Abstract:
A surgical instrument comprises a first elongated member and a second elongated member, the first elongated member and the second elongated member being operatively connected and configured to rotate in opposite directions to substantially limit counter torque. The first and second elongated members are flexible shafts. The surgical instrument can be configured to apply fasteners to a tissue portion. This embodiment of the surgical instrument includes a cartridge having a plurality of fasteners, an anvil, said anvil and cartridge being relatively movable between spaced and approximated positions, and a sled disposed in the cartridge. The sled includes a cam member. The cam member is designed to drive the fasteners through tissue and toward the anvil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 11/787,989 filed Apr. 17, 2007, now U.S. Pat. No. 7,708,182, and the disclosures of each of the above-identified applications are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an apparatus and method for surgical devices. More particularly, the present disclosure relates to a surgical instrument capable of eliminating or substantially limiting counter torque in a surgical fastening apparatus. 
     2. Background of Related Art 
     Surgical fastening devices wherein tissue is first grasped or clamped between opposing jaw structure and then joined by surgical fasteners are well known in the art. Several types of known surgical fastening instruments are specifically adapted for use in various procedures such as end-to-end anastomosis, gastrointestinal anastomosis, endoscopic gastrointestinal anastomosis, and transverse anastomosis among others. U.S. Pat. Nos. 5,915,616; 6,202,914; 5,865,361; and 5,964,394 are examples of surgical fastening instruments. Although the fasteners are typically in the form of surgical staples, two-part polymeric fasteners may also be employed. 
     Surgical fastening instruments can include two elongated jaw members used to capture or clamp tissue. One jaw member typically contains a staple cartridge that houses a plurality of staples arranged in a single row or a plurality of rows while the other jaw member has an anvil that defines a surface for forming the staple legs as the staples are driven from the staple cartridge. The stapling operation is usually effected by one or more cam members that translate through the staple cartridge, with the cam members acting upon staple pushers to sequentially or simultaneously eject the staples from the staple cartridge. A knife may be provided to move axially between the staple rows to cut or open the stapled tissue between the rows of staples. U.S. Pat. Nos. 3,079,606 and 3,490,675 disclose examples of this kind of instrument. 
     Some surgical fastening instruments contain rotating components that facilitate actuation of the surgical instrument, deployment of the surgical fasteners, or articulation of the surgical instrument. For instance, U.S. Pat. No. 7,114,642 to Whitman (“Whitman”) discloses a stapling mechanism including two rotating flexible drive shafts. One drive shaft controls the movement of an upper jaw while the other drive shaft controls the stapling and cutting actions of the mechanism. Essentially, the flexible drive shafts transmit torque from a motor in a handle to the distal end of the shaft. Each drive shaft is driven by a different motor and they are not operatively connected with each other. The torque transmitted by each drive shaft produces a counter torque that can turn or steer the jaws of the surgical mechanism to one direction. This undesirable motion of the jaws can prevent the surgeon from having full control of the surgical instrument. The stapling mechanism of Whitman does not have any mechanism, device, or component to eliminate the detrimental effects of the torque, i.e., the counter torque. Other surgical instruments having torque transmitting components also fail to provide adequate measures to limit or eliminate counter torque. Therefore, it is desirable to develop a surgical instrument capable of eliminating or substantially limiting counter torque. 
     SUMMARY 
     The presently disclosed a surgical instrument includes a first elongated member and a second elongated member. The first elongated member and the second elongated member are operatively connected to each other and configured to rotate in opposite directions to substantially limit counter torque. These elongated members can consist of flexible shafts. Because the shafts are operatively connected to one another, they are redundant and can fully operate the instrument even if one of the shafts breaks. 
     An embodiment of the surgical instrument includes a cartridge housing a plurality of fasteners, an anvil, a sled disposed in the cartridge, and first and second elongated members disposed in the cartridge. The anvil and the cartridge are relatively movable between spaced and approximated positions. The cartridge has a sled positioned therein. The sled includes a cam member designed to drive the fasteners through tissue and toward the anvil, and at least one bore disposed therethrough for receiving at least one drive member. One or more drive members can be operatively attached to the first or second elongated members, or both. The drive member can optionally consist of a lead screw. The surgical instrument further includes a channel partially encompassing the cartridge and a neck. The neck, which is flexible, is secured to the channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the presently disclosed surgical instrument are described herein with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a surgical instrument in accordance with an embodiment of the present disclosure operatively connected to an actuation apparatus; 
         FIG. 2  is a perspective view of the surgical instrument of  FIG. 1 ; 
         FIG. 3  is a perspective exploded view of the surgical instrument of  FIGS. 1 and 2 ; 
         FIG. 4  is an perspective view of a clamp cam of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 5  is a perspective longitudinal cross-sectional view of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 6  is a perspective view of a portion of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 7  is a side cross-sectional view of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 8  is a perspective cross-sectional view of the surgical instrument of  FIGS. 1-3 , as taken through section lines  8 - 8  of  FIG. 7 ; 
         FIG. 9  is a top cross-sectional view of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 10  is a top sectional view of the surgical instrument of  FIGS. 1-3 , taken around section  10  of  FIG. 9 ; 
         FIG. 11  is a top cross-sectional view of the surgical instrument of  FIGS. 1-3 , as taken through section lines  11 - 11  of  FIG. 7 ; 
         FIG. 12  is a top sectional view of the surgical instrument of  FIGS. 1-3 , as taken around section  12  of  FIG. 11 ; 
         FIG. 13  is a perspective view of the gooseneck of a surgical instrument in accordance with an embodiment of the present disclosure; 
         FIG. 14  is a top cross-sectional view of the gooseneck of a surgical instrument in accordance with an embodiment of the present disclosure; 
         FIG. 15  is a top view of the actuation apparatus of  FIG. 1 ; 
         FIG. 16  is a top view of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 17  is a top view of the actuation apparatus of  FIGS. 1 and 15 ; 
         FIG. 18  is a top cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 19  is a perspective cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 , as taken through section lines  19 - 19  of  FIG. 18 ; 
         FIG. 20  is a front elevational view of the portion of the surgical instrument of  FIG. 19 ; 
         FIG. 21  is a side cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 22  is a side sectional view of a portion of the surgical instrument of  FIGS. 1-3 , as taken around section  22  of  FIG. 21 ; 
         FIG. 23  is a top cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 24  is a top view of the actuation apparatus of  FIGS. 1 ,  15  and  17 ; 
         FIG. 25  is a perspective view of a portion of the surgical instrument of  FIGS. 1-3 ; 
         FIG. 26  is a perspective view of the gear couplers and pinions of a surgical instrument in accordance with an embodiment of the present disclosure; 
         FIG. 27  is a top cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 ; and 
         FIG. 28  is a side cross-sectional view of a portion of the surgical instrument of  FIGS. 1-3 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the presently disclosed surgical instrument will now be described in detail with reference to the drawings wherein like reference numerals identify similar or identical elements. In the drawings and in the description which follows, the term “proximal,” as is traditional, will refer to the end of the surgical instrument that is closest to the operator while the term “distal” will refer to the end of the surgical instrument that is farthest from the operator. In the present disclosure, the words “a,” “an,” or “the” are to be taken to include both the singular and the plural. Likewise, any reference to plural items shall, where appropriate, include the singular. 
     The present disclosure relates to a surgical instrument for use with a surgical fastening apparatus or any other suitable surgical device. In fact, the presently disclosed surgical instrument can be applied to a whole line of surgical devices where torque is transmitted from one point to another. In addition, this surgical instrument can be employed in many kinds of surgical procedures. Surgeons may utilize the instrument in endoluminal procedures. During such procedures, surgeons introduce a surgical instrument through a body lumen. Doctors can also use the presently disclosed surgical instrument in endoscopic procedures. In this kind of procedure, doctors use a surgical instrument through or in combination with an endoscope. 
     Referring now to  FIG. 1 , a surgical instrument for use with a surgical fastening apparatus is generally designated as  100 . In the interest of brevity, this disclosure will focus primarily on systems, methods and structures of surgical instrument  100 . A detailed discussion of the remaining components and method of use of a surgical fastening apparatus is disclosed in U.S. Pat. No. 6,241,139, the entire content of which is incorporated herein by reference. Briefly, a surgical fastening apparatus comprising surgical instrument  100  includes an actuation apparatus  10 . Surgical instrument  100  is releasably secured to a distal end of actuation apparatus  10 . 
     Actuation apparatus  10  includes a motor  12 , a gearshift lever  16 , and gears  18 . Motor  12  supplies input rotation to apparatus  10  and is operatively connected to at least one gear  18 . Gears  18  are axially trapped between two columns  20  and are configured to mesh with each other. Each column has a pair of bores  21  extending therethrough. Bores  21  are configured to receive drive members  22 . Drive members  22  are operatively coupled to flexible shafts  139 . Gearshift lever  16  controls the axial movement of flexible shafts  139 . A user can actuate gearshift lever  16  to translate flexible shafts  139  distally or proximally. 
     Additionally, apparatus  10  includes an articulation mechanism  30  including an articulation knob  32  and at least one steering wire  34 . Articulation knob  32  is operatively coupled to at least one steering wire  34 . In embodiment illustrated in  FIG. 1 , articulation knob  32  is operatively connected to two steering wires  34 . A user can axially move steering wires  34  back and forth by rotating articulation knob  32 . This axial motion causes the articulation of surgical instrument  100 . 
     During operation, a user articulates surgical instrument  100  by pulling one steering wire  139 . The movement of the steering wire bends gooseneck  130  and effectively articulates surgical instrument  100  to one side or the other. Gooseneck  130  bends towards the side of the wire that was pulled. In practice, the operator rotates articulation knob  32  apparatus  10  to move a steering wire  34  and thereby articulate surgical instrument  100 . 
     Referring to  FIG. 2 , surgical instrument  100  includes a gooseneck  130 , channel  150 , a cartridge  110 , and an anvil  120  movably secured in relation to cartridge  110 . Channel  150  partially encompasses cartridge  110 . Cartridge  110 , which can be replaceable, houses a plurality of fasteners  190  (see  FIG. 3 ) in retention slots  114 . Retention slots  114  can be arranged in a single row, as shown in  FIG. 2 , or in a plurality of rows. Gooseneck  130  is secured to channel  150 . Specifically, a distal end of gooseneck  130  can be attached to a proximal end of channel  150 . In turn, a proximal end of gooseneck  130  is operatively secured to the distal end of actuation apparatus  10 . (See  FIG. 1 ). Gooseneck  130  facilitates articulation of surgical instrument  100  and can be flexible. 
     Further, gooseneck  130  includes at least one hole  141  configured to receive a steering wire  34 . The depicted embodiment shows a gooseneck  130  having two holes  141  extend therethrough. In addition, gooseneck  130  includes at least one bore  132  adapted to receive a flexible shaft  139 . The illustrated embodiment shows a gooseneck  130  having two bores  132  extending through at least a portion of the length of gooseneck  130 . Although the drawings show bores  132  having a cylindrical shape, bores  132  can have any suitable shape. 
     Flexible shafts  139  are operatively connected to each other and are configured to rotate in opposite directions, i.e., clockwise and counterclockwise. Since the flexible shafts  139  rotate in opposite directions, the torque transmitted by each flexible shaft  139  is canceled, thereby eliminating or substantially limiting the counter torque. As shown in  FIG. 1 , flexible shafts  139  are positioned on a neutral axis that extends along a portion of the length of surgical instrument  100 . The depicted embodiment shows one flexible shaft  139  on top of the other. Flexible shafts  139 , however, can be placed in numerous arrangements. For instance, flexible shafts  139  can consist of coaxial elongated members positioned on a neutral axis extending along at least a portion of the length of surgical instrument  100 . 
     With reference to  FIG. 3 , gooseneck  130  surrounds at least a portion of flexible shafts  139  and steering wires  34 . The distal end of gooseneck  130  is secured to the proximal end of channel  150  by a plurality of screws  160  positioned around the circumference of channel  150 . Screws  160  are disposed in a plurality of threaded bores  144  disposed around the circumference of a transition member  140 . Transition member  140  is internally interposed between gooseneck  130  and channel  150 . Channel  150  has a plurality of holes  152  positioned around the circumference of its proximal end. Each hole  152  is designed to receive screws  160 . Similarly, gooseneck  130  has a plurality of holes  136  configured to receive screws  160 . Holes  136  of gooseneck  130  are located around the circumference of the distal end of gooseneck  130 . Screws  160  attach gooseneck  130  to channel  150  through holes  152  of channel  150 , holes  136  of gooseneck  130  and threaded bores  144  of transition member  140 . To properly fix channel  150  to gooseneck  130 , holes  152  of channel  150 , threaded bores  144  of transition member  140 , and holes  136  of gooseneck  130  are substantially aligned with each other. 
     Transition member  140  has at least one hole  143  disposed therethrough for receiving steering wires  34 . Although  FIG. 3  shows holes  143  having a cylindrical shape, it is envisioned that holes  143  can have any suitable shape. Additionally, transition member  140  includes at least one longitudinal hole  142  extending therethrough for receiving flexible shafts  139 . In one embodiment, transition member  140  includes two holes  142  having a cylindrical shape. (See  FIG. 3 ). Holes  142 , however, can have any shape so long as they are adapted to receive flexible shafts  139 . 
     A distal end of each flexible shaft  139  is operatively secured to a pinion shaft  138 . Pinion shafts  138  are configured to rotate and, consequently, cause the rotation of pinions  154 . Each pinion  154  is attached to a distal end of a pinion shaft  138 . As seen in  FIG. 26 , pinions  154  include at least one tooth  154   a  or a plurality of teeth  154   a . Tooth or teeth  154   a  extends radially as well as longitudinally. The longitudinal portion of tooth or teeth  154   a  is adapted to axially engage with gear couplers  156 . 
     Returning to  FIG. 3 , each pinion  154  is configured to mesh with each other such that the rotation of a flexible shaft  139  rotates the other flexible shaft  139 . As discussed hereinabove, a gear  18  is operatively attached to the proximal end of each flexible shaft  139 . Gears  18  are configured to mesh with each other such that the rotation of one flexible shaft  139  rotates the other flexible shaft  139 . Thus, flexible shafts  139  are operatively connected to each other at their proximal and distal ends. Since flexible shafts  139  are operatively connected with each other, one flexible shaft  139  is redundant. Only one flexible shaft  139  is needed to operate surgical instrument  100 . If, for any reason, one flexible shaft  139  breaks, the other flexible shaft  139  can still actuate surgical instrument  100 . 
     As shown in  FIG. 26 , the longitudinal portion of tooth or teeth  154   a  of each pinion  154  is adapted to axially engage with gear couplers  156 . Gear couplers  156  have at least one longitudinal tooth or a plurality of teeth  156   a , and at least one radial tooth or a plurality of teeth  156   b . Longitudinal tooth or teeth  156   a  of gear couplers  156  extend proximally and are configured to axially engage with tooth or teeth  154   a  of pinions  154 . 
     Returning to  FIG. 3 , clamp pinions  162  have at least one radial tooth or teeth  162   a  for meshing with radial tooth or teeth  154  of pinions  154  and are permanently attached to the distal ends of short lead screws  158 . The longitudinal length of short lead screws  158  is less than the longitudinal length of lead screws  112 . Short lead screws  158  are axially trapped in transition member  140  and cartridge  110 . Surgical instrument  100  can optionally include bearings to axially trap short lead screws  158 . 
     In addition, surgical instrument  100  includes a link  122  positioned within a proximal end portion of channel  150 . Particularly, a first end  122   a  of link  122  is pivotably connected to the proximal end of an anvil  120  by a link pin  126 . A second end  122   b  of link  122  sits in a slot in cam clamp  164 . Optionally, at least one projection  122   c  can extend from second end  122   b  of link  122 . Projections  122   c  can pivotably fix link  122  to clamp cam  164 . 
     Clamp cam  164  is positioned within an inner proximal portion of channel  150  and includes at least one bore  164   a  for receiving pinion shafts  138 , at least one bore  164   b  for receiving at least one short lead screw  158 , and a slot  164   c  configured to receive at least a portion of anvil  120 , as seen in  FIG. 4 . At least a portion of each pinion shaft  138  is disposed in bores  164   a . Short lead screws  158  are threadedly engaged to threaded bores  164   b  of cam clamp  164 . The rotation of short lead screws  158  causes the translation of cam clamp  164  proximally or distally. During operation, as cam clamp  164  moves proximally, projections  122   c  slides along the inner diameter of channel  150 , link  122  becomes more vertical, raising proximal end of anvil  120  and causing the distal end of anvil  120  to drop and clamp tissue. Conversely, the distal motion of cam clamp  164  causes projections  122   c  to slide distally within channel  150 . As projections  122   c  move distally, the proximal end of anvil  120  descends, causing the distal end of anvil  120  to ascend and unclamp tissue. 
     With reference to  FIG. 5-7 , each gear coupler  156  is mounted to the proximal end of each lead screw  112 . Lead screws  112  are at least partially threaded and are at least partially disposed within cartridge  110 , as shown in  FIG. 5 . Cartridge  110  includes a tissue contacting surface  113  having at least one row of longitudinally spaced-apart retention slots  114 , a plurality of pushers  192 , a plurality of fasteners  190 , and a sled  116  slidably positioned therein. Retention slots  114  are adapted to receive fasteners  190 . Those skilled in the art will contemplate a cartridge  110  with any number of rows of retention slots  114 . For example, cartridge  110  may include two rows of retention slots  114 . In this embodiment, a knife can be placed between these two rows of retention slots  114 . Nonetheless, irrespective of the number rows of retention slots  114 , cartridge  110  can include a knife to cut tissue. The knife can be operatively attached to sled  116 . Additionally, the cartridge may include an electrical or mechanical interlock mechanism to prevent distal motion of sled  116  unless anvil  120  is in its closed position. 
     Sled  116  includes a cam member  116   b  and at least one threaded bore  116   a  adapted to receive lead screw  112 . Pushers  192  have a surface  192   a  that cooperates with and is complementary to cam member  116  of sled  116 . During operation of surgical instrument  100 , sled  116  translates through cartridge  110  to advance cam member  116   b  into sequential or simultaneous contact with pushers  192 , to cause pushers  192  to translate vertically within retention slots  114  and urge fasteners  190  from retention slots  114  into the staple deforming concavities  125   a  of an anvil  120 . The staple deforming cavities  120   a  are configured to crimp staples. 
     Anvil  120  includes a tissue contacting surface  125  having a plurality of staple deforming concavities  125   a . A single staple deforming concavity  125   a  can be adapted to cooperate with the legs of one fastener  190 . Alternatively, two or more staple deforming concavities  125   a  can cooperate with the legs of a single fastener  190 . 
     A pivot pin  128  pivotably secures anvil  120  to channel  150 . Channel  150  has at least one hole  150   a  designed to receive pivot pin  128 , as seen in  FIG. 2 . Pivot pin  180  rests on a support surface  164   d  of clamp cam  164 , as shown in  FIG. 6 . A proximal end portion  124  of anvil  120  is positioned within channel  150 . Link pin  126  pivotably attaches proximal end portion  124  of anvil  120  and link  122 . 
     As discussed hereinabove, channel  150  encompasses at least a portion of cartridge  110 . Optionally, screws  153  can connect channel  150  and cartridge  110  with each other, as seen in  FIG. 3 . In this embodiment, channel  150  includes at least one hole  151  configured to receive a screws  153 . 
     In operation, surgical instrument  100  applies fasteners  190  to tissue whilst, at the same time, eliminating or substantially limiting counter torque. During use, an operator must first make sure that the surgical instrument  100  is in its neutral position, as shown in  FIGS. 7 and 8 . When surgical instrument  100  is in its neutral position, anvil  120  and cartridge  110  are spaced apart from each other and pinions  154  are not meshed with clamp pinions  162 , as seen in  FIGS. 7-10 . Additionally, in the neutral position, sled  116  is disposed on a proximal portion of cartridge  110  (see  FIG. 7 ) and pinions  154  are not axially engaged with gear couplers  156  (see  FIGS. 11 and 12 ). It is also contemplated that the surgical instrument could be configured to eliminate the neutral position and simply operate in a sequential closure-fire-open mode. 
     After placing surgical instrument  100  in its neutral position, a user may approximate it to a tissue portion. To position surgical instrument  100  in the desired surgical site, an operator can endoluminally introduce surgical instrument  100  into the body through a body lumen. Alternatively, an operator can use surgical instrument  100  through or in combination with an endoscope to reach the desire location. The tissue portion should be located between anvil  120  and cartridge  110 . 
     A user can articulate surgical instrument  100  to position it on the desired location by moving steering wires  34 . As discussed hereinabove, an embodiment of the presently disclosed surgical instrument  100  includes a gooseneck  130  having two holes  141  each adapted to receive a steering wire  34 , as seen in  FIG. 13 . As seen in  FIG. 14 , gooseneck  130  is at least partially formed by a plurality of triangular shaped sections  130   a  that are spaced apart from each other. In addition, gooseneck  130  is made of a flexible material. Each steering wire  34  includes a knot  34   a  to secure gooseneck  130  and steering wires  34  at their respective distal ends. 
     In use, an operator can rotate articulation knob  32  counterclockwise, as indicated by arrow “CCW,” to translate proximally a steering wire  34 , as indicated by arrow “A.” In response to the proximal motion of steering wire  34 , surgical instrument  100  articulates in the direction indicated by arrow “B.” A user can also articulate surgical instrument  100  in the opposite direction by rotating articulation knob  32  clockwise. 
     Once the user places surgical instrument  100  in the desire surgical site, the user may move gearshift lever  16  proximally, as indicated by arrow “C,” to translate flexible shafts  139  proximally in the direction indicated by arrows “D,” as seen in  FIGS. 17 and 18 . The proximal motion of flexible shafts  139  consequently moves pinion  154  in the direction indicated by arrows “E” into a proximal position, as shown in  FIGS. 18 and 19 . When pinions  154  are located on the proximal position, radial teeth  154   a  of pinions  154  mesh with teeth  162   a  of clamp pinions  162 , as shown in  FIG. 19 . 
     After pinions  154  are placed in their proximal positions, a user can activate actuation apparatus  10  to rotate at least one flexible shaft  139 . In one embodiment, actuation apparatus  10  rotates one flexible shaft  139  clockwise and the other flexible shaft  139  counterclockwise. The rotation of flexible shafts  139  in opposite directions eliminates or substantially reduces counter torque in surgical instrument  100 . While flexible shafts  139  rotate, pinions  154  rotate in the direction indicated by arrows “F”, as seen in  FIG. 20 . Since at this point radial teeth  154   a  of pinions  154  are meshed with teeth  162   a  of clamp pinions  162 , as soon as pinions  154  rotate, clamp pinions  162  begin to rotate in the direction indicated by arrows “G,” as illustrated in  FIG. 20 . 
     With reference to  FIGS. 21-23 , when clamp pinions  162  rotate, cam clamp  164  translates proximally in the direction indicated by arrow “H.” As cam clamp  164  moves proximally, link  122  pivots in a counterclockwise direction “I” with respect to pivot pin  126 , raising proximal end of anvil  120 . While the proximal end of anvil  120  moves vertically, the distal end of anvil  120  descends in the direction indicated by arrow “J” and clamps tissue. 
     With reference to  FIG. 24-28 , after clamping tissue, the operator can move gearshift lever  16 , in the direction indicated by arrow “K,” to translate flexible shafts  139  distally as indicated by arrow “L.” When flexible shafts  139  are distally translated, teeth  154   a  of pinions  154  axially engage with longitudinal teeth  156   a  of gear couplers  156 , as seen in  FIG. 26 . Once pinions  154  and gear couplers  156  are axially engaged with each other, gear couplers  156  rotates in response to the rotation of at least one flexible shaft  139 . The rotation of gear couplers  156  causes the corresponding rotation of lead screws  112  in the direction indicated by arrows “M.” While lead screws  112  rotate, sled  116  translates distally through cartridge  110  in the direction indicated by arrows “N,” as depicted in  FIG. 27 . Sled  116  advances cam member  116   b  into sequential contact with pushers  192 , to cause pushers  192  to translate vertically within retention slots  114  and eject fasteners  190 . Pushers  192  displace fasteners  190  in the direction indicated by arrows “O” and towards the staple deforming concavities  125   a  of anvil  120 , as shown in  FIG. 28 . An electrical or mechanical interlocking mechanism may be provided to prevent firing unless anvil  120  is in the closed position. 
     After clamping and stapling a tissue portion, the user can reverse the input rotation using apparatus  10 . At this moment, at least one flexible shaft  139  rotates and causes the rotation of pinions  154 . When pinions  154  rotate, clamp pinions  162  begin to rotate. The reverse rotation of clamp pinions  162  causes the distal translation of clamp cam  164 . As clamp cam  164  moves distally, projections  122   c  of link  122  translate distally within channel  150 . When projections  122   c  move distally, the proximal end of anvil  120  descends, causing the distal end of anvil  120  to rise and unclamp the tissue portion, as shown in  FIG. 7 . The reversed input rotation can optionally rotate lead screws  112  and translate proximally sled  116  to its original retracted position. 
     It will be understood that various modifications can be made to the embodiments disclosed herein. For example, the surgical instrument may include staples, two-part fasteners or any other suitable fastening element. Further, the cartridge can have a more than one row of longitudinally spaced apart retention slots. Further still, the cartridge can have any suitable elongated member capable of translating the sled instead of lead screws. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.