Abstract:
A surgical device having a sheath and legs slidably received within the sheath. The legs are adapted to move outwardly away from each other when deployed from the sheath to establish a deployed position, and to move inwardly toward each other to collapse within the sheath and define a stowed or grasping position. Each of the legs has a transverse cross-sectional shape defined by a concave surface, an oppositely-disposed convex surface, and lateral sides interconnecting the concave and convex surfaces. The legs and sheath are configured to cause the legs to fully collapse within the sheath such that the lateral sides of adjacent pairs of the legs contact each other, and/or the legs define a tubular shape having a circular opening defined by the concave surfaces of the legs and a circular exterior cross-section defined by the convex surfaces of the legs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a continuation-in-part patent application of U.S. patent application Ser. No. 10/604,297, filed Jul. 9, 2003, which is a continuation-in-part patent application of prior application Ser. No. 09/714,808 filed Nov. 15, 2000, now U.S. Pat. No. 6,416,519. 

   BACKGROUND OF THE INVENTION 
   The present invention generally relates to surgical devices adapted to capture an object within a cavity of the human body, such as when moving, manipulating and extracting biological material during a medical procedure. More particularly, this invention relates to a surgical device comprising elongate members that, when collapsed toward each other, are capable of capturing an object, and wherein each of the elongate members has a cross-sectional shape that promotes the ability of the elongate members to expand and collapse relative to the other members. 
   Various instruments are known in the art for surgically removing stones, calculi and other hard materials from the body. An example is an extraction instrument disclosed in U.S. Pat. No. 5,281,230 to Heidmueller as comprising a pair of bowls that are pivoted toward and away from each other by engaging their proximal ends with a sheath. Other types of extraction instruments make use of multiple wires that are flexed to grasp an object. For example, U.S. Pat. No. 5,944,728 to Bates discloses an instrument having arcuate wires with rectangular, round, D-shaped, or V-shaped cross-sections. The wires form a basket when a plunger associated with the instrument is in a distal position, allowing the legs to radially collapse toward each other. To expand the legs, the plunger must be actuated into engagement with the legs, forcing the legs radially apart from each other. As such, surgically moving, manipulating and extracting material from a body cavity is complicated by the requirement to additionally operate the plunger to expand and contract the legs. 
   Another example of an extraction instrument is disclosed in U.S. Pat. No. 6,203,552 to Bagley et al. As with Bates, the instrument taught by Bagley et al. has arcuate legs that form a collapsible basket when actuated with respect to a sheath. Each leg has a wedge-shaped cross-sectional shape, so that together they fill the cross-sectional area of the sheath. Contrary to Bates, the instrument disclosed by Bagley et al. does not require a separate plunger to expand (dilate) and collapse the basket. 
   U.S. Pat. No. 6,500,182 to Foster and U.S. Patent Application Publication No. 2002/00668954 to Foster disclose other extraction instruments configured to be actuated without the assistance of a plunger. Each instrument taught by Foster has resilient grasping members (legs) that form a basket or forceps when extended from a sheath, and which collapse toward each other when the sheath is advanced over the legs (or the legs are retracted into the sheath). According to Foster, the legs are formed by cutting or forming slots in an elongated cylindrical member, such as a cannula. If formed from a cannula, the legs are said to have semicircular cross-sectional shape. The edges of the legs are said to be spaced apart when in the compact (collapsed) position, a condition which appears to be inherent because each adjacent pair of legs is separated by the slot formed during the cutting/forming operation that defined the legs. As such, it appears the legs cannot be fully collapsed with the sheath, since the sheath cannot have an inner diameter smaller than the cannula from which the legs were defined and which must also be accommodated within the sheath. 
   There is an ongoing effort to devise surgical extraction instruments with greater dilating force when expanding to acquire an object, with greater grasping strength when capturing onto an object, and that maintain their form and alignment throughout their range of motion so as to more easily capture biological material during a variety of medical procedures. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention provides a surgical device having a sheath with an interior passage and legs slidably received within the passage of the sheath. The legs are adapted to move outwardly away from each other when deployed from the sheath to establish a deployed position, and to move inwardly toward each other to collapse within the sheath and define a stowed position. Each leg has a transverse cross-sectional shape defined by a first surface that is concave, an oppositely-disposed second surface that is convex, and lateral sides interconnecting the first and second surfaces. 
   According to one aspect of the invention, the legs and sheath are configured to cause the legs to fully collapse within the sheath such that the lateral sides of adjacent pairs of the legs contact each other, preferably along their entire lengths, when the legs are within the sheath. According to another aspect of the invention, when in the stowed position the legs are substantially parallel to each other and define a tubular shape having a circular opening defined by the first surfaces of the legs and a circular exterior cross-section defined by the second surfaces of the legs. 
   The legs have distal ends that may be connected together so that the legs define a basket in the deployed position, and so that the basket collapses as the sheath is advanced over the legs so as to define a grasping position in which the legs are operable to perform a grasping operation. Alternatively, the legs are not connected such that the device is operable as forceps. With each of these embodiments, each leg is preferably formed to have a parabolic curved shape, enabling the legs to automatically deploy radially outward and away from each other when outside the sheath, thereby eliminating the need for a plunger to expand the basket or forceps formed by the legs. The cross-sectional shape of the legs is capable of contributing greater strength and rigidity to the legs to promote their ability to expand with a sufficient force that eliminates the need for a plunger, to provide greater grasping strength when collapsed, and to maintain their form and alignment throughout their range of motion. Furthermore, because the legs are supported and arranged so that their lateral sides contact each other when the legs are fully within the sheath, the grasping strength of the legs is maximized when attempting to capture an object and thereafter complete containment is possible of very small objects such as renal or ureteral calculi. As a result, the device is capable of reliably moving, manipulating and extracting biological material in a variety of medical procedures. 
   Other objects and advantages of this invention will be better appreciated from the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1 and 2  are side and end views, respectively, of a surgical device in a deployed position in accordance with a first embodiment of this invention. 
       FIGS. 3 and 4  are side views of the surgical device of  FIG. 1  in intermediate and grasping positions, respectively. 
       FIG. 5  is a cross-section along line  5 - 5  of  FIG. 1 . 
       FIG. 6  shows a surgical device in accordance with a second embodiment of this invention. 
       FIG. 7  depicts a multistage process for producing legs for devices in accordance with the present invention. 
       FIG. 8  is a perspective view of distal ends of legs produced by the process depicted in  FIG. 7  and in a fully collapsed position. 
       FIGS. 9 and 10  are perspective views of a surgical device in deployed and stowed positions, respectively, in accordance with a third embodiment of this invention. 
       FIGS. 11 and 12  are perspective views of a surgical device in deployed and stowed positions, respectively, in accordance with a fourth embodiment of this invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference to  FIGS. 1 through 4 , a surgical device  10  is shown in accordance with a first embodiment of this invention. The device  10  is particularly intended and suitable for extraction procedures, in which biological materials are required to be surgically moved, manipulated and/or extracted from a cavity of the human body. As such, the device  10  can be adapted for use as, for example, a urological, gynecological, cardiological, laparoscopical, or gastrointestinal instrument. 
   The extraction device  10  is depicted as comprising a sheath  12 , legs  14  that project from a passage within the sheath  12 , and a cable  18  (or other suitable actuating member) for deploying the legs  14  from the sheath  12  once the distal end of the device  10  is properly positioned within a body cavity for the intended procedure, and then maintaining the positions of the legs  14  within the body cavity while the sheath  12  is advanced over the legs  14  to collapse them. A distal portion  16  of the cable  18  projects from the sheath  12  so as to be surrounded by the legs  14 , as seen in  FIGS. 1 ,  3  and  4 . The sheath  12  can be formed of any suitable material known in the art. The passage within the sheath  12  can be sized to be sufficiently large to not only accommodate the legs  14  and cable  18 , but also provide an irrigation or injection lumen, or a channel for a laser fiber to be passed through so that stones and other biological materials can be captured, held and fragmented to allow the resulting fragments to pass. The sheath  12  may also be equipped with a hollow channel (not shown) through which a sparking wire can be passed to enable the legs  14  (if formed of a conductive material) to be energized with electrosurgical cutting or coagulating current. 
   The embodiment of  FIGS. 1 through 4  shows the ends  28  of the legs  14  as being connected together, so that the legs  14  in combination form a basket  20 . In  FIGS. 1 through 4 , the ends  28  of the legs  14  and the distal portion  16  of the cable  18  are interconnected with a distal connector  30  which, depending on the materials used to form the legs  14  and cable  18 , can be attached by metallurgical joining (e.g., soldering, brazing, etc.) or with a mechanical crimp joint. While the device  10  is shown as being equipped with four legs  14 , it is foreseeable that fewer or greater numbers of legs could be employed. For example, the device could have two legs  14  (forming, in effect, a snare) or as many as eight legs  14  or more. As represented in  FIG. 1 , the legs  14  are formed to have a parabolic curved shape, as by such known methods as stamping, rolling, extruding, etc. The legs  14  are formed from a sufficiently rigid material, such as a stainless steel, or a “shape memory” nickel-titanium alloy such as NITINOL, so that the parabolic curved shape of the legs  14  causes the midportions of the legs  14  to automatically deploy radially outward and away from each other (and away from the distal portion  16  of the cable  18 ) when the legs  14  are deployed outside the sheath  12  with the cable  18 . As a result, the device  10  does not require a plunger capable of being actuated relative to the legs  14  in order to force the legs  14  radially apart to form the basket  20  of  FIG. 1 . The legs  14  are sufficiently elastically deformable so that, when the sheath  12  is advanced over the legs  14 , the legs  14  elastically collapse radially toward each other to acquire an intermediate position ( FIG. 3 ) in which the basket  20  is partially collapsed. With further advancement of the sheath  12  ( FIG. 4 ), the legs  14  are largely stowed within the sheath  12  and substantially parallel to each other and to the distal portion  16  of the cable  18 . 
   A key feature of the present invention is that each leg  14  has a concave-convex cross-section that contributes greater strength to the legs  14 , such that the legs  14  maintain their form and alignment and provide greater grasping strength and expansion force than extraction devices equipped with wires having other cross-sectional shapes. As a result, the device  10  is well suited for moving, manipulating and extracting biological material, such as calculi, stones, etc. As depicted in  FIG. 5 , the legs  14  have a concave-convex cross-section in the sense that the inward surfaces  22  of the legs  14  facing each other are concave, while the oppositely-disposed outward surfaces  24  of the legs  14  are convex. Each surface  22  and  24  is represented in  FIG. 5  as having a substantially constant radius of curvature, with the result that thicknesses of the legs  14  in the direction of a radial of the curvature are substantially constant. The sides  26  of the legs  14  are contiguous with the surfaces  22  and  24 , and can be of any suitable shape, e.g., rounded, flat such as the radials of the curvatures of the surfaces  22  and  24 , etc. When fully collapsed, the legs  14  define a tubular shape in the sense that the legs  14  in combination define a circular exterior cross-section and a circular opening that is sized to accommodate the cable  18 . As such, and also as evident from  FIG. 4 , the sides  26  of the legs  14  contact each other when the legs  14  are fully collapsed within the sheath  12 . This aspect of the invention, in which gaps between adjacent legs  14  are eliminated as the sheath  12  advances over the legs  14 , enables the device  10  to define a circumferentially continuous enclosure capable of fully containing small renal and ureteral calculi and other very small biological material. This aspect of the invention also enables the device  10  to be used to remove polyps or growths for biopsy by placing the basket  20  so that the polyp/growth is between a pair of adjacent legs  14 , after which the basket  20  is completely collapsed with the sheath  12  such that the sides of the legs  14  have a scissor effect on the polyp/growth. 
     FIG. 6  shows a second embodiment of an extraction device  110  of this invention, in which the legs  14  have a longitudinal configuration that causes the basket  120  to have a helical shape. Other than the helical shape of the basket  120 , the device  110  can have an identical construction to the device  10  of  FIGS. 1 through 4 . 
   When used to remove a stone (or calculi or other object) from a cavity of the human body, the legs  14  are extended from the sheath  12  with the cable  18  such that the legs  14  resiliently expand outward to reacquire their parabolic curved shape. Once the stone is surrounded by the legs  14  so as to be nested with the basket  20 , the cable  18  is actuated relative to the sheath  12  to advance the sheath  12  over the legs  14 , causing the basket  20  to collapse and grasp the stone. By subsequently extending the legs  14  from the sheath  12 , the stone can be released. As such, surgically moving, manipulating and extracting bodies and materials within the human body is performed without additionally operating a plunger or other extraneous component to expand and contract the basket  20  formed by the legs  14 . 
   As noted above, the legs  14  can be formed by such known methods as stamping, rolling, extruding, etc. Rolling and stamping are particularly desirable from the standpoint of being able to produce legs  14  that are dense and therefore capable of generating greater strength and expansion force.  FIG. 7  depicts a multistage stamping or rolling process suitable for producing the legs  14  for the devices of  FIGS. 1 through 6 , as well as subsequent embodiments of the invention described in reference to  FIGS. 9 through 12 . In  FIG. 7 , a solid round wire  32  is shown supported on a die (or bottom roller)  34 , and then engaged with a ram (or upper roller)  36  during multiple operations until a leg  14  is produced. Legs  14  produced in this manner can be continuous and spooled in coils for later cutting to length and assembly with the cable  18 . As a result of being formed from round solid wire  32 , the lateral sides  26  of the leg  14  are not as flat as those of the leg  14  depicted in  FIG. 5 , and the edges defined at the intersections of the lateral sides  26  with the concave inward surface  22  and the convex outward surface  24  of the leg  14  are rounded and not sharp. Furthermore, the inward and outward surfaces  22  and  24  are not necessarily equidistant from each other, resulting in the leg  14  having a nonuniform radial thickness. For example, the leg  14  in  FIG. 7  can be seen to be thinner near its sides  26  than at its center. 
   As previously described in reference to the embodiment of  FIGS. 1 through 4 , when fully collapsed the legs  14  define a tubular shape in the sense that the legs  14  in combination define a circular exterior cross-section and a circular opening, which is a result of their lateral sides  26  contacting each other along their entire lengths. The tubular shape defined by the legs  14  is depicted in  FIG. 8 , which evidences that gaps between adjacent legs  14  are eliminated so that the legs  14  define a circumferentially continuous enclosure capable of fully containing very small biological material. This aspect of the invention also maximizes the grasping strength of the legs  14  when attempting to capture an object. 
     FIGS. 9 and 10  represent an extraction device  210  with legs  14  shaped as a result of being produced by the process depicted in  FIG. 7 . As with the previous embodiments, the legs  14  are adapted for being stowed within a sheath  12 , where the legs  14  assume a fully-collapsed position consistent with  FIG. 4 . As before, the legs  14  may be actuated with a cable (not shown) or other suitable actuating member capable of simultaneously retracting the legs  14  into the sheath  12  and deploying the legs  14  from the sheath  12 . In the embodiment of  FIGS. 9 and 10 , the proximal ends of the legs  14  are connected together with a proximal connector  240  while the distal ends  28  of the legs  14  are connected together with a distal connector  230  so that the legs  14  in combination form a basket  220  when deployed.  FIG. 10  is illustrated with a portion of the sheath  12  removed to expose the collapsed legs  14  within the sheath  12  and evidence contact between the lateral sides  26  of the legs  14 . As evident from  FIGS. 9 and 10 , the ability to fully collapse the legs  14  until their sides  26  touch enables the device  210  to fully contain small renal and ureteral calculi. This aspect of the invention also enables the device  210  to be used to remove polyps or growths for biopsy by placing the basket  220  so that the polyp/growth is between a pair of adjacent legs  14 , after which the basket  220  is completely collapsed with the sheath  12  such that the sides  26  of the legs  14  have a scissor effect on the polyp/growth. Though not depicted in  FIGS. 9 and 10 , the device  210  could be configured with the cable  18  of  FIGS. 1 through 4  extending from the sheath  12  alongside the legs  14 , with the distal ends  28  of the legs  14  attached to the distal end  16  of the cable  18  with the distal connector  230  or other suitable means, as discussed in reference to the embodiment of  FIGS. 1 and 4 . 
   An extraction device  310  represented in  FIGS. 11 and 12  is essentially identical to that of  FIGS. 9 and 10 , with the exception that a distal connector is not employed such that the device  310  operates as forceps  320 . As in the embodiment of  FIGS. 9 and 10 , the proximal ends of the legs  14  are connected together with a proximal connector  340 , and a portion of the sheath  12  is removed in  FIG. 12  to illustrate the collapsed legs  14  within the sheath  12 . Also consistent with the previous embodiments of this invention, the ability of the device  310  to fully collapse the legs  14  until their sides  26  touch enables the device  210  to fully contain small renal and ureteral calculi, as well as have a scissor effect to remove polyps and other growths. The embodiment of  FIGS. 11 and 12  provides the additional capability of grasping biological materials with the distal ends  28  of the legs  14 , which together define and operate as jaws capable of extracting materials embedded in a cavity wall. The terminal surfaces of the distal ends  28  can be angled outward in the distal direction so that embedded materials, such as a stone embedded in the wall of the calyces in a kidney, can be more readily extracted. 
   While the invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. For example, appropriate materials could be substituted for those noted. Accordingly, the scope of the invention is to be limited only by the following claims.