Abstract:
A device is disclosed for introducing a flexible elongated element through at least two portions of a subject. In an embodiment, the device includes a proximal end and a distal end, as well as an advancement unit for longitudinally advancing the flexible elongated element toward the distal end such that a proximal end of the elongated element may pass from the distal end of said device with sufficient force to pass through the portions of the subject. The device also includes a securing unit for variably adjusting a securing force applied by the flexible elongated element to secure together the portions of the subject.

Description:
REFERENCE TO EARLIER APPLICATIONS 
   This is a continuation-in-part of pending prior U.S. patent application Ser. No. 10/014,991, filed Dec. 11, 2001 by Gregory E. Sancoff et al. for SURGICAL SUTURING INSTRUMENT AND METHOD OF USE. 
   This patent application also claims benefit of pending prior U.S. Provisional Patent Application Ser. No. 60/307,255, filed Jul. 23, 2001 by Gregory E. Sancoff et al. for SURGICAL SUTURING INSTRUMENT AND METHOD OF USE. 
   The two above-identified patent applications are hereby incorporated herein by reference. 

   FIELD OF THE INVENTION 
   This invention relates to medical instruments and procedures in general, and more particularly to suturing instruments and methods for suturing. 
   BACKGROUND OF THE INVENTION 
   Suturing instruments are typically used to draw together two or more portions of a subject patient (e.g., tissue such as muscle or skin) or to attach an object to the patient (e.g., to attach a piece of surgical mesh to the abdominal wall of the patient during hernia repair surgery). 
   Certain suturing instruments employ a needle that precedes a length of suture material through a subject. 
   For example, U.S. Pat. Nos. 3,470,875; 4,027,608; 4,747,358; 5,308,353; 5,674,230; 5,690,653; 5,759,188; and 5,766,186 generally disclose suturing instruments in which a needle, with trailing suture material, is passed through a subject. 
   U.S. Pat. Nos. 4,890,615; 4,935,027; 5,417,700; and 5,728,112 generally disclose suturing instruments in which suture material is passed through the end of a hollow needle after that needle has been passed through a subject. 
   With all of the foregoing devices, a needle must be passed through the subject in order to deploy the suture. This has the disadvantage that the needle typically leaves a larger hole in the subject than is necessary to accommodate only the suture material itself. In this respect it should be appreciated that it is generally desirable to alter each portion of the material being sutured (e.g., tissue) as little as possible during the suturing process. 
   A suturing instrument has been devised which permits the suture material itself to pierce the subject without the use of a needle. However, this device does not permit adequate flexibility with regard to the amount of tension that may be applied to the suture and tissue. 
   More particularly, U.S. Pat. No. 5,499,990 discloses a suturing instrument in which a 0.25 mm stainless steel suturing wire is advanced to the distal end of a suturing instrument, whereupon the distal end of the suturing wire is caused to travel in a spiral direction so as to create stitches joining together two portions of a subject. After the spiral is formed, the beginning and end portions of the suture may be bent toward the tissue in order to inhibit retraction of the suture wire into the tissue upon removal of the suturing instrument. The stainless steel wire is sufficiently firm to hold this locking set. In addition, after the spiral is formed, the radius of the deployed suture spiral may then be decreased by advancing an outer tube over a portion of the distal end of the instrument. Again, the stainless steel wire is sufficiently firm to hold this reducing set. 
   Unfortunately, however, such a system does not permit much flexibility when it comes to the amount of tension to be applied to the subject, since the wire is relatively firm (i.e., firm enough to hold its sets). Such a system also does not provide any flexibility with respect to the type of suture stitch to be applied, since the device is specifically configured to provide only a spiral suture stitch. 
   In contrast to the aforementioned limitations of the suturing instrument of U.S. Pat. No. 5,499,990, it is desirable that a suturing instrument approximate the portions of the material which is to be joined in the correct physiological relationship, and to urge the portions together with an appropriate amount of force. If too much force (or tension) is applied to the suture material, then the subject portions may become necrotic and/or the sutures may cut through the subject. If too little tension is applied to the suture material, then the healing process may be impaired. 
   U.S. Pat. No. 4,453,661 discloses a surgical instrument for applying staples. The staples are formed from the distal end of a length of wire. More particularly, the distal end of the wire is passed through a subject and thereafter contacts a die that causes the wire to bend, thereby forming the staple. The wire is sufficiently firm to take on the set imposed by the die. The staple portion is then cut away from the remainder of the wire by a knife. Again, such a system suffers from the fact that it does not permit much flexibility when it comes to the amount of tension to be applied to the subject, since the attachment is effected by a staple which has a pre-defined geometry and is formed with relatively firm wire. In addition, the system is limited as to the type of fastening which may be effected, since the surgical instrument is limited to only applying wire staples. 
   There is a need, therefore, for a new suturing device that permits minimally disruptive suturing and permits flexibility in the placement, application, and tensioning of the suture material. 
   SUMMARY OF THE INVENTION 
   The present invention comprises a novel device and method for deploying a flexible elongated element through a subject so as to effect suturing. In one embodiment of the invention, the device includes a proximal end and a distal end, and an advancement unit for longitudinally advancing the flexible elongated element toward the distal end of the device such that a distal end of the flexible elongated element may exit from the distal end of the device with sufficient force to pass through the subject. The device also includes a securing unit for variably adjusting a securing force applied by the flexible elongated element so as to provide the desired seducement to the subject. 
   In further embodiments, the device includes a guide tube for guiding the flexible elongated element through the device, toward the distal end of the device, and a rotation unit for rotating the distal end of the device so as to cause the flexible elongated element to wrap around itself, whereby to adjustably apply the securing force to the flexible elongated element. 
   And in a further feature of the invention, a cutting mechanism is provided to permit the flexible elongated element to be cut with varying lengths. As a result, the flexible elongated element can be tailored to a specific length appropriate for a given anatomical situation. This is a significant advantage over traditional staples, which are formed with a discrete pre-determined length. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiment of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
       FIGS. 1–3  are various views showing a suturing instrument formed in accordance with the present invention; 
       FIGS. 4–8  are various views showing the handle assembly of the suturing instrument shown in  FIGS. 1–3 ; 
       FIGS. 9–21  are various views showing the handle cartridge assembly of the handle assembly shown in  FIGS. 4–8 ; 
       FIGS. 22–24  are various views showing the battery pin assembly of the handle assembly shown in  FIGS. 4–8 ; 
       FIGS. 25–38  are various views showing the cannula assembly of the suturing instrument shown in  FIGS. 1–3 ; 
       FIGS. 39–48  are various views showing the wire drive assembly of the suturing instrument shown in  FIGS. 1–3 ; 
       FIGS. 49–54  are various views showing the wire supply cartridge of the suturing instrument shown in  FIGS. 1–3 ; 
       FIGS. 55 and 56  are various views of the shroud assembly of the suturing instrument shown in  FIGS. 1–3 ; and 
       FIGS. 57–66  show various steps in a suturing operation conducted with the suturing instrument shown in  FIGS. 1–3 ; 
       FIG. 67  is a sectional view showing one possible construction for the suturing instrument&#39;s first jaw  206  and its associated cutting bar; 
       FIG. 68  is a side view showing a piece of wire cut with the apparatus shown in  FIG. 67 ; 
       FIG. 69  is a sectional view showing another possible fixed construction for the suturing instrument&#39;s first jaw  206  and its associated cutting bar; and 
       FIG. 70  is a side view showing a piece of wire cut with the apparatus shown in  FIG. 69 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Overview 
   Looking first at  FIGS. 1–3 , there is shown a suturing instrument  2  which comprises a preferred embodiment of the present invention. Suturing instrument  2  generally comprises a handle assembly  100 , a cannula assembly  200 , a wire drive assembly  300 , a wire supply cartridge  400  and a shroud assembly  500 , as will hereinafter be described in further detail. 
   Among other things, cannula assembly  200  comprises a shaft  202 , an end effector  204  comprising a first jaw  206  and a second jaw  208 , a jaw closing actuator  210 , a wire advance button  212 , a left rotation button  214 , a right rotation button  216  ( FIG. 3 ), and a wire cutting actuator  218 , as will also hereinafter be described in further detail. 
   As will be discussed in further detail below, generally during use, the suturing instrument&#39;s end effector  204  is positioned adjacent to the tissue which is to be sutured and, using jaw closing actuator  210 , jaws  206  and  208  are brought together around the tissue which is to be sutured. Then wire advance button  212  is activated, causing wire drive assembly  300  to draw suture wire out of wire supply cartridge  400  and push the suture wire distally through cannula assembly  200  to end effector  204 . The suture wire is driven from first jaw  206  to second jaw  208  with sufficient force to penetrate the tissue placed between the two jaws, and the suture wire is permitted to pass through second jaw  208 . Jaws  206  and  208  are then separated and moved away from the tissue, as more suture wire is payed out, leaving the suture wire extending from the subject tissue to each of the two jaws. End effector  204  (together with wire supply cartridge  400 ) may then be rotated with respect to the tissue by actuating either left rotation button  214  or right rotation button  216  ( FIG. 3 ). This causes the portions of the suture wire that extend from the tissue to be twisted about one another so as to form a closed loop extending through the tissue. It will be appreciated that the size of this closed loop may be adjustably reduced by increasing the degree of twisting in the wire. The twisted loop of suture wire may then be cut off, at end effector  204 , from the remaining suture wire that extends back through the suturing instrument. Such cutting may be effected by actuating wire cutting actuator  218 . 
   As will be discussed in further detail below, wire supply cartridge  400  may be supplied separately from suturing instrument  2 , with wire supply cartridge  400  being loaded into suturing instrument  2  prior to commencing a suturing operation. As will also be discussed in further detail below, wire supply cartridge  400  may be disposable, such that the cartridge may be discarded after use. 
   Handle Assembly  100   
   Looking next at  FIGS. 4–8 , handle assembly  100  comprises a housing  102 , a battery door  104 , a handle cartridge assembly  106 , a battery pin assembly  108  and a rear cover assembly  110 . 
   Housing  102  is shown in greater detail in  FIG. 8 . Housing  102  defines a main compartment  112 , a battery pin compartment  114  and a battery compartment  116 . A chin pin  118  is secured in the proximal end of housing  102  and extends proximally therefrom. Chin pin  118  is used to secure shroud assembly  500  ( FIG. 2 ) to housing  102 , as will hereinafter be discussed in further detail. 
   Battery door  104  selectively closes off battery compartment  116 . To this end, battery door  104  is hingedly connected to housing  102  by a pin  120  ( FIG. 8 ), and includes a door latch  122  ( FIG. 8 ) for selectively releasing and locking the battery door. 
   Handle cartridge assembly  106  ( FIG. 7 ) is shown in greater detail in  FIGS. 9–13 . Handle cartridge assembly  106  generally comprises a housing  123 , a shaft  124  ( FIG. 13 ), a gear and clutch assembly  126 , a clutch assembly  128 , a motor  130  and a switch  132 . 
   Housing  123  includes a first cavity  134  ( FIG. 10 ) for receiving shaft  124  and portions of gear and clutch assembly  126  and portions of clutch assembly  128 , and a second cavity  136  ( FIG. 10 ) for receiving portions of motor  130  and switch  132 . Housing  132  of handle cartridge assembly  106  also includes a seal  138  ( FIG. 10 ) for sealing handle cartridge assembly  106  within main compartment  112  ( FIG. 8 ) of handle  102 . 
   Shaft  124  ( FIG. 13 ) is selectively coupled to motor  130  via gear and clutch assembly  126 , and is selectively coupled to cannula assembly  200  via clutch assembly  128 , as will hereinafter be discussed in further detail. 
   Gear and clutch assembly  126  is shown in greater detail in  FIGS. 14–16 . Gear and clutch assembly  126  comprises a hub  139 , a large gear  140  and a smaller gear  142  mounted on hub  139 , a seal  144 , a second hub  146 , and a one-way clutch  148  received within second hub  146 . As a result of this construction, when gear and clutch assembly  126  is press fit onto shaft  124  ( FIG. 13 ) and motor  130  is used to turn large gear  140  clockwise (as viewed from the left hand side of  FIG. 13 ), hubs  139  and  146  and smaller gear  142  will also turn clockwise (as viewed from the left hand side of  FIG. 13 ). In addition, due to the nature of one-way clutch  148 , clockwise rotation (as viewed from the left hand side of  FIG. 13 ) of hub  146  will be transferred by clutch  148  to shaft  124 , whereby to cause clockwise rotation (as viewed from the left hand side of  FIG. 13 ) of shaft  124 . When motor  130  is used to turn large gear  140  counterclockwise rotation (as viewed from the left hand side of  FIG. 13 ) hubs  139  and  146  and smaller gear  142  will also turn counterclockwise (as viewed from the left hand side of  FIG. 13 ). However, due to arrangement of one way clutch  148 , rotation of large gear  140  will not be transferred by clutch  148  to shaft  124 . Thus it will be seen that, due to the presence of one-way clutch  148 , motor  130  can only rotate shaft  124  in one direction, i.e., clockwise (as viewed from the left hand side of  FIG. 13 ). 
   Clutch assembly  128  ( FIG. 13 ) is shown in greater detail in  FIG. 17 . Clutch assembly  128  comprises a hub  150 , a one-way clutch  152  received within hub  150 , a seal  154  and a second hub  156 . As a result of this construction, when clutch assembly  128  is press fit onto shaft  124  ( FIG. 13 ) and hubs  150  and  156  are secured to housing  123  ( FIG. 9 ), clutch assembly  128  will permit shaft  124  to rotate clockwise (as viewed from the left hand side of  FIG. 13 ) but will prevent shaft  124  from rotating counterclockwise (as viewed from the left hand side of  FIG. 13 ). 
   By mounting gear and clutch assembly  126  and clutch assembly  128  to shaft  124 , and by configuring one-way clutch  148  and one-way clutch  152  for opposing rotation, shaft  124  can be rotated clockwise (as viewed from the left hand side of  FIG. 13 ) by clockwise rotation (as viewed from left hand side of  FIG. 13 ) of motor  130 . At the same time, however, counterclockwise rotation (as viewed from left hand side of  FIG. 13 ) of motor  130  will not result in any counterclockwise rotation (as viewed from the left hand side of  FIG. 13 ) of shaft  124  due to the arrangement of one-way clutch  152 . 
   Switch  132  ( FIG. 13 ) is shown in greater detail in  FIGS. 18–21 . Switch  132  comprises a front  158 , a first pair of electrical contacts  160 A and  160 B, a body  162 , a second pair of electrical contacts  164 A and  164 B and a back  166 , with all of the foregoing held together as a single unit by a pair of screws  168 . Switch  132  serves to selectively connect a pair of battery poles  170 A and  170 B ( FIG. 21 ), forming part of battery pin assembly  108 , to a pair of motor poles  172 A and  172 B. More particularly, switch  132  is normally disposed so that its electrical contact  164 A is in engagement with battery pole  170 A, and its electrical contact  164 B is in engagement with battery pole  170 B, with motor pole  172 A extending through an opening  174 B ( FIG. 21 ) in electrical contact  164 B and with motor pole  172 B extending through an opening  174 A in electrical contact  164 A. Thus, in this position, no current flows between battery poles  170 A and  170 B and motor poles  172 A and  172 B. 
   However, if the switch&#39;s front  158  is forced rearwardly, toward motor  130 , electrical contact  164 A will come into engagement with both battery pole  170 A and motor pole  172 A, and electrical contact  164 B will come into engagement with both battery pole  170 B and motor pole  172 B, thus completing a first circuit so as to energize motor  130  with a first polarity. 
   Alternatively, if front  158  is rotated either clockwise or counterclockwise (as viewed in  FIG. 21 ), electrical contact  164 A will come into engagement with both battery pole  170 A and motor pole  172 B, and electrical contact  164 B will come into engagement with both battery pole  170 B and motor pole  172 A, thus completing a second circuit so as to energize motor  130  with a second polarity. In this respect it will be appreciated that the aforementioned second circuit is substantially the same as the aforementioned first circuit, except that electrical power is delivered to motor  130  with a reversed polarity. Thus, by rotating the front  158  of switch  132  either clockwise or counterclockwise (as viewed in  FIG. 21 ), motor  130  can be energized with a first polarity, such that it will rotate counterclockwise (as viewed from the left hand side of  FIG. 13 ) and thereby drive shaft  124  clockwise (as viewed from the left hand side of  FIG. 13 ). Alternatively, by pushing front  158  of switch  132  rearwardly, toward motor  130 , motor  130  can be energized with a second opposite polarity, such that it will rotate clockwise (as viewed from the left hand side of  FIG. 13 ). However, this clockwise rotation of motor  130  will not cause any rotation of shaft  124 , due to the configuration of one-way clutches  148  and  152 , which permit shaft  124  to rotate in only a clockwise direction (as viewed from the left hand side of  FIG. 13 ). It should be appreciated that this arrangement of a DC motor with forward and reverse polarity, together with the gear and clutch assembly  126  and clutch assembly  128 , essentially provides a transmission mechanism. By activating wire advance button  212 , or left rotation button  214  or right rotation button  216 , a single motor can be used to drive wire or rotate the jaws. 
   Battery pin assembly  108  is shown in greater detail in  FIGS. 22–24 . Battery pin assembly  108  comprises a body  176  which supports the aforementioned two battery poles  170 A and  170 B, and a pair of battery contacts  178 A and  178 B for engagement with a battery (not shown) housed in battery compartment  116  ( FIG. 8 ). 
   Cannula Assembly  200   
   Cannula assembly  200  ( FIG. 2 ) is shown in greater detail in  FIGS. 25–38 . As noted above, cannula assembly  200  ( FIG. 2 ) comprises shaft  202 , end effector  204  comprising first jaw  206  and second jaw  208 , jaw closing actuator  210 , wire advance button  212 , left rotation button  214 , right rotation button  216  and wire cutting actuator  216 . Cannula assembly  200  also includes a housing  220  ( FIG. 25 ) which acts as a support for the aforementioned elements. 
   Shaft  202  is shown in greater detail in  FIGS. 28–31 . Shaft  202  comprises a body  222  ( FIG. 29 ) which has a tubular proximal end  224  and a trifurcated distal end  226 . 
   A jaw linkage  228  extends through the distal end of tubular proximal end  224  and alongside (i.e., within one of the grooves) of trifurcated distal end  226 . Jaw linkage  228  is connected at its distal end to first jaw  206  and second jaw  208  as will hereinafter be described in further detail, and is connected at its proximal end to an internal mount  230  ( FIG. 33 ). A pin  232  ( FIG. 31 ) extends through a pair of slots  234  in tubular proximal end  224  and connects internal mount  230  ( FIG. 33 ) to an external mount  236 . As a result of this construction, axial movement of external mount  236  will result in axial movement of jaw linkage  228 , whereby to open and close first jaw  206  and second jaw  208  via a scissors-type linkage ( FIG. 34 ), as will hereinafter be discussed in further detail. 
   A cutter bar linkage  238  ( FIG. 29 ) also extends through the distal end of tubular proximal end  224  and alongside trifurcated distal end  226 . Cutter bar linkage  238  is connected as its distal end to a cutter bar  240  via superelastic Nitinol wire flexible coupling ( FIG. 34 ), and is connected at its proximal end to an internal mount  242  ( FIG. 33 ). A pin  244  ( FIG. 31 ) extends through a pair of slots  246  in tubular proximal end  224  and connects internal mount  242  to an external mount  248 . As a result of this construction, axial movement of external mount  248  will result in axial movement of cutter bar linkage  238 , whereby to advance and retract cutter bar  240 , as will hereinafter be discussed in further detail. 
   Also extending through tubular proximal end  224  ( FIG. 29 ) and alongside trifurcated distal end  226  is a hollow wire guide  250  ( FIG. 38 ) which terminates, at its proximal end, in a mount  252 . The distal end of mount  252  is received by the proximal end of tubular proximal end  224 . The distal end of hollow wire guide  250  is received in a channel  254  ( FIG. 35 ) formed in first jaw  206 , as will hereinafter be discussed in further detail. Channel  254  communicates with a suture wire guide  256  formed in first jaw  206 , whereby suture wire emerging from hollow wire guide  250  will enter suture wire guide  256 . Suture wire guide  256  is configured so that when first jaw  206  and second jaw  208  are closed, suture wire guide  256  will receive suture wire advancing parallel to the axis of shaft  202  and redirect it, substantially perpendicularly, toward second jaw  208 . Wire guide  256  is configured to work with a range of different jaw openings, i.e., wire guide  256  is configured to work successfully regardless of whether the jaws are closed on relatively thin tissue or relatively thick tissue. Preferably wire guide  256  has radius of 0.125 inches. In order to permit the fabrication of suture wire guide  256 , first jaw  206  may include a removable cover  259  ( FIG. 37 ) so as to provide access to the interior of first jaw  206 . 
   Second jaw  208  has an opening  257  ( FIG. 36 ) formed therein to receive the wire exiting first jaw  206 . 
   Looking next at  FIGS. 25–27 , it will be seen jaw closing actuator  210  is connected to external mount  236  such that depressing actuator  210  toward handle assembly  100  will cause external mount  236  to move proximally, whereby to move jaw linkage  228  proximally, and whereby to cause first jaw  206  and second jaw  208  to close toward one another. Correspondingly, when jaw closing actuator  210  is released, a coil spring  258  ( FIG. 27 ) will cause external mount  236  to move distally, whereby to move jaw linkage  228  distally, and whereby to cause first jaw  206  and second jaw  208  to separate from one another. 
   Still looking now at  FIGS. 25–27 , it will also be seen that wire cutting actuator  218  is connected to external mount  248  such that depressing wire cutting actuator  218  toward handle assembly  100  will cause external mount  248  to move distally, whereby to move cutter bar linkage  238  distally and whereby to cause cutter bar  240  to move distally within a passageway  260  ( FIG. 35 ) formed in first jaw  206 . In this respect it should be appreciated that cutter bar passageway intersects suture wire guideway  256  near the distal end of first jaw  206 , such that cutter bar  240  can sever a length of suture wire extending through suture wire guideway  256 , as will hereinafter be discussed in greater detail. Correspondingly, when wire cutting actuator  218  is released, a coil spring  262  ( FIG. 27 ) will cause external mount  248  to move proximally, whereby to move cutter bar linkage  238  proximally and whereby to cause cutter bar  240  to move proximally within passageway  260 . Significantly, external mounts  236  and  248  permit the shaft to rotate for wire twisting purposes while simultaneously permitting axial motion for jaw actuation and cutter bar actuation. 
   Still looking now at  FIGS. 25–27 , it will also be seen that wire advance button  212  is connected to a pair of push rods  262  ( FIG. 27 ). Push rods  262  are arranged to that when cannula assembly  200  is mounted to handle assembly  100  and wire advance button  212  is depressed (i.e., pushed toward handle assembly  100 ), push rods  262  will engage front  158  of switch  132 , whereby to drive front  158  proximally, whereby to energize motor  130  with the aforementioned second polarity, such that motor  130  will rotate clockwise (as viewed from the left hand side of  FIG. 13 ). Such motor rotation will cause suture wire to be advanced out of the distal end of suturing instrument  2 , as will hereinafter be discussed in further detail. 
   Still looking now at  FIGS. 25–27 , it will also be seen that the proximal ends  264 ,  266  ( FIG. 25 ) of left rotation button  214  and right rotation button  216 , respectively, are exposed at the proximal end of cannula assembly  100 , whereby they may engage fingers  268 ,  270  ( FIG. 19 ), respectively, formed on front  158  of switch  132 . The various parts are arranged so that engagement of left rotation button  214  or right rotation button  216  will result in rotation of front  158  of switch  132 , which will in turn result in motor  130  being energized with the aforementioned first polarity, such that motor  130  will rotate counterclockwise (as viewed from the left hand side of  FIG. 13 ) and whereby to drive shaft  124  clockwise (as viewed from the left hand side of  FIG. 13 ). 
   Wire Drive Assembly  300   
   Looking next at  FIGS. 39–48 , wire drive assembly  300  comprises a body  302  ( FIG. 44 ), a base plate  304  fastened to body  302  by a pair of screws  306 , a spur gear  308  connected to a miter gear  310  via a shaft  312 , a fixed block  314  mounted on a rod  316 , a screw  318  securing rod  316  to body  302 , a second miter gear  320  connected to a drive shaft roller  322  and a spur gear  324  via an axle  326  passing through fixed block  314 , a second drive shaft roller  328  connected to a spur gear  330  via an axle  332 , a movable block  334  slidably mounted on rod  316 , a block  336 , spring  338 , washer  340  and screw  342  for biasing movable block  334  into engagement with fixed block  314 , and a lever  344  and arm  346  for manually forcing movable block  334  away from fixed block  314 . Wire drive assembly  300  also comprises a cannula lock lever  348  including a keyway  350 . Cannula lock lever  348  is biased outwardly by a spring  352 . 
   As a result of this construction, when movable block  334  is in engagement with fixed block  314 , rotation of spur gear  308  will cause rotation of miter gear  310 , which will in turn cause rotation of miter gear  320  and shaft  326 , which will in turn cause rotation of roller  322  and spur gear  324 , which will in turn cause rotation of spur gear  330  and hence roller  328 . However, depressing lever  344  will cause arm  346  to pivot, whereby to force movable block  334  away from fixed block  314  and whereby to separate roller  322  from roller  328 . 
   In addition, cannula lock lever  348  can be pressed inwardly, against the force of spring  352 , whereby to align enlarged portion  354  of keyway  350  with notches  272  ( FIG. 38 ) of mount  250 , and thereafter released, so as to lock the cannula and wire drive assembly  300  together, as will hereinafter be discussed in further detail. 
   It should be appreciated that wave washers WW 1  and WW 2  ( FIG. 44 ) bias spur gears  324  and  330 , respectively, away from fixed block  314  and movable block  334 , which, via axles  325  and  332  respectively, urge drive wheels  322  and  328  against body  302 , whereby to keep wheels  322  and  328  aligned and in a fixed relative position. Each drive wheel and axle assembly is machined (turned) from a single, continuous piece of metal, using the same tool setup, so that the alignment of both is immune from the inaccuracies that would occur if they were turned at different occasions and assembled using holes and holding means. This operation is important, because the drive wheels are approximately 100 times the diameter of the wire they are driving and even the slightest alignment inaccuracies can rotate the wire as it is moved forward. Since the wire is permanently curved by the exit path in the delivery jaw, any such wire rotation causes the wire to swerve from its normal trajectory from that jaw and possibly prevent the tip of the wire from passing through the opening in the receiving jaw. 
   It should also be appreciated that peripheral grooves may be formed in wheels  322  and  328 . Such grooves provide a seat for the wire being driven and help increase the surface area contact between the wheels and the wire. 
   Wire Supply Cartridge  400   
   Looking next at  FIGS. 49–54 , wire supply cartridge  400  generally comprises a spool housing  402  ( FIG. 50 ), a wire spool  404 , a spool retainer spring  406 , a spool cover  408 , a molded tube support  410  holding a wire support tube  412  and a PEEK wire guide tube  414 . A length of wire  416  extends from spool  404 , through molded tube support  410  and wire support tube  412 , and through PEEK wire guide tube  414 . 
   More particularly, a supply coil of suture wire  416  (comprising wire formed of metal or any other suitable material having the required flexibility and stiffness) may be supplied in the base of cartridge  400  and is fed into molded tube support  410 , where it enters wire support unit  412  before entering PEEK wire guide tube  414 . PEEK wire guide tube  414  surrounds suture wire  416 , from wire support unit  412  to the distal end of suturing instrument  2  where, with the distal end of PEEK tube received in channel  254  ( FIG. 35 ), the suture wire enters suture wire guide  256  in first jaw  206 . PEEK wire guide tube  414  ensures that suture wire  416  does not bend or buckle as the suture wire is pushed through handle assembly  100  and cannula assembly  200 . More particularly, PEEK wire guide tube  414  preferably forms a sufficiently close sliding fit with suture wire  416  such that suture wire  416  cannot bend or buckle as the suture wire is advanced through suturing instrument  2 . At the same time, PEEK wire guide tube  414  is also formed so as to present a minimum of friction to suture wire  416  as the suture wire is advanced through the instrument. In addition, PEEK wire guide tube  414  also provides a flexible support as the suture wire moves from the shaft to the upper jaw, which pivots relative to the longitudinal axis of the shaft. The foregoing characteristics are important, inasmuch as suture wire  416  is extremely thin and flexible and highly susceptible to bending or buckling in the absence of some sort of lateral support. 
   By way of example but not limitation, where suture wire  416  is formed out of stainless steel and has a diameter of 0.006 inch, PEEK wire guide tube  414  might have an inside diameter of 0.008 inch and an outside diameter of 0.016 inch. In addition, PEEK wire guide tube  414  is preferably formed out of polyetheretherketone; however, it may alternatively be formed out of polytetrafluoroethylene (PTFE) or some other relatively lubricious material. Alternatively, the interior of PEEK wire guide tube  414  may be coated with a lubricant so as to facilitate closely-supported, low-friction passage of the suture wire through the wire guide. 
   Further by way of example but not limitation, in one preferred form of the invention, suture wire  416  may comprise 316 LVM stainless steel having a tensile strength of 168,000 psi. 
   Wire support unit  412  and its surrounding molded tube support  410  have aligned openings  418 ,  420  ( FIG. 52 ) respectively, on opposite sides thereof. Openings  418 ,  420  expose a portion of suture wire  416  so that rollers  322 ,  328  ( FIG. 44 ) may contact suture wire  416  and urge the suture wire forward toward the distal end of suturing instrument  2 , as will hereinafter be discussed in further detail. 
   Wire supply cartridge  400  may be attached to wire drive assembly  300  by actuating lever  344  so as to force movable block  334  away from fixed block  314  and thereby separate roller  328 . Once wire roller  322  is separated from roller  328  by a sufficient distance to expose the distal end of mount  252  ( FIG. 38 ), PEEK wire guide tube  414  may be inserted into the interior of wire guide  250  and molded tube support  410  may be inserted between rollers  322  and  328  such that rollers  322  and  328  contact either side of suture wire  416  through openings  420 ,  418  formed in either side of molded tube support  410  and wire support unit  412 , respectively. 
   Shroud  500   
   Looking next at  FIGS. 55 and 56 , shroud  500  comprises a body  502  having a recess  504  and a locking finger  506 . Locking finger  506  selectively engages chin pin  118  for locking and unlocking shroud  500  relative to handle assembly  100 . 
   Operation 
   Suturing instrument  2  may be used to apply wire suture  416  to a subject so as to effect a desired suturing operation. 
   By way of example but not limitation, and looking now at  FIGS. 57–66 , suturing instrument  2  may be used to suture together two portions  600 ,  602  of a subject which is to be sutured. In a typical case, portions  600 ,  602  might comprise two sections of severed tissue which need to be re-attached to one another, or two pieces of previously unattached tissue which need to be attached to one another. However, one or the other of the portions  600 ,  602  might also comprise artificial mesh or some other object being attached to tissue, etc. In addition, in a typical case, portions  600 ,  602  might be located relatively deep within a patient, and might be accessed during an endoscopic or a so-called “minimally invasive”, or a so-called “closed surgery”, procedure; however, in other circumstances, portions  600 ,  602  might be accessed during a conventional, or so-called “open surgery”, procedure. This later situation might include procedures done at the outer surface of the patient&#39;s body, i.e., where portions  600 ,  602  comprise surface subjects. 
   In any case, suturing instrument  2  is initially prepared for use by installing a battery into handle assembly  100 , if a battery is not already installed, and by installing wire supply cartridge  400  into the suturing instrument, if a cartridge  400  is not yet installed. As noted above, wire supply cartridge  30  is installed in suturing instrument  2  by (1) removing shroud  500 , (2) moving the wire drive assembly&#39;s release lever  344  to its open position, so as to move rollers  322  and  328  apart and thereby expose the distal end of mount  252 ; (3) passing the distal end of the cartridge (i.e., the distal end of PEEK wire guide tube  414 ) through cannula assembly  200  until the distal end of PEEK wire guide tube  414  is in communication with the suture wire guide  256  formed in first jaw portion  206 , at which point the cartridge&#39;s molded tube support  410  will be positioned intermediate rollers  322  and  328 ; and (4) moving the wire drive assembly&#39;s release lever  344  back to its closed position, so as to cause rollers  322  and  328  to extend through the wire support unit&#39;s openings  418  and engage suture wire  416 . 
   At this point suturing instrument  2  will be ready for use, with its first jaw  206  and second jaw  208  being open, and with its cutter bar  240  being in its retracted (i.e., non-cutting) position. 
   Next, suturing instrument  2  has its jaws  206 ,  208  placed in their “closed” position) by pulling jaw closing actuator  210  toward handle assembly  100 , and then the distal end of suturing instrument  2  is moved adjacent to subject portions  600 ,  602  ( FIG. 57 ). 
   In the case of a so-called closed surgical procedure, such positioning will generally involve moving the distal end of the suturing instrument through a cannula and into an interior body cavity; however, it is also envisioned that one might move the distal end of the suturing instrument directly into an otherwise-accessible body cavity, e.g., directly into the colon or esophagus, etc. In the case of a so-called open surgical procedure, such positioning might involve positioning the distal end of the suturing instrument adjacent to more readily accessible subject portions  600 ,  602 . 
   In any case, once the distal end of suturing instrument  2  has been placed adjacent to subject portions  600 ,  602 , jaw closing actuator  210  is released, such that biasing spring  258  ( FIG. 27 ) will cause jaws  206 ,  208  to move away from one another ( FIG. 58 ). Then the distal end of suturing instrument  2  is moved so that its jaws  206 ,  208  straddle subject portions  600 ,  602 , and then jaw closing actuator  210  is actuated again, by pulling jaw closing actuator  210  toward handle assembly  100 , so as to close jaws  206 ,  208  against one another, whereby to capture subject portions  600 ,  602  ( FIG. 59 ). 
   Next, wire advance button  212  is activated so as to cause suture wire  416  to be driven forward, out of the distal end of wire guide  256 , through subject portions  600 ,  602 , and finally through opening  257  ( FIG. 36 ) formed in second jaw  208 . Suture wire  416  is preferably advanced so that a length  416 A of wire  416  extends approximately 1 centimeter out of the bottom end of second jaw  208  ( FIG. 59 ). In this respect it will be appreciated that, as suture wire  416  leaves first jaw  206  and engages subject portions  600 ,  602 , the first jaw&#39;s wire guide  256  will support the thin suture wire so as to enable the suture wire to penetrate subject portions  600 ,  602 . Again, it should be appreciated that wire guide  256  is configured to pass the wire to second jaw  208  regardless of whether the jaws are closed on relatively thin tissue or relatively thick tissue. 
   Once this has been done, jaw closing actuator  210  is released so as to permit jaws  206 ,  208  to return to their “open” position, and then wire advance button  212  is used to pay out additional suture wire  416  as the distal end of suturing instrument  2  is stepped back (e.g., by about a centimeter or so) from subject portions  600 ,  602  ( FIG. 60 ). 
   Then jaw closing actuator  210  is used to move jaws  206 ,  208  back into engagement with one another once more ( FIG. 61 ). 
   Next, left rotation button  214 , or right rotation button  216 , is used to rotate shaft  202  and hence end effector  204 . This causes suture wire  416  to twist on itself, initially creating a relatively large loop  417  ( FIG. 61 ) of suture wire  416  extending from subject portions  600 ,  602  toward suturing instrument  2 . However, as left rotation button  214  and/or right rotation button  216  is used to rotate shaft  202  (and hence end effector  204 ) more and more, the loop  417  of suture material will progressively close down ( FIG. 62 ) so as to form a tight binder for subject portions  600 ,  602 . In this respect it will be appreciated that the longer the period of time that end effector  204  is rotated, the greater the amount of twisting of suture wire  416 , and the greater the force holding subject portions  600 ,  602 . In this respect it will also be appreciated that suture wire  416  is preferably carefully selected with respect to its flexibility relative to the strength of subject portions  600 ,  602 . In particular, suture wire  416  is chosen so as to have a flexibility such that the suture wire will twist, and loop  417  will close down, before subject portions  600 ,  602  will undergo substantial deformation and/or tearing. By way of example but not limitation, in practice, it has been found that 0.006 inch diameter stainless steel wire can be used with most types of mammalian tissue such that the suture wire can be twisted closed without causing substantial deformation and/or tearing of the tissue. At the same time, suture wire  416  is also chosen to have an adequate columnar strength, whereby to permit it to be driven through the tool and across the tissue. 
   Once suture wire  416  has been tightened to the desired degree ( FIG. 63 ), rotation of shaft  202  (and hence end effector  204 ) is stopped, i.e., by releasing left rotation button  214  or right rotation button  28 . Then wire cutting actuator  218  is depressed (e.g., it is pulled back toward handle assembly  100 ) so as to move cutting bar  240  distally and thereby sever the suture wire  416  as the suture wire crosses the first jaw&#39;s cutter bar channel  260  ( FIG. 65 ). This action separates the deployed suture wire extending through subject portions  600 ,  602  from the suture wire remaining in wire supply cartridge  400  and first jaw  206 . 
   Then wire cutting actuator  218  is released, allowing biasing spring  262  to return cutting bar  240  to return to its proximal position, and then jaw closing actuator  210  is released, allowing jaws  206  and  208  to move away from one another. Suturing instrument  2  may then be removed from subject portions  600 ,  602 , which action will pull wire length  416 A from second jaw  208  ( FIG. 65 ). 
   The deployed suture wire  416  may then be pressed down flat against subject portions  600 ,  602  or rounded into a ball, or otherwise operated upon, or portions cut away, etc. so as to reduce the profile of, or reduce the tendency to snag on, the deployed suture wire ( FIG. 66 ). 
   Significantly, with the present invention, jaw opening and closing, wire length and the degree of wire twisting are all variable and adjustable by the operator according to the particular surgical application involved. 
   It will be appreciated that suturing instrument  2  will have application in a broad range of different suturing operations. More particularly, it will be appreciated that suturing instrument  2  will have application in both “open” and “closed” surgical procedures, with the former including, but not limited to, large entry procedures, relatively shallow procedures, and surface procedures; and with the latter including, but not limited to, surgical procedures where access is gained to an interior structure through the use of a cannula, and surgical procedures where access is gained directly to an internal body cavity without the use of a cannula, e.g., such as a procedure conducted within the colon or the esophagus. 
   It will also be appreciated that suturing instrument  2  will have application where two portions of tissue must be attached to one another (e.g., where two severed pieces of tissue must be re-attached to one another, or where two separate pieces of tissue must be attached to one another, or where two sections of a single piece of tissue must be approximated to one another), and where an object must be attached to the patient (e.g., where surgical mesh must be attached to the patient&#39;s abdominal wall during hernia repair surgery, etc.). 
   Among other things, it is believed that suturing instrument  2  will have particular application in the areas of general laparoscopic surgery, general thoracic surgery, cardiac surgery, general intestinal surgery, vascular surgery, skin surgery and plastic surgery. 
   Looking next at  FIGS. 67 and 68 , it will be seen that where the first jaw&#39;s guide channel  256  is disposed so as to be substantially aligned with the center of cutting bar  240  ( FIG. 67 ), suture wire  416  will be cut with a relatively flat leading end  416 B ( FIG. 68 ). However, it has sometimes been found helpful to provide suture wire  416  with a relatively sharp leading point. Such a leading point can help open the subject for the following portion of the suture wire. In addition, such a leading point can help the suture wire penetrate the subject with a substantially straight path, so that the suture wire will reliably enter the second jaw&#39;s opening  257 . To this end, it has been found that moving the first jaw&#39;s guide channel  256  off-center relative to cutting bar  240  ( FIG. 69 ) will cause the leading end  416 B of suture wire  416  to be formed with a relatively sharp tip  416 C ( FIG. 70 ). 
   It is also possible to use suturing instrument  2  to ligate a subject rather than to pass a suture through the subject. For example, suturing instrument  2  might be used to ligate a blood vessel or cystic duct with suture wire  416 . In this case, suturing. instrument  2  is deployed so that suture wire  416  will pass around the far side of the subject, rather than through the subject as in the case of the suturing operation of the type described above. 
   By way of example but not limitation, in a typical ligating operation, first and second jaws  206 ,  208  are first opened relative to one another. Then suturing instrument  2  is positioned about the subject so that when the two jaws are thereafter closed toward one another, the first jaw&#39;s guide channel  256  and the second jaw&#39;s opening  257  will both lie on the far side of the subject. The two jaws are then closed against one another, and suture wire  416  is passed from first jaw  206  to second jaw  208 , i.e., around the far side of the subject. The two jaws are then opened, and suture wire  416  is payed out as the instrument is stepped back from the subject. Then the two jaws are closed again. The shaft of the instrument is then rotated so as to form, and then close down, the ligating loop. Then cutting bar  240  is activated so as to cut the ligating loop from the remainder of the suture wire still in the tool, the two jaw members are opened, and the instrument is withdrawn from the surgical site. The deployed suture wire  416  may then be pressed down flat against the subject, or rounded into a ball, or otherwise operated upon, or portions cut away, etc. so as to reduce the profile of, or reduce the tendency to snag on, the deployed suture wire. As will be appreciated by a person skilled in the art, where instrument  2  is to be used for ligating purposes, first and second jaws  206 ,  208  might be formed with a greater longitudinal length so as to facilitate passing the suture wire around the far side of the subject. Furthermore, one or both of the jaw members might be formed with a recess, intermediate their length, for accommodating the subject, whereby to prevent compressing the subject when the two jaw members are moved into engagement with one another. 
   Suture wire  416  may comprise a wire formed out of a metal or any other suitable material having the required flexibility and stiffness. By way of example but not limitation, suture wire  416  may comprise stainless steel, titanium, tantalum, etc. 
   If desired, suture wire  416  may also be coated with various active agents. For example, suture wire  416  may be coated with an anti-inflammatory agent, or an anti-coagulant agent, or an antibiotic, or a radioactive agent, etc. 
   It should also be appreciated that the instrument may also be used to anchor a guide wire into tissue for the purposes of subsequently delivering an object to that tissue anchor point. In such a situation, the jaws would grasp tissue at the desired anchor point in the tissue, drive wire through it and twist the wire ends together. Before cutting the supply side of the wire, however, the user would drive wire, with the jaws open, as the instrument was withdrawn out of the surgical area. The proximal end of this length of wire is then secured. Then the wire could be cut, leaving an open proximal end over which various devices could be pushed to the tissue site (e.g. pH sensors, gastric motility leads, cardiac pacing leads, drug delivery catheters, drug factories, and micro electromechanical “MEM systems,” etc.) 
   Modifications 
   It will be appreciated by those skilled in the art that numerous modifications and variations may be made to the above-disclosed embodiments without departing from the spirit and scope of the present invention.