cannula, with the extruded portion of the needle returning toward its curved configuration by elastic shape memory. 
       FIG. 2-1   c  shows the needle fully extruded from the cannula, and released from the cannula insert 
       FIGS. 2-2   a - e  show alternative modes of the distal end portion of the cannula insert. 
       FIG. 2-3  is a view of the distal end portion of the cannula insert, showing a raised release signal tab formed therein. 
       FIG. 2-4   a  illustrates an integrally constructed mode of the distal end portion of the first embodiment, showing the enlarged transverse dimension of the end portion of the cannula insert. 
       FIG. 2-4   b  shows an alternative, non-integral mode of the distal end portion of the cannula insert, formed of a compressible material. 
       FIG. 2-5  is a view of the distal end portion of the cannula insert, showing an indented distal face therein. 
       FIG. 2-6  is a cross-sectional view of the proximal end portion of the first embodiment showing a suture retention bobbin within the cannula insert. 
       FIGS. 2-7  to  2 - 10  illustrate a second embodiment of the present invention, which extrudes the elastic needle laterally rather than longitudinally. 
       FIG. 2-7   a  is a cross-sectional view showing a cannula, shaft, and plunger of the second embodiment 
       FIG. 2-7   b  is a cross-sectional view of an alternative mode of the proximal end portion of the second embodiment 
       FIG. 2-7   c  is a cross-sectional view of another alternative mode of the proximal end portion of the second embodiment. 
       FIG. 2-7   d  is an enlarged cutaway view of the proximal end portion of the alternative mode shown in  FIG. 2-7   b.    
       FIG. 2-7   e  is a perspective view of the proximal end cap of the alternative mode shown in  FIG. 2-7   c.    
       FIG. 2-8  is a cross-sectional view of the distal end portion of the second embodiment, showing a suture retention bobbin therein. 
       FIG. 2-9  is a cross-sectional view of the second embodiment, taken at line  9 - 9  of  FIG. 2-7   a , showing grooves in the shaft and cannula, and groove engaging tabs in the plunger, for causing rotation of the shaft. 
       FIG. 2-10  is a cutaway perspective view of the distal end portion of the second embodiment, showing the unwinding of the curved needle through the aperture. 
       FIG. 2-11   a  illustrates the present invention being used to deliver the needle to a deep wound for suturing. 
       FIG. 2-11   b  illustrates the present invention being used in arthroscopic surgery on a knee. 
       FIG. 2-12  to  2 - 15  illustrate a third embodiment of the present invention, which is used to insert ring clips into tissue to hold a wound closed. 
       FIG. 2-12   a  is a cutaway view of the third embodiment, illustrating a ring clip held therein. 
       FIG. 2-12   b  illustrates extrusion of the ring clip. 
       FIG. 2-12   c  illustrates an alternative mode of the third embodiment, adapted for use with an extended ring clip which is held therein. 
       FIG. 2-13   a,    2 - 13   b ,  2 - 13   c,  and  2 - 13   d , illustrate a marker which indicates a first and a second direction of extrusion of the ring clip, respectively. 
       FIG. 2-14  is a cross-sectional view of another alternative mode of the third embodiment, adapted for serial extrusion of a plurality of ring clips held therein. 
       FIG. 2-15   a  illustrates yet another mode of the third embodiment, with the plurality of ring clips held in a magazine. 
       FIG. 2-15   b  illustrates an internal piston return spring. 
       FIG. 2-16   a  illustrates manipulation of the extended distal segment of the ring clip of  FIG. 2-12   c.    
       FIG. 2-16   b  illustrates the severing of the extended distal segment of  FIG. 2-16   a.    
       FIG. 2-17   a - c  illustrates various modes of a ring clip. 
       FIG. 3-1  is a view of an unexpanded barrier device (not shown) within a housing. 
       FIGS. 3-2  through  3 - 5  are progressive cross-sectional views through line a-a of  FIG. 3-1 , showing the use of the device of  FIG. 3-1 . The figures show, respectively,  FIG. 3-2 , constrained;  FIG. 3-3 ; expanded (memory);  FIG. 3-4 , pouched; and  FIG. 3-5 , withdrawal configurations. 
       FIGS. 3-6   a, b, c  and  d  show alternate embodiments of the device of  FIG. 3-1  through line b-b. 
       FIGS. 3-7  and  3 - 8  show alternate embodiments of the barrier member in the expanded (memory) configuration. 
       FIGS. 3-9   a, b,  and  c  show cross-sectional embodiments through line b-b of  FIG. 3-7 . 
       FIGS. 3-10   a  and  b ,  3 - 11   a  and  b , and  3 - 12   a  and  b  detail alternate expanded loop configurations. 
       FIG. 3-13  is a schematic representation of another embodiment of a device for deploying an internal drape, and 
       FIGS. 3-14  and  3 - 15  are schematic representations of yet another embodiment of device for deploying an internal bag, showing the device before and after withdrawal of the drape into the shaft of the instrument. 
       FIGS. 3-16 ,  3 - 17  and  3 - 18  illustrate the use of a bushing which can be used with any of embodiments  3 - 1  to  3 - 15 . 
       FIGS. 3-19 ,  3 - 2 O,  3 - 21 , and  3 - 22  illustrate a necked-loop configuration which can be incorporated in any of the embodiments, illustrated in  FIGS. 3-1  to  3 - 18 . 
       FIG. 4-1   a  is a side view of an unexpanded screen device within a duct, placed downstream from the blocking calculus. 
       FIG. 4-1   b  shows the screen device, the deployment end of which has been placed upstream from the blocking calculus. 
       FIG. 4-1   c  shows a screen device which has been expanded upstream from a blocking calculus. 
       FIG. 4-1   d  shows a screen device in place after calculus fragmentation. 
       FIGS. 4-2   a, b, c,  and  d  show various stages of deployment of a tasseled surgical screen. 
       FIGS. 4-3   a  through  4 - 5   b  show alternate embodiments of the surgical screen portion of a device of this invention. 
       FIG. 5-1  is a cross-sectional view of a constrained retractor device. 
       FIGS. 5-2  through  5 - 6  show alternate top views of expanded (unconstrained) retractor devices. 
       FIGS. 5-7  through  5 - 11  show alternate side views of expanded retractor devices. 
       FIGS. 5-12  and  5 - 13  show alternate end views of expanded retractor devices. 
       FIGS. 5-14  and  5 - 15  show alternate cross sectional views of constrained retractor devices, the cross section taken along line a-a of  FIG. 5-1 . 
       FIG. 6-1  is an external view of a device of this invention. 
       FIGS. 6-2  and  6 - 3  are alternate cross-sectional views of a sheath of this invention, the cross sections being taken vertically along the longitudinal axis of  FIG. 6-1 . 
       FIG. 6-4  is an alternate cross-sectional view of a sheath of this invention, the cross section being taken vertically along the longitudinal axis. 
       FIG. 6-5  is a cross-sectional view of the device of  FIG. 1  taken across the longitudinal axis, along line b-b of  FIG. 6-1   
       FIG. 6-6  is a cross-sectional view of the device of  FIG. 6-1  taken across the longitudinal axis, along line c-c of  FIG. 6-1 . 
       FIG. 6-7  is a cross-sectional view of a cutting edge of a cutting blade of this invention. 
       FIGS. 6-8  through  6 - 12  are alternate side views of the device of  FIG. 1  when the cutting blade is deployed. 
       FIGS. 6-13  through  6 - 20  are alternate top views of typical elastic blades of this invention. 
       FIG. 7-1  shows an instrument of this invention. 
       FIGS. 7-2   a, b, c,  and  d  show the deployment end of a bladed instrument of this invention. 
       FIGS. 7-3   a, b  and  c  and  7 - 4   a, b  and  c  are longitudinal cross-sectional views of alternate elastically deployable stems, in longitudinally constrained and longitudinally unconstrained configurations. 
       FIGS. 7-5   a  and  b ,  7 - 6   a  and  b  and  7 - 7   a, b  and  c  each show alternate views of an elastically deformable stem of this invention. 
       FIGS. 7-8   a, b, c, d, e  and  f  and  7 - 9   a, b, c, d, e, f, g, h,  and  i  show alternate elastic members suitable for use in an elastically deformable stem of this invention. 
       FIGS. 7-10   a  and  b  show alternate views of a device of this invention having two pivoted blades, each blade having a longitudinal slot proximal the pivot. 
       FIGS. 7-11   a, b,  and  c  show alternate views of a device of this invention having two blades, two bars, and four pivots. 
       FIGS. 7-12   a, b, c, d, e,  and  f  show alternate cross-sections of the device of  FIG. 7-1 , taken through line  12 - 12 . 
       FIGS. 7-13   a, b, c, d,  and  e  show various blades suitable for use herein. 
       FIGS. 7-14   a, b, c, d,  and  e  show various blade cross-sections, taken through line  14 - 14  of  FIG. 7-13 . 
       FIG. 8-1  is an isometric view of a device of the invention; 
       FIGS. 8-2   a ,  8 - 2   b  and  8 - 2   c  are cross-sections through the device shown in  FIG. 8-1 , taken at lines A-A, B-B and C-C respectively; 
       FIGS. 8-3   a ,  8 - 3   b ,  8 - 3   c ,  8 - 3   d  and  8 - 3   e  are elevational views of a first embodiment of the device shown in  FIG. 8-1  at various stages during a cutting operation; 
       FIGS. 8-4   a ,  8 - 4   b  and  8 - 8   c  are elevational views, partially in section, of another embodiment of the device at various stages during a cutting or grasping operation. 
       FIGS. 8-5   a ,  8 - 5   b ,  8 - 5   c ,  8 - 5   d  and  8 - 5   e  illustrate an embodiment of a device in accordance with this invention in which the end portions and body portions of the elongate elements are integral and are moved by a rotational actuator made of a material other than a pseudoelastic material. 
       FIGS. 8-6   a ,  8 - 6   b ,  8 - 6   c ,  8 - 6   d  and  8 - 6   e  illustrate representative cross sections of end portions of the elements adapted to grasp or cut an obect. 
       FIGS. 8-7   a ,  8 - 7   b ;  8 - 7   c ,  8 - 7   d  and  8 - 7   e  illustrate various actuating means which function to cause the elements to splay apart and come together and, optionally, rotate the elements, and/or withdraw the elements into or out of the hollow component. 
       FIG. 8-8  illustrates an embodiment of the device of this invention in which the end portions are curved when at least partially unconstrained and pinned together pivotally at their tips. 
       FIG. 8-9  demonstrates a method of using a grasping device of this invention. 
       FIGS. 8-10   a ,  8 - 10   b  and  8 - 10   c  illustrate an embodiment of the device of this invention in which the elements are splayed and in which the body portions of the elements are bent when the elements are unconstrained. 
       FIGS. 8-11   a  and  8 - 11   b  illustrate a device of this invention in which the elements have end portions beyond a pivot point, and in which the body portions of the elements are of pseudoelastic material and when unconstrained are bent to splay the end portions and position them at a desired angle with respect to the hollow component. The body portions act as actuating means to open and close the end portions of the elements to dissect, grasp and/or cut an object. 
       FIG. 8-12  illustrates a device similar to the device in  FIG. 8-11   b , but in which the body portions of the elements are made of a pseudoelastic material and have a bend of about 90 degree. 
       FIG. 8-13  illustrates another device in accordance with this invention. 
   

   DETAILED DESCRIPTION 
     FIG. 1-13  shows the use of a prior art apparatus  700  for passing a ligature (not shown) around a particular blood vessel  703  which is situated among other blood vessels  704 . In order to place the operative distal end  710  into a position  715  from which the end  710  is directly accessible, it is necessary to swing the entire apparatus  700  through a very wide angle of motion  720 . This wide angle requires a very large entry wound  740  through the patient&#39;s tissues  730 . It will be understood that such a wide angle of motion is impossible to achieve if the apparatus  700  is being used through an arthroscopic or other small endoscopic surgical entry wound  735  through the patients tissues  730 . 
   As will be understood from the following description and from the accompanying drawings, the present invention is an apparatus usable through such a small entry wound. 
   In a first embodiment  100 , shown in  FIGS. 1-1-  to  1 - 3 , the present invention includes a cannula  10  and a member  12 . Although the present invention may be practiced with a member  12  which is fashioned of another appropriate material, such as spring steel, the preferred material is a pseudoelastic material, preferably a shape memory alloy and in particular a shape memory alloy that exhibits superelasticity. The member  12  will hereinafter be referred to as a elastic member  12 , and its distal segment  14  will be referred to as a elastic distal segment  14 . In a preferred embodiment the member is made of a superelastic shape memory alloy and the elastic distal segment  14  has a first shape when the alloy of the elastic distal segment  14  is in a substantially austenitic phase and the distal segment  14  is extended distally from the cannula  10  and is not subject to mechanical stress. The elastic distal segment  14  may be mechanically stressed into a second shape (i.e., when the distal segment  14  is held within the cannula  10 ), wherein at least a portion of the alloy has changed to a stress-induced-martensite phase. 
     FIGS. 1-1   a - b  show the elastic distal segment  14  elastically deformed into a second, straight shape within the cannula  10 .  FIG. 1-2   a  shows one mode of the first shape, with the elastic distal segment  14  returning toward an arced first shape upon extrusion from the cannula  10 .  FIG. 1-2   b shows an alternative mode of the first shape, wherein the elastic distal segment  14  returns toward a corkscrew first shape upon extrusion from the cannula. 
   As shown in  FIG. 1-1   a , the elastic member  12  also includes a proximal segment  16  which is relatively straight, to allow its easy insertion into the proximal end of the cannula  10 . 
   The distal and proximal segments may, suitably, be integrally formed of a unitary wire or rod, or the proximal segment may be formed of a different material and coupled end-to-end with a elastic distal segment. If the segments  14  and  16  are formed of a unitary construction, the proximal segment  16  does not, preferably, have a curved shape when it is in an unstressed condition, unlike the elastic distal segment  14 . Although the member  12  is referred to herein as a elastic member  12 , it will be understood that, as explained, only the distal end segment  14  need be elastic. It will be further understood that the distal end segment  14  as well as the proximal segment  16  may be formed of any suitable material, which may or may not be the same. 
   The elastic member  12  may also include a distal end structure  18 , as shown in  FIG. 1-1   a . The distal end structure  18  is a contact or grip means which improves the grip of the apparatus  100  upon an object. The distal end structure  18  also prevents the complete withdrawal of the elastic member  12  through the cannula  10 , to preserve the apparatus  100  as an integral unit. The smooth surface and shape of the distal end structure  18  serve as a safety means which helps to reduce issue damage upon insertion of the apparatus  100  into a wound, or through tissue, or through an arthroscopic or other such endoscopic surgical entry wound. In the illustrated embodiment, the distal end structure  18  is substantially semi-spherical, with a diameter roughly equal to that of the cannula  10 . This protects the patient&#39;s tissues from the blunt distal end of the cannula  10 , while also preventing complete withdrawal of the elastic member  12  from the cannula  10 . The distal end structure  18  may be either unitarily constructed with the elastic distal segment  14 , or may be formed of a different material and coupled thereto in any conventional manner. It is to be understood that the distal end structure  18  can have any blunted shape, and may even be spherical or bullet shaped. 
   As shown in  FIG. 1-1   b , the elastic member may have a pointed distal end structure  19 , which, like the distal end structure  18  of  FIG. 1-1   a , improves the mechanical gripping of the apparatus upon a bone or other object. It may be preferred that distal end structure  19  be integral with the elastic member. 
   The apparatus  100  may, suitably, be further adapted with a handle structure for extending the elastic member  12  through the cannula. In one mode, the handle structure may include a thumb ring  20  coupled to the proximal end of the elastic member  12 , and one or more finger rings  22  coupled near the proximal end of the cannula  10 . The surgeon inserts the elastic member  12  through the cannula  10  by pressing on the thumb ring  20  while holding the finger rings  22  stationary, and withdraws the elastic member  12  into the cannula by pulling the thumb ring  20  in the opposite direction. Of course, other handle devices are within the scope of all of the embodiments of this invention, such as a pistol grip, or a scissor-action apparatus, or the like. Withdrawal of the elastic member  12  may be assisted by a spring (not shown). 
   As shown in  FIG. 1-2   a , when the elastic member  12  is inserted through the cannula  10  with motion  24 , the elastic distal segment  14  emerges from the distal end of the cannula  10 . In a preferred embodiment in which superelastic shape memory alloy is utilized, the elastic distal segment  14  has its stress-induced-martensite condition at least partially relieved of stress by the absence of any restraining cannula. The alloy of the elastic distal segment  14  undergoes at least a partial reversion toward the austenitic phase, and the elastic distal segment  14  returns toward its first shape with motion  26 . 
   It will be understood that the curvature of the elastic distal segment  14  need not necessarily be circular, nor coplanar with the axis of the cannula  10 , within the scope of this invention. For example, the distal segment  14  might be formed to curve radially about the axis of the cannula upon extrusion therefrom, in a corkscrew fashion, as shown in  FIG. 1-2   b . As will be understood, the elastic distal segment  14  may be formed to have any desired shape or arc or radius of curvature, to suit the apparatus for a given purpose. 
   As shown in  FIGS. 1-3   a - c , the apparatus  100  may be used to manipulate a bone  3  or other structure in a patient, or any other suitable object. The specific body members which are discussed herein are listed solely to aid in the understanding of the invention, and do not affect the scope of the invention. 
   It will be understood that the first embodiment  100  may be constructed in a variety of sizes and with an elastic member of a variety of lateral dimensions, cross-sectional configurations, and strengths, for suitable use in manipulating a wide variety of body members or other objects. For example, a very small apparatus with a very thin elastic member may be desirable in manipulating small or delicate body members such as individual nerves or terminal arteries. On the other hand, a large apparatus with a thick elastic member having great strength may be required in order to manipulate a larger body member such as a broken femur, or a bulky organ, or a prosthesis or other mechanical object. Also the apparatus may be long and/or flexible, so that it can be used in the channel of an endoscope (rigid or flexible), in the lumen of a catheter, or as a catheter itself. 
   The elastic distal segment  14  of the elastic member  12  may be inserted into or wrapped around the body structure  3 , and the apparatus  100  may be moved, to manipulate the structure  3 . Extension of the elastic member  12  into grasping connection with the body member  3  does not require any lateral movement of the apparatus  100 , but only requires linear insertion of the elastic member  12  through the cannula  10 . This permits the apparatus  100  to be used in closely confined surgical sites, or through a very small surgical opening such as may typically be used to gain arthroscopic access to a knee joint, for example. 
   By forming the elastic distal segment  14  to have a non-stressed shape which curves in a particular direction, the apparatus  100  may be constructed for suitable hooking of a body member which has a given orientation. With the curvature shown in  FIG. 1-3   a , the apparatus  100  may be suited for linear pulling or pushing of the body structure  3  in the direction  28  shown. With the curvature shown in  FIG. 1-3   b , the apparatus  100  may be suited for lateral manipulation of the body structure  3  in the direction  30 , as shown. As shown in  FIG. 1-3   c , if the elastic distal segment  14  curves in a corkscrew shape, the apparatus  100  may be readily used to push or pull the body structure  3  along the axis of the body structure  3 , in direction  32  as shown. 
   The apparatus  100  may be adapted with a marker  31 , as shown in  FIG. 1-3   a , for indicating the direction and orientation in which the particular elastic member  12  will curve upon extrusion. The marker  31  may be, for example, printed upon the cannula  10 , or may be a raised or indented portion thereof. As it is desirable that the marker  31  not cause any trauma to an entry wound, a printed marker may be the preferred mode. It will be understood that the marker may be placed at any desired point along the length of the cannula. For example, a marker placed immediately adjacent to the distal tip of the apparatus will likely be visible to an arthroscopic surgeon through his or her arthroscopic viewing apparatus. On the other hand, or in addition, a marker placed near the proximal end of the apparatus will remain in plain sight during surgery, as it will remain outside the patient&#39;s body. The apparatus  100  may include any suitable means for ensuring that the elastic member  12  curve in the indicated direction. For example, the distal segment  16  may be formed of a square cross-section, with the proximal end opening (not shown) of the cannula  10  being formed of a similar shape, such that the elastic member  12  cannot rotate within the cannula  10 . Alternatively, the cannula  10  may have a peg (not shown) which engages a longitudinal slot (not shown) in the elastic member  12 , or the elastic member  12  may have a peg (not shown) to engage a longitudinal slot (not shown) in cannula  10 . 
     FIGS. 1-4-  to  1 - 12  illustrate a second embodiment  200  of the present invention. In this embodiment, the elastic member  12  need not include a distal end structure, and may be fully withdrawn into the cannula  10 . Although the second embodiment  200  is hereinafter described as being used for passing a ligature around a blood vessel, it will be understood that the ligature may be passed around any other body structure or other object, within the scope of this invention. If the non-deformed shape of the distal segment of the elastic member is substantially circular, this has the important advantage that, during extension and withdrawal of the elastic distal segment, that portion of the elastic distal segment which is already extruded from the cannula and adjacent the blood vessel will not apply any lateral or radial forces upon the blood vessel. It will, therefore, be understood that it is advantageous to form differing modes of the second embodiment, wherein each has an elastic member whose distal segment is of a given radius of curvature in its non-deformed first shape. This allows the surgeon to select an appropriately sized apparatus for passing a ligature around any size of blood vessel, and is within the scope of this invention. It will be understood that the same principle applies equally to the first embodiment described above with regard to  FIGS. 1-1-  to  1 - 3 . Also the apparatus may be long and/or flexible, so that it can be used in the channel of an endoscope (rigid or flexible), in the lumen of a catheter, or as a catheter itself. 
   The elastic distal segment  14  of  FIG. 16  is adapted with a ligature retainer means  34  which releasably retains the ligature  36 .  FIGS. 1-5   a - b  show the ligature retainer  34  as a hook and a hole, respectively. In either mode, the ligature retainer  34  may either be cut into the wire of the elastic distal segment  14 , or may be bent thereinto by plastically deforming the wire of the elastic distal segment  14 . Other suitable means may be employed without departing from the scope of this invention. It will be understood that the ligature retainer  34  may be fashioned in any desired orientation relative to the plane of curvature of the elastic distal segment  14 . If the hook mode of the ligature retainer  34  is used, in order to prevent the hook  34  from catching on the inner lip  33  of the distal opening of the cannula  10  upon withdrawal, the lip  33  may be rounded off, as shown in  FIG. 1-5   a.    
   The second embodiment  200 , like the first, may be adapted with at least one marker  31  for indicating a predetermined direction of curvature of the elastic member, and with suitable handles  20  and  22  or other means for extending and retracting the elastic member. A spring may be used to assist retraction of the elastic member  12 . 
   As shown in  FIG. 1-6 , upon extrusion from the cannula  10 , the elastic distal segment  14  curves around the vessel  5  with motion  38 . It will be understood that the elastic distal segment  14  need not actually touch the vessel  5 , but is shown in such contact for convenience. With the elastic member  12  wrapped around the blood vessel  5 , the ligature (not shown) may be inserted into the ligature retainer  34  using tweezers, forceps, or the like. Withdrawal of the elastic distal segment  14  into the cannula  10  draws the ligature around the blood vessel  5  with motion  40 . As will be understood, the ligature may also be inserted into the ligature retainer  34  before the elastic distal segment  14  is passed around the blood vessel  2 , in which instance the ligature is passed around the blood vessel  5  upon extension of the elastic member  12  around the blood vessel  5  with motion  38 , if the ligature retainer  34  is appropriately formed. 
   The apparatus  200  may further be adapted with means for automating the ligature&#39;s attachment to, or unattachment from the elastic member.  FIGS. 1-7   a - f  illustrate one mode of this means. One end  35  of the ligature  36  is coupled to the cannula  10 , for example by being tied or otherwise coupled to a post  44 . Upon extension from the cannula  10 , the elastic distal segment  14  curves with motion  38  around the vessel  5 , as shown in  FIG. 1-7   b . The elastic distal segment  14  is constructed such that its return toward the unconstrained first shape brings the ligature retainer  34  into grasping contact with the held portion  35  of the ligature  36 , as shown in  FIG. 1-7   c.    
   Upon retraction, the elastic member  12  draws the ligature  36  around the vessel  5  with motion  40  (the reverse of motion  38 ), and the ligature  36  slides through the ligature retainer  34 , as shown in  FIG. 1-7   d . Upon full retraction, shown in  FIG. 1-7   e , the ligature  36  will be doubled around the vessel  5 . If it is desired that only a single loop of ligature  36  pass around the vessel  5 , this may be accomplished by simply releasing the trailing end  37  of the ligature  36 , and withdrawing the apparatus  200  until the trailing end  37  passes around the vessel  5 , as shown in  FIG. 1-7   f . Alternatively, a doubled suture (not shown) can be placed over the post and held by the post such that only one strand of the suture is hooked by ligature retainer  34 . 
   The post  44  in the embodiments shown in  FIGS. 1-7 ,  1 - 9 ,  1 - 10 ,  1 - 11 , and  1 - 12 , and the loop grabber  42  shown in  FIGS. 1-8  and  1 - 9 , are shown to be rigidly attached to the cannula  10 . However, both post  44  and loop grabber  42  could consist of a tongue (not shown) or a cam (not shown) to which sutures may be attached. Such a tongue or cam would preferably be biased flush with the wall of the cannula  10  initially, but would be mechanically forced to extend in a direction sideways from the cannula when the elastic member  12  is extended from the end of the cannula. In this fashion, a suture would be held against the wall of cannula  10  until the elastic member is extended, at which time the post and/or loop grabber would extend sideways from the wall of the cannula  10  such that the post  44  will hold the suture in a better location for the ligature retainer  34 , and/or such that the suture can be attached to the loop grabber  42 . Upon withdrawal of elastic member  12  the tongue or cam will preferably return to their flush position. It is to be understood that the configuration of a post or a loop grabber can be a tongue, cam or other suitable structure. 
   In an alternative mode, the second embodiment  200  may be fashioned such that the ligature is passed around the vessel or bone upon extension, rather than retraction, of the elastic member.  FIGS. 1-8   a - d  illustrate one such mode of the apparatus  200 . A loop  39  is formed in the ligature  36 , and the loop  39  is held in the ligature retainer  34 , preferably facing in the direction in which the elastic distal segment  14  will curve upon extension from the cannula  10 . 
   The cannula  10  includes a proximal facing loop grabber  42 , which may be a hook. Upon extension, the elastic distal segment  14  curves around the vessel  5  and places the loop  39  of ligature  36  over the loop grabber  42 . Upon retraction of the elastic member  12 , the loop grabber  42  prevents the ligature retainer  34  from drawing the loop  39  back around the vessel  5 . If the ligature retainer  34  is a groove or hook, the loop  39  is simply withdrawn therefrom upon retraction of the elastic member  12 . If the ligature retainer  34  is a hole or eye, the ligature  36  slips therethrough upon retraction of the elastic member  12 . Forceps can be used, instead of relying on the loop grabber  42 , to grasp the ligature  36 , if desired. In an alternative embodiment, the ligature  36  may be placed into the ligature retainer  34  as a simple raised strand, to be passed around the vessel and grasped with forceps. 
     FIG. 1-9  illustrates an equivalent mode of the apparatus  200  which passes the ligature  36  during extension of the elastic member  12 . The loop grabber  42  may be elevated such that it has a segment  43  which extends both proximalward and cannulaward. The ligature retainer  34  may be formed as an eye, through which the ligature  36  is positioned. The cannula  10  may, suitably, be adapted with a post  44  to which the ligature  36  may be anchored. It will be understood that, by forming the elastic distal segment  14  to have a curvature upon extension such that the eye  34  is brought into contact with the segment  43  of the loop grabber  42 , and by extending the elastic member  12  until the eye  34  extends slightly past the segment  43 , the ligature  36  will be forced over the segment  43  as shown. This and other alternative modes of the ligature catching means are within the scope of this invention. Alternatively, a doubled suture (not shown) can be placed over the post and held by the post such that only one strand of the suture is hooked by ligature retainer  34 . 
   In any of the modes, the ligature retainer may include two grooves or eyes on opposite ends of a Y-shaped distal end of the elastic member. In such a mode, a segment of the ligature may be held between the arms of the Y for presentation to the cannula&#39;s hook. This may be advantageous if the loop of the ligature is too limp to be easily caught by the cannula&#39;s hook. If formed as a hole, the ligature retainer may include a narrowed, slot-like portion at its proximal end, into which the ligature may be wedged. The narrowed portion will provide a fight grip on the loop of ligature during extension about the vessel, while the larger portion of the hole will enable the ligature to easily slip therethrough during retraction of the elastic member. These, and various other modifications may be made to the ligature, retainer, within the scope of this invention. 
   As shown in  FIGS. 1-10   a - d , the second embodiment  200  may be used to create a knot in the ligature  36 . A loop  39  of the ligature  36  is placed around the cannula  10  in the following manner, as explained with reference to  FIG. 1-10   a . An end  35  of the ligature  36  is held at some point toward the proximal end (not shown) of the cannula  10 . The ligature  36  is passed by a first side (the far side in  FIG. 1-10   a ) of a post  44 , then over the cannula  10  toward a second side (the near side in  FIG. 1-10   a ) of the cannula  10  at a point distalward from the post  44 . From there, the ligature  36  is passed around the cannula  10  back to the first side, then around the post  44  proximal to loop  39  on the second side. The trailing end  37  of the ligature  36  is then drawn toward the proximal end (not shown) of the apparatus  200  to draw the ligature  36  at least somewhat tight around the cannula  10  and post  44 . The post  44  may include a protrusion  46  to keep the trailing end portion  37  of the ligature  36  elevated above the cannula  10 , for ease of grasping the ligature  36 . The cannula  10  may include an indented or grooved segment  48 , to keep the loop  39  of ligature  36  in a given position about the cannula  10 . 
   As seen in  FIG. 1-10   b , with the apparatus  200  in position at the vessel  5 , the elastic member  12  may be extended until the ligature retainer  34  engages the trailing end portion  37  of the ligature  36 . Then, the trailing end portion  37  alone may be drawn around the vessel  5  as shown in  FIG. 1-10   c.  Finally, by sliding the loop  39  distally off of the cannula  10 , with motion  50 , until the loop  39  passes completely over and around the ligature retainer  34 , the trailing end  37  may be drawn through the loop  39 , to form a half-hitch knot as shown in  FIG. 1-10   d . The knot may then be tightened, as needed. 
     FIG. 1-11  illustrates the addition of a sliding sleeve  52 , which slides in and out of the cannula  10 . The sleeve  52  is disposed within the cannula  10 , and the elastic member  12  is, in turn, disposed within the sleeve  52 . Extension and retraction of the elastic member  12  may permit the sleeve  52  to slide a short, restricted distance. The loop  39  of the ligature  36  may be placed over the sliding sleeve  52  rather than over the cannula  10  itself. Then, after the trailing end  37  has been pulled around the vessel as described above, the sleeve  52  may be slid into the cannula  10 , to dislodge the loop  39 . In the final stages of retracting the elastic member  12  back into the sliding sleeve  52 , the elastic member  12  may engage the sliding sleeve  52  such that the sliding sleeve  52  is automatically withdrawn into the cannula  10  and automatically releases the loop  39 , if the tolerance between cannula  10  and sliding sleeve  52  is small and the loop  39  cannot readily pass between sliding sleeve  52  and cannula  10 . If the ligature retainer  34  is kept within the sleeve  52  during the sliding, the loop  39  will not catch on the ligature retainer  34 . The sliding sleeve  52  may be biased toward its extended position by a spring (not shown). 
   Alternatively, in  FIGS. 1-10  and  1 - 11 , end  35  of ligature  36  may be fastened to post  44 . 
     FIGS. 1-12   a - c  illustrate how the apparatus  200 , with or without the sliding sleeve, may be used to form a logger&#39;s knot around a vessel  5 . The ligature  36  is loaded onto the apparatus  200  by simply passing a loop  39  of the ligature  36  over the distal end of the cannula  10 , and by placing both ends  37  and  35  of the ligature  36  over the protrusion  46  on the post  44 . The elastic member is extended and retracted, to catch and retrieve both ends  35  and  37  of the ligature  36 , as described above. Then, both ends  37  and  35  of the ligature  36  are passed around the vessel  5  and are drawn through the loop  39 . Other knots may be tied using the apparatus  200 , within the scope of this invention. In all of the embodiments described herein, any suitable form of activating means may be utilized, for example, syringe-plunger mechanisms, slider mechanisms, scissor action mechanisms, pistol grip mechanisms or the like. 
   Various other modifications may be made to the apparatus, including those suggested by the following description of a “Suturing Instrument”. 
   Another form of the present invention discloses an apparatus and method which, through the properties of elastic materials, preferably pseudoelastic materials, such as pseudoelastic shape memory alloys, overcome the prior art&#39;s disadvantages listed above. The apparatus is a delivery system for delivering, into a deep wound or into an arthroscopic, endoscopic, laparoscopic, or other such surgery site, a needle which is constructed of an elastic material, preferably a shape memory alloy. Although pseudoelasticity is exhibited in both linear and non-linear variations, the present invention deals preferably with superelasticity: and further references to materials having this property will simply be designated as being “pseudoelastic” or having shape memory. It will be understood, however, that the present invention may employ any appropriate elastic material, preferably shape memory alloy, whether linearly or non-linearly pseudoelastic. The term “needle” as used herein includes solid and hollow needles. 
   In a first embodiment, the present invention discloses a deep needle delivery apparatus, including a longitudinally extending cannula which may be inserted through an arthroscopic or other such incision or into a deep wound or into a natural body orifice. Inside the cannula, the apparatus has a cannula insert member, whose distal end includes a means for grasping a needle. The needle is held entirely within the cannula, in a straightened configuration. 
   Holding the needle within the cannula in a straightened configuration offers two advantages in reducing trauma to the patient&#39;s tissues: because no portion of the needle extends from the cannula during insertion of the cannula into the patient&#39;s body, the apparatus will not snag the tissues upon insertion, and because the apparatus has a minimized transverse dimension, only a small entry incision or site is required. The minimized transverse dimension may also permit the cannula to be used in a channel of an endoscope (rigid or flexible), in the lumen of a catheter, or as a catheter itself. 
   The apparatus includes a minimum of moving parts and is, therefore, both less subject to failure and less expensive than prior needle delivery apparatuses. The apparatus&#39; simplicity of design results in a unique simplicity of use, as well. 
   In a second embodiment, the needle is extruded laterally rather than longitudinally, which may permit insertion of the needle into otherwise inaccessible portions of a patient&#39;s tissues. 
   In a third embodiment, the apparatus inserts ring dips (solid or hollow) rather than a needle. 
     FIGS. 2-1   a  to  2 - 6  illstrate the first embodiment of the present inventon, which longitudinally extrudes an elastic needle through the distal end of a cannula. 
     FIG. 2-1   a  is a cross-sectional view, showing the elastic needle held inside the cannula in a straightened configuration under mechanical stress. 
     FIG. 2-1   b  shows partial extrusion of the elastic needle from the cannula, with the extruded portion of the needle returning toward its curved configuration by elastic shape memory. 
     FIG. 2-1   c  shows the needle fully extruded from the cannula, and released from the cannula insert. 
     FIGS. 2-2   a - e  show alternative modes of the distal end portion of the cannula insert. 
     FIG. 2-3  is a view of the distal end portion of the cannula insert, showing a raised release signal tab formed therein. 
     FIG. 2-4   a  illustrates an integrally constructed mode of the distal end portion of the first embodiment, showing the enlarged transverse dimenson of the end portion of the cannula insert. 
     FIG. 2-4   b  shows an alternative, non-integral mode of the distal end portion of the cannula insert, formed of a compressible material. 
     FIG. 2-5  is a view of the distal end portion of the cannula insert, showing an indented distal face therein. 
     FIG. 2-6  is a cross-sectional view of the proximal end portion of the first embodiment, showing a suture retention bobbin within the cannula insert. 
     FIGS. 2-7  to  2 - 10  illustrate a second embodiment of the present invention, which extrudes the elastic needle laterally rather than longitudinally. 
     FIG. 2-7   a  is a cross-sectional view showing a cannula, shaft, and plunger of the second embodiment. 
     FIG. 2-7   b  is a cross-sectional view of an alternative mode of the proximal end portion of the second embodiment. 
     FIG. 2-7   c  is a cross-sectional view of another alternative mode of the proximal end portion of the second embodiment. 
     FIG. 2-7   d  is an enlarged cutaway view of the proximal end portion of the alternative mode shown in  FIG. 2-7B . 
     FIG. 2-7   e  is a perspective view of the proximal end cap of the alternative mode shown in  FIG. 27C . 
     FIG. 2-8  is a cross-sectional view of the distal end portion of the second embodiment, showing a suture retention bobbin therein. 
     FIG. 2-9  is a cross-sectional view of the second embodiment, taken at line  9 - 9  of  FIG. 2-7   a , showing grooves in the shaft and cannula, and groove engaging tabs in the plunger, for causing rotation of the shaft. 
     FIG. 2-10  is a cutaway perspective view of the distal end portion of the second embodiment, showing the unwinding of the curved needle through the aperture. 
     FIG. 2-11   a  illustrates the present invention being used to deliver the needle to a deep wound for suturing. 
     FIG. 2-11   b  illustrates the present invention being used in arthroscopic surgery on a knee. 
     FIGS. 2-12  to  2 - 15  illustrate a third embodiment of the present invention, which is used to insert ring clips into tissue to hold a wound closed. 
     FIG. 2-12   a  is a cutaway view of the third embodiment, illustrating a ring clip held therein. 
     FIG. 2-12   b  illustrates extrusion of the ring clip. 
     FIG. 2-12   c  illustrates an alternative mode of the third embodiment, adapted for use with an extended ring clip which is held therein. 
     FIGS. 2-13   a  and  2 - 13   b , and  2 - 13   c  and  2 - 13   d , illustrate a marker which indicates a first and a second direction of extrusion of the ring clip, respectively. 
     FIG. 2-14  is a cross-sectional view of another alternative mode of the third embodiment, adapted for serial extrusion of a purality of ring clips held therein. 
     FIG. 2-15   a  illustrates yet another mode of the third embodiment, with the plurality of ring clips held in a magazine. 
     FIG. 2-15   b  illustrates an internal piston return spring. 
     FIG. 2-16   a  illustrates manipulation of the extended distal seqment of the ring clip of  FIG. 2-12   c.    
     FIG. 2-16   b  illustrates the severing of the extended distal segment of  FIG. 2-16   a.    
     FIGS. 2-17   a  to  2 - 17   c  illustrate various modes of a ring clip. 
     FIGS. 2-1   a  to  2 - 1   c  illustrate the first embodiment of the present invention, a deep needlesuturing apparatus  100 . The apparatus  100  has a cannula  11  and a needle delivery member which is a cannula insert  12 . Although the drawings and this description specifically show a cannula  11  and cannula insert  12  which are straight and which may be assumed to be rigid, the cannula  11  and cannula insert  12  may be curved, or may even be deformable to some degree, within the scope of this invention. For example, they may be flexible and/or long enough for apparatus  100  to be used within a channel of an endoscope (flexible or rigid), in the lumen of a catheter, or as a catheter itself. 
   The cannula insert  12  has an outer dimension which allows it to fit coaxially within the cannula  11  and move longitudinally therewithin. The cannula  11  has a proximal end portion  11   p  to which are affixed cannula handles  13  which, suitably, may be finger rings into which a surgeon may insert his index and middle fingers. The cannula  11  has a bore  111  extending longitudinally therethrough. The bore  111  extends out the distal end portion  11   d  of the cannula  11 , to allow a distal end portion  12   d  of the cannula insert  12  to extend distally out of the cannula  11 . A cannula insert handle  14  is affixed to the proximal end portion  12   p  of the cannula insert  12 . The handle  14  may, suitably, be a thumb ring through which the surgeon may insert his thumb. By pressing on the thumb ring  14  and pulling on the finger rings  13 , the surgeon may extend the cannula insert  12  through the cannula  11  with motion  201 . It will be understood that, within the scope of this invention, various other means may be employed to extend the cannula insert through the cannula. For example, the apparatus may include a pistol grip with a trigger for extending the cannula insert, or a scissor action mechanism, or the like. 
   The distal end portion  12   d  of the cannula insert  12  grasps an elastic needle  10 . In the preferred embodiment the needle  10  is of a pseudoelastic shape memory alloy and has an arced shape while the needle&#39;s alloy is in a substantially austenitic phase, and the needle  10  may be stressed into a more straight shape in which the needle&#39;s alloy enters an at least partially more martensitic phase. When the needle  10  is held entirely within the cannula  11 , as shown in  FIG. 2-1   a , the needle  10  is straightened and contains more stress-induced-martensite phase. As the needle  10  is extruded from the distal end portion  11   d  of the cannula  11 , that portion of the needle  10  which extends beyond the cannula  11  returns toward its original shape by a martensitic-to-austenitic shape memory phase change caused by at least partial relief of the stress-induced-martensite in the needle&#39;s alloy. 
   The cannula insert  12  includes a longitudinal bore  112 , which may be used to contain a suture  9  attached to the needle  10 . Suitably, the bore  112  may extend longitudinally entirely through the cannula insert  12 , to permit an unlimited length of suture  9  to be pulled therethrough. Although in  FIGS. 2-1   a - c  the suture  9  is shown exiting through the proximal end of the cannula insert and laterally out of the thumb ring  14 , the suture  9  may, within the scope of this invention, exit the apparatus in a variety of manners. For example, the suture may exit through a small aperture (not shown) in the side wall of the distal end portion of the cannula insert, in which case bore  112  would not have to extend further proximally and the proximal portion of cannula insert  12  would be dimensioned such that there would be room for the suture within bore  111  (i.e., the proximal portion of cannula insert  12  could have a smaller transverse dimension than its distal portion, or it may include a longitudinal slot for the suture). Alternatively, the thumb ring may be hollow, and the suture may pass directly from the interior of the cannula insert Into the interior of the thumb ring, and may exit through an aperture (not shown) at some point about the thumb ring. 
   The suture may be attached to the needle in a variety of ways. For example, the proximal end of the needle may include a hollow orifice which may be crimped down upon an end of the suture. Alternatively, a ferrule may be used to couple the suture to the needle. Or, a small wedge-shaped groove may be used to pinch the suture into a slot in the proximal end of the needle. If a more complex needle assembly is economically manufacturable, it may be advantageous to form, into the proximal end of the needle, a longitudinal slot or hole which may also communicate with a transverse slot into which a knotted or thickened portion of the suture may be positioned. Or, it may simply suffice to glue the suture onto the needle. 
   The distal end portion  12   d  of the cannula insert  12  includes a means for holding  15 , which grips the needle  10 , and which is connected to the bore  112 . As the distal end portion  12   d  is distally extended from the cannula  11  with motion  201 , the means for holding  15  releases the needle  10 , permitting the surgeon to manipulate the needle  10  within the patient, to form stitches or perform other procedures. However, if the needle  10  is only partially extended from the cannula  11 , the means for holding  15  will not yet have released the needle  10 , and the cannula insert  12  and needle  10  may be retracted into the cannula with motion  202 , to allow repositioning of the needle  10  in the patient. 
     FIGS. 2-2   a  through  2 - 2   e  illustrate various designs of the means for holding  15  formed in the distal end portion  12   d  of the cannula insert  12 . The distal end portion  12   d  is divided by a slot  16  into a plurality of end sections  19 . Each end section  19  includes a longitudinal groove  17 , which runs substantially parallel to the axis of the cannula insert  12 . In one mode, shown in  FIG. 2-2   a , one slot  16  divides the cannula insert  12  into two end sections  19 , each of which has a flat surface into which the respective grooves  17  are formed. The enlargement in the slot  16 , which is formed by the adjoining groves  17 , constitutes the means for holding  15 . In other modes, however, a plurality of slots may divide the distal end portion  12   d  into three or more end sections  19 , as shown in  FIGS. 2-2   b  and  2 - 2   c. If there are three or more end sections  19 , the grooves  17  lie at a centermost point of the wedge shaped end sections  19 . It will be understood that the exact cross-sectional shape of the grooves  17  is not critical, so long as the grooves  17  remain well adapted to grasp the needle  10 . It will be understood that the slot  16  may merely be a slit cut into the cannula insert  12 , if the material of the cannula insert  12  reacts to the slit by flaring outward to allow later compression of the distal end portion  12   d.    
   With reference to  FIGS. 2-1   c  and  2 - 4   a , it will be understood how the means for holding  15  grips the needle  10 . A proximal, non-piercing end portion  10   p  of the needle  10  has a transverse dimension  10   w , while the means for holding  15  has a transverse dimension  15   w  sufficiently larger than dimension  10   w  to accept the needle  10  without gripping it. The distal end portion  12   d  of the cannula insert  12  has a transverse dimension  12   dw  perpendicular to the slot  16 , and the remainder of the cannula insert  12  has a dimension  12   w  which is smaller than dimension  12   dw . The cannula  11  has an internal transverse dimension  11   w , which is sufficiently larger than dimension  12   w  to allow the cannula insert  12  to move freely therewithin. However, because dimension  11   w  is smaller than dimension  12   dw , in order for the distal end portion  12   d  of the cannula insert  12  to fit within the cannula  11 , the distal end portion  12   d  must compress. It will be understood that by appropriately sizing various portions of the bore  111 , the distal end portion  12   d  may be caused to compress at a determinable point along the cannula  11 . The compression need not occur at the exact distal end of the cannula. 
     FIGS. 2-2   a - e  and  2 - 4   a  illustrate embodiments of the compressible distal end portion  12   d , in which the distal end portion  12   d  is formed as an integral, unitary member with the cannula insert  12 . As the distal end portion  12   d  is drawn into the cannula  11 , the end segments  19  are pressed toward each other, reducing the widths of the slots  16 , which causes the grooves  17  to clamp down on the needle  10 . However, as shown in  FIG. 2-4   b , the distal end portion  12   d  may simply be a separate member made of a compressible material, such as an elastomer, with or without any slots or end sections, which member is coupled to the cannula insert  12 . In such a mode, the entire distal end portion  12   d  elastically compresses onto a needle held in its means for holding  15 . In either mode, as the distal end portion  12   d  of the cannula insert  12  is extended distally out of the open end of the cannula  11 , the distal end portion  12   d  elastically returns toward its original shape, allowing the needle  10  to freely slip from the means for holding  15 . 
     FIGS. 2-2   d  and  e  may be better understood with reference to  FIG. 2-1   a . It will be understood that when the needle  10  is held in the means for holding  15 , and the needle  10  is disposed entirely within the cannula  11 , the elastic properties of the needle  10  exert lateral forces upon both the cannula  11 , and the means for holding  15 . The straightened needle  10  exerts lateral force on the distal end of the cannula insert  12  in the direction shown in  FIG. 2-2   d  by arrow  203 . The needle  10  has a point which bears on the cannula  11  at a location opposite the direction  203 . By forming the means for holding  15  in a position radially removed from the center from the cannula insert  12 , in direction  203 , the needle  10  may be held in a less stressed and less straightened configuration, without changing the transverse dimension of the cannula  11 . 
   The slot  16  may be radially removed from the center of the cannula insert  12 , as shown in  FIG. 2-2   e , to divide the distal end portion  12   d  into two asymmetrical end portions  19 . A needle  10  held in an orientation so as to curve opposite the direction of arrow  203  (generally upward in  FIG. 2-2   e ) will exert a force which is perpendicular to the slot  16  rather than along the slot  16 . This helps prevent the needle  10  from forcing its way out of the means for holding  15  and into another position within the slot  16 , and ensures a more firm grasp on the needle  10 . 
     FIG. 2-3  illustrates a needle release indicator formed in the distal end portion  12   d  of the cannula insert  12 . Near the distal end of the cannula insert  12 , a raised release signal tab  20  is formed in the distal end portion  12   d . A segment  21  immediately proximal to the tab  20  is radially indented relative to the tab  20 . Although segment  21  is shown in  FIG. 2-3  as having a lateral dimension which is smaller than the remaining portions of the cannula insert  12 , this is, in various modes of the cannula insert  12 , not mandatory. For example, the remaining portions of the cannula insert  12  may be of smaller, equal, or greater lateral dimension than segment  21 , so long as the cannula insert  12  remains longitudinally movable within the cannula  11 , and so long as the means for holding  15  remains able to hold and release the needle  10 . 
   When the distal end portion  12   d  of the cannula insert  12  is extended beyond the distal end of the cannula  11 , at the moment the tab  20  completely exits the cannula  11 , the distal end portion  12   d snaps outward until the segment  21  contacts the cannula  11 . This produces a tangible or audible signal to the surgeon, indicating that the cannula insert  12  is emerging from the distal end of the cannula  11 , and, depending on the placement of the tab  20  relative to the means for holding  15 , may indicate to the surgeon that the needle  10  has just been or is about to be, released. It will be understood that, by appropriately sizing various segments of the cannula  11  and by appropriately placing the tab  20 , the release signal may be made to occur at any given stage of needle extension. In an alternative embodiment (not shown), tab  20  can be replaced by one or more elastic tabs directed proximally which spring out as distal end portion  12   d  emerges from the distal end of cannula  11 . 
   Once the needle  10  has been released from the cannula insert  12 , the surgeon may use the needle  10  to insert running stitches or regular stitches into the patient&#39;s tissues. Once the stitching procedure is finished, the needle  10  must be withdrawn from the patient&#39;s body with a minimum of trauma to the patient. The apparatus  100  of the first embodiment can also be used in the withdrawal of the needle  10 . By maneuvering the cannula insert  12  until an end of the needle  10  enters the means for holding  15 , and then distally extending the cannula  11  onto the cannula insert  12 , the surgeon may recompress the distal end portion  12   d  of the cannula insert  12 , which presses the means for holding  15  onto the needle  10 . Then, by withdrawing the cannula insert  12  into the cannula  11 , the needle  10  may be restraightened and drawn entirely inside the cannula  11 . The cannula  11  may then be withdrawn from the patient&#39;s body with an absolute minimum of trauma. This same process may be used if the needle  10  is badly placed when extruded from the cannula  11 . The surgeon may simply regrasp the needle  10  in the cannula insert  12 , retract the needle  10 , and re-extrude the needle  10  into a better position. The same process may even be used repeatedly in the suturing process itself. 
   In order to ease the process of manipulating the cannula insert  12  back onto the needle  10  for withdrawal, the distal end of the cannula insert  12  may include a concave face  22 , as shown in  FIG. 2-5 . The means for holding  15  enters through the distal end of the cannula insert  12  at the deepest point of the indented face  22 . Thus, if the surgeon maneuvers the cannula insert  12  near enough to the needle  10 , so that an end of the needle  10  is within the indented face  22 , during further distalward motion of the cannula insert  12 , the indented face  22  will guide the needle  10  into the means for holding  15 . 
   In order to provide a more self-contained apparatus  100 , the cannula insert  12  may include a means for containing a length of suture. In one mode, the means for containing may be a suture release bobbin  25  around which a length of suture  9  is wound, as shown in  FIG. 2-6 . As the surgeon uses the needle  10  to make stitches in the patient, the suture  9  is pulled from the distal end of the bobbin  25 . By forming the bobbin  25  with a slightly conical shape, the suture  9  may be pulled from the bobbin  25  with reduced friction. Reducing the friction between the apparatus  100  and the suture  9  is not only desirable to make suturing easier for the surgeon, but also to prevent accidental movement of a needle  10  which has been released within the patient. Such unwanted movement might be caused by friction between the suture  9  and the apparatus  100  if the apparatus  100  is moved or inadvertently bumped by the surgeon. 
     FIG. 2-11   a  shows how the first embodiment  100  of the present invention may be used to repair a deep wound  4  in tissues  3  and  5 . The surgeon positions the apparatus  100  near the wound to be repaired, and extrudes the needle  10  from the apparatus, as described above. The needle&#39;s piercing distal end  10   d  first pierces the tissue  5  on one side of the wound  4 . Then, as the needle  10  is further extruded from the cannula  11 , the needle  10  returns toward its unstressed shape. This curves the needle  10  through the tissue  5  beneath or near the bottom of the wound  4 . The piercing distal end  10   d  of the needle  10  eventually penetrates and then protrudes from the tissue  3  at the opposite side of the wound  4 . The distal end  10   d  of the needle may then be grasped to pull the needle through the tissue  5  and  3  to draw the suture across the wound  4 . Knots may then be tied in the suture, or the needle  10  may be repeatedly withdrawn and extruded from the apparatus  100  to form multiple stitches. The means for holding  15  may be used to grasp the distal end  10   d  of the needle during this process, in the same manner described above for withdrawal of the needle  10 . After the distal end  10   d  emerges from the tissue  3 , the surgeon may grasp the distal end  10   d  in the cannula insert&#39;s means for holding, as described. The surgeon may then pull the needle  10  and suture through the tissues  5  and  3 . The surgeon may release the needle  10 , then grasp its proximal end  10   p  in the means for holding and partially or fully resheath the needle  10  inside the cannula  11  preparatory to forming another stitch. 
     FIG. 2-11   b  illustrates the first embodiment  100  of the present invention being used in arthroscopic surgery to repair a torn meniscus  6  in a knee  7 , in much the same manner. It will be understood that, because the needle  10  provides its own curving suture path as it pierces the meniscus  6 , the apparatus  100  need not be swept over any degree of motion in order to suture the meniscus  6 . The apparatus  100  is capable of performing suturing through an entry wound which is of a minimal size. The entry wound need only be big enough so that the apparatus  100  may slip inside the knee. In other words, the entry wound need only be as big as the lateral dimension of the apparatus  100 . 
   As shown in  FIG. 2-7   a , a second embodiment of the present invention is an apparatus  200  which extrudes a needle  10  laterally rather than distally. The second embodiment  200  includes a cannula  30  which is substantially similar to the cannula of the first embodiment. Apparatus  200 , which is preferably rigid, can be long and/or flexible enough for apparatus  200  to be used in a channel of an endoscope (flexible or rigid), in the lumen of a catheter, or as a catheter itself. However, the second embodiment&#39;s cannula  30  does not have an open distal end. Rather, the second embodiment  200  extrudes the needle  10  through an aperture  31  which is located through a side wall of the cannula  30  near its distal end. In this application, it is intended that the term “adjacent the distal end”, when applied to the location of the aperture or of other equivalent means, indicates that the aperture may open either through the side wall of the cannula or actually through the distal end of the cannula. 
   Inside its distal end, the cannula  30  includes a pivot  34 , about which a shaft  29  rotates. The distal end portion of the shaft  29  is a spool portion  29   d  about which the needle  10  is wrapped. When used with the second embodiment  200 , the needle  10  is stressed into a more curved, rather than a more straightened, shape when disposed within the apparatus. Relief of the stress in needle  10  held in the more curved configuration, then, results in the needle  10  returning toward its more straight shape which may be a curve suitable for suturing. 
   Much of the remainder of the shaft  29  includes spiral grooves  27 . A plunger  28  is disposed about the shaft  29  and within the cannula  30 , and has tabs  26  which engage the spiral grooves  27  of the shaft  29 . When the plunger  28  is moved into the cannula  30 , the tabs  26  and grooves  27  impart rotating motion  210  to the shaft  29  and needle  10 . When the plunger  28  is withdrawn, the shaft  29  rotates in the opposite direction. 
     FIG. 2-9  is a cross sectional view of the apparatus  200 , taken across line  9 - 9  of  FIG. 2-7   a , and illustrates the special relationship between the cannula  30 , the plunger  28  with its tabs  26 , and the shaft  29  with its spiral grooves  27 . As will be understood, a functionally identical equivalent may be constructed by affixing the tabs  26  to the shaft  29 , and adapting the plunger  28  with the spiral groves  27 . As further shown in  FIG. 2-9 , the groove-engaging tabs  26  of the plunger  28  may also extend outward from the plunger  28 , and the inner surface of the cannula  30  may also be adapted with grooves  72 . By forming the grooves  72  in the cannula  30  to run substantially linear to the axis of the cannula  30 , the plunger  28  will be prevented from rotating upon insertion into and withdrawal from the cannula  30 . 
   As shown in  FIG. 2-7   b , the tabs  26  may be constructed as a part of the cannula  30 . The thumb ring  14  is coupled to the plunger  28  by a swiveling means. In one mode, the swiveling means may be the simple snap-lock mechanism  28   c  shown in  FIG. 2-7   d , which is held in place by an end cap  28   b . In this mode, the shaft  29  slidably engages the plunger  28  by any non-circular cross-section instead of having spiralled grooves. 
   With reference to  FIGS. 2-7   c  and  2 - 7   e , it will be understood that the exact means for imparting rotation to the shaft  29  may be formed in a variety of ways within the scope of this invention. For example, the tabs and grooves may be eliminated by simply forming the plunger  28  of a spiral-twisted rod of square cross-section, and providing the cannula  30  with an appropriate end cap  57  which has an opening suited for permitting the plunger  28  to pass therethrough only by appropriate rotation. Other non-circular cross-sections are, of course, within the scope of this invention. Again, shaft  29  slidably engages plunger  28  by any non-circular cross-section instead of having spiralled grooves. It is to be understood that any suitable activating means, such as syringe-plunger mechanisms, slidings mechanisms, pistol grip action mechanisms, scissor action mechanisms or the like can be used to depress plunger  28  into cannula  30 . 
   With reference again to  FIG. 2-7   a , the shaft  29  may contain a repository  32  which is a means for containing a length of suture  9 . The shaft  29  includes a needle stop  24 , which prevents the needle  10  from rotating backward relative to the shaft  29 . In one embodiment, the needle stop  24  may simply be a lip on one side of the repository  32 , which lip forms a means for abutting a non-piercing end of the needle  10 . 
     FIG. 2-8  illustrates an alternative mode of the repository  32 , in which the repository may be a bobbin  33  which contains a length of suture. The bobbin  33  rotates freely about the shaft  29  with motion  205 . This, too, reduces friction between the suture and the apparatus  200 , to prevent unwanted movement of the needle  10  via the suture, once the needle  10  has been completely extruded from the cannula  30 . 
     FIG. 2-10  is a cutaway cross-sectional view of the distal end portion of the second embodiment  200 , and illustrates the unwinding of the needle  10  through the aperture  31 . The aperture  31  must have a dimension sufficient to allow the needle  10  to freely pass therethrough in its entirety without binding. As the spool portion  29   d  of the shaft  29  rotates relative to the cannula  30 , the needle  10  unwinds through the aperture  31  and returns to its unstressed shape. It will be understood that the alternative modes shown in  FIGS. 2-7   b - e  are not complete, and must include appropriate components at their distal ends, much like those shown in  FIG. 2-7   a.    
   As will be understood, the second embodiment  200  may be used in a substantially similar fashion as described for the first embodiment of the deep needle suturing apparatus  100  with reference to  FIGS. 2-11   a  and  2 - 11   b , above. The second embodiment  200 , however, may be used to provide surgical access to various suturing sites not accessible with the first embodiment. 
   In some surgical procedures, stitches are not implanted in a wound. In a third embodiment  300  of the present invention, illustrated in  FIGS. 2-12   a - c , the unstressed shape of the needle may be substantially circular to form the needle into a ring clip  8 . Only after the wound has healed are the ring clips removed, if at all. 
     FIG. 2-12   a  shows the third embodiment  300  of the present invention, adapted for inserting ring clips  8  (which can be hollow or solid) rather than needles. The third embodiment  300  includes a cannula or cylinder  35  which is substantially similar to the cannula of the first embodiment. Apparatus  300 , which is preferably rigid, can be long and/or flexible enough for apparatus  300  to be used in a channel of an endoscope (flexible or rigid), in the lumen of a catheter, or as a catheter itself. However, the cylinder  35  has an internal dimension which may be more similar to the outer dimension of the wire of the ring clip  8  than is the inner dimension of the first embodiment&#39;s cannula to the needle. By forming both the wire from which the ring clip is made and the internal bore of the cylinder to have a non-circular cross-section, the ring clip may be prevented from rotating within the bore. The third embodiment  300  further includes a piston  36 , whose transverse dimension is substantially equal to the inner dimension of the cylinder  35 . The piston  36  need not necessarily contain any means for grasping the ring clip  8 , as it is only used to extrude the ring clip  8  from the cylinder  35 . However, adaptations of the third embodiment  300  which provide means for holding and retracting the ring clip  8 , similar to those provided for holding and retracting the needle in the first embodiment, are certainly within the scope of this invention. 
   The ring clip  8  is disposed within the cylinder  35 , with its distal end  8   d  facing toward the open distal end of the cylinder  35 . The piston  36  is disposed within the cylinder  35 , with the distal end of the piston  36  abutting the proximal end  8   p  of the ring clip  8 . Insertion of the piston  36  through the cylinder  35  with motion  206  expels the ring clip  8  from the cylinder  35  as shown in  FIG. 2-12   b . As the ring clip  8  is expelled, it returns to its unstressed shape with coiling motion  207 , as described above for the needle of the first embodiment. Suitably, the ring clip  8  may have an unstressed shape which is substantially circular, in order that it may pass through a patient&#39;s soft tissues with a minimum of lateral pressure, to cause a minimum of structural damage to the tissues. 
   The third embodiment  300  (as well as any of the embodiments of this invention) may be adapted with at least one marker means  55 . The marker  55  may be, suitably, a raised or embossed portion of the cylinder  35 , or may simply be printed thereon. With the ring clip  8  loaded into the cylinder  35  in an appropriate orientation, the marker  55  will indicate the direction in which the ring clip  8  will curl when extruded. This aids the surgeon in properly clipping a wound. It will be understood that any of the various embodiments described herein may also be advantageously adapted with a suitable marker means.  FIGS. 2-13   a - b , and  FIGS. 2-13   c - d , illustrate proper alignment of the marker  55  indicating two respective directions of extrusion of a ring clip  8 . The respective positions of the marker  55  in  FIGS. 2-13   a  or  c  indicate that the ring clip  8  will exit the cylinder  35  in the direction as shown in  FIGS. 2-13   b  or  d , respectively. Marker  55  may be positioned at any suitable location along the cylinder. More that one marker may be present 
   In another mode, shown in  FIGS. 2-12   c  and  2 - 16   a , the ring clip  8  includes an extended proximal segment  49 , whose unstressed shape is relatively straight. This proximal segment  49  may be grasped by the surgeon in any manner and manipulated, in order to adjust the ring clip  8  within the soft tissues. In this mode, the piston  36  has an enlarged diameter and includes a bore  37  extending into the piston  36 . Adapting the piston  36  with the bore  37  allows the third embodiment  300  to contain the lengthened and extended ring clip  8 . This obviates the need to lengthen the cylinder  35 , making the apparatus  300  easier for the surgeon to handle. As shown in  FIG. 2-16   b , after the surgeon has manipulated the extended ring clip  8 , the extended end segment  49  may be removed by any conventional method, such as cutting it off with wire cutters. It will be understood that the proximal segment  49  need not be of an elastic material, but may be any conventional material affixed to the elastic segment  8  in order to minimize the cost of the apparatus  300 . 
   The cylinder and piston of the third embodiment of the apparatus may be used with a variety of different ring clips, such as are shown in  FIGS. 2-17   a - c . As shown in  FIG. 2-17   a , the ring clip  8  may be formed such that, in its unstressed configuration, its distal end  8   d  and proximal end  8   p  come into end-to-end abutting alignment. Alternatively, as shown in  FIG. 2-17   b , the ends  8   d  and  8   p  may come into side-by-side overlapping alignment. Locking of the ring clip may be permitted by having a small barb or barbs (not shown) on end  8   d  which fit(s) into a recess or recesses (also not shown) on end  8   p or vice versa. 
   A slightly modified ring clip may include a proximal coupling hook  8   ph . In such a configuration, in the ring clip&#39;s unstressed configuration, the hook  8   ph  remains somewhat separated from the piercing end  8   d , such that the ring clip does not form a complete circle. The surgeon may stress the ring clip into a tighter arc, and engage the hook  8   ph  with the piercing end  8   d , as shown. The elasticity in the ring clip  8  will cause the hook  8   ph  to remain engaged under mechanical stress. Such a mode of the ring clip is taught in U.S. Pat. No. 5,002,563 (Pyka et al). 
   As shown in  FIG. 2-14 , the third embodiment  300  may have a lengthened cylinder  35 , within which may be disposed a plurality of ring clips  8   a - 8   n . Injection of the piston  36  through the cylinder  35  then causes serial extrusion of the ring clips  8   a - 8   n.    
   Serial extrusion of ring clips  8   a - 8   n  may also be accomplished by adapting the third embodiment  300  as shown in  FIGS. 2-15   a  or  b . In this mode, the third embodiment  300  includes a magazine  38  which holds the plurality of ring clips  8   a - 8   n . The magazine  38  includes a magazine spring  39 , which presses on the ring clips  8   a - 8   n  to keep them in their stressed and more straightened shape, and which introduces them serially into the cylinder  35 , in position for extrusion by the piston  36 . The magazine  38  may be separately attachable, and may also be refillable. It will be understood that any suitable means may be used to keep the plurality of ring clips in any favored orientation, if it is desired that they exit the cylinder  35  in a predetermined orientation of curvature. For example, the ring clips  8   a - 8   n  may be formed of a rectangular cross section, or they may be releasably glued together, to prevent their rotation, within the magazine  38 , away from their preferred orientation. 
   The third embodiment  300  may further be adapted with a piston return spring  40 , which is compressed upon injection of the piston  36 , and which automatically returns the piston  36  to a position allowing introduction of the next ring clip into the cylinder  35 . As shown in  FIG. 2-15   b , the piston return spring  40  may be disposed within the cylinder  35 . In this mode, the cylinder  35  includes an enlarged chamber  41 , within which the spring  40  is disposed. The piston  36  may include an enlarged segment  42 , which is disposed within the cylinder  35 , and which is kept inside the cylinder  35  by an end cap  43  on the cylinder  35 . This maintains the apparatus  300  as a more integral unit, and prevents the complete withdrawal of the piston  36  from the cylinder  35 . This also allows for a precompressed piston return spring  40  to be used, which provides greater return strength and speed for the piston  36 . It is to be understood that any of the embodiment of this invention may be activated by any suitable activating means, such as syringe-plunger mechanisms, slidings mechanisms, pistol grip action mechanisms, scissor action mechanisms or the like. 
   A third form of the present invention provides an endoscopic or laparoscopic surgical device which provides an internal drape, and facilitates tissue collection. The surgical device comprises a housing having an axial bore with a distal deployment opening; and a barrier member which is constrainable within the axial bore. The barrier member comprises a loop of elastically recoverable material, preferably a shape memory alloy, and a barrier membrane loosely spanning the loop. Remote means are provided to project and retract, and optionally to rotate, the barrier member relative to the distal end of the housing. A preferred embodiment uses a shape memory alloy material, especially a pseudoelastic shape memory alloy material, and more preferably a superelastic shape memory alloy material. 
   The barrier member is moveable between a first position wherein the barrier member is constrained within the housing, and a second position wherein the barrier member is extended past the distal deployment opening of the housing, and assumes an expanded shape. In the expanded shape, the barrier member acts as a surgical drape and/or as a surgical collector. The barrier member is preferably moveable to a third position wherein the barrier member is partially or fully retracted, and at least a portion of it is constrained within the housing. 
   The loop of elastically recoverable material may be partially or wholly formed of elastically recoverable material. Thus for example two or more parts of the loop, e.g. two substantially semi-circular halves of the loop, may be connected to each other by another member which may or may not be elastically recoverable. In one embodiment two or more elastically recoverable parts of the loop are connected to each other by a flexible heat-shrinkable sleeve, which preferably comprises a polymeric material. In this case the elastically recoverable parts may comprise a shape memory alloy as described hereinbefore, or traditional resiliently deformable materials such as spring metals. The heat recoverable connecting sleeve, being flexible can bend e.g. by acting as a hinge to allow the loop parts to fold together to be compressed into the housing, and also to spring apart when extended from the housing. The connecting member may itself be resilient, causing the arms of the loop to spring apart when the loop is deployed outside the housing. 
   In one advantageous embodiment the connecting member, can be removed to release the barrier membrane, e.g. the bag or drape, spanning the loop. 
   In preferred embodiments according to the invention, especially where the barrier member is acting as a collecting pouch, a bushing is included in the housing. This bushing is arranged to be pushed out from the distal end of the housing at the same time or after the barrier member is deployed, and then to snap against the outside of the distal end of the housing. Since it is snapped against the housing the bushing can not then be withdrawn back into the housing. This hollow bushing may serve two functions. Firstly, the dimensions of the hollow bushing are preferably such that it allows complete withdrawal back into the housing of the elastically deformable loop, but not a filled barrier membrane, which may now be of larger volume, being filled, for example, with body samples. Thus the bushing ensures that the barrier member remains suspended outside the housing, as desired for some applications. Secondly the bushing is preferably shaped to provide a smooth entrance so that the barrier member is not torn by contact with the ends of the housing. 
   In the above embodiments, where a loop or a frame of an elastically deformable material is constrained within a housing such as a cannula or the like it is particularly advantageous to modify the design of the loop in order to minimize or, to suppress any possibe risk of plastic deformation. Therefore in preferred embodiments the elastically deformable loop preferaby comprises a necked portion, preferably towards the distal end of the loop. The “necked portion” is formed where the sides or arms of the loop come towards each other and then divert outwards of the loop before turning towards each other again to join to each other. A bulbous portion, or second loop portion, is thereby formed adjacent to the main loop portion. The bulbous portion is preferaby of significantly smaller dimensions than the main loop portion. The advantage of the necked-loop design is that when the loop is constrained within the housing any severe deformation is absorbed by the necked region and therefore the risk of any plastic deformation to the main loop portion is substantially eliminated or at least minimized. 
   The necked portion may, for example, be formed in the following two ways. First the sides of the loop may come toward each other, overlap, and then curve outwards in the opposite sense to join to each other. In this case the overall shape is a double loop configuration, similar to a figure “8”. In the second case the sides of the loop divert outwards without overlapping to form a bulbous region, or “nipple” configuration adjacent the main loop. 
   One advantage of the preferred necked-loop configuration is that it allows severe constraints to be put on the elastically deformable loop without introducing any plastic deformation into the main body of the loop. This allows smaller diameter housings to be used to constrain the loop than would be possible without the necked configuration. This can be particularly advantageous, for example, in less invasive surgery. The design also allows the thickness of the loop to be increased without risking plastic deformation. Thus the loop rigidity may be increased which may be advantageous for some applications, especially for example where large bops are to be used. 
     FIG. 3-1  is a view of an unexpanded barrier device (not shown) within a housing. 
     FIG. 3-2  through  FIG. 3-5  are progressive cross-sectional views through line a-a of  FIG. 3-1 , showing the use of the device of  FIG. 3-1 . The figures show, respectively,  FIG. 3-2 , constrained;  FIG. 3-3 , expanded (memory);  FIG. 3-4 , pouched; and  FIG. 3-5 , withdrawal configurations. 
     FIG. 3-6  shows alternate embodiments of the device of  FIG. 3-1  through line b-b. 
     FIG. 3-7  and  FIG. 3-8  show alternate embodiments of the barrier member in the expanded (memory) configuration. 
     FIG. 3-9  shows cross-sectional embodiments through line b-b of  FIG. 3-7 . 
     FIGS. 3-10 ,  3 - 11  and  3 - 12  detail alternate expanded loop configurations. 
     FIG. 3-13  is a schematic representation of another embodiment of a device for deploying an internal drape, and 
     FIGS. 3-14  and  3 - 15  are schematic representations of yet another embodiment of device for deploying an internal bag, showing the device before and after withdrawal of the drape into the shaft of the instrument. 
     FIGS. 3-16  to  3 - 18  illustrate the use of a bushing which can be used with any of embodiments  3 - 1  to  3 - 15 . 
     FIGS. 3-19  to  3 - 22  illustrate a necked-loop configuration which can be incorporated in any of the embodiments, illustrated in  FIGS. 3-1  to  3 - 18 . 
   During surgery, especially “least invasive surgery” (LIS), it is frequently necessary to remove diseased tissue. This tissue may be infected, contain inflammatory secretions (e.g., bile), or contain tumor cells. In any of these situations it is desirable to perform surgery without contaminating surrounding healthy tissues with any of the diseased tissue. Expandable internal barriers of this invention minimize or prevent such contamination. The expandable barrier member comprises (a) a flexible membrane which loosely spans (b) a loop of elastically deformable material. The elastically deformable loop is preferably a pseudoelastic shape memory alloy which defines an expanded loop in its “memory” shape. The expandable barrier is constrained within a housing, and the deployment end of the housing is placed within a body. The barrier is deployed from the housing and expands to its memory shape. 
   The barrier can be placed under diseased tissue, so that undesired materials spill into the barrier by gravity and/or irrigation flow, without contaminating surrounding tissues. The undesired materials can be aspirated from the surface of the barrier prior to withdrawal of the device. Alternatively, the barrier is placed so that it substantially surrounds and encloses the diseased tissue and sequesters it from healthy tissue during surgery. The tissue sample is severed (if necessary). In a preferred embodiment, when the elastically deformable loop is first withdrawn back into the housing the barrier membrane remains suspended outside the housing. The upper edge of the barrier membrane closes to form a pouch as the elastically deformable loop is retracted into the housing. Within the pouch is a tissue sample or other material which has been enclosed by the membrane. The housing, barrier and enclosed materials are removed from the patient. 
   The figures are drawn for purposes of clarity and are not drawn to scale. Like numbers represent like structures. 
     FIG. 3-1  is a lateral external view of a device according to the subject invention. The housing  10  includes a deployment end  12  which is inserted into the patient and which houses the expandable barrier member (not shown) in a constrained configuration; a shaft portion  14  which may be partially or completely inserted within the patient body; and an actuator end  16  opposite the deployment end, which is retained substantially outside the patient. The housing  10  can be flexible or rigid, and its rigidity can vary along its length. A remote actuator means  18  is used to project and/or retract, and, optionally, to rotate the barrier member relative to the distal deployment opening  24 . 
     FIGS. 3-2  through  3 - 5  show the use of a device of this invention to obtain a tissue sample. They are simplified cross sectional representations of the device shown in  FIG. 3-1 , the cross section being taken along line a-a. In use, the device is partially inserted into a human or animal patient (not shown). The housing can be inserted directly into a patient, or the device can be emplaced using an instrument channel of a standard endoscope, laparoscope, catheter, or the like. 
     FIG. 3-2  shows a cross-section of the device of  FIG. 3-1  with the expandable barrier member  22  in a first, constrained configuration. 
   The housing  10  is preferably an elongate sheath, having an axial bore  20  therethrough, the axial bore being sized to receive the expandable barrier member  22  in a constrained configuration. The axial bore  20  opens to the environment at the deployment opening  24 . In one embodiment (not shown), the axial bore also opens to the environment at the activator opening  26 , and access for additional laparoscopic or endoscopic devices, and/or fluid access or withdrawal, is provided. A seal (not shown) may be added at the activator opening  26 , to minimize or prevent fluid (i.e., liquid or gas) leakage. 
   The specific configuration and dimensions of the axial bore  20  will vary with the use of the device, the parameters of the barrier member  22 , and whether access for additional laparoscopic or endoscopic devices is provided. In general the axial bore  20  will have an internal diameter of from less than about 0.3 cm to about 2 cm or greater, preferably from about 0.25 cm to about 2.5 cm. In one embodiment (not shown), the axial bore comprises a working channel of an endoscope. Such an endoscope can also provide surgical implements such as lasers, scalpels, irrigation and aspiration means, visualization means, and the like. 
   The outer diameter of the housing  10  will vary with the application, the size of the expandable barrier, and whether additional working channels are included in the device. The housing in a laparoscopic device will have a diameter of from less than about 1 mm to about 3 cm or greater, preferably from about 0.4 cm to about 1.5 cm. The length of laparoscopic devices will be from less than about 10 cm to about 30 cm or greater, more generally from about 20 cm to about 30 cm. The housing  10  of a device intended for endoscopic use will have a diameter of from less than about 1 mm to about 3 cm or greater. The length of endoscopic devices will be from less than about 10 cm to about 1 meter or greater. 
   The barrier member  22  is extended through the deployment opening  24  remotely. The barrier member  22  can be attached through the actuator opening  26  of the housing  10  by a connecting means  28 . The connecting means  28  can be, for example, soldered or otherwise affixed to the barrier member  22 , as shown. Alternatively, it can be a continuation of the elastic material used in forming the elastically deformable loop  36 . In the shown configuration, the barrier member  22  is attached to the remote actuator means  18  by the connecting means  28 . Longitudinal axial movement of the activator means  18  relative to the housing  10  causes the barrier member  22  to be extended from, or retracted into, the housing  10 , via the deployment opening  24 . Rotational movement of the activator means  18  relative to the housing  10  causes the barrier member  22  to be rotated. If rotational movement is not desirable, a means to prevent rotation can be employed. 
   In the depicted configurations, the remote actuator means  18  slidably engages the activator opening  26 . The remote actuator means  18  can be an extension of the elastically deformable loop  36 , or of the connecting means  28 , and be substantially independent of the housing  10 . Alternatively, the remote actuator means  18  can be connected to the connecting means  28 . 
   The housing  10  includes, or provides integration with, a surgical handling apparatus to deploy and retract the barrier member. In one embodiment, as shown, two finger rings  30  are part of the actuator end  16 . An additional thumb ring  32  is part of the remote actuator means  18 . These rings are for ease of handling. Knobs or ridges, for example, can be provided for ease of integration with a separate actuator means (not shown). Suitable actuator means include slider mechanisms, pistol grip or thumb actuated mechanisms, scissors handles, and syringe-plunger mechanisms (similar to the configuration shown in  FIGS. 3-2  through  3 - 6 ). These and others are well known to the art. The specific type of actuator mechanism is generally determined by the personal preference of the surgeon. 
   In use, the deployment end  12 , and possibly the shaft portion  14 , is inserted into the patient. The housing can be inserted directly into the patient, or it can be introduced using the instrument channel of a standard LIS device. The deployment end  12  possesses lateral integrity such that it is not significantly deformed by the pressure exerted by the constrained barrier member  22 . In a device having a rigid housing (the usual case for a laparoscopic device), the deployment end  12  of the housing can be integral to the shaft portion  14  of the housing, such that there is no obvious demarcation between the functional zones. When a device of this invention functions as a catheter (typical with endoscopic use) and there is little lateral support, the deployment end  12  may require reinforcement to provide consistent constraint of the expandable barrier member. 
   The shaft portion  14  of the housing is located between the actuator (non-inserted) end  16  and the deployment (inserted) end  12  of the device. The shaft portion  14  of the housing may be inserted into the patient (not shown) partially or completely. The shaft portion  14  of a device which is used in laparoscopy must have sufficient structural integrity that it is easily inserted through a surgical opening into the body of the patient without undue deformation. Materials with sufficient structural rigidity include stainless steel and rigid polymeric materials such as plastics. 
   The material of the shaft portion  14 , and the material of the deployment end  12 , can be the same, or can have different physical properties. For example, the shaft portion  14  of an expandable barrier device housing used in endoscopic surgery will generally be flexible, to allow insertion through naturally occurring orifices, ducts, and/or passages, or to allow insertion through the working channel of an endoscope. Suitable polymeric material includes polytetrafluorethylene, polyurethane, polyethylene, Teflon, and the like. The material of such a flexible housing may be reinforced at the deployment end  12  with fibers, rings, or longitudinal ribs, for example, to enable it to withstand the forces exerted on it by the barrier member  22  while it is constrained within and deformed by the housing. 
   The barrier member  22  has two components: the barrier membrane  34 , and the elastically deformable loop  36 . 
   When expanded, the barrier member  22  can have a diameter of from about 1 cm or less to about 5 cm or greater, more generally from about 2 cm to about 4 cm. The barrier membrane  34  spans the elastically deformable loop  36  loosely, forming a rounded plate or bowl. The depth of arc described by the barrier membrane  34  when suspended from the elastically deformable loop  36  is from less than about 1 cm to about 7 cm or greater. In general, the preferred depth of the pouch formed by the barrier membrane  34  will be less when the barrier membrane  34  is used primarily as a tissue protecting surgical drape, and will be correspondingly greater when the barrier membrane is used as a pouch to collect tissue or to remove tissue in toto from the surgery site. In those embodiments in which a relatively deep bow-like pouch is present, it may be desirable to reinforce the barrier membrane. Reinforcing stays or ribs, made of, for example, plastic, thickened barrier membrane material, or a shape memory alloy, provide reinforcement, and assist the barrier membrane to deploy fully into the desired shape. 
   The barrier member  22  is compressed and loaded within the axial bore  20 . In this constrained configuration, the barrier device can be sterilized, packaged and stored for later use. Preferably at least one expandable barrier device is available during surgery: when needed, the surgeon can visually assess the size of the barrier member necessary for tissue protection and/or collection, and select an appropriate expandable barrier device. 
   When constrained, the barrier membrane  34  is collapsed, and may be furled around the elastically deformed loop  36 . The barrier membrane is preferably made of a flexible and impermeable biocompatable material. The composition of the barrier membrane will reflect the specific use of the expandable barrier. The barrier membrane is sufficiently thin that it can be folded or gathered, together with the elastically deformable loop, to fit within the axial bore  20 . 
   In one preferred embodiment the barrier membrane material is substantially impermeable to body fluids and other liquids, such as normal saline solution, which might be present during surgical procedures. The thickness of the membrane is sufficient to provide an effective barrier to noxious or contaminated materials such as bile, spillage from inflamed or infected tissues, or tumor cells. Suitable materials include polyethylene, polyvinyl chloride, urethane, silicone rubber, and the like. 
   In an alternate preferred embodiment, the barrier membrane material is substantially impermeable to tissue samples, but is generally permeable to body fluids and other liquids, such as normal saline solution, which might be present during surgical procedures. In this embodiment, the barrier membrane material can be a net, web, or grid. Suitable materials include perforated, webbed or netted polyethylene, polyvinyl chloride, urethane, silicone rubber, and the like. A similar construct can be made of, or contain, shape memory materials. 
   The elastically deformable loop  36  is a wire, or a strip of elastic material. The term “elastic material” is used herein to mean a metallic material that has spring-like properties, that is, it is capable of being deformed by an applied stress and then springing back, or recovering, to or toward its original unstressed shape or configuration when the stress is removed. The elastic material is preferably highly elastic. The material are metallic. The use of metals such as shape memory alloys is preferred. Shape memory alloys that exhibit pseudoelasticity, in particular superelasticity, are especially preferred. The elastic materials herein exhibit greater than 1% elastic deformation, more generally greater than 2% elastic deformation. Preferably, the elastic materials herein exhibit greater than 3% elastic deformation, more preferably greater than 4% elastic deformation. 
     FIG. 3-3  shows the device of  FIG. 3-2  in an expanded position. The remote actuator means  18  has been moved distally along the axial bore  20 . The elastically deformable loop  36  extends past the confines of the deployment opening  24 . Once the elastically deformable loop  36  is released from the compression of the housing  10 , the loop regains its unconstrained, memory, shape and the barrier member  22  attains its deployed configuration. While the elastically deformable loop  36  is shown as generally circular or oval, other shapes are also possible. Elliptical, rounded, square, and irregular shapes are also possible, and may be desirable for a particular application. 
   The barrier membrane  34  is connected to the elastically deformable loop  36 . As the loop expands, the barrier membrane  34  unfurls to form a generally plate-like or bowl-like enclosure having a mouth  38 . The perimeter, or the mouth  38 , of the barrier membrane  34  is defined by the intersection of the elastically deformable loop  36  and the barrier membrane  34 . 
   The more bowl-like configuration, shown in  FIG. 3-3 , is generally preferred when the device is used to collect or retrieve tissue samples. In use, the expanded barrier member  22  is suspended internally at or near the surgical site. The barrier can be manipulated to underlie the surgical site, so that fluids or other materials which are released at the surgical site flow gently downhill into the expandable barrier by means of irrigation flow and/or gravity. When the barrier membrane  34  is bowl-like, it can substantially contain a tissue sample  40  to be excised and removed during surgery. 
     FIG. 3-4  shows the device of  FIG. 3-3  in a pouched configuration, partially between the expanded configuration of  FIG. 3-3  and the withdrawal configuration of  FIG. 3-5 . The remote actuator means  18  has been moved proximally along the inside of the axial bore  20 . The elastically deformable loop  36  extends only partially past the confines of the deployment opening  24 , and constraining force of the housing  10  has forced the elastically deformable loop  36  into a deformed semi-constrained shape. The barrier membrane  34  can preferably slide relative to the elastically deformable loop  36 . The barrier membrane  34  is preferably not retracted into the housing  10  with the elastically deformable loop  36 , and remains substantially outside of the housing  10 . As the elastically deformable loop  36  is withdrawn into the housing  10 , the barrier membrane  34  catches on the deployment opening  24  of the deployment end  12  of the housing  10 . Therefore, the diameter of the mouth  38  of the barrier membrane  34  becomes reduced as compared to the expanded configuration shown in  FIG. 3-3 , and the barrier membrane  34  forms a pouch. The tissue sample  40  is substantially enclosed in the pouch. 
     FIG. 3-5  shows the device of  FIG. 3-4  in a configuration for withdrawal from the body. The remote actuator means  18  has been moved further along the axial bore  20  in the proximal direction, and is in approximately the position from which it started. The elastically deformable loop  36  is substantially fully retracted into the axial bore  20 , and constraint of the housing  10  has deformed the elastically deformable loop  36  to fit within the axial bore  20 . The mouth  38  of the barrier membrane  34  is retracted into the housing  10  with the elastically deformable loop  36 , preventing any undesired loss of tissue or fluids from within the pouch. The body of the barrier membrane  34 , containing the tissue sample  40 , remains substantially outside of the housing  10 . In this configuration the device is withdrawn. As the filled pouch of the barrier membrane  34  is generally larger than the deployment opening  24 , there is a tendency for the barrier membrane  34  to seal against the deployment opening  24  of the housing  10 . This tendency can be enhanced by placing a seal or gasket means (not shown) at the deployment opening  24 . 
   While the demonstration of the device as shown in  FIG. 3-1  through  FIG. 3-5  is representative of one embodiment of a device of this invention, other embodiments are also within the scope of the invention. For example, in an alternate embodiment, not shown, the barrier membrane  34  is adhered to the elastically deformable loop  36 , so that as the mouth of the barrier membrane  34  is withdrawn into the housing  10  it is only collapsed transversely as the elastically deformable loop  36  is withdrawn into and contained within the axial bore. In yet another embodiment, the barrier membrane and tissue sample are completely withdrawn into the housing for removal from the body. 
   The pouched barrier membrane can provide a transfer means for tissues which have been removed from a patient and are to be delivered, for example, to a pathology laboratory. The entire barrier device can be delivered, or the distal end of the device including the pouched barrier membrane can be separated from the rest of the device and delivered (not shown). If such a transfer is desired, the barrier membrane can be lined with, can contain, or can be filled with a tissue preservative. 
     FIG. 3-6  shows representative embodiments of a cross-section through the housing, taken along line b-b of  FIG. 3-1 . A barrier membrane would normally be enclosed within the housing in a folded, bunched, or furled configuration. For simplicity, however, the barrier membrane is not shown. 
     FIG. 3-6   a  shows a housing  110  having a circular cross-section. This is a preferred cross-section for an expandable barrier device of this invention. A circular housing cross-section has the advantage of being deformable in any radial direction. A circular housing cross-section also permits delivery of an expandable barrier of this invention through a standard laparoscopic trocar, or through the instrument channel of a standard endoscope. However, other cross-sections may be preferable. 
   Within the axial bore  120  is the elastically deformable loop  136 , which has been constrained to fit within the axial bore  120 . The elastically deformable loop  136  is shown having an elongated oval cross-sectional shape. This is a preferred cross-sectional shape, as it permits structural rigidity of the expanded loop in a direction perpendicular to the general plane of the loop, but does not compromise the lateral compressibility of the loop within the general plane of the loop. However, the elastically deformable loop  136  can have any appropriate cross-sectional shape. 
   The axial bore  120  can provide access for auxiliary implements such as an electrocautery device, laser, knife, probe, or other surgical implement an imaging means, or an irrigation or aspiration means. Auxiliary implements can be an integral part of the device as manufactured, or can be introduced as needed through the axial bore  120 . 
     FIG. 3-6   b  shows a housing  110  which has an oval cross-sectional shape. Within the axial bore  120  is the elastically deformable loop  136 , which has been constrained to fit within the axial bore  120 . The elastically deformable loop  136  is shown with a rounded cross-sectional shape. A lumen  142  is present. The lumen  142  can have any desired cross-sectional shape. The lumen  142  is used to introduce auxiliary implements to the surgical site. Auxiliary implements can include, for example, an electrocautery device, laser, knife, probe, or other surgical implement an imaging means, or an irrigation or aspiration means. Auxiliary implements can be an integral part of the device as manufactured, or can be introduced as needed through a provided lumen  142 . 
     FIG. 3-6   c  represents an embodiment in which a cautery wire  144  is provided as an integral part of the expandable barrier device. Various cautery wires are known in the art and are suitable for use with this invention. In the pictured embodiment the cautery wire  144  is a loop through which electrical current can flow. It is located adjacent to the mouth of the barrier membrane when both the expandable barrier and the cautery wire are deployed. Insulation  146  can be provided around sections of the cautery wire, for protection of tissues and of the housing. The cautery wire  144  is used to sever and/or cauterize tissues, which are preferably collected within the expanded barrier member. The deployment and retraction of the cautery wire can be controlled using the same actuator as that which deploys and retracts the expandable barrier element. Alternatively, a second actuator mechanism can be supplied for deployment of the cautery wire. 
   The cautery device can be made of any suitable material. If the cautery device is rigid, then the size of the cautery device is either limited to the size of the lumen  142 , or it protrudes from the deployment end of the lumen at all times. However, the cautery wire can comprise an elastic material. In a preferred embodiment, the cautery wire is a loop of wire, and the loop is constrained within the lumen  142  while the expandable barrier device is placed within the body. In an alternate embodiment, the cautery wire is a hook-shaped span of elastic material which can be linearly constrained within the lumen  142 . 
   It has been discovered that an improved cautery device can be made of a shape memory alloy. The use of an SMA which exhibits pseudoelasticity has the advantage that the amount of elastic deformation that is available is large compared with that available from many other electrically conductive materials. The large amount of elastic deformation of the alloy allows the loop to have a small transverse dimension when it is constrained within a housing. 
     FIG. 3-6   d  shows the cautery wire  144  located within the elastically deformable loop  136 . This arrangement permits the cautery wire  144  to be within the mouth of the barrier membrane. It also permits the cautery wire and the elastically deformable loop to be contained in the same lumen of the housing. The deployment of the cautery wire can be controlled using the same actuator as that which deploys and retracts the expandable barrier element. Alternatively, a second actuator mechanism can be supplied for deployment of the cautery wire. Other embodiments (not shown) include adhering the cautery wire to the mouth portion of the expandable barrier, or having the elastically deformable loop itself function as a cautery wire, with the barrier membrane being perforated at specific locations to permit electricity or heat flow to the issue. Alternatively, a conductive polymer which can be electrically heated from outside the body can be used to line the mouth portion of the barrier membrane, or the barrier membrane itself can support the flow of heat or electricity through its body. Insulation  146  can be provided within the housing, for protection of the housing. 
     FIG. 3-7  and  FIG. 3-8  demonstrate alternative embodiments of the expandable barrier of this invention. 
     FIG. 3-7  shows a shallow barrier member  222  wherein the depth of the barrier membrane  234  is a fraction of the diameter of the mouth  238 . The connecting means  228  fastens to a circular elastically deformable loop  236  which forms a closed ring. This type of expandable barrier member can function as an internal surgical drape. The housing  210  is shown. 
     FIG. 3-8  shows another embodiment of this invention. The barrier member  222  is relatively deep: the depth of the barrier membrane  234  is greater than the diameter of the mouth  238 . The connecting means  228  are wires which are continuations of the elastically deformable loop  236 . The elastically deformable loop  236  is retained within an enclosure  248  formed of the barrier membrane  234 . The barrier membrane  234  is preferably folded over itself, and self-adhered to form the enclosure  248 . The elastically deformable loop  236  enters the enclosure through openings  250 . Each end of the elastically deformable loop  236  can independently enter the enclosure at opening  250 , as shown. Alternatively, both ends of the elastically deformable loop  236  can enter the enclosure through one opening  250 , not shown. The elastically deformable loop  236  slidably engages the loop enclosure  248 : in an especially preferred embodiment, the barrier membrane forms a closed pouch upon retraction of the elastically deformable loop within the housing when the barrier member is used to collect a tissue sample, as shown in  FIG. 3-5 . 
   Also shown in  FIG. 3-8  is a cautery wire  244  which, when deployed, is located proximal the mouth  238  of the barrier member  222 . An insulating sheath  252  is located within the axial bore which houses the cautery wire and projects slightly from the distal end of the housing  210 . 
   While a self-adhered barrier membrane  234  is shown, alternate embodiments are possible.  FIG. 3-9  presents some of the alternatives in cross-sectional view, the cross-section being taken through line b-b of  FIG. 3-7 . The barrier membrane  234  can be a doubled sheet with the elastically deformable loop  236  between the two surfaces, as shown in  FIG. 3-9   a . The doubled sheet can be self-adhered if desired. The barrier membrane  234  can include rings  260  formed either of the membrane material or of some other material as shown in  FIG. 3-9   b . The barrier membrane  234  can be punctured by the elastically deformable loop  236 , as shown in  FIG. 3-9   c . Alternately, the barrier membrane  234  can be affixed to the elastically deformable loop  236  so that sliding of the membrane material over the elastically deformable loop is substantially impeded (not shown). 
     FIGS. 3-10 ,  3 - 11  and  3 - 12  show some alternate top and side views of the elastically deformable loop in the expanded, “memory” configuration.  FIG. 3-10  shows a closed circular loop  336 , with a connecting means  328 . The housing  310  is shown. The elastically deformable loop is flat in side view.  FIG. 3-11  shows a circular loop  336 , in which the connecting means  328  is a continuation of the loop. The loop is flat in side view, and the elastic connecting bar is sharply angled.  FIG. 3-12  shows an oval loop  336  in top view, in which the connecting means  328  is a continuation of the elastically deformable loop. The loop is curved in side view, and the connecting bar is gently angled. 
   The devices of this invention, including the housing and the barrier member, can be reusable. Preferably the device is disposable or semidisposable. The barrier member and the housing are generally disposable, and the remote actuator means is either reused or discarded. 
   A possibly advantageous variation of this form of the invention is shown in  FIG. 3-13 , which shows an arrangement which can be used to insert a catch bag  434  through a trocar entry, deploy the bag, and allow the removal of the insertion device prior to removal of the bag itself. Other devices have not allowed for dissociation of the bag and insertion device. 
   The principle feature of this variation is the replacement of the closed loop of metal in the cuff  448  of the bag by two curved arms  436 , joined in the shaft  410  of the instrument, with their tips meeting at the distal portion of the cuff. Also in the cuff  448  is a drawstring  490  looping completely around the cuff, with ends passing through the shaft  410  of the instrument, and fastened to the actuation handle  448 , in a manner which lets the drawstring move with the arms keeping the drawstring essentially taut. 
   Initial insertion of the device is accomplished with the bag  434  disposed around the straightened arms  436 , all situated in the instrument shaft  410 . 
   Separating the ends  491  of the strings  490  from the insertion tool external to the body will allow the insertion tool to be withdrawn. The arms  436  will slide out of the cuff  448 , and the drawstring ends  491  will pass through the shaft  410 . This will leave the bag  434  behind with the drawstring ends coming out of the trocar. An internal pressure seal may be affected at the proximal end of the shaft  410  or within the shaft. 
     FIGS. 3-14  and  3 - 15  show yet another arrangement which can be used to deploy a catch bag  460  through a trocar entry. 
   In this case, as in the embodiment of  FIG. 3-13  the closed loop of metal is replaced by two curved arms  462  which are joined in the shaft of the instrument. In this case however the arms  462  are connected at their distal end by a heat-shrink polymeric sleeve  464 . This acts both as a connector for the distal ends of arms  462 , and as a hinge, allowing the arms to fold towards each other. Thus  FIG. 3-14  shows the device in its operating position with the loop extending from the distal end of the instrument. In this position the arms  462  spring apart from each other into their unstressed configuration, fexible sleeve  464  allowing this movement.  FIG. 3-15  shows the device when the loop is retracted into the instrument&#39;s shaft e.g. for insertion or withdrawal of the device from the patient. In this case the arms  462  are folded toward each other about sleeve  464  which acts as a hinge, to allow the loop easily to be retracted into the shaft. In this embodiment the arms  462  may comprise a regular resiliently deformable material e.g. a spring metal, or a material exhibiting pseudoelastic, especially superelastic behavior, especially a shape memory alloy. 
     FIGS. 3-16  to  3 - 18  illustrate the additional use of a bushing  470  to prevent accidental withdrawal of a deployed filled barrier member, e.g. collecting pouch, back into the housing  472  and also to prevent tearing of the barrier member.  FIG. 3-16  illustrates the embodiment before deployment of the barrier, and  FIG. 3-17  illustrates the embodiment after deployment of the barrier. 
   Referring to  FIG. 3-16 , a bushing  470  that is substantially funnel shape, comprising a hollow tubular portion  474 , and a frustoconical shaped flange portion  482  is positioned on the connecting member or deployment rod  476 . The flange portion  482  is resiliently biased radially outward and the tubular portion  474  is a push fit on rod  476  but slidably relative thereto when subjected to sufficient force. On the distal side of the bushing  470  a barrier, comprising a superelastic loop  478  and a barrier member  480 , is secured to the deployment rod  476 , as in the previous figures. 
   Referring now to  FIG. 3-17 , when the barrier is deployed outside the housing  472  by extending the deployment rod  476 , the bushing  470  is carried with the rod (because of the push fit tubular portion  474 ) towards the distal end of the housing  472  until it projects from the end of the housing  472 . In this position the flange portion  482 , which is resiliently biased, snaps against the distal end of the housing so that complete withdrawal of the bushing  470  back into the housing is prevented by the flange  482 . Withdrawal of the rod  476  is however possible, the rod sliding relative to the tubular portion  474  of the bushing  470 . 
   Operation and body sample collection by the deployed barrier member  480  can then take place as before, and then the elastically deformable loop retracted back into the housing  472  as illustrated in  FIG. 3-18 . The bore of the bushing  470  is however sufficiently small that the barrier membrane  480 , which is now filled with body samples, is blocked from re-entry into the housing. It therefore remains suspended outside the housing  472 , which is desirable for some applications. The funnel shaped ends of the bushing also act to provide a smooth transition substantially to prevent tearing of the barrier membrane  480  by the housing  472 . 
   It will be appreciated that bushings with shapes other than that illustrated in  FIGS. 3-16  through  3 - 18  can be used. The preferred features to be incorporated in any other shaped bushing are a small diameter bore to prevent barrier member re-entry, a resilient distal end to snap against the housing, and a smooth opening to avoid tearing of the barrier membrane. 
     FIGS. 3-19  and  3 - 20  show a modified necked loop design for use in situations where an elastically deformable loop is to be constrained within a housing. In these figures,  FIGS. 3-19  and  3 - 20  show the modified loop in the pre-constrained and the constrained configuration respectively. The sides  500  of the loop come toward each other, overlap at part  502  (“the necked portion” which is at the distal end of the loop), and then divert outwards, curving in the opposite sense to that previously to join to each other. The result is a smaller loop portion  504  adjacent to the main loop portion  506 , in a roughly figure “ 8 ” configuration. The advantage of this necked configuration is that when the loop is constrained as shown in  FIG. 3-20 , substantially all the severe deformation is absorbed by the small loop portion  504 , especially the overlap point  502 . Thus if the loop is deployed again, at least main loop  502  will regain the prestrained configuration, i.e. the same configuration as illustrated in  FIG. 3-19  which showed the loop before constraining. 
     FIGS. 3-21  and  3 - 22  show an alternative design, in pre-constrained and constrained condition respectively. In this case the sides  508  of the loop turn outwards at points  510  towards the distal end of the loop before they meet or overlap. The sides then turn towards each other again to join. The result is a general nipple shape, with a small bulbous section  512  adjacent the main loop region  514 . As before, a necked region is formed, in this case by the outward diversion of the sides of the loop at points  570 . The necked region absorbs substantially all the severe deformation on constraining as before ( FIG. 3-22 ). 
   In a fourth form of the present invention, a remotely operated device comprises an elongate housing, and an elastic surgical screen which can be constrained within the housing. The surgical screen is deployable from within the housing to assume an expanded memory shape. In the expanded shape the surgical screen can have any of several functions. The screen can act as a duct screen, to collect calculi or calculus fragments, and to prevent the movement of calculus fragments in an undesired direction. The screen can act as an emboli screen, to prevent the movement of emboli at or near an operative site. The screen can act as a surgical tool, to hold or maintain a mass, such as a tissue mass, in a localized area. Generally, the screen is removed from the patient in its expanded memory shape, simultaneously removing calculi or residual calculus fragments, emboli or emboli fragments, or other internal masses. The surgical screen is preferably moveable to a third position wherein the surgical screen is partially or fully retracted, and at least a portion of it is constrained within the housing. 
   The surgical screens of this invention are deployed with radial asymmetry from the mouth of the delivering catheter, and are able to traverse substantially the entire width of a duct with a screening means. The elastic screen comprises, for example, one or more loops of elastic material, which may be partially or completely spanned by a semipermeable material; a graduated series of a loops; or a tassel. Remote means are provided to project, retract and/or rotate the screen means relative to the distal end of the housing. 
   A method of this invention for removing an internal obstruction comprises (a) inserting a catheter end beyond an obstruction; (b) deploying a surgical screen from the catheter end; and (c) retracting the surgical screen to remove the obstruction. 
   A further method of this invention comprises (a) inserting a catheter end beyond an obstruction; (b) deploying a surgical screen from the catheter end; (c) fragmenting the obstruction; and (d) removing the surgical screen to remove obstruction fragments. 
   An alternate method of this invention comprises (a) inserting a catheter end beyond an obstruction; (b) deploying a surgical screen from the catheter end; (c) fragmenting the obstruction; (d) retracting the surgical screen into the catheter; and (e) removing the catheter. 
   Yet another method of this invention comprises (a) inserting a catheter end beyond an obstruction; (b) deploying a surgical screen from the catheter end; (c) fragmenting the obstruction; (d) removing obstruction fragments from the operative site; (e) retracting the surgical screen into the catheter; and (f) removing the catheter. 
     FIG. 4-1   a  is a side view of an unexpanded screen device within a duct, placed downstream from a blocking calculus.  FIG. 4-1   b  shows the screen device, the deployment end of which has been placed upstream from the blocking calculus.  FIG. 4-1   c  shows a screen device which has been expanded upstream from a blocking calculus.  FIG. 4-1   d  shows a screen device in place after calculus fragmentation. 
     FIG. 4-2  shows various stages of deployment of a tasseled surgical screen. 
     FIG. 4-3  through  FIG. 4-5  show alternate embodiments of the surgical screen portion of a device of this invention. 
   The devices of this invention have a variety of potential uses. A surgical screen of the invention herein can be used to capture an undesired mass from within a duct, for example, for removing a gallstone from the bile ducts; for removing a kidney stone from the urinary system; or for removing an emboli from a blood vessel. Alternatively, the surgical screens can be used during an operative procedure, such as to contain or hold a discrete mass for further procedures or for removal. For purposes of example only, and not as a limitation, reference will be made to calculi produced by a kidney and removed from a ureter using an endoscopic device. It is to be understood that this is for simplicity of example only, and that the apparatus, methods and teachings will be similarly applicable to a variety of uses. 
   As used herein, the term “screen” refers to a structure which is screened, perforated, tasseled, or sieve-like, or which functions to separate larger particulate matter from smaller particulate matter, or, more preferably, to separate solid matter from fluids. 
   As used herein, the term “surgical screen” refers to a screen means which is comprised of an elastic material, preferably a shape memory alloy, and more preferably a pseudoelastic shape memory alloy. The surgical screen is compressible for delivery to the operative site. The “operative site” can be, for example, a surgical site, a biopsy site, the site of an angioplasty procedure, the site of a diagnostic procedure, and the like. Once present at the operative site the surgical screen is deployed from the housing, expands to its memory shape, and substantially spans the width of the duct. A tissue “mass” refers to a discrete unit of tissue, a calculus, an embolus, a prosthetic device, and the like. 
   The surgical screen preferably demonstrates radial asymmetry: it is not deployed radially from the housing opening. When deployed from the catheter, the surgical screen is unconstrained, and expands to traverse the duct. In general, at least 80% of the width of the duct will be within the perimeter of the surgical screen. More preferably, the surgical screen is slightly larger than the diameter of the duct, and gently expands apart against the walls of the duct when in the expanded configuration. When the surgical screen is used to localize a tissue mass outside a duct the mass is preferably contained at the surface of the surgical screen. Preferably two or more surgical screen devices of different sizes are available during a procedure. When needed, the surgeon assesses the size of screen necessary for tissue protection and/or internal mass collection, and selects a screen which has an appropriate size, shape and/or filter pore size. 
   The surgical screen is one or more wire or a strip of elastic material. The term “elastic material” is used herein to mean a material that has spring-like properties, that is, it is capable of being deformed by an applied stress and then springing back, or recovering, to or toward its original unstressed shape or configuration when the stress is removed. The elastic material is preferably highly elastic. The material can be polymeric or metallic, or a combination of both. The use of metals, such as shape memory alloys, is preferred. Shape memory alloys that exhibit pseudoelasticity, in particular superelasticity, are especially preferred. The elastic materials herein exhibit greater than 1% elastic deformation, more generally greater than 2% elastic deformation. Preferably, the elastic materials herein exhibit greater than 3% elastic deformation, more preferably greater than 4% elastic deformation. 
   The surgical screen differs from the prior art in several key aspects. The surgical screen is not radially deployed from the housing, nor is the housing preferably centered in a duct when the screen is expanded, as has been the case in the prior art. Prior art stone baskets, for example, provide a radially deployed basket, into which the stone is snagged. Removal of the stone is dependent upon the successful engagement of the calculus within the body of the device, so that the calculus is substantially enclosed within the basket. The devices require manipulation of the deployed basket to ensnare the stone for removal. Stone removal is directly related to the ability of the operator to snag the stone with the basket. In contrast, the surgical screen traverses the diameter of a duct, and the inserted end of the catheter remains near the perimeter of duct. Using a device of this invention, the stone does not have to be caught within the screen, but is removed at the surface of the screen as the catheter and screen are withdrawn from the duct. This provides more control and requires less manipulation than prior art devices. The devices of this invention are therefore less likely to damage duct walls during stone withdrawal than those of the prior art. Devices of this invention are retractable back into the housing for withdrawal, if desired. 
   Similar numbers refer to similar function throughout the Figures. The Figures are drawn for clarity and are not drawn to scale. 
     FIG. 4-1  shows (1 a ) the introduction of a surgical screen housing  10 , in this case a catheter, into the occluded duct  15 ; (1 b ) placement of the distal end  17  of the housing beyond the calculus  20   a ; (1 c ) deployment of the surgical screen  25 ; and (1 d ) fragments  20   b  of the calculus  20   a . The calculus fragments  20   b  can be retracted from the duct with the withdrawal of the catheter housing  10 . In an alternative embodiment (not shown) the calculus  20   a  is retracted from the duct without fragmentation. 
   The surgical screen, when expanded, will have a diameter substantially similar to the inside diameter of the duct being cleared. For example, when used within a ureter, the diameter of the surgical screen will be from about 1 mm to about 1 cm. When used within a bile duct, the diameter of the surgical screen will be from about 1 mm to about 1 cm. When used within a blood vessel, the diameter of the surgical screen will be from about 1 mm to greater than about 5 cm. When used to remove a tissue mass which is not within a duct, the surgical screen will be from about 1 mm or smaller to about 8 cm or greater. The preferred diameter of the surgical screen will vary with the specific application and with the specific anatomy of the patient. In general, the diameter of a surgical screen will be from about 1 mm or less to about 5 cm or greater, more generally from about 2 mm to about 3 cm. 
   The housing  10  is preferably an elongate sheath, having an axial bore therethrough. The housing  10  can be flexible or rigid, and the rigidity can vary by region. Standard catheters and laparoscopic devices well known to the art are appropriate. The axial bore is sized to receive the surgical screen  25  in a constrained configuration. The axial bore opens to the environment at the inserted deployment end  17 . Opposite the inserted deployment end  17  is the actuator end (not shown). The actuator end can include rings, knobs or ridges, for example, for ease of integration with a separate actuator means (not shown). Suitable actuator means include slider mechanisms, pistol grip or thumb actuated mechanisms, scissors handles, and syringe-plunger mechanisms. These and others are well known to the art. The specific type of actuator mechanism is generally determined by the personal preference of the surgeon. 
   The specific configuration and dimensions of the housing will vary with the use of the device, the parameters of the surgical screen  25 , and whether access for additional laparoscopic or endoscopic devices is provided. In general the axial bore, into which the surgical screen is constrained, will have an internal diameter of from less than about 1 mm to about 2 cm or greater. 
   The outer diameter of the housing  10  swill vary with the application and the size of the expandable screen. The housing in an endoscopic device will have a diameter of from less than about 0.7 mm to about 4.5 cm or greater. The length of endoscopic devices will be from less than about 10 cm to about 3 meters or greater. The housing in a laparoscopic device will have a diameter of from less than about 3 mm to about 1.5 cm or greater. The length of laparoscopic devices will be from less than about 5 cm to about 20 cm or greater. 
   The end of the surgical screen housing possesses sufficient lateral integrity that it is not significantly deformed by the pressure exerted by the constrained surgical screen. When an endoscopic device of this invention functions as a catheter and there is little lateral support in the main body of the catheter, the inserted end of the catheter may require reinforcement to provide consistent constraint of the surgical screen element For example, the surgical screen of this invention can be delivered to the operative site using the instrument channel, or working channel, of standard endoscopic devices. Such standard endoscopic devices may also include other devices, especially a laser, lithotriptor, visualization means, or crushing stone basket in separate lumen. In a device having a rigid housing, such as a laparoscopic device, the inserted end of the housing can have the same physical attributes as the remainder of the body of the housing. 
   As shown in  FIG. 4-2 , the surgical screen is moveable between a first position ( FIG. 4-2   a ) wherein the screen is constrained within the housing and assumes a constrained shape, and a second position ( FIGS. 4-2   b ,  FIG. 4-2   c  and  FIG. 4-2   d ) wherein the screen means extends past the distal deployment end and assumes an expanded memory shape. In the expanded memory shape the screen means acts as a surgical screen. After use, the surgical screen and the housing are removed from the patient. If desired, the surgical screen can be removed in its expanded memory shape, simultaneously removing, for example, calculi or residual calculus fragments. Alternatively, the surgical screen is retracted into the housing, assumes a constrained shape, and is replaced within the axial bore before the constrained surgical screen and the housing are removed from the patient. This method can be used when residual calculus fragments, for example, have been removed by irrigation and/or aspiration. 
     FIG. 4-2  shows a longitudinal cross sectional view of a tasseled surgical screen. As  FIG. 4-2   a  shows, the housing  110  maintains the constrained surgical screen  112  in a compressed configuration. Attached to the constrained surgical screen  112  is a connecting means  114 . The connecting means  114  can be, for example, a bar, flexible wire, sheath, and the like. If a guide wire is to be used, the connecting means  114  can include a lumen for placement of the guide wire. Alternatively, a guide wire can be introduced using a separate lumen. The connecting means  114  connects the surgical screen to the remote means (not shown) which project, retract, or rotate the surgical screen relative to the distal deployment opening.  FIGS. 4-2   b ,  4 - 2   c , and  4 - 2   d  show the expanded surgical screen  125  in various degrees of deployment. By varying the amount of deployment, and thus the diameter of the surgical screen, d, the operator can maximize the screening effects of the surgical screen while minimizing potential damage to the duct wall due to surgical screen expansion, or due to the withdrawal of the expanded screen from the body. 
     FIG. 4-3  shows one embodiment of a surgical screen  225  of this invention. Three elastic strips or wires form concentric loops in their expanded configurations. These strips or wires form a surgical screen  225  suitable for removal of entire calculi, or of calculus fragments. It will be obvious to one skilled in the art that while three loops which are curved along their length are pictured, other configurations are also appropriate for use with this invention. One, two, four, or more loops can be used. The loops can be fairly regular (as shown), or they can be eccentric, scalloped, rounded, oval or irregularly shaped. The degree of longitudinal curvature, and curvature across the width of the screen, can be varied to suit the desired application. The loops can be spaced relatively widely, especially where an unfragmented calculus is to be removed, or they can be spaced fairly closely together, especially where a calculus is to be fragmented and/or calculus fragments are to be removed. A perforated sheet can be suspended across a loop of a multiloop surgical screen, similar to the configuration shown in  FIG. 4-5 . Alternatively, a perforated sheet can be suspended between any two loops of a multiloop surgical screen (not shown). 
     FIG. 4-4  shows a side view of a tasseled surgical screen  225  of this invention. Enlargements show various end treatments for the tassels. Pictured are (a) an elastic wire which terminates in a self-closing loop; (b) an elastic wire that terminates in a blunted or truncated end; (c) an elastic wire that terminates in a knob of added material, such as a plastic; and (d) an elastic wire that terminates in a knob formed of the elastic material itself. Each individual strand which makes up a tassel filter can be substantially straight along its length, or it can be curved, wavy, or undulating in two or three dimensions. The strands can be substantially similar in configuration, or they can be different. 
     FIG. 4-5  shows a surgical screen which includes an elastic loop  236 , an elastically deformable ring or loop of elastic material, which is spanned by a barrier material  234 . The elastic loop  236  is preferably pseudoelastic, and more preferably a shape memory alloy. As shown, a connector  228  can be used to orient the surgical screen sharply across the duct. The pictured connector  228  is an extension of the elastic loop  236 . Alternatively, the connector  228  can integrate with, but be separate from the elastic loop  236 . 
   The diameter of the elastic loop  236  will vary with the diameter of duct for which it is intended, as discussed above. The depth of arc described by the barrier material  234  when suspended from the memory loop is from less than about 1 mm to about 1 cm or greater. The surgical screen can provide a sack-like structure which substantially encloses a calculus. The calculus can then be removed without fragmentation, or it can be fragmented. If the calculus is fragmented, the pieces can be removed within the surgical screen, they can be aspirated or irrigated from the face of the surgical screen, or the surgical screen can be retracted and the fragments can be washed from the site by normal duct fluid flow. 
   The barrier material is a flexible and biocompatable material. When constrained, the barrier material  234  is collapsed and furled around the constrained elastic loop  236 . The barrier material is sufficiently thin that it can be folded, furled, or gathered, together with the elastic loop  236 , to fit within the housing. The composition of the barrier material will reflect the specific use of the surgical screen. In one embodiment the barrier material is substantially permeable to fluids. In such an embodiment, the barrier material is a web, net or grid, perforated sheet, and the like, and is substantially permeable to body fluids and other liquids, such as normal saline solution or gases, which might be present during surgical procedures. Suitable materials include nylon or Dacron netting or screen, or a grid of elastic material. 
   The surgical screen is compressed and loaded within the housing. In this constrained configuration, the screen device can be sterilized, packaged and stored for later use. The screen device (i.e., surgical screen and housing) is preferably a disposable device. 
   In one preferred embodiment, a device of this invention comprises (a) a housing having a distal deployment opening; (b) a surgical screen which is constrainable within the housing, the surgical screen comprising an elastic material; and (c) remote means to project, retract and/or rotate the surgical screen relative to the distal deployment opening; the surgical screen being moveable between a first position wherein the surgical screen is constrained within the housing, and a second position wherein the surgical screen is extended past the distal deployment end and assumes an expanded shape. 
   A device of this invention can be used in a variety of procedures, such as the capture an undesired mass from within a duct. For example, a device of this invention can be used to remove a gallstone from the bile ducts; to remove a kidney stone from the urinary system; or to remove an embolus from a blood vessel. A surgical screen of this invention can be used during an operative or surgical procedure, to contain or hold a discrete tissue body for further procedures or for removal. For purposes of example only, and not as a limitation, reference will be made to methods for removal of a calculus from a ureter, wherein the device housing is a catheter. It is to be understood that this is for simplicity of example only, and that the apparatus, methods and teachings will be similarly applicable a variety of such uses. 
   In one method, the deployment end of a housing containing a surgical screen is partially inserted into a human or animal patient. A guide wire may or may not be used for placement of the device. When a guide wire is used, it is introduced into the ureter and placed appropriately, e.g., beyond an obstruction. A catheter is slipped over the guide wire. The guide wire is then removed, and the surgical screen is extended beyond the deployment end of the catheter. The guide wire preferably passes through a separate lumen in the catheter. Alternatively, the guide wire can pass through the catheter lumen which houses the surgical screen, in which case the connecting means can be tubular and provide an internal bore to accept the guide wire. Alternatively, the guide wire can pass through the axial bore of the housing adjacent the connecting means, or the guide wire can be introduced through a bore or slot within the connecting means. The surgical screen can be radiopaque for ease of placement at the operative site. 
   A method for removing an internal obstruction comprises (a) inserting an end of an elongate housing, such as a catheter end, beyond a mass, such as a calculus; (b) deploying a surgical screen from the housing end; and (c) retracting the housing and surgical screen to remove the mass. Alternately, the calculus can be fragmented before removal. Calculus fragmentation can be by, for example, lithotripsy (ultrasound), mechanical fragmentation, or laser fragmentation. This method comprises (a) inserting a catheter end beyond a mass; (b) deploying a surgical screen from the catheter end; (c) fragmenting the mass; and (d) retracting the catheter and surgical screen to remove mass fragments. 
   Yet another method of this invention comprises (a) inserting a catheter end beyond a mass; (b) deploying a surgical screen from the catheter end; (c) fragmenting the mass; (d) removing mass fragments from the operative site; (e) retracting the surgical screen into the catheter, and (f) removing the catheter. The use of this method prevents calculus fragments from migrating from the fragmentation site where they cannot be retrieved and can act as nucleation sites for further obstructions. Fragments of the obstructing mass which remain can be removed, for example, by flushing the operative site with normal saline or other liquids, by aspiration of the fragments, by mechanical means, or by a combination of means. 
   As a separate embodiment of this invention, it has been discovered that stone baskets of the prior art can be advantageously made of a shape memory alloy, preferably a pseudoelastic shape memory alloy, and more preferably a superelastic shape memory alloy. The attributes of, and processes for obtaining, such shape memory alloys have been discussed above. 
   Stone baskets use a trap, or cage, effect. They facilitate passage of the obstruction (e.g., a calculus or other mass) inside the basket, but then prevent escape of the obstruction when it is in place in the basket. The basket and obstruction are then withdrawn. Prior art stone baskets include baskets of helically deployed wires (U.S. Pat. No. 4,347,846, to Dormia), baskets of flat spring strips (U.S. Pat. No. 4,590,938 to Segura et al.), baskets which facilitate the insertion of a prosthesis (U.S. Pat. No. 4,592,341 to Omagari et al.), baskets which are used to capture and then crush the calculus (U.S. Pat. Nos. 4,691,705 and 4,741,335 to Okada, and U.S. Pat. No. 4,768,505 to Okada et al.). 
   Stone baskets generally are classed as medical retriever devices. They are adapted for delivery and use through a catheter, or through the working channel of an endoscope. Stone baskets generally comprise a narrow, elongated sheath; a basket of relatively large diameter extendible from the distal end of the sheath and collapsible when withdrawn into the sheath; and a remote means to project, retract, and/or rotate the basket relative to the distal end of the sheath. The basket is defined by a multiplicity of spaced apart, outwardly bowed spring arms or wires which extend generally axially from the sheath, and are joined at each of the distal and proximal ends of the basket. 
   The use of shape memory alloys which exhibit pseudoelasticity in the stone baskets of the prior art allow the use of thinner arms (wires or strips, as the case may be) in the makeup of a basket having a desired expanded diameter, or permit a much greater deformation of the basket upon deployment. This permits the use of catheters or working channels having a significantly decreased diameter than those of the prior art Introduction of a thinner shape memory alloy stone basket catheter beyond a calculus is easier than introducing the stone basket catheters of the prior art. The increased diameter and/or thinner wires produce a stone basket which is easier to use than those of the prior art. The thinner wires and/or larger diameter provide more unimpeded area into which the blocking calculus can be captured for removal. 
   In a fifth form of the present invention, a remotely operated device of this invention comprises an elongate housing, and a retractor of a shape memory alloy. Remote means are provided to project retract and/or rotate the retractor means relative to the distal end of the housing. The retractor preferably comprises one or more loops of a shape memory material. The retractor is preliminarily constrained within a housing, such as a laparoscope or an endoscope. It is deployed from within the housing at an operative site. The retractor is generally used to manipulate organs or other tissues. The retractor can be replaced within the housing. The housing is then withdrawn from the patient. 
   The shape memory retractor means is a strip or wire of a shape memory material which forms one or more loop in the expanded configuration. All or part of the retractor can be spanned by a semipermeable or permeable membrane. 
     FIG. 5-1  is a cross-sectional view of a constrained retractor device.  FIGS. 5-2  through  5 - 6  show alternate top views of expanded (unconstrained) retractor devices.  FIGS. 5-7  through  5 - 11  show alternate side views of expanded retractor devices. FIGS. - 12  and  5 - 13  show alternate end views of expanded retractor devices.  FIGS. 5-14  and  5 - 15  show alternate cross sectional views of constrained retractor devices, the cross section taken along line a-a of  FIG. 5-1 . 
   A remotely operated device of this invention comprises an elongate housing having a distal end and a proximal end; a retractor of a shape memory alloy; and remote means to project, retract and, optionally, to rotate the retractor means relative to the distal end of the housing. The retractor comprises one or more loops of a shape memory material. A loop can be substantially round, oval, or shaped like a teardrop, for example, or it can be eccentric in its shape. When two or more loops are present, they can be of similar shape, or they can be dissimilar in shape. Two or more fingers or lobes can be present. One or more loop can be partially or completely spanned by a membrane. The proximal ends of the retractor loop can integrate with, or function as, the remote means to project, retract and rotate the retractor means relative to the distal end of the housing. 
   The retractor is preliminarily constrained within the housing. The retractor is deployed at an operative site, where the retractor is used, for example, to manipulate organs or other tissues. The retractor can be moved back to the preliminary position, so that the retractor is again constrained within the housing. The device can then be repositoned and the retractor redeployed at an alternate site, or the housing can be withdrawn from the patient. 
   The operative site can be, for example, a surgical site, biopsy site, the site of diagnostic procedures, and the like. For purposes of example only, and not as a limitation, reference will be made to a housing which is a catheter. It is to be understood that this is for simplicity of example only, and that the apparatus, methods and teachings will be similarly applicable to devices in which the housing is, for example, a laparoscopic or alternate endoscopic device. 
   As used herein, the term “retractor” refers to a looped retractor means which is comprised of a shape memory alloy. The retractor is preferably a pseudoelastic shape memory alloy, and most preferably a superelastic shape memory alloy. The shape memory alloy can have a biocompatable coating, if desired. 
   The retractor differs from the prior art in several key aspects. The elastically compressible retractor material makes use of the property of shape memory to achieve its desired effect. Materials which are deformable and which return to a predetermined shape demonstrate shape memory. Spring steel and plastic materials, for example, can demonstrate shape memory. Preferably, the compressible retractor material is a shape memory alloy (SMA) which demonstrates pseudoelasticity when deformed under an applied stress. Articles made of a pseudoelastic shape memory alloy can be deformed from an original undeformed configuration to a second deformed configuration. Such articles revert to the undeformed configuration under specified conditions and are said to have “shape memory.” 
   The use of an SMA which exhibits pseudoelasticity has the advantage that the amount of elastic deformation that is available is large compared with that available from many other materials. The large amount of elastic deformation of the elements allows the device to be used to form retractors of relatively large dimension and relatively eccentric shape, while simultaneously ensuring that the device has a small transverse dimension when the retractor elements are constrained within a housing, allowing the device to pass through small passages or surgical entry sites. 
     FIG. 5-1  shows a cross-sectional view of the distal end of a retractor device of this invention. The retractor  8  is constrained within the housing  10 . The distal (inserted) deployment end  12  is shown. Remote means to project and retract, and optionally to rotate, the retractor is located at the proximal end of the device (not shown), and is in the direction of the arrow. The housing  10  is preferably an elongate sheath, having an axial bore  14  therethrough. Standard catheters, endoscopic and laparoscopic devices well known to the art are appropriate. The axial bore  14  is sized to receive the retractor  8  in a constrained configuration. The axial bore  14  opens to the environment at the deployment end  12 . 
   The specific configuration and dimensions of the housing will vary with the use of the device, the parameters of the operative site, the size of the retractor, the mass of tissue or the prosthetic device which is to be manipulated, and whether access for additional laparoscopic or endoscopic devices is provided within a retractor device. In general the axial bore  14 , into which the retractor is constrained, will have an internal diameter of from less than about 1 mm to about 2 cm or greater. The outer diameter of the housing  10  will vary with the application, the diameter of the axial bore, and whether access for additional or alternate instruments is provided within the housing. For example, the housing in an endoscopic device will have a diameter of from less than about 0.7 mm to about 4.5cm or greater. The length of endoscopic devices will be from less than about 10 cm to about 3 meters or greater. The housing in a laparoscopic device will have a diameter of from less than about 3 mm to about 1.5 cm or greater. The length of laparoscopic devices will be from less than about 5 cm to about 30 cm or greater. 
   The end of the retractor device possesses sufficient lateral integrity that it is not significantly deformed by the pressure exerted by the constrained retractor. The housing  10  may be rigid or flexible, and its rigidity can vary along its length. When an endoscopic device of this invention functions as a catheter, and there is little lateral support in the main body of the catheter, the inserted end of the catheter may require reinforcement to provide consistent transverse compression of the retractor element. A retractor of this invention can be delivered to the operative site using the instrument channel, or working channel, of a standard laparoscopic or endoscopic device. Such a standard device may also include other devices, especially a cautery device, laser, lithotriptor, visualization means, scalpel means, and the like, in one or more separate lumens. 
     FIG. 5-2  shows a top view of an expanded retractor of this invention. The retractor  108  has three loops  116  which fan out from the housing  110  upon deployment. One or more of the loops can be spanned by a membrane (see  FIG. 5-4 ). While three loops are shown, it will be apparent to one skilled in the art that one, two, four, or more loops can be provided to form the retractor. While the loops  116  pictured are substantially drop-shaped, other configurations are easily imagined. The loop or loops  116  can be, for example, round, oval, triangular, square, rectangular, irregularly shaped, and the like. When two or more loops are present the loops can be substantially similar in shape, or they can be dissimilar in shape. 
   The loops  116  can overlap, or they can be substantially independent from one another. In such a case a deforming pressure placed upon one loop perpendicular to the general plane of the loop will deform that loop, but will not affect the other loops. In a preferred embodiment, the loops  116  are interconnected and/or overlapping, and a deforming pressure placed upon one loop perpendicular to the general plane of the loop will be transmitted to the other loops. All loops thus act together, providing strength across the width of the retractor. The loops can be coated with a biocompatable material. The coated or uncoated loops can have a surface that prevents slippage of the retracted tissue. For example, the biocompabtble coating can provide a roughened or non-slippery texture to the loops. Alternatively, the loops can have gentle ridges or serrations upon all or part of the exposed surface. 
     FIG. 5-3  shows a top view of an expanded retractor of this invention. This preferred retractor  108  has three lobes, or finger means  118  which fan out from the housing  110  upon deployment. One or more of the finger means can be spanned by a membrane (see  FIG. 5-4 ). Alternatively, one or more of the spaces between fingers can be spanned by a membrane (see  FIG. 5-5 ). 
     FIG. 5-4  shows a top view of another expanded retractor of this invention. This retractor  108  has one loop means  116  which expands upon deployment from the housing  110 . As shown, the loop is spanned by a permeable, semipermeable or substantially impermeable membrane  120 . The membrane  120  is preferably made of a flexible and impermeable biocompatable material. The membrane is sufficiently thin that it can be folded or gathered, together with the elastically deformable retractor means  108 , to fit within the housing  110 . Suitable membrane materials include sheets of polyethylene, polyvinyl chloride, urethane, silicone rubber, and the like. 
   In an alternative embodiment, the membrane  120  is substantially impermeable to tissue, but is generally permeable to body fluids and other liquids which might be present during surgical procedures. In this embodiment, the membrane  120  can be a grid of shape memory material, a net, a web, and the like. Suitable materials include perforated, webbed or netted polyethylene, polyvinyl chloride, urethane, silicone rubber, and the like. 
     FIG. 5-5  shows a top view of yet another expanded retractor of this invention. This retractor  108  has two lobes, or finger means  118  which fan out upon deployment from the housing  110 . The space between the fingers is spanned by a membrane  120 . 
     FIG. 5-6  shows a top view of an alternate expanded retractor of this invention. Emerging from the housing  110  is a retractor  108  which has two loops  116 . As shown, a smaller loop  116   a  is nested within a larger loop  116   b . In the pictured embodiment, the smaller loop  116   a  is spanned by a membrane  120 . It will be apparent to one skilled in the art that any number of such loops, in various configurations, whether or not spanned by a membrane  120  either across or between loops, can be provided to form the retractor. 
     FIGS. 5-7  through  5 - 11  show side views of a deployed retractor of this invention. 
     FIG. 5-7  shows a side view of a deployed retractor of this invention. The amount of elastic curvature of the retractor  208  is greatest at the base of the retractor, where the retractor emerges from the housing  210 . 
     FIG. 5-8  shows an alternate side view of a deployed retractor of this invention. The amount of elastic curvature of the retractor  208  is fairly consistent across the length of the retractor  208 . 
     FIG. 5-9  shows yet another side view of a deployed retractor of this invention. The retractor  208  has the smallest radius of curvature at its distal end. 
   In  FIG. 5-10 , the retractor  208  is substantially straight upon deployment from the housing  210 . 
     FIG. 5-11  shows a retractor  208  which is gently curved. 
     FIGS. 5-12  and  5 - 13  show alternate end views of an expanded (unconstrained) retractor, such as shown by arrow E in  FIG. 5-10 . In end view, the expanded retractor can be flat. However, using the shape memory material retractors of this invention, other configurations are possible.  FIG. 5-12  shows a retractor which is gently curved across its width.  FIG. 5-13  shows a retractor  308  which is asymmetrical: it is flattened on one side, and curved or hooked on the other side. These configurations find particular application when the mass to be gently manipulated by the retractor is substantially parallel to the length of the retractor device or retractor housing. As used herein, the term “mass” refers to a tissue mass, or to a prosthetic device. Other configurations in addition to the flattened silhouette, and the curved configurations shown in  FIGS. 5-12  and  5 - 13 , will be readily apparent to one skilled in the art. For example, the retractor may be sharply angled, or it may be twisted along its length. The retractor may also have curvature in two or more directions in any of the planes described, such that the retractor may have a zig-zag or undulating appearance. 
   The various embodiments shown in  FIGS. 5-2  through  5 - 13  can be combined as desired. A retractor of this invention can comprise, for example, the three-fingered shape of  FIG. 5-3 , curved along its length as shown in  FIG. 5-8 , and curved along its width as shown in  FIG. 5-12 . Such a retractor is generally cup-shaped. 
     FIGS. 5-14  and  5 - 15  show alternate cross-sectional views of a constrained retractor, taken at line a-a of  FIG. 5-1 .  FIG. 5-14  shows a retractor made of wires  408  having a circular cross section, the retractor being constrained within the housing  410 .  FIG. 5-15  shows a retractor of strips  408  having an oval cross section. It will be clear to one skilled in the art that many other wire or strip cross-sections are equally appropriate for use in the retractors of this invention. For example, the retractor can be made of a strip member which is squared, rectangular, triangular, and the like. A cross-section such as the oval shape of  FIG. 5-15  is generally preferred for the refractors of this invention. Such a cross-section provides strength upon the application of force which is perpendicular to the general plane in which the retractor is elastically deployed, but provides minimized dimensions and resistance upon constraint of the retractor within the housing  410 . 
   In one preferred embodiment, a device of this invention comprises (a) a housing having an axial bore with a distal deployment opening; (b) a retractor which comprises a loop shape, the retractor being constrainable within said axial bore, and the retractor comprising a shape memory alloy; and (c) remote means to project and retract, and, optionally, to rotate, said retractor relative to the distal deployment opening. The retractor is moveable between a first position wherein the retractor is housed within the axial bore and assumes a constrained shape, and a second position wherein the retractor is extended past the distal deployment end and assumes an expanded memory shape. 
   The retractor is compressed and loaded within the housing. In this constrained configuration, the retractor device can be sterilized, packaged and stored for later use. The retractor device (i.e., retractor, housing, and deployment means) is preferably a disposable device. When needed, the surgeon visually assesses the size of retractor necessary for tissue manipulation, and selects a retractor which has an appropriate diameter, curvature and/or membrane. 
   In use, the device is partially inserted into a human or animal patient and used to manipulate organs or other tissues at an operative site. A guide wire may or may not be used for placement of the device. When a guide wire is used, it is introduced into the operative site and placed appropriately. A catheter containing a retractor is slipped over the guide wire. The guide wire is then removed, and the retractor is extended beyond the deployment end of the catheter. The guide wire preferably passes through a separate lumen in the catheter. Alternatively, the guide wire can pass through the catheter lumen which houses the retractor. The retractor can be radiopaque for ease of identification and use at the operative site. 
   A sixth form of the present invention provides a sheath-protected blade wherein the sheath is substantially straight. When it is constrained within the sheath, the blade is substantially linear. Upon deployment from the sheath, the blade is unconstrained, and assumes a configuration which is elastically deflected away from the longitudinal axis of the sheath. The blade is an elastically deformable material, preferably a pseudoelastic material, and more preferably a shape memory alloy. 
   One or more exposed edge of the elastic blade can provide a cutting edge. Exposed surfaces which are blunted can provide a means for manipulation of tissues or artificial devices. 
     FIG. 6-1  is an external view of a device of this invention. 
     FIGS. 6-2  and  6 - 3  are alternate cross-sectional views of a sheath of this invention, the cross sections being taken vertically along the longitudinal axis of  FIG. 6-1 . 
     FIG. 6-4  is an alternate cross-sectional view of a sheath of this invention, the cross section being taken vertically along the longitudinal axis. 
     FIG. 6-5  is a cross-sectional view of the device of  FIG. 6-1  taken across the lonqitudinal axis, along line b-b of  FIG. 6-1 .  FIG. 6-6  is a cross-sectional view of the device of  FIG. 6-1  taken across the longitudinal axis, along line c-c of  FIG. 6-1 . 
     FIG. 6-7  is a cross-sectional view of a cutting edge of a cutting blade of this invention. 
     FIGS. 6-8  through  FIG. 6-12  are alternate side views of the device of  FIG. 6-1  when the cutting blade is deployed. 
     FIG. 6-13  through  FIG. 6-20  are alternate top views of typical elastic blades of this invention. 
   A remotely operated device of this invention comprises an elongate housing, and an elongate blade which can be linearly constrained within the housing. The elastic blade is deployable from within the housing, and assumes a curved unconstrained shape upon deployment. Remote means are provided to project and retract, and optionally to rotate, the elastic blade relative to the distal end of the housing. Alternatively, remote means are provided to project and retract the sheath relative to the elastic blade. 
   The sheathed blade device of this invention differs from the prior art in several key aspects. The sheath is substantially straight along its length. When constrained within the sheath, the elastic blade is also substantially straight along its length. When deployed from the sheath the elastic blade assumes, as much as possible, its curved unconstrained shape. 
   The blades of this invention are curved (e.g., curled or twisted) along their length to a greater or lesser degree. The degree of curvature can be consistent along the length of the blade, or the curvature can vary in degree and/or in direction. A cutting surface can be provided at any desired exposed edge of the blade. When the unconstrained shape of the elastic blade is generally semicircular (such as shown in  FIG. 6-8 ) a cutting surface can be provided along the sides of the blade (such as shown in  FIGS. 6-13 ,  6 - 14 , and  6 - 19 ). Alternatively, a cutting surface can be provided at the tip of the blade (such as shown in  FIGS. 6-15 ,  6 - 16 , and  6 - 17 ) to provide a scalpel which has a cutting surface directed 180° from the opening of the sheath. Varying the amount of deployment of the blade varies the cutting angle, so that a blade can be provided in which the cutting surface is angled from 0° to 180° or greater from the axis of the sheath. 
   The elastic nature of the blade allows for a complete retraction of the blade into the sheath for a complete protective enclosing of the blade, protecting both the blade and the body tissue during both the insertion and removal of the instrument. The sheath not only protects the blade but also guides and directs the blade whereby the extension of the blade from the sheath can comprise a cutting movement of the blade, rather than merely a means for exposing the blade for subsequent manipulation. The user, upon selection of the appropriate elastic blade (i.e., a blade having a desired curvature and position of cutting edge), orients the sheath, and then extends the blade. The blade is extended either by moving the blade outward from the sheath, or retracting the sheath relative to the blade. 
   Similar numbers refer to similar function throughout the Figures. The Figures are drawn for clarity and are not drawn to scale. 
     FIG. 6-1  is an external view of a device of this invention. The housing  10  is an elongate member, having an axial bore therethrough. The housing has a distal end  12 , which acts as a sheath for the elastic blade, and a proximal end  14 , which provides integration with a means to project and retract the elastic blade relative to the distal end of the housing  10 . Between the distal end  12  and the proximal end  14  is the housing body  16 . 
   The housing preferably also includes a remote means  18 , the actuation of which causes the elastic blade to be deployed from the housing, or the housing to be retracted from the blade. The remote means  18  can be actuated by any manual or motorized means (not shown). In one embodiment, as pictured, two finger rings  20  are part of the proximal end  14 . An additional thumb ring  22  is part of the remote means  18 . When the thumb ring  22  is depressed, the elastic blade (not shown) is deployed from the housing at the distal end  12 . The pictured rings are for ease of handling. Alternatively, knobs or ridges, for example, can be provided for ease of integration with a separate actuator means (not shown). Separate actuator means include slider mechanisms, pistol grip or thumb actuated mechanisms, scissors handles, and pistol-grip mechanisms. These and others are well known to the art. The specific type of actuator mechanism is generally determined by the personal preference of the surgeon. The orientation of the blade relative to the actuator mechanism can be configured to suit the specific application or the preference of the surgeon. 
   The distal end  12  of the housing acts as a sheath which constrains the elastic blade in a substantially linear configuration. It possesses sufficient lateral integrity that it is not significantly deformed by the pressure exerted by the constrained elastic blade. When an endoscopic device of this invention is a catheter and there is little lateral support in the housing body  16 , the distal end  12  of the catheter may require reinforcement to provide consistent constraint of the elastic blade (not shown). In a device having a rigid housing, such as a laparoscopic device, the distal end  12  of the housing can have the same physical attributes as the remainder of the housing. Standard endoscopic and laparoscopic devices well known to the art are appropriate for use with the elastic blades of this invention. 
   The housing body  16  of a device which is used in laparoscopy must have sufficient structural integrity that it is easily inserted through a surgical opening into the body of the patient without undue deformation. Materials with sufficient structural rigidity include stainless steel and rigid polymeric materials such as plastics. The material of the proximal end of the housing  14 , the material of the housing body  16 , and the material of the distal end  12 , can be the same, or can have different physical properties. For example, the housing body  16  used in endoscopic surgery will generally be flexible, to allow insertion through naturally occurring orifices, ducts, and/or passages, or to allow insertion through the working channel of an endoscope. Suitable polymeric material includes polytetrafluorethylene, polyurethane, polyethylene, Teflon, and the like. The material of such a flexible housing may be reinforced at the distal end  12  with fibers, rings, or longitudinal ribs, for example, to enable it to withstand the forces exerted on it by the elastic blade while it is constrained within, and deformed by, the housing. 
   The specific configuration and dimensions of the housing  10  will vary with the use of the device, the parameters of the elastic blade, and whether access for additional laparoscopic or endoscopic devices is provided. The housing  10  can be substantially uniform along its length, as shown in  FIG. 6-1 , or it can vary in diameter or shape, as shown in  FIG. 6-4 . Preferably, the housing  10  has a circular cross-section. A circular cross-section permits delivery of an elastic blade of this invention through a standard laparoscopic trocar, or through the instrument channel of a standard endoscope. However, other cross-sections may be preferable, for example, to adapt an endoscopic device to the orifice through which it will enter the body. 
   In general, the housing in an endoscopic device will have an outside diameter of from less than about 0.7 mm to about 4.5 cm or greater. The length of endoscopic devices will be from less than about 10 cm to about 3 meters or greater. The housing in a laparoscopic device will have an outside diameter of from less than about 0.3 mm to about 1.5 cm or greater. The length of laparoscopic devices will be from less than about 5 cm to about 30 cm or greater. 
     FIGS. 6-2  and  6 - 3  are alternate cross-sectional views of a device of this invention, the cross section being taken vertically along the longitudinal axis of the distal end  12  of  FIG. 6-1 . 
     FIG. 6-2  shows the distal end  112  of a housing  110  which is made as one unit. An axial bore  130  runs axially through the housing. At the proximal end  132  of the axial bore  130 , the axial bore can have any convenient size and shape. In general the axial bore will have an internal diameter of from less than about 0.5 mm to about 2 cm or greater. At the distal end, the axial bore becomes flattened, and forms the sheath bore  134  for the constrained elastic blade  136 . The sheath bore  134  is sized to slidably accept the constrained elastic blade  136 , and to constrain the elastic blade  136  in a substantially linear configuration. When the elastic blade  136  is fully housed within the sheath bore  134 , the sheath bore  134  contains at least those portions of the elastic blade  136  which have cutting edges. Preferably the cutting edges of the elastic blade  136  do not touch or rub against the sheath bore  134  when stored, or upon deployment or retraction, as such contact can dull the cutting edges. 
   In general the proximal end  132  of the axial bore  130  will be circular and relatively large, to facilitate the loading of the connecting means  138  and the elastic blade  136  within the sheath. A circular conformation is for general ease of manufacture and handling, and alternate conformations can be used, as desired. The proximal end  132  of the axial bore  130  houses the connecting means  138 . The connecting means  138  can be, for example, soldered or otherwise affixed to the elastic blade. Alternatively, it can be a continuation of the elastic material used to form the elastic blade  136 . 
     FIG. 6-3  shows the distal end  112  of a housing  110  which is made as two units. One unit is a tube  140  through which extends an axial bore  130 . A bushing  142  is fitted within the tube, for example by press fit or by thread. The bushing  142  provides the sheath bore  134  for the constrained elastic blade  136 . The bushing  142  can be made of any suitable material, polymeric and/or metallic. It may be desirable to pass an electric current through the elastic blade  136 , so that the elastic blade  136  acts as an electrocautery device. In such an embodiment the bushing can be a non-conducting polymer, and it can act to keep the elastic blade  136  electrically insulated from the housing  110 . The elastic blade  136  is held for reciprocal motion by the connecting means  138 . 
     FIG. 6-4  is an alternate cross-sectional view of the distal end  112  of a housing  110  of this invention, the cross section being taken vertically along the longitudinal axis. In this embodiment the housing  110  is a metal or plastic tube which has been flattened at one end. The flattened end provides the sheath bore  134  in which the elastic blade is slidably constrained. The elastic blade  136  is held for reciprocal motion by the connecting means  138 . 
   If the housing  110  is a tubular structure having a flattened end, as shown in  FIG. 6-4 , it may be desirable to provide a covering of any suitable material (not shown). The covering provides a uniform outer dimension for the device. A covering which provides a substantially uniform circular cross-section is advantageous if the blade device is to be introduced into the body through a standard laparoscopic trocar, or through the instrument channel of a standard endoscope. The covering acts to minimize the escape of fluids (either liquid or gas) from the body. The covering can be made of a polymeric material such as polyurethane, polyethylene, and the like. 
     FIG. 6-5  is a cross-sectional view of the device of  FIG. 6-2  taken across the longitudinal axis at line b-b. The housing  210  surrounds the axial bore  230 . Within the axial bore is the connecting means  238 . The connecting means  238  can have any suitable cross-sectional shape. In the shown embodiment the connecting means  238  spans axial bore  230  to minimize lateral motion as the sheath and elastic blade (not shown) are moved longitudinally relative to each other. If an electric current is passed through the connecting means  238  and the elastic blade, so that the elastic blade acts as an electrocautery device, it may be desirable to include a layer of a non-conducting material (not shown) around connecting means  238  to insulate the connecting means  238  from the housing  210 . 
     FIG. 6-6  is a cross-sectional view of the device of  FIG. 6-2  taken across the longitudinal axis at line c-c. The housing  210  surrounds the sheath bore  234 . Within the sheath bore is the elastic blade  236 . 
   One or more edges of the elastic blade  236  can remain dull, and can aid the non-cutting manipulation of tissues or artificial devices during surgery. For instance, the blade can have no cutting edges. This minimizes the amount of trauma to surrounding tissues upon manipulation of the blade. More generally, the elastic blade  236  has one or more sharpened edges  240 . The sheath bore  234  is substantially flattened, and holds the elastic blade  236  so that the elastic blade  236  is constrained linearly. In a preferred embodiment, the sheath bore  234  is slightly enlarged in the region of the sharpened edges  240 . This acts to protect the sharpened blade from wear as it is deployed from, and withdrawn into, the housing. Alternatively, the sheath bore  234  closely mimics the outer shape of the elastic blade  236 . Other embodiments are also possible, such as a sheath bore  234  which is substantially rectangular or eccentric, and such embodiments will be readily apparent to one skilled in the art. 
     FIG. 6-7  is a cross-sectional view of a cutting edge of a cutting blade of this invention. A cutting edge can be provided at any edge of the elastic blade. In a preferred embodiment, the edge of the elastic material is beveled, and provides a cutting blade.  FIG. 6-7  shows a cutting edge which is beveled on both sides. The bevel or bevels can be at any appropriate angle from the plane of the blade. When two bevels are present, they can have the same angle of bevel, or different angles of bevel. In  FIG. 6-7 , the bevels are β and .phi degrees from the plane of the blade. Alternatively, only one bevel may be present (not shown). The honing of an edge to form a cutting blade is well known in the art. If desired, the cutting blade can be serrated. The cutting edge is preferably derived from the beveled elastic material itself. However, it may be desirable or necessary to provide a honed blade edge to the elastic material. This additional blade can be added mechanically, as shown in  FIG. 6-12 . Alternatively, two or more elastic materials can be used to form the blade. For example, a non-cutting elastic blade can be combined with an elastic alloy blade having a cutting edge. 
     FIGS. 6-8  through  6 - 11  are side views of the device of  FIG. 6-1  when the elastic blade is deployed. A cutting surface can be provided at any desired exposed edge of the blade. 
     FIG. 6-8  shows an elastic blade  336  which is substantially semicircular upon deployment from the housing  310 . The degree of curvature can be substantially consistent along the length of the blade, as shown, or the curvature can vary, i.e., the elastic blade can have a uniform or non-uniform radius of curvature. 
     FIG. 6-9  shows an elastic blade  336  which describes an S-shaped curve upon deployment from the housing  310 . 
     FIG. 6-10  shows an elastic blade  336  which is twisted along its longitudinal axis upon deployment from the housing  310 . The elastic blade is shown having a clockwise spiral, but counterclockwise spirals, and combinations of the two, are also appropriate for use herein. 
     FIG. 6-11  shows an elastic blade  336  which is sharply curved in the region closest the housing  310 , and substantially linear in the region furthest from the housing  310 . 
     FIG. 6-12  shows a standard surgical blade  350 , which is attached to a strip of elastic material  352  by a mechanical means  354 . The standard surgical blade  350  is not curved. However, the strip of elastic material  352  is strongly bent and upon deployment from the housing it acts to bend the surgical blade  350  sharply away from the housing  310 . 
     FIGS. 6-13  through  6 - 19  are each a top view of an alternate elastic blade of this invention. 
     FIG. 6-13  shows a top view of an elastic blade  436  which has one longitudinal sharpened (cutting) edge  460 . 
     FIG. 6-14  shows a top view of an elastic blade  436  in which the entire perimeter of the blade provides the sharpened edge  460 . 
     FIG. 6-15  shows a top view of an elastic blade  436  in which only the most distal surface provides the sharpened edge  460 . 
     FIG. 6-16  shows a top view of an elastic blade  436  in which only the most distal surface provides the sharpened edge  460 . The sharpened edge  460  has two angled sections,  460   a  and  460   b , each of which is angled relative to the longitudinal axis of the blade. The angled sections can have any desired degree of angle relative to the longitudinal axis of the blade, and the degree of angle for each section can be similar to, or dissimilar to, that of the other section. 
     FIG. 6-17  shows a top view of an elastic blade  436  in which an outwardly curved surface provides the sharpened edge  460 . 
     FIG. 6-18  shows a top view of an elastic blade  436  in which an inwardly curved surface provides the sharpened edge  460 . 
     FIG. 6-19  shows a top view of a preferred embodiment of the elastic blade  436  in which the distal perimeter of the blade provides the sharpened edge  460 , and the proximal edges of the blade are unsharpened. The width of distal section of the elastic blade  436  is somewhat less than the width of the proximal section. The distal portion of the elastic blade having the sharpened edge  460  is narrower than proximal unsharpened portion, so that the sharpened edge  460  will not touch the sides of the sheath bore. The sharpened edge  460  is therefore protected during the process of deployment and retraction of the elastic blade  436 . 
     FIG. 6-20  shows a top view of an embodiment of the elastic blade  436  in which all edges of the blade are unsharpened. This embodiment is preferred when the blade is not used to cut tissues, and can function to manipulate tissues or artificial devices. 
   The elastic blade is compressed and loaded within the sheath. In this constrained configuration, the blade and sheath can be sterilized, packaged and stored for later use 
   In one preferred embodiment, a device of this invention comprises (a) a housing having a distal deployment opening; (b) a curved elastic blade which is linearly constrainable within the housing; and (c) remote means to project and retract the elastic blade relative to the distal deployment opening; the elastic blade being moveable between a first position wherein the elastic blade is linearly constrained within the housing, and a second position wherein the elastic blade is extended past the distal deployment end and assumes a memory shape. 
   In a preferred embodiment, a blade of this invention comprises an elastically deformable curved blade. 
   According to a seventh form of the present invention, it has now been discovered that a pivoted two-bladed device, such as a forceps, scissors, snips, and the like, can be combined with an elastically deformable stem. Remote blade actuator means are used to cause the blades to splay apart or come together. An elastic member and a constraining member, for deforming the elastically deformable stem, are present. The elastic member and the constraining means are longitudinally slidable relative to one another, causing the angular deformation of the elastically deformable stem. 
   The elastically deformable stem includes an elastic member which is substantially linear when it is constrained, and assumes a substantially non-linear shape when it is unconstrained. When a constraining elongate housing is present and serves as the constraining member, the elastic member is moveable between a first position wherein the elastic member is linearly constrained within the housing, and a second position wherein the elastic member is deployed from the housing and is unconstrained. Alternatively, the housing is moveable between a first position wherein the elastic member is linearly constrained, and a second position wherein the elastic member is unconstrained. The elastically deformable stem, which includes the elastic member, assume a nonlinear shape. The amount of deformation of the elastically deformable stem can be controlled by adjusting the amount of the elastic member which is not constrained by the elongate housing. 
   If the device does not include an elongate housing, and in embodiments in which the elongate housing is present but is not a constraining member, an internal constraining member is present. The deformation of the elastically deformable stem can be controlled by moving the elastic member between a first position wherein the elastic member is linearly constrained, and a second position wherein the elastic member is substantially unconstrained. Alternately, the deformation of the elastically deformable stem can be controlled by moving the constraining member between a first position wherein the elastic member is linearly constrained, and a second position wherein the elastic member is substantially unconstrained. Between the first, constrained, position and the second, unconstrained, position, is a range of partial or variable deployment. 
   The elastic member is formed of an elastic material, preferably a pseudoelastic material such as a shape memory alloy, which is capable of being greatly deformed without permanent deformation. This provides an improved instrument that can be used in applications in which there is a limited amount of space. The instrument can be operated remotely, and at angles to the line of insertion, more conveniently than previous instruments. The instrument, with appropriately configured blade edges and/or tips, can be used to grasp, cut, and/or dissect tissue. 
   A remotely operated instrument of this invention comprises (a) a bladed element having a first pivoted blade, and a second opposing blade; (b) an elastically deformable stem connected to the bladed element, the elastically deformable stem including an elastic-member; (c) a constraining member which can constrain the elastic member in a substantially linear configuration; (d) a blade actuator means for controlling pivotal motion of the pivotable blade(s); and (e) a stem deforming means for controlling deformation of the elastically deformable stem. A separate blade rotator means, for controlling rotation of the plane through which the blade(s) are pivoted, is preferably included. 
   An alternate remotely operated instrument of this invention comprises: (a) a bladed element, having opposable blades including a first blade which is mounted for movement relative to the second blade; the first blade being moveable between a closed position wherein the axes of the blades are substantially parallel, and an open position, wherein the axes of the blades are deflected from the parallel; (b) an elastically deformable stem including an elastic member which is substantially non-linear in its unconstrained shape; (c) a constraining member which constrains the elastic member in a substantially linear shape; (d) a blade actuator means, said blade actuator means controlling position of the opposing blades between the open position and the closed position; and (e) a stem deformation controlling means. A rotation means, for controlling the plane of the blades, is preferably included. 
   The elastically deformable stem includes at least one elastic member which assumes a linear configuration when constrained, and which is curved when unconstrained. The elastic member is held in a constrained configuration by the presence of the constraining member. Elastic materials which are suitable for use in the elastic member include pseudoelastic and superelastic materials, as described below. 
   When an elongate housing is present and acts as the constraining member, the instrument is moveable between a first position wherein the elastically deformable stem and, optionally, the bladed element, are within the housing, and a second position wherein the bladed element and at least part of the elastically deformable stem are deployed from the housing. The elastically deployable stem includes an elastic member which is curved at a predetermined angle with respect to the elongate housing when the elastically deformable stem is deployed from the housing. When the housing acts as the constraining member, varying the amount of deployment of the elastically deformable stem varies the angle of presentation of the bladed element. 
   In an alternate embodiment, the elastic member is constrained in a linear configuration by the action of an internal constraining member, such as an internal constraining rod. Movement of the internal constraining member relative to the elastic member causes variable deformation of the elastically deformable stem. An elongate housing may or may not be present in embodiments in which an internal constraining member is present. 
   The bladed instrument can comprise a grasping device (e.g., a forceps), a cutting device (e.g., a scissors), or a dissecting device. 
     FIG. 7-1  shows an instrument of this invention. 
     FIGS. 7-2  show the deployment end of a bladed instrument of this invention. 
     FIGS. 7-3  and  7 - 4  are longitudinal cross-sectional views of alternate elastically deployable stems, in longitudinally constrained and longitudinally unconstrained configurations. 
     FIGS. 7-5  through  7 - 7  each show alternate views of an elastically deformable stem of this invention. 
     FIGS. 7-8  and  7 - 9  show alternate elastic members suitabe for use in an elastically deformable stem of this invention. 
     FIGS. 7-10  show alternate views of a device of this invention having two pivoted blades, each blade having a longitudinal slot proximal the pivot. 
     FIGS. 7-11  show alternate views of a device of this invention having two blades, two bars, and four pivots. 
     FIGS. 7-12  show alternate cross-sections of the device of  FIG. 7-1 , taken through line  12 -- 12 . 
     FIGS. 7-13  show various blades suitable for use herein. 
     FIGS. 7-14  show various blade cross-sections, taken throuh line  14 - 14  of  FIG. 7-13 . 
   A surgical instrument of this invention consists essentially of a bladed element having opposable blades, at least one of which is pivotally mounted for movement; a blade actuator means for causing pivotal motion of the pivotable blade(s); an elastically deformable stem connected to the bladed element, and a variable constraining means for causing deformation of the elastically deformable stem. 
   The instrument is particularly useful in applications in which access to an object to be cut, grasped, or dissected is restricted. For example, the instrument is especially useful in medical applications in which the object to be cut, grasped, or dissected is part of a human or animal body. In such applications, the surgical instrument generally includes or is passed through a sheath in the form of a cannula, catheter, or endoscope. The distal end of the sheath is introduced through an opening into a body cavity, duct, or joint, for example during laparoscopic surgery. 
   The instrument may also be useful in the assembly of mechanical, electrical or other equipment, especially when access to the worksite is limited, or when the worksite is located at an angle to the access. 
   The instrument includes an elastically deformable stem, so that the bladed element can be variably angled away from the angle of introduction. When an elongate housing (e.g., a sheath) is present, the bladed elements can be arranged such that the axis on which the elements cut, grasp, and/or dissect the object is not coaxial with the axis of at least a significant portion of the elongate housing. 
   The elastically deformable stem includes at least one elastic member, which is made of an elastic material. The elastic member is manufactured in a non-linear shape. For example, the elastic member is manufactured having one or more (generally one) bend, curve or twist. The bend, curve or twist can describe any desired angle. The angle described by the elastic member is generally less than 270°, more generally less than about 180°. For many applications, an angle of about 90° is preferred. The angle described by the elastic member in its unconstrained shape is the maximum amount of deformation which can be attained by the elastically deformable stem. 
   The elastic member is deformed (constrained) from the bent configuration towards the straight configuration, and held in the straight (constrained) configuration during positioning of the instrument. Preferably, the bladed element is fully functional when the blades are not housed within the elongate housing, whether or not the elastically deformable stem has been deployed. When the elastically deformable stem is to assume an angled (unconstrained) configuration, the constraining member is removed. When the elastically deformable stem is constrained by an elongate housing, the housing is withdrawn to permit the elastic member to regain its bent (unconstrained) shape, and thus deform the elastically deformable stem. When the elastically deformable stem is constrained by a constraining rod, for example, the rod is preferably withdrawn to permit the elastically deformable stem to regain its bent (unconstrained) shape. Alternately, the elastic member can be deployed beyond the constraining member to permit the elastic member to assume its unconstrained shape and to deform the elastically deformable stem. 
   The amount of deformation of the elastically deformable stem can be variably controlled between the maximum and the minimum by manipulation of the constraining member. The constraining means is generally a longitudinally slidable rigid member. The constraining member can comprise, for example, a stiff elongate housing, or a substantially linear stiff constraining rod. Alternatively, the constraining member can be fixed, and the elastic member can be slidable relative to the constraining member. 
   The elastically deformable stem can be, for example, a rod, one or more wires, a hollow tubular element, or the like. 
   When the instrument includes a housing which acts to constrain the elastic member into a substantially linear shape, the housing and the elastically deformable stem are moved longitudinally relative to each other to release the elastic member from lateral constraint. The elastic member regains its original (unconstrained) non-linear shape, and thus to deform the elastically deformable stem. This approach is shown in graphic cross-section in  FIG. 7-3 . 
   Alternatively, the elastically deformable stem can include a substantially linear constraining rod. This constraining rod deforms the elastic member into a substantially linear shape. As the constraining rod and the elastic member are withdrawn relative to one another, the elastic member regains its original non-linear shape and causes the elastically deformable stem to deform. This approach is shown in graphic cross-section in  FIG. 7-4 . 
   In yet another embodiment (not shown), the instrument includes a substantially linear constraining means which has a fixed position. This constraining means deforms the elastic member into a substantially linear shape. As the elastic member and the constraining rod are withdrawn relative to one another, the elastic member regains its original non-linear shape and causes the elastically deformable stem to deform. 
   The elastic member of the elastically deformable stem comprises an elastic material which is substantially linear in its constrained configuration, and is curved in its unconstrained, or “memory”, configuration. The term “elastic material” is used herein to mean a material that has spring-like properties, that is, it is capable of being deformed by an applied stress and then springing back, or recovering, to or toward its original unstressed shape or configuration when the stress is removed. The elastic material is preferably highly elastic. The material can be polymeric or metallic, or a combination of both. The use of metals, such as shape memory alloys, is preferred. Shape memory alloys that exhibit pseudoelasticity, in particular superelasticity, are especially preferred. The elastic materials herein exhibit greater than 1% elastic deformation, more generally greater than 2% elastic deformation. Preferably, the elastic materials herein exhibit greater than 4% elastic deformation, more preferably greater than 6% elastic deformation. 
   Preferably, the elastic member is at least partially formed from a pseudoelastic material, such as a shape memory alloy. 
   The Figures are drawn for clarity and are not drawn to scale. 
     FIG. 7-1  shows a bladed instrument of this invention. As shown, a scissors-type blade actuator mechanism  110  controls the pivotal movement of the blades  112 . A finger-activated stem deformation controlling means  114  is used to control the deployment of the bladed element  116  and the elastically deformable stem  118  from the elongate housing  120 . A rotator mechanism  122  is shown in the form of a knob, and is used to rotate the elastically deformable stem  118  and the bladed element  116  around the long axis of the elongate housing  120 . Each of: the actuator mechamism  110 , the stem deformation controlling means  114 , and the rotator mechanism  122  can take any suitable manually operated configuration. The specific configuration of each of the actuator mechanism  110 , the stem deformation controlling means  114 , and the rotator mechanism  122  can be the same, or they can be different, as shown. Examples of suitable manually operated mechanisms include one or more slider, pistol grip handle, scissors handle, and/or plunger arrangement. These and other such devices are well known to the art. 
   An elongate housing  120  maintains, the elastic member  124  in a substantially linear configuration prior to deployment of the elastically deformable stem  118  and the bladed element  116 . Upon full deployment from the elongate housing, the bladed element  116  assumes a position which is at an angle from the elongate housing  120 . It should be noted that the angle .phi between the elongate housing  120  and the bladed element  116  can be any number of degrees desired. As shown, angle .phi. is approximately 60°. Angle .phi. is defined by the axis of the elongate housing β, and the plane which is perpendicular to the axis of the pivot  126  around which the blades pivot. Angle .phi. can be any desired angle. Preferably a rotator mechanism  122  is provided, and permits rotation of the bladed element  116  and the elastically deformable stem  118  around the long axis of the elongate housing β. The rotation of the bladed element  116  is preferably independent of the amount of deployment of the elastically deformable stem  118 . 
   The elongate housing  120  is an elongate sheath having an axial bore (not shown) therethrough. The axial bore is sized to receive the elastically deformable stem and, optionally, the bladed element, in a constrained configuration. The axial bore can have a consistent dimension through the length of the elongate housing  120 , or the axial bore can widen and narrow as necessary to conform to the shape of the elastically deformable stem  118  and, optionally, to the bladed element  116 . 
   In general, the elongate housing  120  can be flexible or rigid, and the rigidity can vary by region. When the elongate housing does not act as the constraining member, an alternate constraining member (such as an internal constraint) must be present. Standard catheters and laparoscopic devices well known to the art are appropriate housings for the bladed element and the elastically deformable stem. The stiff-sheath elongate housing of  FIG. 7-1  can be polymeric or metallic, for example stainless steel. A preferred stiff elongate housing is a rigid elongate tube of stainless steel. 
   The elongate housing  120  can be circular in cross-section, but other cross-sections may be preferable in some situations. For example, squared, oval, or eccentric cross-sections can be used. The elongate housing can be substantially uniform in cross-section along its length, or it can vary. 
   The specific configuration and dimensions of the elongate housing  120  will vary with the use of the device, the parameters of the bladed element, and whether access for additional surgical devices is provided. The outer diameter of the elongate housing will vary with the application and the size of the bladed element. For example, the elongate housing in a laparoscopic device will have a diameter of from less than about 3 mm to about 1.5 cm or greater; the length of a laparoscopic device will be from less than about 20 cm to about 30 cm or greater. 
   In any of the embodiments of this invention, a suitable means may be provided for passing a fluid (liquid or gas) through the device for irrigation, aspiration, insufflation, and the like. In any of the embodiments of this invention, electricity may be passed to one or both end portion(s) of the blade(s) for purposes of electrocautery or electrocutting. 
     FIGS. 7-2   a  through  7 - 2   d  are side views of the distal end of an instrument of this invention. The instrument shown in  FIG. 7-2  includes a rigid elongate housing  128  which acts as the constraining means. 
   As shown in  FIG. 7-2 , the instrument is moveable between a first position ( FIG. 7-2   a  or  FIG. 7-2   b ) wherein the elastically deformable stem  132  is constrained within the elongate housing  128 , and a second position ( FIG. 7-2   d ) wherein the bladed element  130  and the elastically deformable stem  132  extend past the constraint of the elongate housing  128  and assume a memory shape. In one embodiment, both the elastically deformable stem  132  and the bladed element  130  are fully retractable into the elongate housing  128 , as shown in  FIG. 7-2   a . Between the first position and that shown in  FIG. 7-2   d  are degrees of deployment (for example that shown in  FIGS. 7-2   b  and   7 - 2   c ) in which the bladed element  130  is deployed sufficiently for use ( FIG. 7-2   b ), and in which the elastically deformable stem  132  is partially deployed ( FIG. 7-2   c ). In an alternate embodiment, the bladed element  130  is not retractable into the elongate housing  128 . Such an embodiment is demonstrated in  FIGS. 7-2   b  through  7 - 2   d . These variable degrees of partial deployment allow the operator to choose the angle of deflection that the bladed element assumes relative to the elongate housing  128 . (Pivotal actuation of the blades is not shown in this series of figures.) 
   After use, the instrument is removed from the worksite. When the worksite is within a patient the elastically deformable stem  132  and, optionally, the bladed element  130 , are retracted back into the elongate housing  128  before the instrument is removed from the patient: the various elements therefore resume the configuration shown in  FIG. 7-2   a  before removal. If only the elastically deformable stem  132  is retracted back into the elongate housing  128  before the instrument is removed from the patient, the elements resume the configuration shown in  FIG. 7-2   b  before removal. 
     FIG. 7-2   b  shows the blades  134  free of the elongate housing  128 . The blades  134 , the pivot  136 , and other elements necessary for pivotal motion of one or more blade (but not including the blade actuator) comprise the bladed element  130 . A portion of the elastic member  138  is shown. In the pictured embodiment, the elastic member  138  comprises two strips of elastic material, each strip being secured to the pivot  136 . The elastic member  138  can have any desired cross-sectional shape, and the cross-sectional shape can vary along its length. Preferred cross-sectional shapes include a tubular shape or rod shape, and a rectangular or roughly rectangular shape. In the embodiment shown the elastic member  138  comprises two strips which are not in the neutral plane of bending of the elastically deformable stem  132 : this is a less preferred configuration. The preferred placement of the elastic member is at or near the neutral plane of bending of the elastically deformable stem  132 , and is discussed further below. 
     FIG. 7-2   c  shows the bladed element  130  as it is deployed axially from the elongate housing  128 . Also shown is a portion of the elastic member  138 . Shown next to the elastic member  138  is the blade actuator rod  140 . In this embodiment, the elastic member  138  and the blade actuator rod  140  are included within the elastically deformable stem  132 . The actuator rod  140  is preferably centrally located within the elastically deformable stem. 
   The blade actuator rod  140  can comprise a rod, strip, filament, cord, conduit catheter, pipe, lever, or other suitable connecting means which allows the remote pivotal manipulation of the blade(s). More than one such element can be present. The cross-sectional parameters of the blade actuator rod can vary along its length. Any suitable material, including a shape-memory material, can be used to form the blade actuator rod  140 . In one embodiment the elastic member also acts as the blade actuator rod  140 . The blade actuator rod  140  preferably has sufficient flexibility that it does not interfere with the elastic deformation of the elastic member  138 . The blade actuator rod  140  can be positioned as desired within the elastically deformable stem  132 . Preferably, the blade actuator rod  140  is located in a position that does not interfere with the longitudinal motion of the elastic member  138  or of the constraining member, and does not interfere with the bending motion of the elastic member  138 . At the actuator end of the instrument (not shown), the blade actuator rod  140  can integrate with an actuator means, such as a slider mechanism, pistol grip or thumb actuated mechanism, scissors handle, and/or plunger mechanism. Alternatively, the actuator rod  140  projects proximally from the elongate housing  128 , and can be directly manipulated to cause pivotal motion of the opposing blades. The blade actuator means includes the actuator rod  140 , any apparatus necessary to integrate with the bladed element and the actuator mechanism (if any). The blade actuator means is used remotely to open and close the bladed element. Illustrative actuating means are described more fully below with reference to the drawings and include rack and pinion means, pin and slot means, four-bar linkages, and the like. In certain embodiments, the actuating means may be formed of a pseudoelastic material. The actuating means may permit the bladed element to be axially rotated. The actuating means can also provide suitable means for irrigating or aspirating the workfield of the bladed elements, or can conduct electrical current to one or both of the blades, if desired. 
     FIG. 7-2   d  shows the bladed element  130  in the fully deployed configuration. The elastically deformable stem  132  is fully deployed (i.e., has achieved its fully unconstrained shape), and, as depicted, holds the bladed element  130  in position approximately 90° from the axis of the body of the instrument. 
   Reconstraining the elastically deformable stem  132  as shown in  FIG. 7-2   d  is accomplished by reversing the process, i.e, by moving the elements to the configuration shown in  FIGS. 7-2   c ,  7 - 2   b , and (optionally)  7 - 2   a , sequentially. 
     FIG. 7-3  provides cross-sectional views of one segment of an elastically deformable stem  142  in constrained ( FIG. 7-3   a ), partially constrained ( FIG. 7-3   b ), and unconstrained ( FIG. 7-3   c ) configurations. 
     FIG. 7-3   a  shows a section of an elongate housing  144  which surrounds the elastically deformable stem  142 . The elastically deformable stem  142  is fully constrained by the elongate housing  144 , and is in a substantially linear configuration. The elastically deformable stem  142  includes an elastic member  146  in the shape of a tube, and the enclosed blade actuator rod  148 . 
   The elongate housing  144  and the elastically deformable stem  142  are capable of reciprocal longitudinal motion, e.g., are longitudinally slidable relative to one another. For example, the elongate housing  144  can be moved in direction L (arrow) to deploy the elastically deformable stem  142 . The same effect can be achieved by moving the elastically deformable stem  142  in direction R (arrow). Alternatively, the elongate housing  144  can be moved in direction L (arrow) while the elastically deformable stem  142  is moved in direction R (arrow), to achieve deployment of the elastically deformable stem  142 . Point a is labeled on  FIGS. 7-3   a ,  7 - 3   b  and  7 - 3   c , and shows the relative movement of the elastically deformable stem  142  relative to the elongate housing  144 . 
     FIG. 7-3   b  shows the section of elastically deformable stem  142  in a partially deployed configuration. The elastically deformable stem  142  is partially constrained in a linear configuration by the elongate housing  144 , and partially unconstrained. 
     FIG. 7-3   c  shows the section of elastically deformable stem  142  in a fully deployed configuration. The elastically deformable stem  142  is unconstrained, and shows the maximum deformation available from the specific elastic member  146 . 
   Reconstraining the elastically deformable stem  142  as shown in  FIG. 7-3   c  is accomplished by reversing the process, i.e., by moving the elements to the configuration shown in  FIGS. 7-3   b  and  7 - 3   a , sequentially. 
     FIG. 7-4  provides views of one segment of an elastically deployable stem  150  in constrained ( FIG. 7-4   a ), partially constrained ( FIG. 7-4   b ), and unconstrained ( FIG. 7-4   c ) configurations. 
     FIG. 7-4   a  shows a section of an elastically deformable stem  150  which is constrained by the constraining rod  152 , and is held in a substantially linear configuration. The elastically deformable stem  150  comprises an elastic member  154 , the blade actuator rod  156 , and the constraining rod  152 . 
   The constraining rod  152  and the elastically deformable stem  150  are longitudinally slidable relative to one another. For example, the constraining rod  152  can be moved in direction L (arrow) to cause deformation of the elastically deformable stem  150 . The same effect can be achieved by moving the elastically deformable stem  150  in direction R (arrow). Alternatively, the constraining rod  152  can be moved in direction L (arrow) while the elastically deformable stem  150  is simultaneously moved in direction R (arrow), to achieve deformation of the elastically deformable stem  150 . Point b is labeled on  FIGS. 7-4   a ,  7 - 4   b  and  7 - 4   c , and shows the relative movement of the elastically deformable stem  150  relative to the constraining rod  152 . 
     FIG. 7-4   b  shows the section of elastically deformable stem  150  in a partially deployed configuration. The elastically deformable stem  150  is partially constrained in a linear configuration by the constraining rod  152 , and partially unconstrained. 
     FIG. 7-4   c  shows the section of elastically deformable stem  150  in a fully deployed configuration. The elastically deformable stem  150  is unconstrained, and shows the maximum deformation available from the specific elastic member  154 . 
   Reconstraining the elastically deformable stem  150  as shown in  FIG. 7-4   c  is accomplished by reversing the process, i.e., by moving the elements to the configuration shown in  FIGS. 7-4   b  and  7 - 4   a , sequentially. 
   In one embodiment (not shown) the elastically deformable stem and the rigid constraining rod are present only at the distal (introduced) end of the instrument, near the bladed element. The major portion of the introduced body of the instrument is relatively flexible. Such an embodiment finds particular use as an endoscopic device, i.e., a device which can be introduced through naturally occurring openings. In the human body, endoscopic devices are appropriate for use in the respiratory tract (introduced through the mouth or nose), gastrointestinal tract (introduced through the mouth, nose, or rectum), or in the urogenital tract (introduced through the ureter or, in women, the vagina). 
   The material of the flexible housing of the endoscopic instrument may be polymeric. If made of a flexible polymeric material, the material may be reinforced, for example, with fibers. A suitable polymeric material for the component is, for example, polytetrafluorethylene, reinforced with braided fibers. 
   The elongate housing in an endoscopic device will have a diameter of from less than about 0.7 mm to about 4.5 cm or greater; the length of endoscopic devices will be from less than about 10cm to about 3 meters or greater. 
     FIGS. 7-5  through  7 - 7  each show a different embodiment of the elastically deformable stem of this invention. 
     FIG. 7-5   a  shows a portion of an elastically deformable stem  158  and of an elongate housing  160 . Shown in cutaway view are the blades  162  and the pivot  164 , sheathed within the elastically deformable stem  158 . In the shown embodiment, the blades  162  must be deployed from the elastic member  166  prior to pivotal blade movement, controlled by the blade actuator rod  168 . The plane through which the blades  162  open can be in any orientation desired relative to the elastically deformable stem  158  or to the elongate housing  160 . 
     FIG. 7-5   b  shows a cross-sectional view of the elastically deformable stem  158 , taken through line  5   b - 5   b  of  FIG. 7-5   a . The blade actuator rod  168  is fully enclosed by the elastic member  166 . 
     FIG. 7-6   a  shows a portion of an elastically deformable stem  170  having a rod-and-groove configuration, and of an elongate housing  172 . The blade actuator rod  174  is partially enclosed by the elastic member  176 , and is partially exposed. 
     FIG. 7-6   a  shows an embodiment wherein the blades  178  and the pivot  180  are not substantially sheathed within the elastically deformable stem  170  when the elastically deformable stem  170  is fully withdrawn into the housing  172 . The blades  178  do not need to be deployed from the elastic member prior to pivotal blade movement, controlled by the blade actuator rod  174 . The plane through which the blades  178  open can be in any orientation desired relative to the elastically deformable stem  170  or to the elongate housing  172 . 
     FIG. 7-6   b  shows a cross-sectional view of the elastically deformable stem  170 , taken through line  6   b - 6   b  of  FIG. 7-6   a . The blade actuator rod  174  is partially enclosed in a groove in the elastic member  176 . 
     FIG. 7-7   a  shows a portion of a housing  182 , and an elastically deformable stem  184  with a windowed configuration. The windows are shown on the convex surface of the elastically deformable stem  184 . Such windows can be present on any of the concave or lateral surfaces of the elastically deformable stem  184 , as desired. Any number of windows can be used, including one, two, or a multiplicity. 
   Shown in cutaway view are curved blades  190  and the pivot  192 , which are substantially sheathed within the elastically deformable stem  184 . As shown, the blades  190  must be deployed prior to pivotal blade movement. When the blades  190  are curved, it is generally preferable that the curve of the blades  190  continue the curve of the elastically deformable stem  184 , but that is not necessary. 
   The plane through which the blades  190  open can be in any orientation desired to the elastically deformable stem  184 , or to the elongate housing  182 . In a currently preferred embodiment, the blades  190  are not retracted into the elongate housing  182  or into the elastically deformable stem  184  even when the blades are fully retracted, a configuration which is shown in  FIG. 7-2   b.    
     FIG. 7-7   b  shows a cross-sectional view of the elastically deformable stem  184 , taken through line  7   b - 7   b  of  FIG. 7-7   a . The blade actuator rod  186  is partially enclosed in a groove in the elastic member  188 . 
     FIG. 7-7   c  shows -a cross-sectional view of the elastically deformable stem  184 , taken through line  7   c - 7   c  of  FIG. 7-7   a . The blade actuator rod  186  is fully enclosed by the elastic member  188 . 
     FIG. 7-8  demonstrates the use of an alternate elastic member  194 . As shown in  FIG. 7-8   a , the elastic member  194  is an element such as a wire which describes a closed shape in its unconstrained shape. The elastic member  194  has a stem  196 , which can be a continuation of the elastic member  194 , as shown, or can be a handle means connected to the elastic member  194 . Point g and point h are labeled to show the progression of the loop as it is withdrawn into the constraining housing  198 .  FIG. 7-8   b  demonstrates that when the stem  196  and the elastic member  194  are retracted into a constraining housing  198 , the circle deforms into a cupped configuration. As shown in  FIG. 7-8   c , further retraction of the stem  196  and the elastic member  194  into the constraining housing  198  causes further deformation. The closed shape becomes narrowed and sharply angled. This occurs because as the sides of the closed shape take less stress to rotate out of the plane of the undeformed shape than to straighten within the plane of the undeformed shape. The figure thus deforms by bending at the apex, with the sides rotating out of the plane of the undeformed shape. 
     FIGS. 7-8   d ,  7 - 8   e  and  7 - 8   f  show the incorporation of the closed shape of  FIGS. 7-8   a ,  7 - 8   b and  7 - 8   c , respectively, into an enclosing flexible sheath  200 .  FIGS. 7-8   d ,  7 - 8   e  and  7 - 8   f  are side views of the flexible sheath  200  and constraining housing  198  which show the bending which takes place as the stem (not shown) and the circular elastic member (not shown) are drawn into the constraining housing  198 . 
     FIG. 7-9  demonstrates another method of constraining an elastic member.  FIG. 7-9   a  shows two unconstrained elastic members  202   a  and  202   b . Each is curved when it is not constrained. Each is capable of independent rotation. As shown in  FIG. 7-9   a , the elastic members  202   a  and  202   b  are angled away from each other. 
     FIG. 7-9   b  shows the elastic members  202   a  and  202   b  held within a flexible sheath  204 . The sheath causes each elastic member to act as a constraint for the elastic member having an opposite bend. As a result the flexible sheath  204  is straight. 
     FIG. 7-9   c  shows the elastic members  202   a  and  202   b  held within a flexible sheath  204 . Elastic member  202   b  has been rotated to align its curve to the curve of elastic member  202   a . The sheath bends to conform to the bend of the two elastic members  202   a  and  202   b.    
     FIGS. 7-9   d  through  7 - 9   f  graphically represent the forces involved in  FIGS. 9   a  through  9   c , respectively, as represented in top view. 
     FIG. 7-9   d  depicts vectors for the elastic members  202   a  and  202   b , as shown in  FIG. 7-9   a . Elastic member  202   a  is shown as a vector arrow pointing to the left; elastic member  202   b  is shown as a vector arrow pointing to the right. 
     FIG. 7-9   e  depicts vectors for the elastic members  202   a  and  202   b  as shown in  FIG. 7-9   b.  The flexible sheath  204  is shown. The flexible sheath  204  does not curve, as the forces exerted by the elastic member  202   a  are cancelled out by the forces exerted by elastic member  202   b.    
     FIG. 7-9   f  depicts vectors for the elastic members  202   a  and  202   b , as shown in  FIG. 7-9   c . The flexible sheath  204  is shown. The flexible sheath  204  curves to the left represented by the resultant arrow  205 . The vector forces exerted by the elastic member  202   a  are reinforced by the vector forces exerted by elastic member  202   b.    
     FIG. 7-9   g  depicts alternate vectors for elastic members  202   a  and  202   b . The flexible sheath  204  is shown. Elastic member  202   a  is represented by a vector leftward, while elastic member  202   b  is represented by a vector which is at a 90° angle from that of elastic member  202   a . The forces exerted by the elastic member  202   a  are only partially reinforced by the forces exerted by elastic member  202   b . The flexible sheath  204  curves to the upper left, represented by the resultant arrow  206 . 
     FIG. 7-9   h  depicts another vector set for elastic members  202   a  and  202   b . The flexible sheath  204  is shown. Elastic member  202   a  is represented by a vector downward, while elastic member  202   b  is represented by a vector to the right. The forces exerted by the elastic member  202   a  are only partially reinforced by the forces exerted by elastic member  202   b . The flexible sheath  204  curves to the lower right, represented by the resultant arrow  207 . 
     FIG. 7-9   i  depicts yet another vector set for elastic members  202   a  and  202   b . The flexible sheath  204  is shown. Elastic member  202   a  is represented by a vector downward, as is elastic member  202   b . The forces exerted by the elastic member  202   a  are reinforced by the forces exerted by elastic member  202   b . The flexible sheath  204  curves to the bottom, represented by the resultant arrow  208 . By rotation of one or more of the elastic members  202   a  and  202   b , the flexible sheath  204  can be curved through a 360° circle. 
     FIG. 7-10  shows a device of this invention having two pivoted blades, each blade having a longitudinal slot next to the pivot. 
     FIG. 7-10   a  is a side view of an instrument in the unconstrained configuration with a partial cutaway near the bladed element. A bend of approximately 90° is present in the elastically deformable stem  210 . The actuating rod  212  is enclosed within the elastic member  214 . The movement of the actuating rod  212  and of the elastically deformable stem  210  are preferably independent, and each is controlled by longitudinal motion of the proximal ends. Opening and closing of the blades is caused by reciprocal motion of the proximal portion of the actuating rod  216 . Deflection of the elastically deformable stem  210  is caused by reciprocal motion relative to the elongate housing  220  of the proximal portion of the elastically deformable stem  218 . 
     FIG. 7-10   b  shows a cut-away top view of the instrument of  FIG. 7-10   a . Two blades  222   a and  222   b  are present. As shown, each blade is V-shaped. In a preferred embodiment, not shown, each blade is substantially straight. A pivot  224  is present intermediate to the ends of the blade. The pivot allows pivotal motion of the two blades, and holds the blades in position on the elastically deformable stem. A longitudinal slot  226  is present in each blade proximal to the pivot. The two blades  222   a  and  222   b  are moveable between a closed position, wherein the axes of the distal portions of the blades are substantially parallel, and an open position, wherein the axes of the distal portions of the blades are deflected from the parallel. Pivotal movement of the blades  222  is caused by a sliding pin (not shown) which is part of the actuator rod  212 , and which integrates with the longitudinal slot  226  present in each of the blades. In alternate embodiments, the blades can be located partially within the elastically deformable stem; the blades can be fixed to opposite sides of the elastically deformable stem; or the blades can be fixed to a concave, convex, or lateral edge of the elastically deformable stem. The pivotal connection shown is for demonstration purposes only, and any appropriate toggle, gear, or pivotal connection can be used. 
     FIG. 7-11   a  shows a longitudinal cross-sectional view of an instrument in the unconstrained configuration. The bladed element  228  includes two blades, two bars, and four pivots. A bend of approximately 90° is present in the elastically deformable stem  230 . The actuating rod  232  is enclosed within the elastic member  234 . The movement of the actuating rod  232  and of the elastically deformable stem  230  are each controlled by longitudinal motion of the proximal ends. Opening and closing of the blades is caused by reciprocal notion of the proximal portion of the actuating rod  236 . Deflection of the elastically deformable stem  230  is caused by reciprocal motion of the proximal portion of the elastically deformable stem  238  relative to the elongate housing  240 . 
     FIGS. 7-11   b  and  7 - 11   c  show cut-away-top views of the instrument of  FIG. 7-11   a . Two blades  242   a  and  242   b  are present. Two bars  244   a  and  244   b  are present. A pivot  246   a  is present intermediate to the ends of the blades  242   a  and  242   b , joining the blades and attaching the blades to the elastically deformable stem  230 . Two pivots  246   b  are present at the proximal ends of the blades  242   a  and  242   b , where they join the distal ends of bars  244   a  and  244   b . A pivot  246   c  is present at the proximal end of the bars  244   a  and  244   b , joining the bars. Pivotal movement of the blades  242   a  and  242   b  is caused by a sliding motion of the blade actuating rod  232 .  FIG. 7-11   b  shows the blades in a relatively closed configuration.  FIG. 7-11   c  shows the blades in a relatively open configuration. 
     FIGS. 7-12   a  through  7 - 12   f  show alternate cross-sections of an elastically deformable stem of the instrument of  FIG. 7-1 , taken through line  12 - 12 . 
     FIG. 7-12   a  shows an elastic member  248  and a blade actuator rod  250  within a flexible material  252 . The flexible material  252  describes a squared pyramid shape in cross-section. The elastic member  248  and the blade actuator rod  250  each comprise a strip of material which is roughly oval in cross-section. 
   The use of a flexible material  252  which encloses an elastic member  248  and a blade actuator rod  250  permits the easy use of one or more elastic member  248  and/or blade actuator rod  250  members which is eccentrically shaped in cross-section. Additionally, the material of the flexible material  252  is generally less expensive and easier to work than the material of either the elastic member  248  or the blade actuator rod  250 . The flexible material  252  can be, for example, a flexible polymer, or a braided, coiled, segmented, hinged, or zig-zagged metal component. If made of a flexible polymeric material, the material may be reinforced, for example, with fibers, to enable it to withstand the forces exerted on it by the elastic member while it is constrained within and deformed by the elongate housing. A suitable polymeric material for the component is, for example, polytetrafluorethylene, optionally reinforced with braided fibers. 
   The preferred cross-sectional embodiments include the actuator rod in or close to the neutral plane, i.e., that plane which is neither compressed nor stretched during the bending of the elastically deformable stem.  FIGS. 7-12   a  through  7 - 12   f  are each labeled with a plane z-z, representing a preferred neutral plane; and with a plane n-n, representing a preferred plane through which the elastically deformable stem bends. 
     FIG. 7-12   b  shows two elastic members  248  on either side of an actuator rod  250 , within a flexible material  252 . The flexible material  252  is a rounded rectangle in cross-section. The elastic members  248  are rods which are round in cross-section, and the blade actuator rod  250  comprises a strip of material which is oval in cross-section. 
     FIG. 7-12   c  shows two elastic members  248  on either side of an actuator rod  250 , within a flexible material  252 . The flexible material  252  has an oval cross-section. The elastic members  248  are square in cross-section. The blade actuator rod  250  is a rod which is round in cross-section. 
     FIG. 7-12   d  shows two elastic members  248  on either side of an actuator rod  250 , within a flexible material  252 . The flexible material  252  has an oval cross-section. The elastic members  248  are square in cross-section. The blade actuator rod  250  is a piece which resembles a rounded “H” in cross-section. In an alternate embodiment, not shown, the blade actuator rod includes a third elastic member within it, and the blade actuator rod slides freely along the third elastic member. In another embodiment, not shown, the elastic members and the actuator rod are held in position without the action of a flexible material. In yet another embodiment, the elastic member is intermediate to two blade actuator rods. 
     FIG. 7-12   e  shows an elastic member  248  and a blade actuator rod  250  within a flexible material  252 . The flexible material  252  has a squared pyramid shape in cross-section. The elastic member  248  comprises a strip of material which is rectangular in cross-section. The blade actuator rod  250  comprises a strip of material which is round in cross-section. 
     FIG. 7-12   f  shows an elastic member  248 , a constraining rod  254 , and an actuator rod  250 , within a flexible material  252 . The flexible material  252  has a squared cross-section. The elastic member  248 , the constraining rod  254 , and the actuator rod  250  are each oval in cross-section. Note that the constraining rod is not within the neutral axis: only in the absence of the constraining rod does the elastic member  248  assume its unconstrained (bent) configuration. A configuration such as that shown in  FIG. 7-7   f  can be used in embodiments which do not include an elongate housing. A lumen  255  is present. The lumen  255  can be used, for example, to provide access for one or more apparatus for irrigation, aspiration, cautery, and the like. 
     FIG. 7-13  shows a bladed element which only one pivoting blade  256  is mounted for pivotal motion. The pivoting blade  256  is biased in the open (splayed) position by a spring  258 . The fixed blade  260  is mounted in a fixed position. The pivoting blade is closed by longitudinal motion of the actuator rod  262 . The housing  264  is shown in partial cutaway view. 
   Preferred embodiments of this invention include a symmetrical blade action, so that both of the blades are actuated by the manually operated mechanism and dissection, cutting, and/or grasping is done by symmetrical motion of the two blades. However, in some situations, it may be desirable to have embodiments in which one blade is moved more by the manually operated mechanism than the other blade. In some cases, it may be desirable to have one blade function as a stationary (and therefore passive) blade, where the manually operated mechanism moves only the other blade. 
   The blades of this invention can be made of any appropriate material. Metals known for scissor, knife, and/or forceps use are appropriate. Stainless steel, for example, can be used. Rigid plastics can also be used. 
   One use of the instruments of this invention involves cutting, e.g, when one or more of the opposable blade provides a cutting edge. The honing of an edge to form a cutting blade is well known in the art. If desired, the cutting blade can be serrated. The cutting edge is preferably derived from beveling blade material itself. However, it may be desirable or necessary to provide a honed edge of a secondary material to the blade material. For example, a non-cutting plastic blade can be combined with an alloy cutting edge. A cutting surface can be provided at any desired exposed edge of the blade. 
   The blades can be straight, or they can be curved along their length, as shown in  FIG. 7-7   a . When curved blades are present the curved blades are preferably made of an elastic material as described above. 
     FIG. 7-13   b  shows a cutting blade  266  which has one longitudinal cutting edge  268 . 
     FIG. 7-13   c  shows cutting blade  266  in which the perimeter of the blade provides the cutting edge  268 . 
     FIG. 7-13   d  shows a blade  266  which has no cutting edges. The end portion of the blade is pointed to facilitate dissection of tissues. 
     FIG. 7-13   e  shows a blade  266  which has no cutting edges. The end portion of the blade is curved. 
     FIGS. 7-14   a  through  7 - 14   e  show various blade cross-sections, taken through line  14 - 14  of  FIG. 7-13   a . The cutting surfaces of the blades may abut one another in the manner of wire cutters, or they may cross one another in the manner of shears. The grasping surfaces of the blades may abut one another and be sufficiently blunt to avoid cutting the object to be grasped. Alternatively, the grasping surfaces need not be configured so as to contact each other in the manner of cutting devices. The object being grasped need merely be entrapped between the end portions of the blades. The grasping surfaces may be ridged or contain protuberances to assist in grasping the object. 
     FIG. 7-14   a  shows a cross-sectional view of two opposing blades. The blades are roughly rectangular in cross-section. The blades meet at a flattened surface, and are appropriate for grasping objects. 
     FIG. 7-14   b  shows a cross-sectional view of two opposing ridged blades. The blades are roughly rectangular in cross-section. The blades meet at a ridged surface, and are especially appropriate for grasping objects. 
     FIG. 7-14   c  shows a cross-sectional view of two opposing blades in which the blades are not symmetrical. One blade is roughly rectangular in cross-section, while the other blade is triangular. Such a configuration is appropriate for cutting objects. 
     FIG. 7-14   d  shows a cross-sectional view of two opposing cutting blades. The blades are roughly triangular in cross-section. The blades meet at a pointed cutting surface. 
     FIG. 7-14   e  shows a cross-sectional view of two opposing cutting blades. The blades are roughly triangular in cross-section. The blades meet and slide along their surfaces in the manner of shears. 
   An eighth form of the present invention provides a device for dissecting an object which comprises at least two elongate elements, positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   i being capable of being splayed apart from one another when free of transverse constraint to dissect said object from surrounding material; and 
   ii being capable of being moved toward one another; 
   wherein a portion of at least one of the elements is formed from a pseudoelastic material. 
   In another aspect, the eighth form of the present invention provides a device for grasping or cutting an object which comprises at least two elongate elements, positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   (i) being capable of being splayed outwardly apart from one another when free of transverse constraint and presenting grasping or cutting surfaces to an object to be grasped or cut that is placed between them; and 
   (ii) being capable of being moved inwardly towards one another to grasp or cut said object; 
   wherein a portion of at least one of the elements is formed from a pseudoelastic material. 
   A further aspect of the eighth form of this invention comprises a device (or dissecting an object which comprises 
   a. at least two elongate elements, positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   i. being capable of being splayed apart from one another when free of transverse constraint for dissecting said object from surrounding material; and 
   ii. being capable of being moved toward one another; and 
   b. actuating means; 
   wherein a portion of at least one of the elements and/or said actuating means is formed from a pseudoelastic material. 
   Another aspect of the eighth form of this invention comprises a device for grasping or cutting an object which comprises 
   (a) at least two elongate elements, positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   (i) being capable of being splayed outwardly apart from one another when free of transverse constraint and presenting grasping or cutting surfaces to an object to be grasped or cut that is placed between them; and 
   (ii) being capable of being moved inwardly towards one another to grasp or cut said object; and 
   (b) actuating means; 
   wherein a portion of at least one of the elements and/or said actuating means is formed from a pseudoelastic material. 
   A further aspect of the eighth form of this invention comprises a device for dissecting an object which comprises 
   a. a hollow elongate component; and 
   b. at least two elongate elements, at least part of which are positioned within said component, said elements being positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   i. being capable of being splayed apart from one another when free of transverse constraint; and 
   ii. being capable of being moved toward one another; 
   wherein the elements and the component are longitudinally slidable relative to one another so that at least the end portions of the elements can be slid into and out of said component and wherein a portion of at least one of the elements is formed from a pseudoelastic material. 
   Yet another aspect of the eighth form of this invention comprises a device for grasping or cutting an object which comprises 
   (a) a hollow elongate component; 
   (a) at least two elongate elements, at least part of which are positioned within said component, said elements being positioned alongside one another, each having a body portion and an end portion, the end portions of the elements: 
   (i) being capable of being splayed outwardly apart from one another when free of transverse constraint and presenting grasping or cutting surfaces to an object to be grasped or cut that is placed between them; and 
   (ii) being capable of being moved inwardly towards one another to grasp or cut said object; 
   wherein the elements and the component are longitudinally slidable relative to one another so that at least the end portions of the elements can be slid into and out of said component and wherein a portion of at least one of the elements is formed from a pseudoelastic material which can be deformed when under an applied stress. 
   A still further aspect of the eighth form of this invention comprises a method of dissecting an object from surrounding material, which comprises: 
   A. providing a device which comprises at least two elongate elements, positioned alongside one another, each having a body portion and an end portion, the end portions of the elements being capable of being splayed apart from one another when free of transverse constraint to dissect said object from surrounding material; and wherein a portion of at least one of the elements is formed from a pseudoelastic material; 
   B. positioning end portions adjacent the object; and 
   C. causing said end portions to splay apart so as to dissect said object from surrounding material. 
   A further aspect of the eighth form of this invention comprises a method of grasping or cutting an object, which comprises: 
   i. providing any one of the cutting or grasping devices as described above; 
   ii. positioning the object between splayed apart end portions of the elements; and 
   iii. causing said end portions to move toward one another so as to grasp or cut said object. 
   The pseudoelastic material used in any of the aspects of this eighth form of the invention is preferably a shape memory alloy, such as a nickel/titanium-based alloy, as discussed hereinbefore. The pseudoelastic material may be, for example, a superelastic material, especially a superelastic shape memory alloy. 
   Where the device according to the invention comprises a hollow component this may be in the form of an elongate polymeric or metal tube. 
   According to two various aspects of the invention, at least a portion of at least one of the elongate elements exhibits pseudoelasticity. For example the end portion, or instead or in addition at least part of the body portion, of at least one of the elements, may be formed from a shape memory alloy which exhibits pseudoelasticity, especially superelasticity. 
     FIG. 8-1  is an isometric view of a device of the invention; 
     FIGS. 8-2A  to  8 - 2 C are cross-sections through the device shown in  FIG. 8-1 , taken at lines A-A, B-B and C-C respectively; 
     FIGS. 8-3A  to  8 - 3 E are elevational views of a first embodiment Of the device shown in  FIG. 8-1  at various stages during a cutting operation; 
     FIGS. 8-4A  to  8 - 4 C are elevational views, partially in section, of another embodiment of the device at various stages during a cutting or grasping operation. 
     FIGS. 8-5A  to  8 - 5 E illustrate an embodiment of a device in accordance with this invention in which the end portions and body portions of the elongate elements are integral and are moved by a rotational actuator made of a material other than a pseudoelastic material. 
     FIGS. 8-6A  to  8 - 6 E illustrate representative cross sections of end portions of the elements adapted to grasp or cut an object. 
     FIGS. 8-7A  to  3 - 7 E illustrate various actuating means which function to cause the elements to splay apart and come together and, optionally, rotate the elements, and/or withdraw the elements into or out of the hollow component. 
     FIG. 8-8  illustrates an embodiment of the device of this invention in which the end portions are curved when at least partially unconstrained and pinned together pivotally at their tips. 
     FIG. 8-9  demonstrates a method of using a grasping device of this invention. 
     FIGS. 8-10A  to  8 - 10 C illustrate an embodiment of the device of this invention in which the elements are splayed and in which the body portions of the elements are bent when the elements are unconstrained. 
     FIGS. 8-11A  and  8 - 11 B illustrate a device of this invention in which the elements have end portions beyond a pivot point, and in which the body portions of the elements are of pseudoelastic material and when unconstrained are bent to splay the end portions and position them at a desired angle with respect to the hollow component. The body portions act as actuating means to open and close the end portions of the elements to dissect, grasp and/or cut an object. 
     FIG. 8-12  illustrates a device similar to the device in  FIG. 8-11B , but in which the body portions of the elements are made of a pseudoelastic material and have a bend of about  90 .degree.. 
     FIG. 8-13  illustrates another device in accordance with this invention. 
   The device of the eighth form this invention comprises a hollow elongate component and two elongate elements. Preferably, the hollow component is tubular. This has the advantage that the device can be operated remotely. 
   The material of the hollow component may be polymeric. It may be flexible or rigid. If made of polymeric material, the material may be reinforced, for example, with fibers, to enable it to withstand the forces exerted on it by the elements while they are constrained within and deformed by the component. A suitable polymeric material for the component is, for example, polytetrafluoroethylene, reinforced with braided fibers. Alternatively, the material of the hollow component may be metallic, for example stainless steel. A preferred hollow component is an elongate tube, preferably formed from stainless steel. The elongate hollow component can be, for example, a tubular housing, cannula, catheter or sheath. 
   The hollow component may be circular in cross-section which can have the advantage that it permits deformation of the elements substantially uniformly in all directions. Other cross-sections may be preferable in some situations. For example, it can be advantageous to use a hollow component which has the same shape in cross-section as the elements which are received within it, to minimize twisting of the elements relative to one another. 
   Preferably, the elements are at least partially formed from a pseudoelastic material, such as a shape memory alloy that exhibits pseudoelasticity. Shape memory alloys which exhibit superelasticity, are especially preferred. As explained above as a superelastic shape memory alloy is increasingly deformed from its unconstrained shape, some of its austenitic phase changes Into stress-induced-martensite and the stress/strain curve presents a plateau during this phase change. This means that while the alloy undergoes this phase change, it can deform greatly with only minimal increases in loading. Therefore, cutting, dissecting and grasping elements comprising superelastic shape memory alloys have a built-in safety feature. These elements can be designed (using appropriately treated alloys and appropriate dimensions) such that when they are loaded beyond a certain amount, the elements will tend to deform with a concomitant austenite to stress-induced-martensite phase change, instead of merely presenting a greater resistance with limited deformation to the load, which is seen with conventional metals. 
   While the alloy that is used in the devices of this eighth form of the invention may exhibit either linear pseudoelasticity or superelasticity (which is sometimes referred to as non-linear pseudoelasticity), or pseudoelasticity of an intermediate type, it is generally preferred that it exhibit superelasticity because of the large amount of deformation that is available without the onset of plasticity. Any of the materials described hereinbefore including elastically deformable materials, pseudoelastic materials, superelastic materials, and shape memory alloys can be used in this eighth form of the invention. 
   The device according to the eighth form of the invention has the advantage that, by use of elongate elements formed at least partially from a pseudoelastic material which can be deformed, it can be used in applications in which there is a limited amount of space. Furthermore, the device can be operated remotely or at an angle more conveniently than many previously used devices. 
   In certain embodiments of the invention, at least one of the end portions of the elongate elements is formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy, and that end portion may have a curved configuration when not constrained and can be deformed into a straightened configuration when within a constraint, such as a hollow component. The term “straightened configuration” means that the configuration of the element is straighter when deformed than it is when not deformed. This may be used in dissection (the separation of tissues). When the end portion of the element (or end portions of the elements if both are of a pseudoelastic material) is extruded from the hollow component it is no longer constrained and reverts or recovers to splay away from the other element. When the end portion is withdrawn back into the hollow component, or the hollow component is drawn over the end portion, it moves toward the other end portion grasping or cutting any object placed between them. 
   In some embodiments of the invention, the end portions of the elongate elements are formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy, and are deformed into a straightened configuration when within the hollow component and curve at an angle to the end of the component when extended therefrom. 
   In certain other embodiments the end portions of the elongate elements are formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy, and are deformed into a curved configuration when within the component and are substantially straight when extruded from the component. 
   In still other embodiments, the body portion of one or both of the elongate elements is formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy, and the body portion of the element becomes curved on exiting the component, thereby splaying the end portion away from the other end portion. 
   In any embodiment, an actuating means, which may be formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy, can be provided to splay the end portions apart from one another and/or to move them toward one another. In such embodiments, it is not necessary for the elongate elements to be formed from a pseudoelastic material. 
   In summarizing, at least a portion of at least one, preferably each, of the elongate elements is formed from a pseudoelastic material, preferably a pseudoelastic shape memory alloy. The use of a shape memory alloy which exhibits pseudoelasticity has the advantage that the amount of elastic deformation that is available is large compared with that available from many other materials. In certain preferred embodiments, the end portion of one or both of the elements is formed from a pseudoelastic shape memory alloy. In other embodiments, a section of the body portion of one or both of the elements is formed from a pseudoelastic shape memory alloy. The large amount of elastic deformation of the elements allows the device to be used to dissect, grasp and/or cut large objects, while ensuring also that the device has a small transverse dimension when the elements are deformed inwardly, allowing the device to pass through small spaces. 
   The end and body portions of the elongate elements may be formed from the same material, for example, both may be formed from a shape memory alloy, for convenience. Frequently, however, it may be preferable to use different materials because of the different functions that the end and body portions might have to serve. For example, the end portions may be of stainless steel or the like to provide a sharp cutting edge or a cutting edge of stainless steel may be provided on a part of end portions formed from a sharp memory alloy. The cross-sections of the end and body portions will generally be different, although this need not necessarily be the case. For example, the end portions may be rectangular to present a grasping surface or triangular to present a cutting surface, and the body portions may be rectangular for rigidity. 
   In some embodiments, the end portions of the elongate elements are pivotally connected to one another towards their free ends. This minimizes the possibility of an object becoming dislocated from the device before it is grasped or cut. The device may then be used to move an object once it has been positioned between the elements. This can also be achieved when the elements are not joined together at their free ends, but with less control in some situations. When the elements are not connected directly at their free ends, they may be connected by a flexible component which extends between the end portions of the elements so as, together with the end portions of the elements, to form a closed loop. Leaving the elements unattached at their free ends can facilitate positioning the device so that the object is located between the elements. The tips of the free ends may be blunt, especially when the elements are not attached at their free ends. Alternatively, the free ends may be pointed to facilitate dissection, for example. 
   The end portions of the elongate elements may be provided with a cutting edge of a material other than a shape memory alloy. The cutting edge may be inlaid in the end portion or can extend from the end portion of the device. 
   Preferably the body portions of the elongate elements are attached to one another. This can facilitate manipulation of the two elements. For example, the elements may be attached to one another by adhesive material or by fasteners such as screws or rivets, or the elements may be formed as a single body of material. Alternatively, the elements may be attached to an elongate member by which they are moved longitudinally relative to the hollow component. For example, such a member may be hollow, at least at its end, and the elements may be received within the member. 
   The elongate elements may be symmetrical when they are splayed outwardly apart, and preferably also when deformed inwardly. However, for some applications, it might be appropriate for the elements not to be symmetrical, or for the elements not to be deformed symmetrically (for example only one of the elements might be deformed), or both. 
   The cutting surfaces of the elongate elements may abut one another in the manner of wire cutters, or they may cross one another in the manner of shears. The grasping surfaces of the elements may abut one another and be sufficiently blunt to avoid cutting the object to be grasped. Alternatively, the grasping surfaces need not be configured so as to contact each other in the manner of cutting devices. The object being grasped need merely be entrapped between the end portions of the elements. The grasping surfaces may be ridged or contain protuberances to assist in grasping the object. 
   In certain embodiments, an object may be grasped or cut using the device of the invention by ringing the device and the object together while the elongate elements are positioned at least partially within the component, and by then moving the hollow component and the elements longitudinally relative to one another, so that the end portions of the elements extend from the object and become splayed outwardly. This action can be used to spread or dissect surrounding material from the object, if desired, to isolate the object. The object can Then be positioned between the elements to be grasped or cut in accordance with the method described above. 
   In other embodiments, the device is provided with means for actuating the end portions of the elongate elements, which are not necessarily formed from a pseudoelastic. Illustrative actuating means are described more fully below with reference to the drawings and include rack and pinion means, pin and slot means, four-bar linkages and the like. In certain embodiments, the actuating means may be formed of a pseudoelastic material. The actuating means may permit the elements to be rotated. The actuating means may also provide suitable means for irrigating the elements, or conduct electrical current to one or both of the elements, if desired. 
   The device will be particularly useful in applications in which access to an object to be dissected, cut or grasped is restricted, for example in medical applications in which the object to be dissected, cut or grasped is a part of a human or animal body. In these applications, the elongate elements may be positioned in the body by means of a hollow component in the from of a cannula, catheter or sheath introduced, for example, through an opening into a body cavity. 
   The device may be arranged so that the axis on which the elements dissect, cut and/or grasp the object is not coaxial with the axis of at least a significant portion of the hollow component. This may be arranged, for example, by providing the elongate elements with a suitable bend. The elements may be deformed from their bent configuration towards their straight configuration, and held in the straight configuration, by the hollow component while they are within it. Alternatively, it may be arranged by use of a hollow component which is bent towards the end from which the elements extend. 
   The device may also be useful in the assembly of mechanical, electrical or other equipment, for example by means of robots. 
   Turning now to the drawings,  FIGS. 8-1  and  8 - 2  show a cutting or grasping device which comprises two elongate elements  1  and  3 , each having a body portion  5  and an end portion  7 . The end portions are joined together pivotally at their free ends by a pin  9 . The end portions preferably have a triangular cross-section, where the apex of the triangle provides a cutting surface  10 . Alternatively, any flat cross-sectional area may present a grasping surface. Other possible cross-sectional areas are illustrated in  FIGS. 8-6A  to  8 - 6 E. 
   The elongate elements are preferably formed from a pseudoelastic material, preferably a shape memory alloy which has been treated so that it exhibits pseudoelasticity in the temperature range between ambient temperature and a temperature above body temperature. 
   Elongate elements  1  and  3  are located within an elongate housing  11  within which they can slide longitudinally, the housing preferably being a stiff tubular sheath. The elongate elements can be extended beyond the end of housing  11  by longitudinally moving them relative to housing  11  via any suitable manually operated mechanism. 
     FIG. 8-2  shows the cross-sectional configurations of elongate elements  1  and  3  at positions A-A, B-B, and C-C of  FIG. 8-1 , which illustrates the elongate elements splayed apart. 
     FIG. 8-3A  shows a cutting device with elongate elements  1  and  3  restricted completely within housing  11 , which holds the elongate elements in a deformed configuration inwardly towards one another. The housing is positioned as desired relative to an object to be cut (or dissected or grasped) while the elongate elements are in this configuration. Once so positioned, the end portions  7  of the elongate elements are caused to extend from the housing, by relative movement of the elements and the housing. Once released from the transverse constraint imposed by the housing, end portions  7  of the elements splay outwardly apart, as shown in  FIG. 8-3B , allowing an object  15  to be positioned between them, as shown in  FIG. 8-3C . 
   Object  15  is caused to engage the surfaces  10  of elongate elements  1  and  3 . Relative longitudinal movement of the elongate elements and the housing will force at least parts of the elongate elements together, thereby grasping or cutting the object, as shown in  FIGS. 8-3D  and  8 - 3 E. If desired, object  15  can be moved by holding the housing and moving the elongate elements. If it is desired not to move object  15 , the elongate elements are held fixed and the housing is moved. The elongate elements can be retracted into the housing for removal of the device from the site of the dissecting, cutting and/or cutting operation. 
   The end portions  7  (or any other portion, as desired) of elongate elements  1  and  3  may represent sections of spherical surfaces to facilitate the splaying and closing. End portions  7  may be used to grasp, instead of cutting, tissues. The grasping function would be facilitated if end portions  7  do not have cutting surfaces  10 , and if end portions  7  are not fully retracted back into housing  11 . Furthermore, the splaying action of elongate elements  1  and  3  may be utilized to separate tissues for dissection. 
     FIG. 8-4  shows a device which comprises two elongate elements  21  and  23  that are preferably formed from a pseudoelastic material and more preferably a shape memory alloy which has been treated so that it exhibits superelastic behavior. The elements can slide longitudinally within a tubular housing  25 .  FIG. 8-4A  shows the device with the elongate elements  21  and  23  positioned almost entirely within the tubular housing  25 . Housing  25  constrains elongate elements  21  and  23  in straightened and deformed shapes. 
   As elongate elements  21  and  23  are moved longitudinally relative to housing  25 , the elongate elements extend from the end of housing  25 , as shown in  FIGS. 8-4B  and  8 - 40 . As they extend from the end of housing  25 , the elongate elements become unconstrained and recover toward their preset curved shapes pseudoelastically. They pseudoelastically splay outwardly so that they can receive an object  27  between them or, alternatively, be used to dissect surrounding material. The elongate elements may be interconnected indirectly towards their free ends  29  by a flexible component, such as a piece of wire  31 , which helps to prevent dislocation of object  27  from between the elongate elements. Object  27  is cut or grasped by relative movement between housing  25  and the elongate elements, such that the elongate elements become constrained within the housing, generally as described above with reference to  FIG. 8-3 . The splaying action of elongate elements  21  and  23  may also be utilized to separate tissues for dissection. Elongate elements  21  and  23  may curve out of the plane of the paper. 
     FIG. 8-5A  illustrates an embodiment of the invention in which elongate elements  51  and  52  are substantially planar and straight in their unconstrained shapes, but are located in a plane which deviates by an angle phi from a plane which includes the axis x-x of a hollow tube  53 . In this embodiment, elongate elements  51  and  52  are attached to outer tube  53  and inner tube  55 , respectively, as shown in  FIG. 8-5B . The proximal end (i.e., the end opposite the elongate element  52 ) of inner tube  55  is provided with a groove  58 , and inner tube  55  is positioned within outer tube  53 . The proximal end of outer tube  53  is provided with a groove  59 , which extends in a direction opposite to groove  58  of inner tube  55 . Plunger  60  is provided with a peg  60 a. The plunger may be positioned at the proximal end of the tubes. The proximal ends  58 p and  59 p of grooves  58  and  59 , respectively, are positioned such that they overlap and are engaged by peg  60 a. When peg  60 a engages proximal ends  58 p and  59 p of grooves  58  and  59 , elongate elements  51  and  52  are preferably splayed apart in the plane defined by their respective flat surfaces. When plunger  60  is pushed into inner tube  55  in a distal direction toward the elongate elements, peg  60 a engages grooves  58  and  59 , causing tubes  53  and  55 , and thereby the elongate elements  51  and  52 , to rotate in opposite directions. Preferentially, this rotation would cause the elongate elements to rotate into a more overlapped configuration. The elongate elements can thereby grasp an object placed between them. If the elongate elements have cutting edges, they could thereby cut an object placed between them. When plunger  60  is withdrawn from inner tube  55  again, peg  60 a could cause tubes  53  and  55  to rotate such that elongate elements  51  and  52  splay apart from their overlapped configuration. Elongate elements  51  and  52  could thereby be used to separate tissues for dissection. 
   With respect to this embodiment, it should be noted that the angle .phi. between elongate elements  51  and  52  and tubes  53  and  55  can be any number of degrees desired. In addition, the elongate elements may be curved, not only within the plane generally described by their plane of motion, but also out of the plane generally described by their plane of motion. Furthermore, there may be more than one peg on plunger  60 . Correspondingly there would be additional grooves (or slots) in tubes  53  and  55 . The grooves may be spiraled, and longer, such that elongate elements  51  and  52  could be caused to rotate in both directions of their overlapped position in one stroke of plunger  60 . The grooves may also be located anywhere along the lengths of tubes  53  and  55 . Consequently, peg  60 a may be appropriately located anywhere along plunder  60 . Finally, grooves  58  and  59  could be made configured such that elongate elements  51  and  52  could be brought to their overlapped configuration by withdrawing plunger  60  in a proximal direction away from the elongate elements. 
     FIG. 8-5C  shows one method of the attachment of elongate elements  51  and  52  onto inner and outer tubes  53  and  55 , respectively. Elongate element  52  is provided with aperture  63  which fits over stem  64 , which is integral with or is secured to the distal end of inner tube  55 . The length of stem  64  is equal to or less than the thickness of elongate element  52 . The cross-sectional shapes of aperture  63  and stem  64  are preferably noncircular, and they may, for example, be square, serrated, notched, etc. Screw  65  and washer  66  fasten elongate element  52  to inner tube  55 . Washer  66  may have a beveled side to accommodate the angle .phi. between the axis x-x of inner tube  55  (and tube  53 ) and the plane of elongate elements  51  and  52  as shown in  FIG. 8-5C . The distal face of tube  55  and the distal face of stem  64  should also be slanted (not shown) at f relative to the axis x-x of tube  55 . 
   Elongate element  51  is provided with an aperture  68  which fits over stem  69 , which is integral with or is secured to the distal end of outer tube  53 . The length of stem  69  is preferably slightly greater than the thickness of elongate element  51 , so that rotation of elongate element  51  relative to elongate element  52  is not hindered. The cross-sectional shapes of aperture  68  and stem  69  are preferably noncircular, and they may, for example, be square, serrated, notched, etc. The distal face of tube  53  and the distal face of stem  69  should be slanted (not shown) at an angle f relative to the axis x--x of tube  53 . 
   Inner tube  55 , with attached elongate element  52 , fits into outer tube  53 . Elongate element  51  will be captured between the base of stem  69  and elongate element  52 . Outer tube  53 , with inner tube  55  contained therein, and elongate elements  51  and  52  attached, can be inserted into a sheath  61 . As shown in  FIG. 8-5D , when elongate elements  51  and  52  are drawn into sheath  61  (shown in cross-section), they will be deformed in a direction more parallel to axis x--x. This deformation will be facilitated if elongate elements  51  and  52  are transversely curved along their longitudinal dimensions (i.e., trough shaped). Also, if the outer diameter of tube  53  is only slightly smaller than the inner diameter of sheath  61 , the circumferences of elongate elements  51  and  52  along portions  81  and  83  (i.e., the circumferences of elongate elements  51  and  52  around their respective apertures  68  and  63 , except for their longitudinally extended portions), should preferably not extend beyond the outer diameter of outer tube  53 . When outer tube  53  is extended distally beyond the end of sheath  61 , elongate elements  51  and  52  will no longer be constrained, and they will elastically recover their preset shapes again. This deformation and shape recovery is enhanced if the elongate elements are made of a pseudoelastic shape memory alloy. 
     FIG. 8-5E  is a bottom view of a possible embodiment of washer  66 . Projection  62  has an outer diameter which is equal to or smaller than the outer diameter of outer tube  53 . The surface of projection  62 , which holds elongate element  52 , may be rough, or it may even have teeth or protrusions, in order to obtain a better grip on elongate element  52 . Projection  62  preferably encompasses less than half of the circumferential arc of washer  66 . The remaining circumference of washer  66  has a outer diameter which is equal to or smaller than the maximum diameter of the head of screw  65 . The head of screw  65  preferably has a diameter which is equal to or less than the smallest diametral dimension of stem  64 . As shown in  FIG. 8-5D , projection  62  covers the back end of elongate element  52 . In this manner, elongate element  52 , and secondarily, elongate element  51 , can be given as much bending length as possible when they are both constrained within sheath  61 . The sides  33  and  34  of projection  62  are preferably parallel to axis y--y, where axis y--y is perpendicular to the longitudinal dimension of elongate element  52  and is perpendicular to the axis of symmetry of washer  66 . This will permit ready bending of elongate element  52  along a zone which is perpendicular to its longitudinal dimension. 
   There may be any suitable means between outer tube  53  and inner tube  55  to prevent plunger  60  from pushing inner tube  55  out of outer  53  tube when plunger  60  is pushed in a distal direction in inner tube  55 . In addition, there may be any suitable means between outer tube  53  and sheath  61 , so that outer tube  53  can not be completely pushed out of sheath  61  once elongate elements  51  and  52  are adequately extended out of sheath  61  and plunger  60  is used to cause rotation of elongate elements  51  and  52 . Plunger  60  can be pushed relative to sheath  61  and tubes  53  and  55  by any suitable manually operated mechanism. Examples of manually operated mechanisms include sliders, pistol grip handles, scissors handles, and syringe-plunger arrangements. 
   An alternate version of the embodiment of  FIG. 8-5  would have a stiff central rod slid along an inner longitudinal bore in the plunger. In this case, the elongate elements would be attached to their respective tubes along one side of the wall of each tube, e.g. by welding or by longitudinally slitting the walls instead of being herd by a screw. The central rod could then be used to straighten the elongate elements (assuming the elongate elements do not have any apertures) and deform them to be more in line with the axis of the tubes. 
   While most of the specific embodiments are directed to cutting devices, it is to be understood that blunt edges can replace the cutting edges in any of the embodiments. Illustrative blunt and cutting edges are shown in FIGS.  8 - 6 A-E. The cutting and grasping edges may be integral with the elements or may be formed separately and/or of different materials and attached thereto.  FIG. 8-6A  illustrates grasping surfaces  71  and  72 . Surfaces  71  and  72  may be flat or they may contain ridges, protrusions or the like to aid in gripping an object.  FIG. 8-6B  illustrates shearing cutting edges  73  and  74  which cut an object by a shearing action.  FIG. 8-6C  illustrates another pair of edges for cutting. In  FIG. 8-6C , surface  75  is flat, while edge  76  provides a sharp edge for cutting an object.  FIG. 8-6D  illustrates cutting edges  77  and  78 . Sharp edges  77  and  78  of the triangular cross-sections meet to permit cutting.  FIG. 8-6E  illustrates cutting edges  80  and  82 , which are at any desired angles .alpha. and .beta. relative to the direction of opening and closing of the elongate elements. In all of these embodiments, as well as in all of the embodiments described herein, the cutting edges or gripping surfaces could be made of any material such as steel, diamond, plastic, etc., which is attached to the elongate elements. 
   In any of the embodiments, dissection could be performed by providing any suitable edge opposite edges  71 - 78  and  80  and  82  of FIGS.  8 - 6 A-E. 
     FIGS. 8-7A , B and C illustrate several different means of actuating elongate elements. In  FIG. 8-7A , the body portions of elongate elements  150  and  151  are joined together at pivot  152 . Also joined at pivot  152  is one end of a linkage composed of four links  153 ,  154 ,  155 , and  156 , which are pivotally connected to each other. Elongate elements  150  and  151  are preferably rigidly attached to links  153  and  154 , respectively. Alternatively, links  153  and  154  may merely represent extensions of elongate elements  150  and  151 , respectively. Pivot  152  is preferably fixed to a cannula  159 . The pivot  157  at the other end of the linkage is joined to rod  158 . When rod  158  is pushed in direction  301 , pivot  157  is pushed closer to pivot  152 . This will cause elongate elements  150  and  151  to splay apart. Since the transverse dimension of linkage  153 ,  154 ,  155 , and  156  which is perpendicular to rod  158  becomes larger as pivot  157  approaches pivot  152 , slots  160  and  161  may be provided in cannula  159  to permit pivot  157  to approach closer to pivot  152  if the transverse dimension of cannula  159  is small. Rod  158  may be pushed (or pulled) relative to cannula  159  by any suitable manually operated mechanism. Examples of manually operated mechanisms include sliders, pistol grip handles, scissors handles, and syringe-plunger arrangements. 
   Elongate elements  150  and  151  may be constrained in deformed and straightened shapes within a sheath  162 . This will permit compact and relatively atraumatic entry into a body. Rod  158  can then be pushed axially in direction  301  within sheath  162 . The linkage  153 ,  154 ,  155 , and  156  will partially extend through slots  160  and  161  in cannula  159 , but the inner surface of sheath  162  will prevent pivot  157  from fully approaching pivot  152 . Therefore, cannula  159  will be forced to move in direction  301 , and elongate elements  150  and  151  will extend from the end of sheath  162  in direction  301 . In their extended position, elongate elements  150  and  151  will not be constrained, and they may recover toward their preset shape, which may, for example, be curved out of the plane of the paper. Slots  163  and  164  are provided in sheath  162  to permit rod  158  to push pivot  157  fully toward pivot  152  in order to fully splay elongate elements  150  and  151  apart. Slots  163  and  164  in sheath  162  may be made to overlap slots  160  and  161  in cannula  159  by simply extending cannula  159  far enough within sheath  162 , or by extending cannula  159  far enough within sheath  162  and then rotating sheath  162  relative to cannula  159  to allow the respective slots to coincide. Rod  158  may then be used to splay or increasingly overlap elongate elements  150  and  151  as desired. 
   Rod  158  can be moved in direction  302  so that pivot  157  is moved as far away as possible from pivot  152 . This will cause elongate elements  150  and  151  to be in their most overlapped configuration. Moving rod  158  further in direction  302  relative to sheath  162  will cause cannula  159  to slide in direction  302 , and will cause elements  150  and  151  to be drawn into straightened (i.e. non-curved) shapes within sheath  162 . This will permit the entire assembly to be withdrawn from the body in a compact and relatively atraumatic fashion. 
   The passive (reference) member of the manually operated mechanism would preferably be mounted to sheath  162 . In this fashion, the extension and withdrawal of elongate elements  150  and  151  from or into sheath  162  can be accomplished by utilizing an expanded stroke of the same manually operated mechanism which is used to splay or increasingly overlap elongate elements  150  and  151 . In this case, a means must be provided to prevent cannula  159  from sliding beyond a certain location within sheath  162  in direction  301 . Also, a means may be provided to minimize relative motion between cannula  159  and sheath  162  while the linkage is being used to repeatedly move elongate elements  150  and  151  toward their splayed or overlapped configurations. Furthermore, the manually operated mechanism would preferably permit axial rotation of the entire assembly of sheath  162  and its contents relative to the manually operated mechanism, so that elongate elements  150  and  151  can be oriented in any desired direction relative to the manually operated mechanism, 
   In the configuration illustrated in  FIG. 8-7A , it will be noted that movement of rod  158  in direction  301  will tend to splay elongate elements  150  and  151  apart. As described above, one method of minimizing this splaying before the device is in the correct location is to create slots in specific locations of sheath  162 . In an alternative method, links  156  and  155  are shorter than links  153  and  154 , and pivot  157  is already positioned as close as possible to pivot  152  during placement of the device into a body. (In this configuration, links  155  and  156  would overlap links  153  and  154 , respectively.) Moving rod  158  in direction  301  will then urge elongate elements  150  and  151  toward their overlapped configuration, even though the elongate elements can be extended beyond the end of sheath  162  by motion in direction  301  when the sheath is held fixed. Elongate elements  150  and  151  can then be splayed apart by moving rod  158  in direction  302 , When the device is to be withdrawn from a body, rod  158  is moved further in direction  302 , so that pivot  157  is as far as possible from pivot  152 , where the configuration shown in  FIG. 8-7A  would be an intermediate position. Elongate elements  150  and  151  will thereby be urged back toward their overlapped configuration. Moving rod  158  even further in direction  302 , relative to sheath  162 , will permit withdrawal of elongate elements  150  and  151  into sheath  162 . 
     FIG. 8-7B  shows an embodiment in which elongate elements  150  and  151  have a pivot  165  and body portions  166  and  167 , respectively. Body portions  166  and  167  have slots  168  and  169 , respectively. A rod  190  has a peg  191  which is oriented to slidably engage slots  168  and  169 . Pivot  165  is fixed to the cannula  192 , and slots  168  and  169  are preferably oriented so that motion of rod  190  in direction  310  will urge elongate elements  150  and  151  toward their overlapped configuration, and motion of rod  190  in direction  320  will splay elongate elements  150  and  151  apart. However, slots  168  and  169  could be curved such that extreme motion of rod  190  in direction  320  will again bring elongate elements  150  and  151  to their overlapped configuration. Cannula  192  may be substantially the same as cannula  159  shown in  FIG. 8-7A . In addition, a sheath  193 , which may substantially be the same as sheath  162  shown in  FIG. 8-7A , can be utilized. The function and use of the embodiment shown in  FIG. 8-7B  is then substantially the same as the embodiment shown in  FIG. 8-7A . 
   A variation of the embodiment illustrated in  FIG. 8-7B  would include elongate elements in which the slots are placed distal to the pivot point between the elongate elements. (That is, the slots are located between the pivot point and the tips of the elongate elements). Body portions  166  and  167  as shown in  FIG. 8-7B , and slots  160 ,  161 ,  163 , and  164  as shown in  FIG. 8-7A  may then not be necessary. However, the actuating rod (such as rod  190  shown in  FIG. 8-7B ), would have to be designed so that it does not interfere with the pivot point between the elongate elements. 
     FIG. 8-7C  shows another embodiment in which the elongate elements  150  and  151  may be made to splay apart or increasingly overlap each other. Elongate elements  150  and  151  are hinged at pivot  170 , which is preferably fixed to a cannula  176 . Surrounding pivot  170 , elongate elements  150  and  151  each have a rounded body portion with teeth along edges  171  and  172 , respectively. The teeth engage the corresponding grooves located in jaws  173  and  174  of sliding member  175 . The degree of splaying or overlapping of elongate elements  150  and  151  may be limited by limiting the lengths of edges  171  or  172  which are toothed. Additionally, or alternatively, the degree of splaying or overlapping of elongate elements  150  and  151  may be limited by limiting the lengths of the grooved zones in jaws  173  and  174 . Sliding member  175  is moved in direction  303  or  305  by any suitable manually operated mechanism. Examples of manually operated mechanisms include sliders, pistol grip handles, scissors handles, and syringe-plunger arrangements. Elongate elements  150  and  151  are preferably moved toward their overlapped configuration when sliding member  175  is moved in direction  303  and moved toward their splayed apart configuration when sliding member  175  is moved in direction  305  (not shown). However, toothed edges  171  and  172  can be located on elongate elements  150  and  151  such that moving sliding member  175  in direction  303  moves elongate elements  150  and  151  toward their splayed configuration and moving sliding member  175  in direction  305  moves elongate elements  150  and  151  toward their overlapped configuration. 
   Elongate elements  150  and  151  may be constrained in straightened shapes within a sheath  178 . This will permit compact and relatively atraumatic entry into a body. Sliding member  175  can then be moved in direction  303  relative to sheath  178  in order to extend elongate elements  150  and  151  from the end of the sheath. In the preferred mode, this motion will also tend to keep elongate elements  150  and  151  in their overlapped configuration without splaying these elements apart in the wrong direction. (As described above, toothed edges  171  and/or  172  and/or the jaws  173  and/or  174  can be designed to prevent splaying in the wrong direction). Elongate elements  150  and  151  can then be repeatedly moved toward their splayed configuration or their overlapped configuration by moving sliding member  175  in directions  305  or  303 , respectively, and a means may be provided to minimize relative motion between cannula  176  and sheath  178  during this repetitive motion. 
   Elongate elements  150  and  151  can be withdrawn back inside sheath  178  by forcibly moving sliding member  175  in direction  305  relative to sheath  178 . In a preferred version (not shown) the end of sheath  178  would force elongate elements  150  and  151  into their overlapped configuration, as well as forcing elongate elements  150  and  151  into straightened shapes into sheath  178  in order to permit the entire assembly to be withdrawn from a body in a compact and relatively atraumatic fashion. Alternatively, sheath  178  can be extended over elongate elements  150  and  151  to straighten these elements into sheath  178  and to permit the entire assembly to be withdrawn from a body in a compact and relatively atraumatic fashion. 
   If a sheath  178  is utilized, it could be mounted to the passive (reference) member of the manually operated mechanism. In this fashion, the extension and withdrawal of elongate elements  150  and  151  from or into sheath  178  can be accomplished by utilizing an expanded stroke of the same manually operated mechanism which is used to move sliding member  175  in order to splay or increasingly overlap elongate elements  150  and  151 . In addition, in order to permit the elongate elements  150  and  151  to be oriented in any desired direction relative to the manually operated mechanism, this mechanism would preferably permit axial rotation of the entire assembly of sheath  178  and its contents relative to the manually operated mechanism. 
   When elongate elements  150  and  151  are to be removed and replaced, it would be advantageous to move cannula  176  far enough in direction  303  so that pivot  170  is beyond the end of sheath  178 . Then the pivot pin can be removed, sliding member  175  can be extended in direction  303  beyond the end of cannula  176 , and elongate elements  150  and  151  can be simply slid out of jaws  173  and  174  in a direction perpendicular to the longitudinal axis of sliding member  175 . 
     FIG. 8-7D  shows how sliding member  175  could be configured around a pivot fixing member  185 , which has holes  181  and  182 . Elongate elements  150  and  151  are rotatably mounted on a pin  180 . The ends of pin  180  can be placed into holes  181  and  182  when sheath  178  is pulled back in direction  400 , since the ends of sliding member  175  and the ends of pivot fixing member  185  can gently splay apart when they are not held within sheath  178 . When sheath  178  is moved back in direction  401 , elongate elements  150  and  151  will be securely held when pin  180  is within sheath  178 . The end of pivot fixing member  185  which has holes  181  and  182  can be fork shaped. Preferably a means is provided which minimizes motion of pivot fixing member  185  relative to sheath  178  when sliding member  175  is utilized to repeatedly move elongate elements  150  and  151  toward their splayed or overlapped configurations.  FIG. 8-7E  shows the device before sheath  178  is pulled back to permit insertion of elongate elements  150  and  151 . In this configuration, pin  180  is preferably longer that the dimension between the two fork ends of pivot fixing member  185 , so that pin  180  is firmly locked into place. 
   In the embodiments described for  FIGS. 8-7A , B, C, and D, the elongate elements are preferably made of a pseudoelastic material, preferably a pseudoelastic shape memory alloy. The unconstrained shapes may be curved in directions away from the general planes of the body portions of the elongate elements (e.g. out of the plane of the paper). Also, in any of the embodiments described for  FIGS. 8-7A , B, C, and D, the elongate elements can be used for cutting, grasping, and/or dissecting tissues. The end portions of the elongate elements can be fashioned appropriately for any of these functions, or separate appropriately designed parts may be attached to the end portions of the elongate elements. 
     FIG. 8-8  shows a cutting device, similar to the device shown in  FIG. 8-1 , with curved elongate elements  91  and  93  extended from a housing  92 . This permits the elongate elements to be both open for dissecting, cutting and/or grasping and curved at an angle  94  away from axis  95  of housing  92 . Angle  94  is defined by the axis  95  of housing  92  and the straight line  96  which passes through the point of intersection of axis  95  with the distal end of housing  92  and the pin  99 . Angle  94  can be any desired angle, even greater than  90  degrees, thus permitting dissecting, cutting and/or grasping in a direction off axis  95 . This provides access to difficult to reach locations in the body. Elongate elements  91  and  93  are preferably shaped so that they circumscribe spherical arcs which allow the elements to engage each other and perform the cutting or grasping function, either as they are retracted back into housing  92 , or as housing  92  is extended over the elongate elements. The portions of elongate elements  91  and  93  which enter housing  92  assume a less curved shape. Elements  91  and  93  may be formed of a pseudoelastic material, preferably a pseudoelastic shape memory alloy. 
     FIG. 8-9  shows a device in which elongate elements  102  and  106 , preferably made of a pseudoelastic material and more preferably a superelastic shape memory alloy, are first held constrained in straightened and deformed shapes inside a cannula  103 . This permits compact placement into a body through tissue incision or orifice  108 . Elongate elements  102  and  106  are then extended out of cannula  103  by moving elongate elements  102  and  106  in direction  501  relative to cannula  103 . Since at least part of extended elongate elements  102  and  106  are no longer constrained, they will splay apart due to recovery of the pseudoelastic material into its preset curved unconstrained shape. Cannula  103  can be then be extended onto elongate elements  102  and  106  to force these elements to approach each other. Alternatively, elongate elements  102  and  106  can be withdrawn back into cannula  103  to force these elements to approach each other. In either mode, the tips of elongate elements  102  and  106  can be used to grasp tissue  107  or an object. The grasping function of elongate elements  102  and  106  can be enhanced by providing the end portions of these elements with bends  104  and  105 , teeth (not shown), or the like at their tips. Elongate elements  102  and  106  may also be ribbed or toothed along their entire lengths (not shown). The described mode of action may permit the instrument to be used multiple times in each location. 
   In embodiments of the invention in which the elongate elements are made of a pseudoelastic shape memory alloy, the large pseudoelastic deformation (up to 11% or more) permits much wider splaying of elongate elements  102  and  106  over a much shorter distance  109  than would be possible with conventional metals. This permits working in more confined spaces, particularly in endoscopic or laparoscopic surgery. A variation of this embodiment may include more than two elongate elements. 
   Shape memory alloys have a special feature which is beneficial for any of the embodiments of this invention, but in particular for any of the embodiments in which a grasping action is desired (especially in the embodiment shown in  FIG. 8-9 ). As a superelastic shape memory alloy is increasingly deformed from its unloaded shape, some of its austenitic phase changes into stress-induced-martensite. The stress strain curve presents a plateau during this phase change. This means that while the alloy undergoes this phase change, it can deform greatly with only minimal increases in loading. Therefore, elongate elements comprising superelastic shape memory alloys have a built-in safety feature. These elements can be designed (using appropriately treated alloys and appropriate dimensions) such that when they am loaded beyond a certain amount, the elements will tend to deform with a concomitant austenite to stress-induced-martensite phase change, instead of merely presenting a greater resistance with limited deformation to the load, which is seen with conventional metals. 
   Just as the stress strain curves of shape memory alloys present a plateau upon loading, they also present a plateau in the stress strain curve upon unloading. Unloading occurs when an elongate element made of superelastic shape memory alloy is permitted to revert from a significantly deformed shape toward its original unstressed shape, Because of the plateau, such an element can maintain an almost constant force during much of the unloading cycle until just before it is completely unloaded. This feature is especially useful for any grasper embodiment of this invention, because it means that an object held between one or more elongate elements made of a superelastic shape memory alloy can be gripped with nearly a constant force despite decreases in the amount(s) of deformation of the element(s). 
     FIGS. 8-10A , B, and C illustrate three views of another embodiment. As elongate elements  121  and  123  are extended outside the housing  120 , they splay outward causing end portions  122  and  124  to separate also. When elongate elements  121  and  123  are partially withdrawn into housing  120 , they cause end portions  122  and  124  to approach each other. If elongate elements  121  and  123  are further withdrawn into housing  120 , the sections  121 e and  123 e of elongate elements  121  and  123  are forced to deform into straightened shapes in order to pass into housing  120 , thus causing the direction of orientation of end portions  122  and  124  to approach the direction of axis  126  of housing  120 , and the angle  125  approaches zero degrees (angle  125  is defined by axis  126  of housing  120  and the plane of end portions  122  and  124 ). End portions  122  and  124  may also be fully or partially withdrawn into housing  120 , if desired. The straight configuration permits easy placement and/or removal of the instrument into or from a body in a compact and relatively atraumatic fashion. However, with elongate elements  121  and  123  in a completely extended position, angle  125  permits access to difficult to reach locations. 
   In the embodiments shown in  FIGS. 8-10A , B, and C, the body portions of elongate elements  121  and  123  are preferably made of a pseudoelastic material and more preferably a superelastic shape memory alloy. Alternatively, sections  121 e and  123 e may be the only parts of elongate elements  121  and  123  which are made of a pseudoelastic material. End portions  122  and  124  may also be made of a pseudoelastic material, but they could be made of any suitable material, even if elements  121  and  123  are made at least in part of a pseudoelastic material. End portions  122  and  124  may have a cutting function or a grasping function. Also, end portions  122  and  124  may be curved. They may also be used to separate (dissect) tissues. The described mode of action may permit the instrument to be used multiple times in each location. 
     FIGS. 8-11A  and  8 - 11  B show embodiments similar to the embodiments shown in  FIGS. 8-1  and  8 - 8 , respectively. In  FIGS. 8-11A  and  8 - 11 B, the elongate elements  131  and  133  extend beyond the pin  139  in order to provide end portions  135  and  134 . End portions  135  and  134  may be unitary extensions of elongate elements  131  and  133  or they may be separate portions bolted or attached to elongate elements  131  and  133 . The action of withdrawing elongate elements  131  and  133  into housing  111  closes and deforms body portions  117  and  116 , and the scissor action is transmitted to end portions  135  and  134 . In this manner, the body portions of the elongate elements act as the actuating means for the end portions of the elongate elements.  FIG. 8-11B  illustrates a curved version of  FIG. 8-11A . The angle  112  is defined by the axis  113  of housing  111  and the straight line  114  passing through the point of intersection of axis  113  with the distal end of the housing and pin  139 . Angle  112  can be any number of degrees, even greater than 90 degrees, thus permitting dissection, cutting and/or grasping in a direction off axis  113 . This provides access to difficult to reach locations within a body. 
   In the embodiments of  FIGS. 8-11A  and  8 - 11 B, body portions  116  and  117  are preferably made of a pseudoelastic material, preferably a superelastic shape memory alloy. Alternatively, only end portions  134  and  135  may be made of a pseudoelastic material, but these end portions could be made of any suitable material, even if body portions  116  and  117  are made of a pseudoelastic material. End portions  134  and  135  may have a cutting function or a grasping function. They may also be used to separate and dissect tissues. The described mode of action may permit the instrument to be used multiple times in each location. 
     FIG. 8-12  illustrates another embodiment similar to the embodiment shown in  FIG. 8-11B . Body portions  141  and  143  of elongate elements  119  and  118  are used to create both a scissors action through a pinned location  149  and also to provide the ability to direct the scissor action at an angle of about ninety degrees off the axis  148  of housing  140 . Elongate elements  119  and  118  splay apart when they are outside of housing  140 . As housing  140  is pushed over the body portions  141  and  143  in direction  144 , sections  141 e and  143 e move toward one another. This action in turn causes the end portions  146  and  147  to approach each other in a scissor fashion by pivoting around pin  149 , which is substantially parallel to axis  148 . Because the relative movement of housing  140  in directions  144  and  145  is perpendicular to end portions  146  and  147 , the position of these end portions is unchanged with respect to the tissue location. After end portions  146  and  147  have closed, withdrawal of elongate elements  119  and  118  into housing  140  (or moving housing  140  in direction  144  relative to elongate elements  119  and  118 ) causes sections  141  e and  143 e to straighten from their curved shapes. This permits end portions  146  and  147  to generally align with axis  148  of housing  140 . End portions  146  and  147  may also be fully or partially withdrawn into housing  140 , if desired. The straight configuration permits easy placement and/or removal of the instrument from a body in a compact and relatively atraumatic fashion. 
   In the embodiments of  FIG. 8-12 , body portions  141  and  143  of elongate elements  119  and  118  are preferably made of a pseudoelastic material, more preferably a superelastic shape memory alloy. Alternatively, sections  141 e and  143 e may be the only parts of body portions  141  and  143  which are made of pseudoelastic material. End portions  146  and  147  may also be made of pseudoelastic material, but they could be made of any suitable material, even if body portions  141  and  143  are made at least in pad of a pseudoelastic material. End portions  146  and  147  may have a cutting function or a grasping function. They may also be used to separate (dissect) tissues. The described mode of action may permit the instrument to be used multiple times in each location. 
   A variation of the embodiment shown in  FIG. 8-12  would still have the bent portions  141 e and  143 e, but would have end portions  146  and  147  in a plane which is parallel to axis  148 , so that pivot  149  is perpendicular to axis  148 . In this embodiment, moving body portion  141  in direction  144  and/or moving body portion  143  in direction  145  would tend to splay end portions  146  and  147  apart. Moving body portion  141  in direction  145  and/or moving element  143  in direction  144  would tend to bring end portions  146  and  147  into a more overlapped configuration. In this manner, the body portions of the elongate elements act as the actuating means for the end portions of the elongate elements. In order to facilitate the requisite bending in sections  141 e and  143 e, body portions  141  and  143  would preferably be either round or made of flat material oriented in a plane perpendicular to the plane of end portions  146  and  147 . If body portions  141  and  143  are made of flat material, they may include a 90 degree twist in the material between sections  141 e and  143 e and end portions  146  and  147 , respectively. 
     FIG. 8-13  shows a device of this invention in which the elongate elements  186  and  187  are bent, preferably about  90  degrees, relative to the longitudinal axis of housing  188 . The elongate elements are slid longitudinally along the axis of housing  188  by means of any suitable manually operated mechanism in order to separate end portions  183  and  184  from each other or to bring end portions  183  and  184  toward each other or even in contact with each other. End portions  183  and  184  can have any suitable surfaces in order to permit dissection, cutting, and/or grasping. Elongate elements  186  and  187  are preferably made of a pseudoelastic material, more preferably a superelastic shape memory alloy. This permits the bent portions of elongate elements  186  and  187  to be deformed and straightened so that the elongate elements can be withdrawn into housing  188 . The straight configuration permits easy placement and/or removal of the instrument from a body in a compact and relatively atraumatic fashion. End portions  183  and  184  may be made of any suitable material, whether it is pseudoelastic or not. 
   In any of the embodiments of this eighth form of the invention, preferably both of the elongate elements are actuated by the manually operated mechanism, so that dissection, cutting, and/or grasping is done by an equal symmetrical motion of each elongate element. However, in some situations, it may be desirable to have embodiments in which one elongate element is moved more by the manually operated mechanism than the other elongate element. In some cases, it may even be desired to have one elongate element function as a stationary and thereby passive element, where the manually operated mechanism only moves the other elongate element. 
   In any of the embodiments of this eighth form of the invention, any suitable manually operated mechanism may be utilized to move the elongate elements. Possible mechanisms include sliders, pistol grip handles, scissors handles, and syringe-plunger arrangements. In any of the embodiments of this invention, it may be desirable to be able to axial rotate the elongate elements relative to the manually operated mechanism, so that the elongate elements can be pointed in a preferred direction without having to rotate the manually operated mechanism itself. This feature would enhance the comfort of using a device of this invention. However, a means is preferably provided to prevent any undesired axial rotation of the elongate elements relative to the manually operated mechanism while the manually operated mechanism is being used to splay or overlap the elongate elements. 
   In any of the embodiments of this invention, a suitable means may be provided for passing a fluid (liquid or gas) through the device for irrigation, aspiration, insufflation, etc. In any of the embodiments of this invention, electricity may be passed to one or both end portion(s) of the elongate element(s) for purposes of electrocautery or electrocutting. 
   In any of the embodiments of this invention, the tips (of the end portions) of the elongate elements may be pointed or blunt. Pointed tips may facilitate the use of the device of this invention in the separation (dissection) of tissues, while blunt tips would minimize the risk of any undesired trauma that the tips could inflict upon tissues. 
   While the invention has been described in connection with specific embodiments thereof, those skilled in the art will recognize that various modifications are possible within the principles described herein. Such modifications, variations; uses, or adaptations of the invention, including such departures from the present disclosure as come within known or customary practice in the art, fall within the scope of the invention and of the appended claims.