Abstract:
An adjustable, tissue cutting tool for use in arthroscopic surgery and including a distal-end cutting mechanism adapted to be adjustably angled relative to the principal axis of the tool in order to reach tight, difficult to reach areas of tissue damage within a joint and to thereby minimize risk of iatrogenic, articular cartilage damage.

Description:
FIELD OF INVENTION 
       [0001]    The invention relates generally to a device for use in arthroscopic surgical removal of soft tissue damage within a joint, e.g., a knee of a human or animal. 
       BACKGROUND OF INVENTION 
       [0002]    Arthroscopy is a medical term used to describe a minimally-invasive procedure in which a camera is inserted through a narrow incision into a body joint for the purpose of accurate diagnosis and treatment of various intra-articular injuries. The camera is then used to guide the use of an instrument also inserted into the joint through a narrow incision. There currently are various instruments designed for arthroscopic removal of damaged tissue available. These devices are rigid, reusable instruments and can be acquired with the cutting end fixed at various angles. The surgeon selects a particular instrument set at a particular angle based on the particular cutting task being performed at that moment. 
         [0003]    Surgical devices providing some degree of adaptability in the form of flexibility in the shaft of the device are known. For example, U.S. Pat. No. 3,915,169 (“the &#39;169 patent”) describes a knife specifically designed for removing meniscus from knee joints that has a “malleable” shank. U.S. Pat. No. 6,139,563 (“the &#39;563 patent”) describes a forceps-like device for grasping, securing and occluding body tissues and conduits which features a shaft that can be bent and adjusted to minimize its intrusion and allow for better positioning of the jaws of the device within the body. 
       SUMMARY OF INVENTION 
       [0004]    Embodiments of an adjustable arthroscopic tissue-cutting device that allows for angulation of the cutting head of the device at the time of surgery by the using surgeon (or surgical staff) to the degree desired by the surgeon described herein provide the first known such device. 
         [0005]    The Adjustable Tissue Cutter Tool can be used in various joints such as the knee, shoulder, elbow, wrist, and ankle. 
         [0006]    Certain embodiments of the device feature a knob-controlled mechanism to adjust the angle of the cutting end relative to the shaft of the instrument. Other embodiments feature a shaft that has a rigid/flexible region, which is manipulated into a desired angle by the using surgeon (or surgical staff). Such embodiments of the device allow for a potentially-disposable single-use device that avoids the common problem of diminishing sharpness of the cutting edge associated with reusable devices. In some embodiments, the shaft of the device preferably tapers towards the end for the advantage of reaching tight, difficult areas in and near the joint to remove damaged tissue with less potential for iatrogenic, articular cartilage damage. 
         [0007]    These and other embodiments, features, aspects, and advantages of the invention will become better understood with regard to the following description, appended claims and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The foregoing aspects and the attendant advantages of the present invention will become more readily appreciated by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a side view of a preferred embodiment adjustable tissue cutter with a rigid/flexible shaft region with the shaft in its initial, straight configuration; 
           [0010]      FIG. 2  is a top view of the  FIG. 1  embodiment with the rigid/flexible shaft region bent to provide a 30° horizontal offset of the distal end from the centerline of the instrument; 
           [0011]      FIG. 3  is a cut-away, top view of the rigid/flexible portion of the shaft and adjoining regions of the  FIG. 1  embodiment configured as in  FIG. 2 ; 
           [0012]      FIG. 4  is a cut-away, close-up, side view of the distal end of the  FIG. 1  embodiment oriented at a downward angle; 
           [0013]      FIG. 5  is a close-up, side view of the distal end of the  FIG. 1  embodiment; 
           [0014]      FIG. 6  is a side view of a preferred embodiment adjustable tissue cutter with gear-controlled adjustment of the horizontal angle of the distal-end cutter with that distal-end cutter in its initial, straight configuration; 
           [0015]      FIG. 7  is a top view of the  FIG. 6  embodiment with the distal-end cutter in its initial, straight configuration; 
           [0016]      FIG. 8  is a perspective view of the  FIG. 6  embodiment with the distal-end cutter in its initial, straight configuration; 
           [0017]      FIG. 9  is three close-up, top views of the distal end of the  FIG. 6  embodiment with the distal-end cutter (from top to bottom) (A) offset to the left from the centerline of the instrument; (B) in its initial, straight configuration, corresponding to  FIG. 7 ; and (C) offset to the right from the centerline of the instrument; 
           [0018]      FIG. 10  is a cut-away, close-up, perspective view of the actuator end of the  FIG. 6  embodiment. 
           [0019]      FIG. 11  is a cut-away, close-up, perspective view of the distal end of the  FIG. 6  embodiment. 
           [0020]      FIG. 12  is a second cut-away, close-up, perspective view of the distal end of the  FIG. 6  embodiment. 
           [0021]      FIG. 13  is an exploded, cut-away, close-up, perspective view of the distal end of the  FIG. 6  embodiment. 
           [0022]      FIG. 14  is a cut-away, close-up, perspective view of the control-knob portion of the actuator end of the  FIG. 6  embodiment with the control knob in an active (unlocked or disengaged) position. 
           [0023]      FIG. 15  is a cut-away, close-up, perspective view of the control-knob portion of the actuator end of the  FIG. 6  embodiment with the control knob in its initial, resting (locked or engaged) position. 
           [0024]      FIG. 16  is a cut-away, close-up, perspective view of the central adjustment-transfer portion of the  FIG. 6  embodiment. 
           [0025]      FIG. 17  is a side view of a preferred embodiment adjustable tissue cutter with wire-controlled adjustment of the horizontal and vertical angles of the distal-end cutter with that distal-end cutter tipped upward relative to the centerline of the device; 
           [0026]      FIG. 18  is a perspective view of the  FIG. 17  embodiment with the distal-end cutter in its initial, straight configuration; 
           [0027]      FIG. 19  is a cut-away, close-up, perspective view of the actuator end of the  FIG. 17  embodiment. 
           [0028]      FIG. 20  is a cut-away, close-up, perspective view of the distal end of the  FIG. 17  embodiment. 
           [0029]      FIG. 21  is an exploded, close-up, perspective view of the distal end of the  FIG. 17  embodiment. 
       
    
    
       [0030]    Reference symbols or names are used in the figures to indicate certain components, aspects or features shown therein. Reference symbols common to more than one Figure indicate like components, aspects or features shown therein. 
       DETAILED DESCRIPTION 
       [0031]    With reference to  FIGS. 1-21 , preferred embodiments of the adjustable tissue cutter will be described. 
       Rigid/Flexible Adjustable Cutter 
       [0032]      FIGS. 1-5  depict a preferred embodiment featuring a tissue cutter with a rigid/flexible shaft region that is manipulated directly by the using surgeon (or surgical staff) to obtain a desired angle relative to the main shaft of the instrument. As depicted in  FIG. 1 , the rigid/flexible embodiment  100  of the adjustable tissue cutter includes three distinct parts: a hand piece  101  preferably featuring a scissor-grip actuator comprising a fixed part  101   a  and a cutter jaw operator  101   b  pivotably joined to the fixed part in order to provide a scissor-like action, the hand piece  101  connected to a shaft  102  in turn connected to a distal-end tissue cutter  103 . The shaft  102 , in turn, comprises a length of rigid tubing  102   a  at the hand-piece end connected to a length of rigid/flexible tubing  102   b  at the distal end. 
         [0033]    The scissor-grip of the hand piece  101  of the preferred embodiment will be familiar to surgical staff as it is the same type of grip used on arthroscopic scissors, forceps and the like already in common use. In one embodiment the hand piece  101  is primarily composed of plastic. Other materials may be used in other embodiments. 
         [0034]    In one embodiment, the three components of the tool (the hand piece  101  and the two regions of the shaft  102 ) are permanently connected to one another as by welds or other means. In other embodiments, one or more of the connections may be a detachable connection allowing replacement of the individual components. 
         [0035]    The rigid/flexible portion  102   b  of the shaft  102  is intended to be bent by the surgeon (or surgical staff) to a particular desired angle at the time of use. The material of the rigid/flexible portion  102   b  of the shaft is  102  sufficiently flexible so that it may readily be bent by hand, but sufficiently rigid so that, once in its desired configuration, it will maintain that configuration under the pressures ordinarily exerted on the device during surgery. 
         [0036]    In the preferred embodiment, the rigid/flexible portion  102   b  of the shaft  102  tapers down from a wider region at the end attached to the rigid portion  102   a  of the shaft  102  to a narrower end where it meets the distal cutting end  103 . In other embodiments the rigid/flexible portion  102   b  of the shaft  102  may be of a constant diameter. 
         [0037]      FIG. 2  depicts the device from above, configured with the rigid/flexible portion  102   b  of the shaft  102  bent to the right. In one embodiment, the rigid/flexible portion  102   b  of the shaft  102  has a limited range of adjustment of from zero (0) to thirty (30) degrees offset in any direction from the centerline of the rigid portion  102   a  of the shaft  102 . Other embodiments may allow a different range of motion or allow unlimited flexibility. In some embodiments the rigid/flexible shaft will be bendable both horizontally and vertically, while, in alternate embodiments, it may be bendable only in a single plane. 
         [0038]    As depicted in  FIGS. 3, 4 and 5 , both portions of the shaft  102  are hollow, and a length of flexible cable  104  connecting the cutter jaw actuator  101   b  of the hand piece  101  to the tissue cutter  103  runs through a channel  105  in the center of the shaft  102 . The cable  104  functions to translate the opening-closing motion of the hand piece  101  into a cutting action of the distal-end tissue cutter  103 . 
         [0039]    The channel  105  of the rigid/flexible portion  102   b  of the shaft is filled with an internal cable-support medium to maintain the position of the cable. In the preferred embodiment this cable support is made of a flexible plastic, though other materials may be used in other embodiments. The rigid portion  102   a  of the shaft  102  may be constructed either of thin-walled tubing, that may include the same, or a similar, cable-support medium inside the channel, or it may be constructed of thick-walled tubing such that the internal channel of the tubing is narrow enough that no separate cable support is needed. 
       Tube-Gear Adjustment Tissue Cutter 
       [0040]      FIGS. 6-16  depict an alternate preferred embodiment tissue cutter, in which the horizontal angle of the distal-end tissue cutter relative to the centerline of the device is set by use of a knob at the actuator end which controls gears within the body of the device, providing precise and reproducible adjustment of that angle. 
         [0041]    As depicted in  FIGS. 6-9 , the knob/gear embodiment  200  of the adjustable tissue cutter includes five primary parts: a hand piece  201  preferably featuring a scissor-grip actuator comprising a fixed part  201   a  and a cutter-jaw operator  201   b  pivotably joined to the fixed part in such a manner as to provide a scissor-handle-like motion of the two parts; a distal-end cutting tool  203 ; a shaft  202  connected to the hand-piece  201  at one end and to the cutting tool  203  at the distal-end; a knob assembly  204  preferably positioned at the actuator end of the cutter; and a control-transfer assembly  205  situated at the juncture between the hand piece  201  and the shaft  202 . The knob assembly  204  is connected through the control-transfer assembly  205  so as to control the horizontal angle of the distal-end tissue cutter  203  relative to the centerline of the device as shown in  FIG. 9  and in a manner discussed below. The mechanism of opening and closing the distal-end tissue cutter is described first. 
         [0042]    In one embodiment, as depicted in  FIGS. 10-13 , the cutter-jaw operator  201   b  is operatively coupled to the distal-end tissue cutter  203  by a pair of rods  206   207  running through the center of the shaft  202 . The first, main rod  206  runs the length of the device from the top of the cutter-jaw operator  201   b  nearly to the point where the distal-end tissue cutter  203  is joined to the shaft  202 , and where the main rod  206  connects to the short ball-joint rod  207  which passes through the joint between the shaft  202  and the distal-end tissue cutter  203  and is, in turn, coupled at its distal end to the distal-end tissue cutter  203 . 
         [0043]    At its rear end, the main rod  206  preferably features a t-shaped head  206   a  that preferably fits into a slot  201   c  at the upper end of the cutter-jaw operator  201   b —so that pivoting motion of the operator  201   b  is translated into lengthwise sliding motion of the main rod  206  within the shaft  202 . (In other alternate embodiments the t-shaped head  206   a  and slot  201   c  may be replaced with other suitable means of pivotably coupling the main rod to the top of the cutter-jaw operator  201   b .) 
         [0044]    The connection between the main rod  206  and the ball joint rod  207  is preferably made by way of a ball  206   b  on the end of the main rod that fits into a socket  207   a  on that end of the ball-joint rod  207 . In one embodiment, the socket is comprised of two threaded parts, a collar  207   b  slipped over the main rod  206  behind the ball  206   b  and a receiver  207   c , which two parts screw together to capture the ball  206   b.    
         [0045]    At its other end, the ball-joint rod  207  terminates in a second ball  207   d  that fits into a cavity  203   e  in the back of the upper jaw  203   b  of the distal-end tissue cutter  203  so that the ball-joint rod  207  protrudes through an opening  203   c  in the back of the lower jaw  203   a . In one embodiment, similar to the construction of the ball joint, there is a threaded collar  203   d  with an inner diameter larger than that of the shaft of the ball joint rod  207  but smaller than the outer diameter of the ball  207   d . Collar  203   d  screws onto rear of the upper jaw  203   b  capturing the ball  207   d  in the cavity  203   e  in the upper jaw  203   b.    
         [0046]    The upper jaw  203   b  of the distal-end tissue cutter  203  is pivotably joined to the lower jaw  203   a  by means of a pin  203   f , around which the upper jaw  203   b  pivots. 
         [0047]    Through cooperation of the operative components, the basic opening and closing of the distal-end tissue cutter  203  in response to the motion of the scissor-grip actuator  201  is described as follows. 
         [0048]    When the scissor-grip actuator  201  is in the initial, closed position, the jaws  203   a    203   b  of the distal-end tissue cutter  203  are, correspondingly closed. As the scissor-grip actuator is opened—by pushing the lower part of the cutter-jaw operator  201   b  forward—the top of cutter-jaw operator  201   b  pivots backward. This pulls the t-shaped head  206   a  of main rod  206 —captive in the slot  201   c  at the top end of the cutter jaw operator  201   b —backwards as well. The distal end of the main rod therefore moves backwards correspondingly. The ball  206   b  at that distal end—captive in the receiver  207   a  of the ball-joint rod  207 —thereby transmits the motion of the main rod  206  to the ball-joint rod  207 . Thus the ball joint rod  207 , and its distal-end ball  207   d , move backwards as well. 
         [0049]    The backwards motion of the distal-end ball  207   d  of the ball-joint rod  207 —in turn, captive within the receiver of the upper jaw  203   b  of the distal-end tissue cutter  203 —therefore exerts a backwards force on the rear of the upper jaw  203   b , causing it to pivot around the pin  203   f  connecting it to the lower jaw  203   a  and, thereby, opening the jaws of the distal-end tissue cutter  203 . 
         [0050]    In this embodiment, as depicted in  FIGS. 10-16 , the adjustment of the horizontal angle of the distal-end tissue cutter  203  relative to the centerline of the device is preferably accomplished as follows. Mounted above the actuator  201  at the rear of the device is an angle-adjustment rod  208  housed in a tube  209 . At the rear, this rod terminates in a gear  208   a  which has external teeth and extends through a toothed aperture in the knob  204  so that the external teeth of the gear engage with the internal teeth of the aperture. The gear and aperture engage loosely enough that the knob  204  can slide forward and backward within this aperture  208   a . A cavity at the rear of the knob  204  holds a spring  204   a  which is fitted around the extension  208   a  and held in place by a cap  208   b  screwed into the end of the extension  208   a.    
         [0051]    Thus, when there is no external pressure applied to the knob, the spring  204   a  pushes the knob forward toward the distal end of the tissue cutter. Slightly below the tube  209  on the rear of the body of the device there is a small protrusion/tab stop  209   a —in one embodiment in the shape of a cube. On the distal side of the knob  204 , a series of multiple depressions  209   b —sized and positioned to accept the protrusion/tab stop  209   a —are arrayed in a concentric ring around the aperture through which the extension  208   a  fits. When the knob  204  is pulled back manually (as depicted in  FIG. 14 ), it may, at that point, be freely rotated. When the backward force is released, the knob  204  will slide forward under the pressure of the spring  204   a . As the knob  204  is further rotated, the protrusion/tab stop  209   a  will slip into one of the complementary depressions  209   b  (as depicted in  FIG. 15 ), barring further rotation of the knob  204 , which will be locked in place until manually pulled back again. 
         [0052]    The rotation of the knob  204 , in turn, causes the attached angle-adjustment rod  208  to rotate inside the tube  209 . At its distal end, where it emerges from the tube  209 , the angle-adjustment rod  208  terminates in a gear  208   c  having external teeth. The teeth of the gear  208   c  mesh with the internally extending teeth on the inside of the ring gear  205   a  situated at the rear of the control-transfer assembly  205  situated at the juncture between the hand piece  201  and the shaft  202 . Rotation of the knob  204  thereby causes rotation of the ring gear  205   a  in the same direction. 
         [0053]    The main shaft  202  of the device is comprised of two tubes  202   a    202   b  concentric around the main rod  206 . Outer tube  202   a  is fixedly joined to the front part  205   b  of the control-transfer assembly  205  which is, in turn, fixedly joined to the hand piece  201  through element  201   d  passing through the opening in the ring gear  205   a . The inner tube  202   b  rotates freely around its long axis within the outer tube  202   a  and around the main rod  206 . The outer, fixed tube  202   a  terminates at its rear where it is fixed to the forward part  205   b  of the control transfer assembly  205 . 
         [0054]    The inner, rotating tube  202   b  terminates further back, with a flange  202   c  that fits into a groove  201   e  in the hand assembly member  201   c , which flange and groove hold the inner tube  202   b  in place front-to-back while allowing the inner tube  202   b  to rotate freely within the outer tube  202   a . Tab  205   c  protrudes from the inside of the forward part of the body of the ring gear  205   a  into a slot  202   d  in the inner, rotating tube  202   b . The tab  205   c  transmits rotation of the ring gear  205   a  to the inner tube  202   b.    
         [0055]    The distal end of inner tube  202   b  has gear teeth that engage the gear teeth of gear  203   g  that is mounted on upper-rear portion of the lower jaw  203   a  of the distal-end tissue cutter  203 . Rotation of the inner tube  202   b  around its axis is thus transformed by 90° and causes the distal-end tissue cutter  203  to horizontally pivot around the pins  203   h  by which it is mounted into the outer, fixed tube  202   a.    
         [0056]    The horizontal angle of the distal-end tissue cutter  203  relative to the centerline of the device imparted by a particular degree of rotation of the knob  204  depends on the gear ratios among the various gears and those, and any other gear ratios of the device, may vary among embodiments of the invention. 
       Knob/Wire Adjustment Cutter 
       [0057]      FIGS. 17-21  depict an alternate preferred embodiment in which the horizontal and vertical angle of the distal-end cutter relative to the centerline of the device is set by use of knobs at the actuator end which control wires within the body of the device, providing precise and reproducible adjustment of those angles. 
         [0058]    As depicted in  FIGS. 17 and 18 , the knob/wire embodiment  300  of the adjustable tissue cutter preferably includes five primary parts: a hand piece  301  preferably featuring a scissor-grip actuator comprising a fixed part  301   a  and a cutter jaw operator  301   b  pivotably-joined to the fixed part in such a manner as to provide a scissor-handle-like motion of the two parts; a distal-end cutting tool  303 ; a shaft  302  connected to the hand-piece  301  at one end and to the cutting tool  303  at the distal-end; a horizontal-angle control knob assembly  304  and a vertical-angle control knob assembly  305  both situated on the upper body of the hand piece in line with the shaft  302 . The knob assemblies  304 ,  305  are connected so as to control the horizontal and vertical angles, respectively, of the distal-end tissue cutter  303  relative to the centerline of the device as described below. 
         [0059]    In this embodiment, the distal-end tissue cutter preferably is attached to the shaft as follows. An x-shaped attachment mounting  307  is fixedly mounted at the distal end of the shaft. A short, fixed ball joint rod  307   a  protrudes outward from the attachment mounting  307  and terminates in a ball  307   b  that fits into the lower jaw  303   a  of the distal-end tissue cutter  303  so that the rod  307   a  protrudes through an opening  303   c  into a cavity  303   e  in the back of the lower jaw  303   a  of the distal-end tissue cutter  303 . This mounting fixes the distal-end tissue cutter to the device while enabling it to pivot freely both horizontally and vertically relative to the centerline of the device. In alternate embodiments the attachment mounting  307  may not be x-shaped but rather may take on any other shape that functions to provide a base for the ball-joint rod  307   a  while having sufficient appropriately-positioned openings through which the wires, discussed below, may pass. 
         [0060]    In one embodiment, there is a collar  303   d  with a diameter larger than that of the shaft of the rod  307   a  but smaller than the diameter of the ball  307   b . That collar  303   d  screws onto the rear of the lower jaw  303   a  capturing the ball  307   b  in the cavity  303   e  in the lower jaw  303   a.    
         [0061]    The mechanism of opening and closing the distal-end tissue cutter is as follows. In one embodiment, as depicted in  FIGS. 19, 20 and 21  this mechanism operates in a manner similar to that described in the knob/gear embodiment above. In such embodiment, the cutter-jaw operator  301   b  is operatively coupled to the distal-end tissue cutter  303  by a rod  306  running through the upper portion of the shaft  302 . The rod  306  runs the length of the device from the top of the cutter-jaw operator  301   b  to the rear of the distal-end tissue cutter  303 . 
         [0062]    At its rear end, the rod  306  preferably features a t-shaped head  306   a  that fits into a slot  301   c  at the end of the cutter jaw operator  301   b —so that the pivoting motion of the operator  301   b  is translated into lengthwise reciprocation of the main rod  306  within the hollow shaft  302 . (In other alternate embodiments the t-shaped head  306   a  might be replaced with a ball, or any other means that functions to pivotably couple to the top of the cutter-jaw operator  301   b .) 
         [0063]    At its other, distal end, the rod  306  passes through the upper opening of the x-shaped attachment mounting  307  and terminates in a ball  306   b  that fits into the upper jaw  303   b  of the distal-end tissue cutter  303  so that the rod  306  protrudes through an opening  303   g  into a cavity  303   i  in the back of the upper jaw  303   b  of the distal-end tissue cutter  303 . In one embodiment, there is a threaded collar  303   h  with a diameter larger than that of the shaft of the rod  306  but smaller than the diameter of the ball  306   b . That collar  303   h  screws onto rear of the upper jaw  303   b  capturing the ball  306   b  in the cavity  303   i  in the upper jaw  303   b . That upper jaw  303   b  of the distal-end tissue cutter  303  is pivotably joined to the lower jaw  303   a  by means of a pin  303   f , around which the upper jaw  303   b  pivots. 
         [0064]    Cooperation of the operative structural components of the tissue cutter functions to provide opening and closing of the distal-end tissue cutter  303  in response to the motion of the scissor-grip actuator  301  is as follows. When the scissor-grip actuator  301  is in the initial, closed position, the jaws  303   a ,  303   b  of the distal-end tissue cutter  303  are closed. 
         [0065]    As the scissor-grip actuator is opened—by pushing the lower part of the cutter-jaw operator  301   b  forward—the top of that cutter-jaw operator  301   b  pivots backward. This pulls the t-shaped end  306   a  of the rod  306 —captive in the slot  301   c  at the top end of the cutter jaw operator  301   b —backward as well. The distal end of the rod  306  therefore moves backwards as well. The ball  306   b  at that end—captive within the receiver of the upper jaw  303   b  of the distal-end tissue cutter  303 —therefore exerts a backward force on the rear of the upper jaw  303   b  causing it to pivot around the pin  303   f  connecting it to the lower jaw  303   a  and, thereby, opening the jaws of the distal-end tissue cutter  303 . 
         [0066]    In this embodiment, as depicted in  FIGS. 17-21 , the adjustment of the horizontal angle of the distal-end tissue cutter  303  relative to the centerline of the device preferably is accomplished as follows. A short shaft  304   a  is mounted vertically into the rear-upper portion of the actuator  301  in such a manner as allows the shaft to rotate around its axis. At the lower end, the shaft  304   a  terminates in a small spool  304   b  inside the actuator  301 ; at its upper end it terminates in knob  304   c  located above the actuator  301 . 
         [0067]    A wire  308  is wrapped at least once around the spool  304   b  such that two segments  308   a    308   b  extend forward from the spool  304   b  through the shaft  302  at approximately the vertical center of the shaft and to the left and right, respectively, of the horizontal center of the shaft. Viewed from above and to the rear of the device, one wire segment  308   a  extends forward from the left-hand side of the spool  304   b  while the other wire segment  308   b  extends forward from the right-hand side of the spool  304   b . At the distal end of the device, the wire segments protrude, respectively, through the left-hand and right-hand openings in the x-shaped attachment mounting  307 . The end of each wire segment is, in turn, fixedly attached to the rear of the lower jaw  303   b  of the distal-end tissue cutter  303  by conventional means. 
         [0068]    The adjustment of the horizontal angle of the distal-end tissue cutter  303  operates as follows. As the horizontal-angle control knob  304   c  is rotated in a clockwise direction, the corresponding attached shaft  304   a  and spool  304   b  rotate in the same manner. The surface of the spool  304   b  and surface of the wire  308  are such that the friction between them is sufficient to prevent the wire from slipping relative to the spool during rotation of the spool, thus causing the wire segments to move during rotation of the spool. As the spool rotates in a clockwise manner, the left-hand (viewed from above, rear) wire segment  308   a  will unspool from the spool such that the length of the segment will increase, while the right-hand wire segment  308   b  will be drawn onto the spool and shortened by the same amount. 
         [0069]    As this occurs, the attachment of the wire segments  308   a ,  308   b  to the left-hand and right-hand sides, respectively, of the rear of the lower jaw  303   a  of the distal-end-tissue cutter  303  will, thereby, cause the right-hand side of the distal-end tissue cutter  303  to be drawn toward the rear of the device while the corresponding slack created in the left-hand segment of the wire will permit the left-hand side of the distal-end tissue cutter  303  to move an equal distance away from the rear of the device. 
         [0070]    The mechanism for the adjustment of the vertical angle of the distal-end tissue cutter  303  preferably operates in an essentially identical manner by means of a horizontally mounted shaft  305   a  connecting a corresponding spool  305   b  and knob  305   c . A second wire  309  is wrapped around the spool  305   b  so that upper and lower segments  309   a    309   b  extend from the spool approximately along the horizontal center of the shaft  302  above and below, respectively, the vertical center of the shaft and pass through the upper and lower openings of the x-shaped attachment mounting  307 . The end of each wire segment is, in turn, fixedly attached to the rear of the lower jaw  303   b  of the distal-end tissue cutter  303  by any appropriate means. The rotation of the knob  305   c  causes motion of the wire segments  309   a ,  309   b  and in turn the change in the vertical angle of the distal-end tissue cutter  303  relative to the centerline of the device. 
         [0071]    In some embodiments the knob assemblies  304 ,  305  may include spring-loaded, tabbed, positional-locking structures as previously described with respect to the knob/gear adjustment embodiments. 
         [0072]    In some embodiments, each single wire  308 ,  309  may be replaced by two separate wire segments each independently, fixedly joined to the corresponding spool. In such embodiments the surface of the spool and wire need not be frictionally linked, as one end of each wire segment will be fixed to the spool and friction will not be necessary to transfer force from the rotation of the spool to the wire. 
         [0073]    In some embodiments, only one of either the horizontal angle or the vertical angle of the distal-end tissue cutter may be adjustable and there would, in such embodiments, be only a single knob controlling a single spool and wire-segment-pair assembly to adjust that angle.