Abstract:
A surgical instrument is disclosed. The instrument comprises a rotary motion generator, a trigger configured to actuate the rotary motion generator, and a shifting assembly. The shifting assembly comprises a first gear selectively drivable by the rotary motion generator, a second gear selectively drivable by the rotary motion generator, and a toggle configured to switch between the selective drivability of the first gear and the selective drivability of the second gear. The shifting assembly further comprises a biasing mechanism engaged with the toggle, wherein the biasing mechanism is configured to motivate and maintain an operative meshment between the rotary motion generator and one of the first gear and the second gear. The surgical instrument further comprises a rotatable shaft, an end effector comprising a first iaw and a second iaw, and a firing member moveable relative to the end effector during a firing motion.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application under 35 U.S.C. §1.20 of U.S. patent application Ser. No. 11/475,412, now U.S. Pat. No. 8,322,455, entitled MANUALLY DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT, filed on Jun. 27, 2006, the entire disclosure of which is hereby incorporated by reference herein. 
    
    
     BACKGROUND 
     The present invention generally concerns surgical instruments and, more particularly, surgical cutting and fastening instruments. The present invention may have application in conventional endoscopic and open surgical instrumentation as well as application in robotic-assisted surgery. 
     Surgical staplers have been used in the prior art to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil. 
     Over the years, a variety of improvements have been made to such instruments. For example, some surgical staplers have been manufactured with electrically powered or pneumatically powered drive mechanisms. Such staplers, while extremely effective and easy to use, can be cost prohibitive for some users. 
     Consequently there is a need for a surgical stapling device that is effective and easy to use, yet more economical than other powered surgical stapling devices. 
     SUMMARY 
     In one general aspect, the present invention is directed to a surgical instrument that comprises a handle assembly that supports a closure drive that is configured to generate a closing motion and an opening motion. A firing drive is supported by the handle assembly and is configured to selectively generate a rotary firing motion and a rotary retraction motion upon manual actuation of a firing trigger that is operably coupled to the handle assembly. An elongate shaft assembly is coupled to the handle assembly and communicates with the closure drive and the firing drive to separately transfer the closing motion and the rotary firing motion. Various embodiments of the surgical instrument further comprises an end effector that is coupled to the elongate shaft assembly. The end effector comprises an elongate channel that is sized to receive a staple cartridge therein. An anvil is pivotally coupled to the elongate channel. The anvil is pivotally responsive to the open and closing motions from the elongate shaft assembly. A cutting and severing member is operably supported within the elongate channel and is responsive to the rotary firing and retraction motions from the elongate shaft assembly. In various embodiments, the elongate channel may be fabricated from metal utilizing conventional progressive die stamping techniques. Likewise, the anvil may be stamped from a piece of metal to reduce manufacturing costs. 
     In another general aspect, the present invention is directed to a method for processing an instrument for surgery. The method may comprise obtaining a surgical instrument of the type describe above, sterilizing it and thereafter storing it in a sterile container. 
     In another general aspect, the present invention is directed to a surgical stapling and severing apparatus that comprises a handle assembly that movably supports a closure shuttle therein. A closure trigger is operably supported by the handle assembly and is operable to apply a closing and opening force to the closure shuttle. An elongate spine assembly that has a distal end and a proximal end is oriented such that the proximal end is supported by the closure shuttle and the distal end is coupled to an elongate channel configured to receive a staple cartridge therein. An anvil is pivotally coupled to the elongate channel. A closure tube assembly is supported on the elongate spine assembly and is coupled to the handle assembly. The closure tube assembly cooperates with the anvil such that upon application of the closure force to the closure shuttle, the spine assembly moves distally within the closure tube assembly causing the anvil to pivot to a closed position and whereupon application of the opening force to the closure shuttle, the spine assembly moves proximally within the closure tube assembly causing the anvil to pivot to an open position. A cutting and severing member is operably supported within the elongate channel and a shifter assembly is supported in the handle assembly. The shifter assembly is selectively movable between a firing orientation and a retraction orientation. The shifter assembly cooperates with a firing trigger such that upon actuation of the firing trigger when the shifter assembly is in the firing orientation, the shifter assembly applies a rotary firing motion to the cutting and severing member to drive the cutting and severing member distally through the elongate channel and such that upon another actuation of the firing trigger when the shifter assembly is in the retraction orientation, the shifter assembly applies a rotary refraction motion to the cutting and severing member to drive the cutting and severing member proximally through the elongate channel. 
    
    
     
       DRAWINGS 
       Various embodiments of the present invention are described herein by way of example in conjunction with the following Figures, wherein like numerals may be used to describe like parts and wherein: 
         FIG. 1  is a perspective view of an embodiment of a surgical cutting and fastening instrument of the present invention; 
         FIG. 2  is a cross-sectional side elevational view taken along the line  2 - 2  of  FIG. 1  of an end effector embodiment of the present invention; 
         FIG. 3  is an enlarged side elevational view of a portion of a knife bar of the end effector embodiment of  FIG. 2 ; 
         FIG. 4  is an enlarged front view of the knife bar of the end effector of  FIG. 3 ; 
         FIG. 5  is an isometric view of the end effector of  FIG. 2  at the distal end of the surgical cutting and fastening instrument of various embodiments of the present invention with the anvil in the open position; 
         FIG. 6  is an isometric exploded view of the end effector or implement portion and spine assembly of various embodiments of the present invention; 
         FIG. 7  is an isometric view of the end effector of  FIG. 2  with the anvil in the open position and the staple cartridge largely removed exposing a single staple driver and double staple driver and the wedge sled in its start position against a middle pin of the knife bar; 
         FIG. 8  is an isometric view of the end effector of  FIG. 2  with the anvil in the open position and the staple cartridge completely removed and a portion of the elongate channel removed to expose the lowermost pin of the knife bar; 
         FIG. 9  is a side elevational view in cross-section showing a mechanical relationship between the anvil, elongate channel, and staple cartridge in the closed position of the surgical cutting and fastening instrument of  FIG. 1 , the section generally taken along lines  9 - 9  in  FIG. 5  to expose the wedge sled, staple drivers, staples, but also depicting the knife bar along a longitudinal centerline; 
         FIG. 10  is an isometric exploded assembly view of a surgical cutting and fastening instrument embodiment of the present invention; 
         FIG. 11  is a side elevational view of the surgical cutting and fastening instrument of the present invention with the anvil in the open position and the handle assembly shown in cross-section to illustrate the positions of the various components housed therein; 
         FIG. 12  is a side elevational view of the surgical cutting and fastening instrument of the present invention with the anvil in the closed position and the handle assembly shown in cross-section to illustrate the positions of the various components housed therein; 
         FIG. 13  is an isometric exploded assembly view of a planetary gear assembly embodiment of the present invention; 
         FIG. 14  is an end view of the planetary gear assembly of  FIG. 13  with the cover plate removed therefrom; 
         FIG. 15  is an isometric exploded assembly view of a shifter assembly embodiment of the present invention; 
         FIG. 16  is a cross-sectional view of a handle assembly embodiment of the present invention in a starting position wherein the anvil is in the open position; 
         FIG. 17  is another cross-sectional view of a handle assembly embodiment of the present invention with the closure trigger locked in the closed or clamped position resulting in the anvil being locked in the clamped or closed position; 
         FIG. 18  is another cross-sectional view of a handle assembly of the present invention illustrating movement of the closure trigger to a position wherein it is unlocked from the handle portion; 
         FIG. 19  is another cross-sectional view of a handle assembly of the present invention illustrating the movement of the closure trigger to the fully actuated position; and 
         FIG. 20  is an isometric view of an alternative anvil embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Turning to the Drawings wherein like numerals denote like components throughout the several views,  FIG. 1  depicts a surgical stapling and severing instrument  10  that is capable of practicing several unique benefits of the present invention. The surgical stapling and severing instrument  10  incorporates an end effector  12  that is manually actuated by manipulation of control members on a handle assembly  200  to which it is attached. A variety of different end effector constructions are known. One type of end effector  12  that may be employed with various embodiments of the present invention is depicted in  FIGS. 1, 2, and 5-9 . As can be seen in some of those Figures, the end effector  12  employs an E-beam firing mechanism (“knife bar”)  30  that advantageously controls the spacing of the end effector  12 . Various aspects of E-beam firing mechanisms are described in U.S. Pat. No. 6,978,921, entitled Surgical Stapling Instrument Incorporating an E-Beam Firing Mechanism to Shelton, IV et al., the relevant portions of which are herein incorporated by reference. As the present Detailed Description proceeds, however, those of ordinary skill in the art will appreciate that other knife and firing bar configurations may be advantageously employed without departing form the spirit and scope of the present invention. 
     It will further be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping a handle of an instrument. Thus, the end effector  12  is distal with respect to the more proximal handle assembly  200 . It will also be understood that for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute. 
     As can be seen in  FIGS. 2, 6, and 7 , the end effector  12  includes an elongate channel  20  that has a pivotally translatable anvil  40  attached thereto. In one embodiment, the channel  20  may be fabricated from metal utilizing conventional progressive die techniques and may be provided with corresponding openings for receiving the knife bar  30  therein. Such manufacturing methods may result in manufacturing costs that are lower than those conventional methods that are otherwise commonly employed to manufacture the elongate channels. 
     The elongate channel  20  is configured to receive and support a staple cartridge  50  that is responsive to the knife bar  30  to drive staples  70  into forming contact with the anvil  40 . It will be appreciated that, although a readily replaceable staple cartridge is advantageously described herein, a staple cartridge consistent with aspects of the present invention may be permanently affixed or integral to the elongate channel  20 . 
     With particular reference to  FIGS. 2-4 , in various embodiments, the knife bar  30  includes three vertically spaced pins that control the spacing of the end effector  12  during firing. In particular, an upper pin  32  is staged to enter an anvil pocket  42  near the pivot between the anvil  40  and elongate channel  20 . When fired with the anvil  40  closed, the upper pin  32  advances distally within a longitudinal anvil slot  44  extending distally through anvil  40 . Any minor upward deflection in the anvil  40  is overcome by a downward force imparted by the upper pin  32 . 
     Knife bar  30  also includes a lower most pin  34 , or knife bar cap, that upwardly engages a channel slot  23  formed in the elongate channel  20 , thereby cooperating with the upper pin  32  to draw the anvil  40  and the elongate channel  20  slightly closer together in the event of excess tissue clamped therebetween. In various embodiments, the knife bar  30  may advantageously include a middle pin  36  that passes through a firing drive slot  52  formed in a lower surface of the cartridge  50  and an upward surface of the elongate channel  20 , thereby driving the staples  70  therein as described below. The middle pin  36 , by sliding against the elongate channel  20 , advantageously resists any tendency for the end effector  12  to be pinched shut at its distal end. However, the unique and novel aspects of various embodiments of the present invention may be attained through use of other knife bar arrangements. 
     Returning to  FIGS. 2-4 , a distally presented cutting edge  38  between the upper and middle pins  32 ,  36  on the knife bar  30  traverses through a proximally presented, vertical slot  54  in the cartridge  50  to sever clamped tissue. The affirmative positioning of the knife bar  30  with regard to the elongate channel  20  and anvil  40  assure that an effective cut is performed. 
     The end effector  12  of the surgical stapling and severing instrument is depicted in further detail in  FIGS. 5-10 . As will be described in further detail below, manipulation of various control members on the handle assembly  200  produces separate and distinct closing and firing motions that actuate the end effector  12 . The end effector  12  advantageously maintains the clinical flexibility of this separate and distinct closing and firing (i.e., stapling and severing). 
       FIG. 5  depicts the end effector  12 , which is in an open position by a refracted spine assembly  100  ( FIG. 6 ), with a staple cartridge  50  installed in the elongate channel  20 . On a lower surface  41  of the anvil  40 , a plurality of stapling forming pockets  46  are arrayed to correspond to a plurality of staple apertures  58  in an upper surface  56  of the staple cartridge  50 . The knife bar  30  is at its proximal position, with the upper pin  32  aligned in a non-interfering fashion with the anvil pocket  42 . The anvil pocket  42  is shown as communicating with the longitudinal anvil slot  44  in the anvil  40 . The distally presented cutting edge  38  of the knife bar  30  is aligned with and proximally removed from the vertical slot  54  in the staple cartridge  50 , thereby allowing removal of a spent cartridge  50  and insertion of an unfired cartridge  50 , which is snapfit into the elongate channel  20 . Specifically, extension features  60 ,  62  of the staple cartridge  50  engage recesses  24 ,  26 , respectively (shown in  FIG. 7 ) of the elongate channel  20 . 
       FIG. 6  shows an embodiment of an implement portion  12  of the surgical stapling and severing instrument  10  in disassembled form. The staple cartridge  50  is shown as being comprised of a cartridge body  51 , a wedge sled  64 , single and double drivers  66 , staples  70 , and a cartridge tray  68 . When assembled, the cartridge tray  68  holds the wedge sled  64 , single and double drivers  66 , and staples  70  inside the cartridge body  51 . 
     The elongate channel  20  is coupled to the handle assembly  200  by means of a spine assembly  100  that includes a distal spine section  110  and a proximal spine section  130 . The elongate channel  20  has proximally placed attachment cavities  22  that each receive a corresponding channel anchoring member  114  formed on the distal end  112  of the distal spine section  110 . The elongate channel  20  also has anvil cam slots  28  that pivotally receive a corresponding anvil pivot  43  on the anvil  40 . A closure sleeve assembly  170  is received over the spine assembly  100  and includes distal closure tube segment  180  and a proximal closure tube segment  190 . See  FIG. 6 . The distal closure tube segment  180  includes a distally presented tab  182  that engages an anvil closure tab  48  proximate but distal to the anvil pivots  43  on the anvil  40  to thereby effect opening and closing of the anvil  40  by axially moving the spine assembly  100  within the closure tube assembly  170  as will be discussed in further detail below. 
     With particular reference to  FIG. 7 , a portion of the staple cartridge  50  is removed to expose portions of the elongate channel  20 , such as recesses  24 ,  26  and to expose some components of the staple cartridge  50  in their unfired position. In particular, the cartridge body  51  (shown in  FIG. 6 ) has been removed. The wedge sled  64  is shown at its proximal, unfired position with a pusher block  65  contacting the middle pin  36  (not shown in  FIG. 7 ) of the knife bar  30 . The wedge sled  64  is in longitudinal sliding contact upon the cartridge tray  68  and includes wedges  69  that force upward the single and double drivers  66  as the wedge sled  64  moves distally. Staples  70  (not shown in  FIG. 7 ) resting upon the drivers  66  are also forced upward into contact with the staple forming pockets  42  on the anvil  40  to form closed staples. Also depicted is the channel slot  21  in the elongate channel  20  that is aligned with the vertical slot  54  in the staple cartridge  50 . 
       FIG. 8  depicts the end effector  12  of  FIG. 7  with all of the staple cartridge  50  removed to show the middle pin  36  of the knife bar  30  as well as portion of the elongate channel  20  removed adjacent to the channel slot  21  to expose the lower pin or knife bar cap  34 . Projecting downward from the anvil  40  near the pivot, a pair of opposing tissue stops  45  prevent tissue from being positioned too far up into the end effector  12  during clamping. 
     In other embodiments of the present invention, the anvil employed may comprise an anvil  40 ′ that is stamped or otherwise formed out of metal or other suitable material as illustrated in  FIG. 20  to reduce manufacturing costs. As can be seen in that Figure, the anvil  40 ′ may be provided with a slot  44 ′ for accommodating movement of a firing bar therethrough and also be formed with anvil pivots  43 ′ and a closure tab (not shown) to facilitate its operation in the manner described above with respect to anvil  40 . In this embodiment, the lower surface  41 ′ of the anvil is not provided with staple forming pockets. The staples simply close as they come into contact with the hard lower surface  41 ′. Also, the embodiment depicted in  FIG. 20  is formed with tissue stops  45 ′. Those of ordinary skill in the art will understand, however, that the anvil  40 ′ may be formed with or without staple forming pockets and tissue stops if so desired. In addition, other variations of stamped anvils may be employed without departing from the spirit and scope of the present invention. 
       FIG. 9  depicts the end effector  12  closed in a tissue clamping position with the knife bar  30  unfired. The upper pin  32  is in the anvil pocket  42 , vertically aligned with the anvil slot  44  for distal longitudinal movement of the knife bar  30  during firing. The middle pin  36  is positioned to push the wedge sled  64  distally so that wedges  69  sequentially contact and lift double drivers  66  and the respective staples  70  into forming contact with staple forming pockets  42  in the lower surface  41  of the anvil  40 . 
     As indicated above, the channel  20  is coupled to the handle assembly  200  by a spine assembly  100  that, in various embodiments, consists of a distal spine section  110  and a proximal spine section  130 . As can be seen in  FIG. 6 , the distal spine section  110  has a distal end  114  that is attached to the elongate channel  20  and a proximal end  116  that is attached to a distal end  132  of the proximal spine section  130 . The knife bar  30  is slidably received in a distal slot  118  in the distal end of the distal spine segment  110 . A proximal end  31  of the knife bar  30  has an upstanding connector tab  33  formed thereon that is adapted to be received in a slot  162  in a connector block  160 . The connector block  160  is attached to a firing rod  210  that is slidably supported within the proximal spine section  130 . The connector block  160  is sized to be slidably received within a proximal slot  120  in the distal spine section  110 . 
     The firing rod  210  may be fabricated from a polymer or other suitable material and be configured with a hollow shaft portion  212  that is sized to permit it to axially travel within the proximal slot  120  in the distal spine section  110 . The firing rod  210  further has a proximal connector portion  220  that is sized to axially travel within an axial passage in the proximal spine section  130  as will be discussed in further detail below. The connector block  160  has a connector tab  164  protruding therefrom that is sized to be frictionally inserted into the tapered end  214  of the hollow shaft portion  212  of the firing rod  210 . The tapered end  214  may have a series of slits  216  provided around its circumference to enable the protruding connector tab  164  on the connector block  160  to be inserted into the tapered end  214  and be frictionally attached thereto. 
     As can also be seen in  FIG. 6 , the proximal spine section  130  may be fabricated in two pieces to facilitate easy installation of the firing rod  210  therein and attachment to the distal spine section  110 . More specifically, the proximal spine section  130  may comprise a right proximal spine segment  140  and a left proximal spine segment  150 . The right proximal spine segment  140  has a right axial passage portion  146  that cooperates with a left axial passage portion  156  in the left proximal spine segment  150  to form an axial passage  132  in the proximal spine section  130  that is sized to axially and movably support the connector portion  220  of the firing rod  210  therein. In addition, the distal end  142  of the right spine segment  140  has a groove  144  therein that cooperates with a groove  154  in the distal end  152  of the left spine segment  150  to form an annular retention groove (not shown) in the proximal spine segment  130  for rotatably receiving a connection tab  124  protruding from the distal end  132  of the proximal spine section  130 . Such arrangement permits the distal spine section  110  to be rotated relative to the proximal spine section  130 . See arrow “A” in  FIG. 6 . 
     In various embodiments, the firing rod  210  is axially movable within the proximal spine section  130  by a firing screw  240 , the operation of which will be discussed in further detail below. The firing screw  240  is coupled to the firing rod  210  by a bifurcated firing nut  244  that comprises nut segments  246  and  248 . Nut segment  246  has an upstanding tab  247  protruding therefrom that is sized to protrude through a slot  222  in the connection portion  220  of the firing rod  210 . Likewise, the nut segment  248  has an upstanding tab  249  that is sized to protrude through a slot (not shown) in the connection portion  220  of the firing rod  210 . The portion of the tabs  247 ,  249  that protrude outward from the connection portion  220  are received in axial slots formed in the proximal spine segments  140 ,  150 . Such tabs  247 ,  249  and slots, serve to facilitate axial travel of the firing rod  210  within the proximal spine segment  140  without permitting rotation of the firing rod  210  relative to the proximal spine segment  130 . 
     Journaled on the spine assembly  100  is the closure tube assembly  170 . See  FIG. 6 . The closure tube assembly  170  comprises a distal closure tube segment  180  and a proximal closure tube segment  190 . The distal closure tube segment  180  and the proximal closure tube segment  190  may be fabricated from a polymer or other suitable material. The proximal closure tube segment  190  is hollow having an axial passage  192  extending therethrough that is sized to receive the spine assembly  100  therein. An axially extending slit  193  may be provided in the proximal closure tube  190  to facilitate easy installation of the spine assembly  100  therein. The distal end  194  of the proximal closure tube segment  190  may be provided with an extension  196  over which the proximal end  184  of the hollow distal closure tube segment  180  is inserted. The two closure tube segments  180 ,  190  may then be attached together with an appropriate adhesive material. The proximal end  196  of the proximal closure tube segment may be provided with a flange  197 , the purpose of which will be discussed below. 
       FIG. 10  illustrates an exploded view of the handle assembly  200  and the components housed therein of various embodiments of the present invention for controlling the movement of the spine assembly  100  and the knife bar  30 . As can be seen in that Figure, the handle assembly  200  comprises a pistol grip-type housing  250  that is fabricated in two pieces. For example, the housing  250  may comprise a right hand case member  260  and a left hand case member  280  that are molded or otherwise fabricated from a polymer material and are designed to mate together. Such case members  260  and  280  may be attached together by snap features, pegs and sockets molded or otherwise formed therein and/or by adhesive, screws, etc. 
     Supported within the housing  250  is a closure shuttle  300  that is coupled to a closure trigger  320  by a linkage assembly  330 . Closure shuttle  300  may be configured as shown in  FIG. 10  with a distal cradle portion  310  and a proximal cradle portion  314 . The distal cradle portion  310  is configured to cradle the proximal end  136  of the proximal spine segment  130  therein. A base flange  138  is formed on the proximal end  136  of the proximal spine segment  130  and is received within a slot  312  in the closure shuttle  300 . The base flange  138  is formed by a right side flange segment  149  formed on the proximal end  145  of the right proximal spine segment  140  and a left side flange segment  159  formed on the proximal end  154  of the left proximal spine segment  150 . See  FIG. 6 . 
     As can be seen in  FIG. 10 , the closure shuttle  300  is provided with laterally extending rails  302  that are configured to be slidably received within rail guides  262  and  282  in the right hand case member  260  and left hand case member  280 , respectively. Such arrangement permits the closure shuttle  300  to move axially in a distal direction (arrow “B”) and a proximal direction (arrow “C”) within the handle housing  250 . Axial movement of the closure shuttle  300  (and the spine assembly  100 ) in the distal direction is created by moving the closure trigger  320  toward the pistol grip portion  252  of the handle housing  250  and axial movement of the closure shuttle  300  in the proximal direction (arrow “C”) is created by moving the closure trigger  320  away from the pistol grip portion  252 . 
     In various embodiments, the closure shuttle  300  is provided with a connector tab  304  that facilitates the attachment of the closure linkage assembly  330  thereto. See  FIGS. 10-12 . The closure linkage assembly  330  includes a closure arm  340  and a closure link  350 . The closure arm  340  is pivotally pinned within the housing  250  by a closure pin  344  that extends through a first pivot hole  342  in the closure arm  340 . The ends of the closure pin  344  are received in sockets  264  formed in the right hand case member  260  and left hand case member  280 . Such arrangement permits the closure arm  340  to pivot about a first closure axis  346 . See  FIG. 10 . The distal end  341  of the closure arm  340  is pinned to a proximal end  351  of the closure link  350  such that the proximal end  351  of the closure link  350  can pivot relative to the distal end  341  of the closure arm  340  about a proximal pivot axis  355 . Likewise, the distal end  352  of the closure link  350  is pinned to the connection tab  304  on the closure shuttle  300  such that the distal end  355  can pivot relative to the connection tab  304  about a distal pivot axis  357 . See  FIG. 11 . 
       FIG. 11  illustrates the end effector  12  in an open (unclamped) position. As can be seen in that Figure, the closure trigger  320  is pivoted away from the pistol grip portion  252  and the closure shuttle  300  is in its proximal position. When the closure shuttle  300  is in the proximal position, it draws the spine assembly  100  in the proximal “C” direction within the closure tube assembly  170 . Such axial movement of the spine assembly  100  within the closure tube assembly  170  causes the closure tab  48  on the anvil to engage tab  182  on the distal closure tube segment  180  in such a manner as to cause the anvil  40  to pivot to the open position. 
     When the clinician desires to close the anvil  40  and to clamp tissue within the end effector  12 , the clinician draws the closure trigger  320  toward the pistol grip  252  as shown in  FIG. 12 . As the clinician draws the closure trigger  320  toward the pistol grip  252 , the closure linkage assembly  330  moves the closure shuttle  300  in the distal “B” direction until the closure linkage assembly  330  moves into the locked position illustrated in  FIG. 12 . When in that position, the linkage assembly  330  will tend to retain the closure shuttle  300  in that locked position. As the closure shuttle  300  is moved to the locked position, the spine assembly  100  is moved proximally within the closure tube assembly  170  causing the closure tab  48  on the anvil to contact the tab  182  on the distal closure tube segment  180  to thereby pivot the anvil  40  to the closed (clamped) position. 
     In various embodiments, to further retain the closure shuttle  300  in the closed position, the closure trigger  320  may be provided with a releasable locking mechanism that is adapted to engage the pistol grip  252  and releasably retain the closure trigger in the locked position. Other locking devices may also be used to releasably retain the closure shuttle  300  in the locked position. In the embodiment depicted in  FIGS. 11 and 12 , a lock member  322  in the form of a piece of spring steel or other flexible material is attached to the closure trigger  320 . The free end of the lock member  322  is situated to enter into a retention pocket  254  in the pistol grip portion  252  of the handle  250 . The lock member  322  frictionally engages the retention pocket  254  and retains the closure trigger  320  in the closed position. 
     To release the closure trigger  320  and thereby permit it to be pivoted to the open position, the clinician simply draws the closure trigger  320  further inward toward the pistol grip portion  252  as shown in  FIG. 18 . As the lock member  322  is moved further into the retention pocket  254 , the end of the lock member  322  contacts a sloped surface  258  in the rear of the retention pocket  254  which causes the lock member  322  to flex a sufficient amount to permit it to release from the retention pocket  254  thereby permitting the closure trigger  320  to move away from the pistol grip  252  ( FIG. 16 ). Other releasable locking arrangements could also be employed. 
     As indicated above, the advancement and retraction of the knife bar  30  is controlled by the firing rod  210  and rotary driven firing screw  240 . The firing screw  240  has a splined proximal end  242  that is configured to be coupled to a planetary gear assembly  400  that is supported in the proximal cradle portion  314  of the closure shuttle  300 . One embodiment of a planetary gear assembly  400  is depicted in  FIGS. 13 and 14 . As can be seen in those Figures, the planetary gear assembly  400  includes a planetary case  410  that has a ring gear  412  formed therein. The planetary case  410  supports a first stage gear assembly  420  that has a 3:1 ratio and a second stage gear assembly that has a 3:1 ratio. 
     The first stage gear assembly  420  includes a first sun gear  422  that is keyed onto an input shaft  414  with a key  416 . The input shaft  414  protrudes through a coverplate  418  that mates with the planetary gear case  410  and serves to seal the first stage gear assembly  420  and second stage gear assembly  440  therein. In various embodiments, the first stage gear assembly  420  comprises three first planetary gears  424 ,  426 ,  428  that are journaled on corresponding planetary spindles  425 ,  427 ,  429 , respectively that are attached to a first planetary plate  430 . The first planetary gears  424 ,  426 ,  428  are in meshing engagement with the first sun gear  422  and the ring gear  412  in the planetary gear case  410 . As can be seen in  FIG. 13 , a first output shaft  432  is attached to the first planetary plate  430  with a key  434 . 
     The second stage gear assembly  440  includes a second sun gear  442  that is also keyed to the first output shaft  432  by key  434 . Three second planetary gears  444 ,  446 ,  448  are in meshing engagement with the second sun gear  442  and the ring gear  412 . The second planetary gears  444 ,  446 ,  448  are journaled on three corresponding second planetary spindles  445 ,  447 ,  449  that are attached to a second planetary plate  450 . A second output shaft  460  is keyed to the second planetary plate  450  by key  462 . The second output shaft  460  has an elongate shaft portion  464  that extends through a thrust bearing assembly  470 . As can be seen in  FIG. 13 , the thrust bearing assembly  470  includes a bearing cage  472  that support a plurality of bearings  474 . The bearing cage  472  and bearings  474  are located between first and second thrust washers  476  and  478 . The elongate shaft portion  464  protrudes through a distal end of the planetary case  410  and is attached to a shaft coupler  480  with a pin or a set screw  482 . The shaft coupler  480  is internally splined and adapted to receive therein a splined proximal end  242  of the firing screw  240 . 
     As was indicated above, the movement of the knife bar  30  in the distal direction (“B”) is ultimately controlled by the rotation of the firing screw  240  which drives the firing rod  210  and ultimately the knife bar  30 . Thus, by rotating the firing screw  240  in the clockwise direction (arrow “D” in  FIG. 13 ) the firing bar  210  is advanced distally (“B”). The rotation of the firing screw  240  is ultimately controlled by a unique and novel shifter assembly  500 . As will be discussed in further detail below, the shifter assembly  500  transmits rotational power to the planetary gear set  400  and ultimately to the firing screw  240 . 
     In various embodiments, the shifter assembly  500  includes a shifter case  510  that is supported in the housing  250 . As can be seen in  FIG. 15 , the shifter case  510  includes a left hand support arm  520  and a right hand support arm  540  that are separated by a central support member  530 . A left hand pinion gear  550  is rotatably supported in a hole  522  in the left hand support arm  520 . A right hand pinion gear  560  is similarly rotatably supported within a hole  542  in the right hand support arm  540 . A central bevel gear  570  is rotatably supported in a hole  532  in the central support member  530  and is centrally disposed between the right hand pinion gear  560  and left hand pinion gear  550  and is in meshing engagement therewith such that rotation of the central bevel gear causes the right hand pinion gear  560  to rotate in the clockwise “D” direction and the left hand pinion gear  550  to rotate in a counterclockwise “E” direction. 
     As can be seen in  FIG. 15 , a ratchet disc  580  is keyed to the central bevel gear  570  with a key  572 . Thus, when the ratchet disc  580  is rotated, it causes the central bevel gear  570  to rotate with it. In various embodiments, the shifter assembly  500  further includes a drive disc  590  that has a series of drive springs  594  protruding therefrom around its circumference. The drive springs  594  may be fabricated from spring steel or similar material and each have an attachment stem portion  595  that is inserted into corresponds slots  592  in the drive disc  590 . The drive springs  594  may be retained within the corresponding slots  592  by virtue of a friction fit or appropriate adhesive may also be used. The ends  596  of the drive springs  594  protrude out from the drive disc  590  to engage tooth-like ratchet grooves  582  formed into the ratchet disc  580 . Thus, when the drive disc  590  is rotated in the direction represented by arrow “F” in  FIG. 15 , the ends  596  of the drive springs  594  engage the corresponding tooth-like ratchet grooves  582  in the ratchet disc  580  and cause the ratchet disc  580  and central bevel gear  570  to rotate in the “F” direction. However, when the drive disc  590  is rotated in the opposite direction represented by arrow “G” in  FIG. 15 , the drive springs  594  simply ratchet or slip over the tooth-like ratchet grooves  582  in the ratchet disc  580  and do not transmit rotation to the ratchet disc  580  and central bevel gear  570 . In addition, a drive gear  600  is keyed onto a case spindle  604  that is rotatably supported in a spindle socket  266  provided in the right hand case member  260  by a key  602 . See  FIGS. 10 and 15 . 
     The drive gear  600  is adapted to be drivingly engaged by a firing gear segment  620  formed on an upper end portion  612  of firing trigger  610 . More specifically and with reference to  FIG. 10 , a firing trigger  610  is rotatably supported on a firing post  268  that protrudes from the right hand case member  260  and is received in a corresponding socket (not shown) in the left hand case member  280 . The firing post  268  extends through a hole  614  in the upper end of the firing trigger  610  such that the firing trigger  610  can be freely pivoted thereon. The firing trigger  610  may be fabricated from a polymer material and have a segment of gear teeth  620  formed on the upper end  612  of the firing trigger  610  as shown. The gear teeth  622  are adapted to selectively mesh with the teeth  602  of the drive gear  600 . As can be seen in  FIGS. 16-19 . the upper end portion  612  of the firing handle  610  has an arcuate shape. The gear segment  620  is formed on the proximal portion  613  of the upper end portion  612  and a stop member  626  is formed on the distal portion  614  of the upper end portion  612 . 
       FIG. 16  illustrates the firing trigger  610  in the neutral (unfired) position. As can be seen in that Figure, when in that position, the gear teeth  602  of the drive gear  600  that are adjacent the upper end  612  of the firing trigger  610  are not in meshing engagement with the gear segment  620  on the upper end  612  of the firing trigger  610 . A firing handle return spring  630  extends between a post  284  on the left hand case member  280  and a post  617  on the upper end  612  of the firing trigger  610 . The spring  630  serves to pull the firing trigger  610  into the position shown in  FIG. 16 . The gear teeth  602  on the drive gear  600  contact the stop member  626  formed on the upper end  612  of the firing trigger  610  to retain the firing trigger  610  in that position and to prevent the firing trigger  610  from rotating in the “G” direction beyond that position. Those of ordinary skill in the art will appreciate that when the clinician draws the firing trigger  610  toward the pistol grip  252  (direction “H”), the gear segment  620  begins to mesh with the gear teeth  602  on the drive gear  600  ( FIG. 17 ) and causes the drive gear  600  to rotate in the direction “I”. Once the clinician reaches the end of the stroke, the firing trigger  610  is released and the return spring  630  causes the firing trigger  610  to move to the unfired position depicted in  FIG. 16 . 
     The rotational direction of the firing screw  240  is controlled by a shifter gear  650  located in the shifter assembly  500 . As can be seen in  FIG. 15 , the shifter gear  650  is centrally disposed between the right hand bevel gear  560  and the left hand bevel gear  550  and is movable by a shift arm yoke  660  into engagement with those gears  550 ,  560 . More specifically, the shifter gear  650  has a proximal set of gear teeth  652  formed thereon for selective meshing engagement with the right hand pinion gear  560 . In addition, the shifter gear  650  has a distal set of gear teeth  654  formed thereon for selective meshing engagement with the left hand pinion gear  550 . 
     In various embodiments, a shifter shaft  680  is coupled to the first input shaft  414  of the planetary gear set  400  and the shifter gear  650 . In particular, the shifter shaft  680  has a distal end  682  that is attached to a first coupler  684  by a set screw, adhesive, welding, etc. which is in turn attached to the first input shaft  414  by a set screw, adhesive, welding, etc. The shifter shaft  680  has a splined portion  686  that extends through a hole  552  in the left hand pinion gear  550 . The left hand pinion gear  550  does not engage the splined portion  686  of the shifter shaft  680  and can freely rotate in either direction relative thereto. The splined section  686  of the shifter shaft  686  also may extend into a hole  562  in the right hand pinion  560 . However, the right hand pinion  560  does not engage the splined section and can freely rotate relative thereto. The splined section  686  of the shifter shaft  680  extends into a splined hole  655  in the shifter gear  650  such that the shifter gear  650  can move axially on the splined section (arrows “J”), but transmits rotation to the shifter shaft  680  by means of the splined interconnection therebetween. 
     As can be seen in  FIG. 15 , a yoke groove  656  is formed around the circumference of the shifter gear  650 . The yoke  660  includes two opposing yoke arms  662  that each have an inwardly extending pin  664  thereon that is received in the yoke groove  656 . Such arrangement permits the shifter gear  650  to rotate relative to the yoke  660 . However, the yoke  660  may be used to move the shifter gear  650  axially on the splined section  686  of the shifter shaft  680  between the left hand pinion gear  550  and the right hand pinion gear  560 . The shifter assembly  500  has a top member  514  that is attached to the shifter case  510  by adhesive or other suitable fastener means. A shifter arm  667  protrudes from the yoke portion  660  and extends through an opening  513  the top member  514  and is pivotally pinned thereto by a shift arm pin  517 . A shifter button  519  is attached to the top end of the shifter arm  667  by adhesive, etc. 
     In various embodiments, a shifter spring  700  is pinned or otherwise attached to the top of the shifter arm  667  and pinned or other wise attached to the left hand case member  280  such that the shifter spring  700  serves to pull the shifter arm  667  into the position shown in  FIG. 12  to thereby cause the proximal gear teeth  652  on the shifter gear  650  to mesh with the gear teeth  564  on the right hand pinion gear  560 . When in that position, the clinician can trigger the knife bar  30  by ratcheting the firing trigger  610  as will be discussed below. 
     In use, the surgical stapling and severing instrument  10  is used as depicted in  FIGS. 1, 11, 12 and 16-19 . In  FIGS. 11 and 16 , the instrument  10  is in its start position, having had an unfired, fully loaded staple cartridge  50  snap-fitted into the distal end of the elongate channel  20 . Both triggers  320 ,  610  are forward and the end effector  12  is open, such as would be typical after inserting the end effector  12  through a trocar or other opening into a body cavity. The instrument  10  is then manipulated by the clinician such that tissue to be stapled and severed is positioned between the staple cartridge  50  and the anvil  40 . 
     With reference to  FIGS. 12 and 17 , next, the clinician moves the closure trigger  320  proximally until positioned directly adjacent to the pistol grip  252  such that the retention member  256  frictionally engages the retention pocket  252  in the housing  250  locking the closure trigger  320  in the closed and clamped position. When in that position, the closure linkage  330  also serves to retain the closure trigger  320  in that position as shown in  FIG. 12 . The retracted knife bar  30  in the end effector  12  does not impede the selective opening and closing of the end effector  12 , but rather resides within the anvil pocket  42 . With the anvil  40  closed and clamped, the E-beam knife bar  30  is aligned for firing through the end effector  12 . In particular, the upper pin  32  is aligned with the anvil slot  44  and the elongate channel  20  is affirmatively engaged about the channel slot  21  by the middle pin  36  and the firing bar cap  34 . 
     With reference to  FIGS. 16-19 , after tissue clamping has occurred, the clinician moves the firing trigger  610  proximally towards the pistol grip portion  252 . Such action cases the gear segment  620  on the upper end  612  of the firing trigger to engage and rotate the drive gear  600  in the “I” direction. Rotation of the drive gear  600  in the “I” direction causes the drive disc  590  to also rotate in that direction. As the drive disc  590  rotates in that direction, the drive springs  594  engage the ratchet teeth  582  on the ratchet disk  580  and cause the ratchet disc  580  to also rotate in the “I” direction. The central bevel gear  570  also rotates with the ratchet disc  580  because it is keyed thereto. As the central bevel gear  570  rotates, it also causes the left hand pinion gear  550  to rotate in the “E” direction and the right hand pinion gear  560  to rotate in the “D” direction. See  FIG. 15 . 
     When the shifter gear  650  is brought into meshing engagement with the right hand pinion gear  560  as shown in  FIGS. 11 and 12 , movement of the central bevel gear  570  causes the right hand pinion gear  560  and shifter gear  650  to rotate in the “D” direction. Because of the splined connection between the shifter shaft  680  and the shifter gear  650 , the shifter shaft  680  is also caused to rotate in the “D” direction. Such rotary drive motion is transferred to the firing screw  240  through the planetary gear assembly  400 . As the firing screw  240  rotates in the “D” direction, the firing bar  210  is driven distally which causes the connection block  160  and knife bar  30  to move proximally. The clinician continues to ratchet the firing trigger  610  until the knife bar  30  is returned to the unfired position. 
     When the clinician has moved the firing trigger  610  to the proximal position adjacent the closure trigger  320 , the clinician can release the firing trigger  610  and the return spring  630  will return the firing trigger  610  to the unfired position ( FIG. 16 ). As the firing trigger  610  is returned to the unfired position, the gear segment  620  thereon will impart a rotation in the “H” direction to the drive gear  600 . The drive gear  600  also causes the drive disc  590  to rotate in the direction “H”. However, the drive springs  594  ratchet over the ratchet teeth  582  in the ratchet disc  580  and thus the rotational motion is not transmitted thereto. The clinician continues to ratchet the firing trigger  610  until the knife bar  30  can no longer be advanced distally through the cartridge  50 . 
     The clinician can then return the knife bar  30  to the unfired position, by moving the shifter button  519  in the distal direction to cause the shifter gear  650  to disengage the right hand pinion gear  560  and mesh with the left hand pinion gear  550 . Thereafter, the clinician simply ratchets the firing trigger  610  in the same manner which causes the left hand pinion gear  550  to rotate in the “E” direction. Such rotational motion is transmitted to the shifter shaft  680  and to the firing screw  240  through the planetary gear assembly  400 . As the firing screw  240  rotates in the “E” direction, the nuts  247  draw the firing bar  210  proximally. The firing bar  210  then draws the connector block  160  and knife bar  30  proximally until the knife bar  30  reaches the unfired position wherein the spent cartridge  50  may be removed from the elongate channel  20  and replaced with a new unfired cartridge or, in the alternative the entire unit  10  may be properly discarded. 
     As can be appreciated from the above-described firing and refraction sequences, the firing and retraction actions are accomplished through multiple actuations of the firing trigger. For example, in one embodiment, the clinician must actuate (i.e., move the firing handle from its unfired position ( FIG. 16 ) to its fired position ( FIG. 19 )) six times to completely fire all of the staples in a conventional 60 mm end effector. Likewise, to completely retract the knife bar  30  to the unfired position wherein the staple cartridge  50  may be removed from the elongate channel  20 , the clinician would have to move the shifter button  519  to the retraction position and actuate the firing trigger an equal number of times—in this example six times. However, the unique and novel attributes and advantages of the present invention may be employed in connection with a host of different sizes of end effectors. Thus, when shorter end effectors are employed, less actuations of the firing trigger may be required to completely fire the staples and thereafter return the knife bar to a fully retracted position. For example, it is within the scope of this invention to be employed with end effectors that would require only one or more than one actuations of the firing trigger to fire the staples and only one or more than one actuations to move the firing and cutting device to a fully refracted position. 
     As indicated above, the distal spine section  110  is attached to the proximal spine section  130  such that it can freely rotate relative thereto. Likewise, the closure tube assembly  170  can freely rotate on the spine assembly  100 . To facilitate rotation of the end effector  12  relative to the handle assembly  200 , the handle assembly  200  is provided with a rotation grip assembly  710  that can be rotated relative to the handle assembly  200  and cause rotation of the end effector  12 . More specifically and with reference to  FIGS. 1 and 10 , the grip assembly  710  comprises a right hand grip segment  720  and a left hand grip segment  730  (shown in  FIG. 1 ) that are adapted to mate with each other and rotate around the distal end  251  of the housing  250 . The right hand grip segment  720  and left hand grip segment  730  may be fabricated from polymers or other suitable materials and attached to each other by snap features, adhesive, screws, etc. Each segment  720 ,  730  has an arcuate rail segment  722  formed therein that is adapted to ride in a groove  259  formed in the housing  250  when the right hand case member  260  and left hand case member  280  are attached together. Thus, the rail segments  722  serve to retain the grip assembly  710  on the housing  250  while facilitating its rotation relative thereto. Each grip segment  720 ,  730  further has a tube rotation segment  724  formed therein that cooperate together to extend into a hole  191  in the proximal closure tube segment  190 . Thus, rotation of the grip housing  710  relative to the handle housing  250  causes the closure tube assembly  170  to rotate on the proximal spine segment  130 . It will be understood that the distal closure tube segment  180  does not rotate relative to the distal spine section  110 , but rather causes the distal spine section  110  to rotate with it relative to the proximal spine section  130 . The flange  197  on the proximal end  196  of the proximal closure tube segment is received within a corresponding groove in the grip assembly  710 . Such arrangement permits the clinician to easily rotate the end effector  12  relative to the handle assembly  200  after the end effector  12  has been inserted through the trocar into the patient. 
     While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. 
     For example, by manufacturing the elongate channel utilizing convention dies stamping techniques may lead to reduced manufacturing costs for that component. Likewise by stamping the anvil from metal utilizing conventional stamping techniques can also reduce the manufacturing costs commonly encountered when manufacturing such components. In addition, the unique and novel ratchet drive arrangement for firing the device eliminates the need the for battery or pneumatically powered components which can increase the overall cost of the device. 
     The devices disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include an combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the device can be disassembled, and any number of particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the device can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those of ordinary skill in the art will appreciate that the reconditioning of a device can utilize a variety of different techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application. 
     Preferably, the invention described herein will be processed before surgery. First a new or used instrument is obtained and, if necessary, cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK® bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or higher energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. 
     Any patent, publication, or information, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this document. As such the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. 
     The invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. The embodiments are therefore to be regarded as illustrative rather than restrictive. Variations and changes may be made by others without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such equivalents, variations and changes which fall within the spirit and scope of the present invention as defined in the claims be embraced thereby.