Abstract:
A system for rapid manipulation and cutting that includes a housing, a first cutting element, and a drive mechanism adapted to be mounted at least partly within the housing and connected to the first cutting element for imparting relative motion to the first cutting element as a combination of slicing and downward forces at the portion of the first cutting element which is adapted to contact the tissue.

Description:
RELATED APPLICATION 
     This application claims the benefit of provisional U.S. Patent Application Ser. No. 60/444,326, filed Jan. 31, 2003 and having the same inventors and same title as the present application, and which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present inventions relate to devices and techniques for manipulation and cutting, and more particularly relate to eccentric rotary mechanisms for the cutting and manipulation and methods therefore. 
     BACKGROUND OF THE INVENTION 
     A known cutting device is the rotary slicer. Where meat is advanced into a thin blade rotating at relatively high speeds. The cutting action of this device is defined by the high slicing to chopping ratio. The resultant blade velocity vector is nearly normal to the direction of advancement. Webb, U.S. Pat. No. 5,569,285 describes a hand powered circular rotary surgical blade with a concentrically mounted cylindrical depth guard. Mueller, U.S. Pat. No. 5,507,764, describes a powered rotary scalpel method that is capable of developing a relatively high blade velocity relative to linear hand speed in the direction of cutting. 
     For certain clinical procedures, it is very important to make incisions to a precisely controlled pre-determined depth. Certain known devices and methods can be found that address the need to control depth of cut such as Feldman, U.S. Pat. No. 2,882,598 and Williams, U.S. Pat. No. 4,473,076, which describe a depth limiting foot or ski element used in conjunction with a scalpel. Another known method is Urban, U.S. Pat. No. 5,860,996, that discloses a blade actuating assembly, which permits selective longitudinal linear reciprocal movement of a tissue cutting blade positioned at a distal end of a trocar assembly, from a non-deployed position to a deployed position and back to a non-deployed position. The Urban device moves in a longitudinal motion only and punches into the tissue. 
     The known methods of tissue incision include the use of scalpels and scissors that mechanically cut the target tissue. Scalpels and scissors are useful tools when the sharp edges of the devices are clearly in view of the clinician. However, during certain procedures the sharp edge or edges may be hidden from view and prohibit the safe use of the cutting instrument. Furthermore, as the edges are hidden, it is very difficult to determine the precise depth of cut. Other methods of tissue manipulation include the dissection of different structures along natural lines by dividing or tearing the connective tissues. A blunt or sharpened obturator, such as those used with trocars, may also be used to cut and/or dissect tissue. Again, with these devices it is difficult to determine the precise depth of cut. Electrocautery devices are commonly used to surgically separate tissue. Other means of tissue manipulation include the use of energy-assisted scalpels. These devices make use of ultrasonic, laser, and radio frequency energies to assist in the manipulation of tissues. Excess energy delivered by these devices can result in collateral tissue damage, such as thermal charring and desiccation. Therefore, what is needed is a system and method for cutting that will allow precise control of the cutting edge and for rapid cutting of various materials including incision or dissection of tissues in a more controlled manner than currently exists. 
     SUMMARY OF THE INVENTION 
     The present invention provides a means for rapid cutting of various materials including incision or dissection of tissues in a more controlled manner than currently exists. As an aspect of one exemplary embodiment of the invention, a blade and blade actuation mechanism is provided that allows for simultaneous rotation and advancement of a cutting edge. In one arrangement of the invention, the system of the present invention provides an appropriate blend of slicing and downward force in order to cut efficiently. In one exemplary arrangement, at least two such motions are combined when cutting, thereby enhancing the efficiency of a blade element in at least some applications. 
     Another aspect of the invention, present in at least some embodiments, is to optimize the efficiency of the cutting action by providing, for a cut along a straight path, linear motion along two of the three principal axes which beneficially affect cutting performance (slicing and downward forces) and in addition provide beneficial torque about the lateral axis, while minimizing motion and torque which is not beneficial, such as linear motion along the lateral axis or torque on the principal axes. It will be appreciated that, for a straight cut, linear motion relative to the longitudinal axis of the cutting element results in a slicing cut, and linear motion relative to the vertical axis results in a chopping or plunge cut. It will also be appreciated that a slicing motion is the result of torque. 
     In another aspect of at least certain embodiments of the invention, a system of optimized load parameters is determined. The factors used in determining load parameters may include some or all of the: type of tissue to be incised, desired incision results including incision depth, curved or straight cutting edge, and curvilinear or straight cutting paths. The resultant optimized load parameters include, in at least certain embodiments: the resultant force vector; velocity and acceleration; and uniformity and/or consistency of load rates and velocity. 
     Another aspect of at least some embodiments of the invention is the flexibility to use the cutting system as a tissue manipulator for blunt dissection, or as a tissue probe. Various housings, drive mechanisms and cutting element shapes are proposed, with the application impacting the particular implementation of each of these elements in each specific implementation. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIGS. 1A-1B  illustrate a cutting assembly in accordance with the present invention mounted at the distal tip of a pen-style housing, with  FIG. 1B  further showing a front elevational view including an illumination source. 
         FIGS. 2A-2B  illustrate a cutting assembly in accordance with the present invention mounted on a handpiece. 
         FIGS. 3A-3D  illustrate various details of a first implementation of a cutting assembly in accordance with the invention. 
         FIGS. 4A-4B  illustrate the range of motion of a first implementation of a cutting assembly in accordance with the invention. 
         FIGS. 5A-5B  illustrate an alternative range of motion for a cutting assembly in accordance with the invention. 
         FIGS. 6A-6D  illustrate a further alternative range of motion for a cutting assembly in accordance with the invention. 
         FIGS. 7A-7D  illustrate various details of a cutting assembly having a shark-fin style blade. 
         FIGS. 8A-8D  illustrate various details of a cutting assembly having an elliptical style blade. 
         FIGS. 9A-9D  illustrate various details of a cutting assembly having an advancing round blade. 
         FIGS. 10A-10D  illustrate various details of a cutting assembly having a retreating bearing block. 
         FIGS. 11A-11D  illustrate a few of the many possible blade shapes usable with the cutting assembly of the present invention. 
         FIGS. 12A-12C  illustrate a dual blade configuration. 
         FIGS. 13A-13B  illustrate an implementation of a cutting assembly having monopolar and bipolar electrocautery, respectively. 
         FIG. 14  illustrates a pinion gear drive assembly for actuating the blade. 
         FIG. 15  illustrates a pulley drive assembly for actuating the blade. 
         FIG. 16  illustrates a bevel gear drive assembly for actuating the blade. 
         FIG. 17  illustrates a direct motor drive assembly for actuating the blade. 
         FIG. 18  illustrates a crank arm drive assembly for actuating the blade. 
         FIGS. 19A-19D  illustrates an implementation of a cutting assembly having a cantilever spring element. 
         FIG. 20  illustrates a detailed perspective view of the cutting assembly of  FIGS. 19A-19D . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to  FIGS. 1A and 1B , a cutting assembly  100  may be mounted at the distal tip of a pen like housing  110 . The cutting assembly  100  may be used for cutting various materials. As one example, not intended to be a limitation, the cutting assembly can be used to cut commercially manufactured materials, such as paper or plastic, as well as organic material, such as animal or human tissue. The cutting assembly  100  can be made in a variety of shapes, but for the sake of clarity the cutting assembly  100  is shown to emulate the shape of a hand held cutting instrument, such as a scalpel. Furthermore, for the sake of clarity, the cutting assembly will be discussed or described herein in the context of cutting or manipulating organic tissue. However, the functional elements discussed and the methods set forth can easily be applied to applications relating to cutting manufactured materials, such as Kevlar or other fabrics. 
     Considered in the context of cutting animal or human tissue, the cutting assembly  100  described herein requires less lateral tissue stabilization, thus allowing the user—for example, a clinician—to perform more precise curvilinear incisions. Furthermore, illumination elements, such as LED&#39;s  120 , which are best seen in  FIG. 1B  may be added to enhance the clinician&#39;s view of the target tissue. An activation button  130  is typically provided to actuate the cutting assembly  100  as described in greater detail hereinafter. The housing  110  may also contain batteries, appropriate connectors, and/or a power switch, and may be disposable or reusable, depending on the particular implementation. 
     Referring next to  FIGS. 2A and 2B , a cutting element assembly  200  in accordance with the present invention may alternatively be mounted at the distal tip  210  of an elongate cannula-like structure  220  that is connected to a hand piece  230 , thus forming a tool  235  suitable for Laparoscopic surgical uses, as well as any other application in which a hand piece will simplify repositioning or operation of the cutting assembly  200 . Additionally, an articulating mechanism  240  may be added proximally to the cutting element  200  to enhance user-directed positioning of the tool  235 , which may in turn be adjusted by articulation control  250 . A trigger or other actuator  260  is provided to actuate the cutting assembly  200 . The trigger  260  could be implemented as a conventional trigger, a variable speed switch, an on/off pushbutton, or any other form of actuator. The housing could also include an internal working channel, a light, a scope or a camera, again chosen based on the particular implementation. 
     As a still further alternative, the cutting element assembly  200  in accordance with the present invention may be mounted at the distal tip of an elongate cannula like structure  220  and connected to robotic assembly. 
     Referring next to  FIGS. 3A-3D , a first implementation of a cutting assembly  300  that incorporates at least some of the features of the invention can be better appreciated.  FIG. 3A  illustrates in top plan view the distal end of a housing  310  and the cutting assembly  300 .  FIG. 3B  illustrates a front elevation view of the cutting assembly  300  including a rotary cutting blade  320 .  FIG. 3C  illustrates a side elevation view of the cutting assembly  300  and the housing  310  and  FIG. 3D  illustrates a cut-away view showing the cutting blade  320  and the housing  310  along the line A-A in  FIG. 3A . The cutting assembly  300  includes a bearing block  330  that supports a bearing  340 . An axle  350  passes through an eccentric bore in the cutting blade  320  and into the bearing  340 , such that the bearing block  330  provides a low friction pivot for the cutting blade  320 , provides protection from the cutting blade  320  when not actuated, and limits the amount of the cutting blade  320  that is exposed when actuated during a cutting event. Furthermore, the bearing block  330  aligns the cutting blade  320  along a desired cutting path, allows cutting motions only in beneficial directions and inhibits or prevents motion in non-beneficial directions. The degree of blade eccentricity, as defined by the location of the eccentric bore in the cutting blade  320 , defines the depth of cut and the ratio of slicing motion to plunging motion. 
     A separate external driver mechanism, discussed hereinafter in connection with  FIGS. 14-18 , is required to urge the blade about the pivot and to define the cutter velocity. A source of motive force, such as a motor and energy storage device, form part of the driver mechanism. The incision system of  FIGS. 3A-3D  operates as follows. For the sake of convenience only, a housing of the sort shown in  FIG. 1  will be assumed, although the particular form of housing is not limiting. A user initiated cutting event begins by actuating an activation switch, such as the activation switch  130  of  FIG. 1 , which causes the driver mechanism to provide a resultant rotational movement of the cutting blade about the cutting blade pivot or axle. The cutting blade, such as the cutting blade  320  of  FIGS. 3A-3D , has an eccentric bore and, hence is eccentrically mounted. Accordingly, upon rotation of the eccentrically mounted cutting blade about the pivot, the cutting edge simultaneously advances and rotates into the target tissue. 
     In one arrangement, the eccentrically mounted circular cutting blade is intermittently rotated at least one complete revolution as a means of cutting tissue. Many other cutting motions are possible, including reciprocating movement, partial rotation, continuous rotation, and intermittent rotation through less than a full revolution. 
     As shown best in  FIG. 3D , in a first position, the eccentrically mounted cutting blade  320  is “parked” or rotated to a safe state where no part of the cut-ting blade  320  extends beyond a distal tip  370  of the bearing block  330  in order to protect against and prevent accidental contact with the cutting blade  320 . In this position, clinicians and the patient are protected from the cutting blade  320  by the distal tip  370  of the bearing block  370 . In this first position the cutting assembly  300  may be used as a tissue manipulator for blunt dissection, or as a tissue probe. 
     By rotating the cutting blade  320  about the axle  350 , the eccentric mounting of the cutting blade  320  causes a portion of the cutting blade  320  to be exposed beyond the bearing block  330 , thus allowing tissue to be cut. The exact amount of the cutting blade  320  that is exposed by such rotation is determined by the location of the eccentric bore in the cutting blade  320  relative to the blade center  380 , and the extent to which the cutting blade  320  is rotated about the bearing block  330 , which can be better appreciated from  FIGS. 4A-4B . 
       FIG. 4A  shows a side elevation view of the bearing block  330  and the cutting blade  320 , and  FIG. 4B  shows a cut-away view of the cutting blade  320  mounting relative to the bearing block  330 . In the position shown in  FIGS. 4A and 4B , the eccentrically mounted cutting blade  320  reaches peak extension as limited by the degree of eccentricity. In this position, the maximum depth of a cut  410  is regulated and the exposed edge of cutting blade  320  is moving at maximum velocity relative to the bearing block, as the blade is rotated as shown by arrow  420  in  FIG. 4B . 
     By continued rotation of the eccentrically mounted cutting blade  320 , the cutting blade  320  returns to the safe or parked state as described above. In an aspect of the invention implemented in some embodiments, the cutting blade is caused to automatically return to the parked position when the clinician or other user turns off the device by de-actuating the on/off switch, such as depressing the activation switch, or other actuator. 
     As noted previously, the exact cutting motion may vary depending on the particular implementation and may, for example, comprise multiple uninterrupted rotations with the cutting blade starting and ending in the safe position or, as a further alternative, may comprise reciprocal rotation about the pivot as a means of cutting tissue. 
       FIGS. 5A and 5B  show an alternative configuration of the eccentrically mounted circular cutting blade  320 , according to a further embodiment of the invention. In  FIG. 5A , the blade  320  is shown exposed to its full extent. The axle  350  is positioned further from the tip of the bearing block  330 , compared with the configuration shown in  FIGS. 4A and 4B . Therefore less of the cutting blade  320  is exposed during rotation of the blade. Furthermore, in  FIG. 5B  the position of axle  350  is rotated from its position in  FIG. 4B , resulting in a different blade profile being exposed beyond the bearing block as the blade is rotated. 
     Referring next to  FIGS. 6A-6D , an embodiment wherein a blade  600  that is capable of reciprocating motion is shown, where  FIG. 6A  is a side elevation view of a bearing block  610  and the blade  600 ,  FIG. 6B  shows one exemplary rotation about a bearing or pivot  620 ,  FIG. 6C  shows the blade at maximum exposure, and  FIG. 6D  is a cut-away view showing a drive shaft  630  affixed to the blade  600  to cause the reciprocating motion about the pivot  620 . Again the amount of blade exposed is determined by the degree of eccentricity in the mounting, or the position of the pivot  620  relative to the blade center  640 . 
     In another alternative implementation, shown in  FIGS. 7A-7D , a housing  700  shown in side elevation view in  FIGS. 7A and 7B  and cut-away side views in  FIGS. 7C and 7D  a concentrically mounted cutting blade  710  having at least one protruding or “shark-fin” style blade element  720  is intermittently or continuously rotated a fractional revolution, a complete revolution or a multiplicity of revolutions as a means of cutting tissue. As shown in  FIG. 7B , the cutting blade  710  is contained within the housing  700  while the blade element  720  is exposed. The blade element  720  may be constructed in a manner to provide a cam like cutting edge with increasing blade engagement as the blade element  720  advances, until the blade element  720  reaches maximum exposure and the exposed edge of the blade reaches maximum velocity relative to the bearing block, as the blade is rotated as indicated by arrow  730  in  FIG. 7D . 
     As an alternative to the “shark-fin” style blade element  720 , the cutting blade  710  may have an elliptical shape as shown in  FIGS. 8A-8D  or any other non-circular shape, including rectangular, triangular, trapezoidal, and so on, such that the blade has a tip portion as a cutting surface which serves to intermittently contact the tissue during rotation. 
     In a still further alternative implementation shown in  FIGS. 9A-9D , a concentrically mounted circular blade  900  is intermittently or continuously rotated about a moveable pivot  910  housed within a protective bearing block  920 . A clinician initiated cutting event is actuated by means of a driver  930  that causes the blade to rotate about the pivot  910  and simultaneously advances the blade out of the protective bearing block  920 . 
     Alternatively, as shown in  FIGS. 10A-10D , a protective bearing block  1000  is configured to retreat relative to a blade  1010  when a driver mechanism  1030  is actuated, thus exposing the blade  1010  to the tissue. 
     In either case, the blade rotation mechanism will be an independent element (such as a drive shaft with pinion gear, bearing element, and enclosure) that is able to move longitudinally relative to a shaft within a blade protection housing. In such an arrangement, the bearing block and protective housing may be divided, if desired, and either the blade would be moved forward or the housing moved back. Optionally, the blade may be serrated to enhance cutting specific tissues, and a few of the many examples of available blade designs suitable for use with the present invention are shown in  FIGS. 11A-11D . 
     In another implementation shown in  FIGS. 12A-12C , more than one blade, such as blades  1210  and  1220 , may be utilized.  FIG. 12A  illustrates in top plan view the cutting assembly  1200 .  FIG. 12B  illustrates a front elevation view of the cutting assembly  1200 , including rotary cutting blades  1210  and  1220 .  FIG. 12C  illustrates a side elevation view of the cutting assembly  1200 . The blades are mounted parallel to one another and may be used to make parallel incisions or strips of tissues. Furthermore, blades may be mounted so as to move synchronously or asynchronously with respect to the axle; that is, if synchronous, the two blades rotate or advance together, and if asynchronous, the two blades move independently (at different times or rates, for example) relative to one another. 
     Additionally, as shown in  FIGS. 13A-13B , mono-polar or bi-polar electrocautery may be added for further tissue manipulations. Thus, in  FIG. 13A , showing a monopolar electrocautery arrangement, a blade  1300  is polarized with a first polarity (for example, positive). Or, as shown in the bipolar arrangement of  FIG. 13B , insulators  1320  may be mounted on either side of the blade  1300  and within the housing  1310  such that the blade  1300  has a first polarity and closely juxtaposed contacts  1330  are maintained at the opposite polarity, or at around. 
     Referring next to  FIGS. 14-18 , many different means of power transmission may be employed to drive the cutting elements. The cutting elements may be driven in a rotary or oscillating mode depending on the clinical application. For example, as shown in  FIG. 14 , an arrangement of a pinion gear  1410  and shaft  1420  may be used with the blade  1430  notched concentrically about the axle  1440 . Or, as shown in  FIG. 15 , a drive belt, chain or cable  1500  mounted on an input pulley  1510  and a drive pulley  1520  connected to a blade  1530  and an axle  1540  may also be used to transmit power to the blade  1530 , where a drive mechanism such as a motor, air turbine or other source of motive force is connected to the axle of the input pulley  1510 . 
     As shown in  FIG. 16 , a rotating shaft  1600  mounted perpendicular to an axle  1610  and a blade  1620  may also be used in conjunction with a variety of well known mechanisms such as bevel gears, crown gear sets or spatial revolute-cylindrical-cylindrical-revolute couplings  1630 A-B to drive the blade. 
     As shown in  FIG. 17 , a motor  1700  may be directly connected to an axle  1710  and electronically controlled. Or, as shown in  FIG. 18 , reciprocating motion to a cutting element may also be achieved through the use of a slider crank type mechanism  1800  connected to a cam arm  1810  attached to a blade pivot axle  1820 . Alternatively, by mounting the crank  1800  on the outside of the cam arm  1810 , full rotation may be achieved. Optionally, the cutting element may also be driven by hydraulic or pneumatic means. 
     Referring next to  FIGS. 19A-19D  and  FIG. 20 , a cutting assembly  1900  is shown having a shaft  1910 , a blade  1920 , and a housing  1930  with a cavity located at the end of the housing  1930  proximate to the blade  1920 . A cantilever spring element  1912  is located at one end of the shaft  1910 . The spring element  1912  is located proximate to and in contact with a central axle  1922  of the blade  1920  as shown in  FIGS. 19A-D  and  FIG. 20 . The central axle  1922  is positioned within the cavity of the housing  1930 , such that the forward motion of the blade  1920 , which is caused by the linear motion of the shaft  1910 , is limited as seen in the cross-section view of  FIG. 19D  taken along the line C-C of  FIG. 19C . When the central axle  1922  has reached the maximum linear travel in a direction  1950 , the blade  1920  is extended the maximum distance out from the housing  1930  as shown in  FIG. 19B . However, the shaft  1910  can continue its linear travel in the direction  1950 . Accordingly, this linear travel of the shaft  1910  is translated into rotational motion  1960  of the blade  1920  as the shaft  1910  forces a pin  1924 , which is secured to the blade  1920 , to rotate about the axle  1922  until the spring element  1912  is compressed and the maximum linear motion of the shaft  1910  is reached as shown in  FIG. 19C . Consequently, the rotation of the pin  1924  about the axle  1922  results in the rotational motion  1960  of the blade  1920 . Thus, the linear motion  1950  of the shaft  1910  first results in extension of the blade  1920  from the housing  1930  and then rotational motion  1960  of the blade  1920  about the axle  1922 .  FIG. 20  shows a perspective view of the stationary configuration shown in  FIG. 19A . 
     Mounting of the cutting element assembly is generally application specific. However, it is important to note that certain configurations may be useful for multiple applications. 
     It will thus be appreciated that a new and novel design of incision system has been disclosed. Among the advantages offered by one or more implementations of the invention are a controlled depth of cut, a retractable blade offering increased user and patient safety, high velocity (relative to the prior art) cutting element permitting lower cutting forces to be applied by the user, and flexible mounting arrangements including articulated and more conventional mountings. Having fully disclosed a variety of implementations of the present invention, it will be appreciated by those skilled in the art that numerous alternatives and equivalents exist which do not materially alter the invention described herein. Therefore, the invention is not intended to be limited by the foregoing description, but instead only by the appended claims.