Abstract:
In accordance with the present invention, there is provided a method for performing a surgical stapling procedure by providing a stapler comprising a handle and a staple cartridge with an opposing anvil. The staple cartridge contains a plurality of surgical staples. The stapler also has an actuator module for deploying staples, wherein the actator has a longitudinally movable member for sequentially ejecting staples towards the anvil. The method involves operating the actuator module so as to eject the plurality of staples, and removing the actuator module from the body and discarding the actuator module. The method also involves sterilizing the body.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to surgical stapling instruments and, more particularly, to a surgical stapler which can be disassembled and portions reconditioned and sterilized for reuse in subsequent surgical procedures, and which includes a removable actuating module that can be reused with multiple staple cartridges during a single patient procedure. 
       BACKGROUND OF THE INVENTION 
       [0002]    Before surgical staplers were introduced, surgeons had to spend a great deal of time sewing the tissue of patients back together. This was the most time intensive aspect of a surgical procedure. Surgical staplers have decreased the amount of time that a user spends sewing tissue back together. Such surgical staplers are described in the following issued U.S. patents which are hereby incorporated herein by reference: U.S. Pat. No. 4,633,861 Chow et al.; U.S. Pat. No. 4,633,874 Chow et al.; and U.S. Pat. No. 5,129,570 Schulze et al. 
         [0003]    One concern with surgical staplers has been assuring that the staplers used during a procedure are sterile. Reusable staplers have typically been relatively complicated mechanical instruments which are difficult to sterilize after use. Hence, it was once desired that surgical staplers be completely disposable. As more than one surgical stapler may be required in a surgical procedure, for economical reasons disposable surgical staplers having reloadable staple cartridges have been developed. These reloadable staple cartridges have comprised a combination of staples and a firing module for discharging the staples. Typically the cutting instrument is included in the firing module. Therefore, each time a stapler is reloaded with a new staple cartridge, a new knife and firing assembly is also inserted into the stapler. Numerous staple cartridges are normally used during a single patient procedure, resulting in the repeated replacement of the knife and firing elements for the same patient. Since a knife is usually not worn out after a staple cartridge has been emptied, the knife and firing assembly could be reused with additional staple cartridges within the same patient. Reusing the firing assembly within a single patient procedure would not require additional sterilizing and can decrease the costs incurred during the procedure. Recently, there has also been a desire to make portions of a surgical stapler reusable, so that a portion is disposable and a portion is reusable in subsequent procedures. Reusing portions of the stapler reduces the costs associated with surgical procedures, and also decreases the surgical waste. 
         [0004]    Thus, to reduce the costs associated with surgical procedures, there is a need for a surgical stapler that can be disassembled and portions of the stapler reconditioned for subsequent use. In particular, there is a need for a surgical stapler in which the firing and cutting components may be reused with multiple staple cartridges within a single patient procedure in order to decrease the amount of materials utilized with the stapler. There is also a need for a surgical stapler that can be easily assembled and disassembled to allow reconditioning and reuse of some of the stapler parts. In addition, there is a need for a partially reusable stapler that incorporates a disposable firing module to allow the more complex cutting and stapling components to be easily replaced between surgical procedures. Further, there is a need for a partially reusable stapler in which the reusable parts have a simple, one-piece design to facilitate effective reconditioning of the parts between procedures. The present invention provides a partially reusable surgical stapler which achieves these objectives. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with the present invention, a partially reusable surgical stapler is provided for deploying staples into tissue. The stapler has a body with a distal end, a proximal end and a longitudinal axis therebetween. The proximal end includes a handle while the distal end includes a staple cartridge holder and an opposing anvil. The stapler also has an actuator module for deploying staples. The actuator module includes at least one longitudinally movable member for sequentially ejecting staples towards the anvil. The actuator module is readily removable and replaceable to and from the body. 
         [0006]    In another embodiment, the present invention provides a partially reusable surgical stapler having an upper jaw member with a proximal handle end and a distal anvil end. A lower jaw member having a proximal channel-shaped frame and a distal staple cartridge channel is aligned with the upper jaw. An actuator module, having at least one longitudinally moveable member for sequentially ejecting staples towards the anvil, is readily removable and replaceable to and from the lower jaw frame. A staple cartridge containing a plurality of staples is removably disposed within the staple cartridge channel. A latching member for connecting the upper and lower jaws together is provided at an intermediate position along a longitudinal axis of the stapler. The latching member is moveable relative to the upper and lower jaw members to place the stapler in a series of different locking states. The different locking states include an assembly state for connecting and disconnecting the latching member to the jaw members, and a closed, latched state in which the latching member is locked to the jaw members. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is an isometric view of an exemplary surgical stapler showing the stapler in a closed position; 
           [0008]      FIG. 2  is a front view of the stapler in an open position; 
           [0009]      FIG. 3  is an isometric view of the stapler in an open position; 
           [0010]      FIG. 4  is an isometric bottom view of the reusable upper jaw member for the stapler; 
           [0011]      FIG. 5  is an isometric top view of the stapler upper jaw member; 
           [0012]      FIG. 6  is an isometric view of the reusable lower jaw member including the cartridge channel; 
           [0013]      FIG. 7  is an isometric view of the disposable staple cartridge; 
           [0014]      FIG. 8  is a bottom view of the disposable staple cartridge; 
           [0015]      FIG. 9  is an isometric view of the reusable latching member; 
           [0016]      FIG. 10  is a front view of the reusable latching member; 
           [0017]      FIG. 11  is a detailed isometric view of the distal end of the latching member; 
           [0018]      FIG. 12  is a partial front view of the stapler showing the latching member in a ready to assemble state; 
           [0019]      FIG. 13  is a partial front view of the stapler showing the latching member in an initial inserted state; 
           [0020]      FIG. 14  is a partial front view of the stapler showing the latching member in a rotated and partially locked-in state; 
           [0021]      FIG. 15  is a partial front view of the stapler showing the relative positions of the latching and upper jaw members in a pre-close position; 
           [0022]      FIG. 16  is a partial front view of the stapler showing the relative positions of the latching and upper jaw members in an open position during use; 
           [0023]      FIG. 17  is an isometric view of the disposable actuating module; 
           [0024]      FIG. 18  is another isometric view of the disposable actuating module looking forward from the proximal to the distal end; 
           [0025]      FIG. 19  is an isometric view of the actuating module pan; 
           [0026]      FIG. 20  is a detailed, isometric view of the proximal end of the actuating module; 
           [0027]      FIG. 21  is a top view of the actuating module; 
           [0028]      FIG. 22  is an isometric view of the actuating knob; 
           [0029]      FIG. 23  is an isometric view of the guide block; 
           [0030]      FIG. 24  is an isometric view of a pusher bar; 
           [0031]      FIG. 25  is an isometric view of the knife support bar; 
           [0032]      FIG. 26  is a close-up, isometric view of the distal end of the actuating module showing the protector cap; 
           [0033]      FIG. 27  is a front view of the actuating module; 
           [0034]      FIG. 28  is a sectional view of the actuating module proximal end, showing the relationship between the actuating knob and the detent spring in a full back position; and 
           [0035]      FIG. 29  is a sectional view of the actuating module proximal end, showing the actuating knob moved forward during firing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    Referring now to the drawing figures, in which like numerals indicate like elements throughout the views,  FIGS. 1 through 3  illustrate a first exemplary surgical stapler  20  of the present invention. The body of stapler  20  includes an upper jaw member  22 , a lower jaw member  24 , and a latching member  30 . Latching member  30  is pivotable relative to the upper and lower jaws members  22 ,  24 , as shown in  FIGS. 2-3 . Latching member  30  can be pivoted through a series of different latching states to lock the stapler closed for use or to open the stapler varying degrees to allow for adjustment of tissue within the stapler, the replacement of a staple cartridge, or disassembly of the stapler. Upon completion of a surgical procedure, latching member  30  can be pivoted to a fully open position to allow stapler  20  to be disassembled in preparation for the resterilization and reuse of portions of the stapler. 
         [0037]    As shown in  FIGS. 4 and 5 , upper jaw  22  comprises a single piece, elongated channel-shaped frame having a pair of opposing sidewalls  32   a ,  32   b  connected by a top wall  36 . Top wall  36  is suitably shaped on the outer surface to form a hand grip and includes an upper handle protrusion  40  to facilitate the handling and operation of the stapler by a surgeon. The distal end of upper jaw  22  comprises a pair of inwardly extending flanges  42  which define an anvil  44  of the stapler. Flanges  42  are separated by a central, longitudinal slot  46  which extends along the entire length of anvil  44 . The inner surface of each flange  42  is provided with two longitudinal rows of uniformly spaced staple-forming pockets  50 . Staple forming pockets  50  allow the fashioning of B-form staples when U-shaped staples are ejected against the anvil flanges during firing. Anvil  44  includes a tapered tip at the distal-most end for facilitating insertion of the stapler into hollow, tubular body organs. A pair of tissue stops  52  is provided on opposite sides of anvil  44  adjacent the proximal end of staple forming pockets  50 . Tissue stops  52  are laterally aligned with the proximal end of staple forming pockets  50  to prevent tissue from being placed into the stapler beyond anvil  44 . Blocking tissue at the proximal end of anvil  44  prevents the pinching or cutting of unstapled tissue. 
         [0038]    Cylindrical pins  54  extend from opposite sides of upper jaw  22  proximal of tissue stops  52 . Pins  54  fit inside vertical slots on lower jaw  24  to connect the upper and lower jaws together. Upper jaw  22  also includes a pair of curved notches  60  near the proximal end of channel sidewalls  32   a ,  32   b . Notches  60  interact with projections  62  on lower jaw  24 , as shown in  FIG. 2 , to provide a means for easily aligning the jaws during use. Upper jaw  22  is preferably comprised of a single piece of a biocompatible metal, such as, for example, stainless steel. Using a single piece of material for upper jaw  22  increases the structural integrity of the stapler. Alternatively, upper jaw  22  can be manufactured as two or more separate pieces that are joined together during the manufacturing process by known joining methods such as, for example, welding. 
         [0039]    As shown in  FIG. 6 , lower jaw  24  comprises a single piece, elongated U-shaped frame having a pair of sidewalls  64   a ,  64   b  connected by a bottom wall  66 . At the distal end of lower jaw  24 , side walls  64   a ,  64   b  are reduced in size to form a cartridge channel  70  for supporting a single use staple cartridge within the stapler. Notches  72  are provided in sidewalls  64   a ,  64   b  adjacent the distal end of cartridge channel  70 . Notches  72  engage side projections on the staple cartridge to hold the cartridge within the channel. Vertical alignment slots  56  are located proximal of cartridge channel  70  in the upper edge of sidewalls  64   a ,  64   b . As mentioned above, pins  54  on upper jaw  22  interface with alignment slots  56  to align and connect the jaw members together. The width between upper jaw sidewalls  32   a ,  32   b  is slightly greater than the width between lower jaw sidewalls  64   a ,  64   b  to enable the upper jaw to fit over the lower jaw when pins  54  are inserted into alignment slots  56 , and projections  62  into notches  60 . Indentations  74  are formed in the outer surface of sidewalls  64   a ,  64   b , distal of alignment slots  56 . Indentations  74  facilitate the attachment of an actuating module to lower jaw member  24 , as will be described in further detail below. 
         [0040]    An opening  76  is formed through bottom wall  66  at an intermediate position along lower jaw  24 . Sidewalls  64   a ,  64   b  extend downward on opposite sides of opening  76  to form distally angled projections  80 . Along the distal edge of projections  80 , sidewalls  64   a ,  64   b  are shaped to form a straight-sided slot  82  having a circular end  88 . The diameter of circular end  88  is slightly larger than the width of the slot  82 . Proximal of projections  80  the outer surfaces of sidewalls  64   a ,  64   b  include a latching member positioning feature. As shown in  FIG. 6 , the positioning feature can comprise a plurality of detent bumps  84 , or other surface indentations, that are machined into the surface of the sidewalls  64   a ,  64   b .  FIG. 6  shows only a positioning feature on the front side of lower jaw  24 , however, it should be understood that the back side of the lower jaw is fashioned in the same manner so that latching member  30  may be retained in a series of latching states by both sides of the lower jaw, as will be described below. A retention feature  86  is formed at the proximal end of lower jaw  24  at the junction between sidewalls  64   a ,  64   b  and bottom wall  66 . Retention feature  86  can comprise an inward expansion of sidewalls  64   a ,  64   b  which facilitates a snap connection with an actuating module during assembly of stapler  20 . 
         [0041]      FIGS. 7 and 8  show an exemplary removable staple cartridge  90  for use in stapler  20  of the invention. Cartridge  90  is adapted to receive a plurality of surgical staples arranged in at least two laterally spaced longitudinal rows. Cartridge  90  has a body which includes opposite side walls  92   a ,  92   b  configured to be slidably received in the interior of lower jaw cartridge channel  70 . Staple cartridge  90  is divided longitudinally by a central elongated slot  94  which extends from the proximal end of the cartridge toward its distal end. A plurality of staple openings  96 , defined by the cartridge body, are disposed along the elongated center slot  94 . In the illustrated embodiment, the staple openings are arranged in two laterally spaced, staggered rows, with each pair of rows disposed on opposite sides of central longitudinal slot  94 . The staple openings in adjacent rows are staggered to provide more effective stapling of the tissue when the instrument is operated. Referring to  FIG. 8 , staple cartridge  90  includes a pair of longitudinal slots  100  located on opposite sides of elongated central slot  94  and disposed between the staggered rows of openings  96 . Each longitudinal slot  100  extends from the proximal end of cartridge  90  towards the distal end. A plurality of staple drivers (not shown) are slidably mounted in staple openings  96  for actuating the staples which are loaded into staple cartridge  90 . Each staple driver is designed to simultaneously actuate two staples located in the adjacent rows provided in staple cartridge  90 . Thus, a first set of staple drivers is provided for actuating the staples in the staggered rows located on one side of central longitudinal slot  94 , and a second set of staple drivers is provided for actuating the staples in the pair of adjacent rows located on the other side of the central longitudinal slot. 
         [0042]    The distal end of staple cartridge  90  includes a tapered tip to facilitate the insertion of lower jaw member  24  into a hollow tubular body organ. Proximal of the tapered tip, staple cartridge  90  is provided with a pair of outwardly extending protrusions  102 . A pair of spaced, parallel flanges  104  extends rearward from opposite sides of staple cartridge  90 . Legs  110  extend downward from flanges  104  at the proximal end of the staple cartridge. Each leg  110  is provided with a rounded, downwardly facing notch  112 . When cartridge  90  is assembled on lower jaw  24 , protrusions  102  are loosely received in notches  72  in the lower jaw side walls, and legs  110  extend through opening  76  in the lower jaw bottom wall  66 . Leg notches  112  engage a pin on latching member  30 , as will be described below, to hold the cartridge within lower jaw channel  70 . A pair of wings  114  extends upward and outward from sidewalls  92   a ,  92   b  at the proximal end of cartridge  90 . Wings  114  function as finger grips which allow staple cartridge  90  to be manually inserted into and removed from lower jaw  24 . Using wings  114 , cartridge  90  can be lifted out of jaw opening  76  and notches  72 , to remove the cartridge from lower jaw  24  following use. Additionally, wings  114  engage lower jaw sidewalls  64   a ,  64   b  at the proximal end of cartridge channel  70 , as shown in  FIG. 3 , to lock the cartridge in place within lower jaw  24 . A short extension  116  is formed at the rear of cartridge  90  and located between rearwardly projecting legs  110 . Central knife slot  94  extends longitudinally through extension  116 , which can be provided with inwardly sloped guide surfaces on its opposite sides at the proximal end of the slot. A lock out pin  106  is connected at one end to extension  116  and is pivotable about the connection point. Initially, when staple cartridge  90  is loaded into stapler  20 , lock out pin  106  extends transversely across central knife slot  94 . 
         [0043]    As mentioned above, stapler  20  includes a latching member  30  for connecting the upper and lower jaws members together at an intermediate position along the longitudinal length of the stapler. Preferably, jaw members  22 ,  24  are connected together at a location adjacent to the proximal ends of anvil  44  and staple cartridge  90 . In the preferred embodiment, shown in  FIG. 9 , latching member  30  comprises a single piece, channeled-shaped frame having opposing side walls  124   a ,  124   b  connected by a top wall  130 . Latching member  30  further includes a latch pin  122  for pivotally connecting the latching member to lower jaw  24 . Preferably, the latching member is comprised of a single piece of stainless steel, or another similar biocompatible metal. The distance between the opposing latching member side walls  124   a ,  124   b  is sufficient to span the sidewalls  64   a ,  64   b  of lower jaw  24 . Side walls  124   a ,  124   b  include outwardly extending, elongated flanges  132  which serve as finger grips to enable latching arm  120  to be manually pivoted between latching positions. The outer surface of latching arm  120  includes a handle extension  134 . When connected to lower jaw member  24 , handle extension  134  combines with upper jaw handle extension  40  to form a hand grip for manipulation of the stapler by a surgeon. 
         [0044]    Each side wall  124   a ,  124   b  of latching member  30  includes a distally-extending C-shaped hook member  140  provided with a forwardly facing notch  142  for engaging upper jaw pins  54 . As shown in  FIGS. 9 and 10 , hook members  140  include an inner cam surface  144  extending rearward from the tip of the hook member into notch  142 . When latching member  30  is moved to a closed, operative state, notches  142  engage upper jaw pins  54 , acting as an over-center latch to maintain the latching member in the latched state. Below notches  142 , each hook member  140  projects distally downward, beyond the end of latching member top wall  130 . Latch pin  122  extends between the down turned ends of hook members  140 , as shown in  FIG. 11 , across the end of latching member  30 . Latch pin  122  has a cylindrical shape with flat surfaces  152  adjacent each end. The diameter of latch pin  122  is greater than the narrow opening for lower jaw slot  82 . Latching member  30  is detachably connected to lower jaw  24  by inserting latch pin  122  into lower jaw slot  82 . Latch pin  122  is inserted into slot  82  by orienting latching member  30  so that flat ends  152  lie in parallel with the straight sides of the slot. In this position, latch pin  122  can be inserted into slot  82  despite the pin diameter being greater than the slot width. With flat ends  152  aligned with the linear sides of slot  82 , latch pin  122  is inserted into the slot, as shown in  FIG. 12 , until the pin rests within circular slot end  88 , as shown in  FIG. 13 . 
         [0045]    Stapler  20  also includes means for retaining the latching member in a series of different latching states. Referring to  FIGS. 9 and 10 , the retaining means includes a spring arm  150  extending from the top edge of each latching arm sidewall  124   a ,  124   b . Spring arm  150  curves distally upward, following the upper contour of hook member  140 , and includes a bulbous free end. With latching pin  122  assembled within slot  82 , and latching member  30  angled distally, as shown in  FIG. 13 , stapler  20  is in an initial, open state. To close stapler  20 , latching member  30  is rotated towards the proximal end of the stapler, to draw the latching member closer to the body of lower jaw member  24 . As flat ends  152  rotate out of alignment with the sides of slot  82 , the difference in width between pin  122  and slot  82  prevents the pin from slipping out of slot end  88 . Pin  122  is thus fixed within slot end  88 , locking latching member  30  to lower jaw member  24 . 
         [0046]    As latching member  30  rotates, hook members  140  are drawn along the sides of lower jaw member  24 . As hook members  140  swing alongside lower jaw sidewalls  64   a ,  64   b , the bulbous ends of spring arms  150  contact detent bumps  84  on the sidewalls. To move spring arms  150  between the detent bumps  84 , additional force is applied to latching member  30  to cause the spring arms to flex towards the hook members  140 , so that the ends of the spring arms can ride over the bumps. With spring arms  150  positioned between detent bumps  84 , as shown in  FIG. 14 , latching member  30  is in a partially locked-in state. In the partially locked-in state, latching member  30  is attached to lower jaw  24  and alignment slots  56  are just distal of the tip of hook members  140 . Upper jaw pins  54  can be freely inserted or removed from lower jaw slots  56 , allowing the upper and lower jaw members to be separated and rejoined together. 
         [0047]    As latch pin  122  continues to rotate within slot end  88 , drawing latching member  30  closer to lower jaw member  24 , hook member inner cam surfaces  144  rotate over the opening of alignment slots  56 , blocking the slots and locking upper jaw pins  54  within the slots. Spring arms  150  also ride along detent bumps  84  to engage the concave outer edge of the top bump. In this pre-closed state, shown in  FIG. 15 , latching member  30  and upper and lower jaw members  22 ,  24  are connected together to form the body of stapler  20 , but upper jaw pins  54  can slide within slots  56 , between the bottom of the slot and cam surface  144 , to allow some relative movement between the jaw members. Latching member  30  maintains the jaw members in a loosely latched position to permit relative movement between the staple cartridge and anvil. The relative movement at the distal end of jaw members  22 ,  24  allows for tissue adjustments without disconnecting the jaw members from each other. 
         [0048]    When latching member  30  is rotated to a closed, operative state (shown in  FIG. 1 ) the latching member surrounds lower jaw member  24 , and pins  54  on upper jaw member  22  are lodged within hook member notches  142 . Spring arms  150  advance distally upward along the sides of lower jaw member  24  beyond detent bumps  84 . In this state, the upper and lower jaw members are locked together to compress tissue between the anvil and cartridge surfaces, and the stapler is ready for stapling and cutting tissue. In the closed state, a minimum spacing may be maintained between the anvil and cartridge surfaces by a spacer pin  160 . To adjust the placement of tissue between the anvil and cartridge surfaces, latching member  30  can be rotated back to the pre-close state, as shown in  FIG. 16 , to dislodge pins  54  from hook member notches  142 . As latching member  30  rotates back, spring arms  150  reengage with detent bumps  84  to hold the latching member in place. Returning to the pre-close state loosens the connection between hook members  140  and pins  52 , to allow the pins to slide within slots  56  without disconnecting the upper and lower jaws. 
         [0049]    To disassemble stapler  20 , latching member  30  is rotated away from lower jaw member  24  to draw upper jaw pins  54  out of hook notches  142 . Latching member  30  may be rotated away from upper and lower jaw members  22 ,  24  by pulling on the curved latching arm tip  162 . As a counter rotating force continues on latching arm  120 , spring arms  150  move through detent bumps  84 , enabling hook members  140  to swing through and way from the lower jaw sidewalls  64   a ,  64   b . Latching member  30  is rotated around in the direction of staple cartridge  90  until latching member  30  returns to the initial, open position shown in  FIG. 13 . With latching member  30  in the open state, flat ends  152  on latch pin  122  are again aligned in parallel with the straight sides of slot  82 , enabling the latch pin to be withdrawn through slot  82  to separate the latching member from lower jaw member  24 . With latching member  30  detached, stapler  20  can be disassembled into three separate, one-piece components, namely, upper jaw  22 , lower jaw  24  and latching member  30 . The one-piece channel-shaped construction of these reusable components provides for easy yet thorough reconditioning and sterilization of the components between uses. 
         [0050]    Turning now to  FIGS. 17 and 18 , which show an actuator module  170  for stapling and cutting tissue clamped between the upper and lower jaw members  22 ,  24 . Actuator module  170  comprises a U-shaped, longitudinal module pan  172  which provides the supporting structure for the actuator module components. Module pan  172  includes a pair of sidewalls  174  connected together by a bottom wall  176  ( FIG. 19 ). The distance between module pan sidewalls  174  is less than the distance between lower jaw sidewalls  64   a ,  64   b  to enable the module pan to be slidably mounted within the proximal channel of lower jaw  24 . As shown in  FIGS. 19 and 20 , the proximal end of module pan  170  includes one or more detent bumps  178  protruding from the outer surface of sidewalls  174 . Detent bumps  178  engage retention features  86  on the inside channel of lower jaw member  24  when the actuator module  170  is slid proximally into the lower jaw channel. The interaction of detent bumps  178  with retention features  86  snaps and retains the actuator module in place within lower jaw member  24 . 
         [0051]    As shown in  FIG. 21 , a plurality of moveable actuating members are situated within module pan  172  for longitudinal movement within the pan relative to upper and lower jaw members  22 ,  24 . The actuating members include a pusher block  180  which is disposed within module pan  172  for reciprocal, longitudinal movement within the pan. Pusher block  180  is attached to an actuator knob  182  by a lateral flange  184 . When actuator module  170  is mounted within lower jaw  24 , as shown in  FIG. 3 , flange  184  extends through an elongated guide slot  186  formed in a sidewall  64  of the lower jaw. Flange  184  positions knob  182  on the outside of jaw members  22 ,  24  to allow manual access of the knob. In  FIG. 3 , knob  182  is shown extending through a guide slot  186  in lower jaw sidewall  64   b . However, a guide slot could also be formed in the opposite lower jaw sidewall  64   a , in which case actuating knob  182  would extend out the opposite side of stapler  20 . Flange  184  extends through and rides along guide slot  186  as knob  182  is manually moved along the outside of jaw members  22 ,  24 . 
         [0052]    Returning now to  FIG. 21 , actuator module  170  also includes a pair of longitudinally extending, parallel pusher bars  190 . The proximal ends of pusher bars  190  are secured within laterally spaced pusher block slots  192  (shown in  FIG. 22 ) to allow the pusher bars to move longitudinally with pusher block  180  through module pan  172 . Pusher bars  190  extend distally from pusher block  180  and are slidably received in longitudinal slots  194  formed in a guide block  200 , shown in  FIG. 23 . As shown in  FIG. 18 , guide block  200  is mounted at the distal end of module pan  172 . The upper edges of module pan sidewalls  174  are bent inward over the side edges of guide block  200  to retain the guide block within the module pan. Additionally, tabs  202  extend from the sides of guide block  200  through openings  204  in module pan sidewalls  174  to secure the guide block within the pan. The distal end of guide block  200  extends beyond the end of module pan  172  and between rear flanges  104  of staple cartridge  90 . Lateral slots  194  within guide block  200  align pusher bars  190  with the elongated staple driver slots  100  of staple cartridge  90 . The distal ends of pusher bars  190  extend forward of guide slots  194  and are provided with a wedge-shaped tip  206 , shown in  FIG. 24 , which defines an inclined cam surface for engaging the staple drivers within cartridge  90  as the pusher bars are moved distally through the cartridge. The longitudinal movement of the pusher bar tips  206  sequentially drives the staple drivers, through a camming action, to fire staplers from the cartridge. 
         [0053]    Returning to  FIG. 23 , guide block  200  includes a depending center section  210  which extends downward through opening  76  in the lower jaw bottom wall  66 . Center section  210  includes a distally angled, straight-sided slot  212  with a circular end  218 . When stapler  20  is assembled, guide block slot  212  is longitudinally aligned with slot  82  in lower jaw sidewalls  64   a ,  64   b  to enable latch pin  122  to engage both lower jaw  24  and guide block  200  when latching member  30  is connected to the stapler. As latch pin  122  is inserted through slot  82  into slot end  88 , the pin also passes through guide block slot  212  and lodges within circular end  218 , locking the actuator module  170  and lower jaw  24  together. 
         [0054]    As shown in  FIGS. 18 and 21 , actuator module  170  further comprises a knife support bar  214  positioned between pusher bars  190 . Knife support bar  214  and pusher bars  190  are preferably manufactured as sheet metal components. The proximal end of knife support bar  214  is secured within a center slot  216  of pusher block  180  ( FIG. 22 ) to connect the knife support bar to the pusher block for movement by firing knob  182 . Distal of pusher block  180 , knife support bar  214  is slidably received in a center slot  220  formed in guide block  200  (shown in  FIG. 23 ) to align the knife support bar with the elongated center slot  94  of the staple cartridge. As shown in  FIG. 25 , an inclined knife blade  222  having a beveled cutting edge is located at the front end of knife support bar  214 . The beveled cutting edge of knife blade  222  is oriented at an angle relative to jaw members  22 ,  24 , and is slidably received in central longitudinal slot  220  of guide block  200 . Proximal of knife blade  222 , knife support bar  214  includes a cartridge locking notch  228  and a locking cut out section  224 , which are part of a safety lockout mechanism described below. The proximal end of knife support bar  214  includes an offset section, indicated by reference number  226 . Knife offset  226  is formed by cutting away a section of the knife support bar  214  near the proximal end, to produce two elevated points  230 ,  232  on the support bar. 
         [0055]    As shown in  FIGS. 26 and 27 , a protector cap  234  covers the distal end of guide block  200 . A center section  236  of cap  234  surrounds knife blade  222  and the wedged tips  206  of pusher bars  190 . An inwardly directed lip  240  extends along the bottom edge of the cap. During assembly, downward pressure is applied to protector cap  234  to snap the distal end of the actuator module in place inside the lower jaw channel. As cap  234  is pressed downward, cap lip  240  snaps into indentations  74  on the outer surface of lower jaw  24 . 
         [0056]    A leaf spring  250 , shown in  FIG. 19 , is integrated into module pan bottom wall  176  beneath guide block  200 . Spring  250  provides a safety lockout feature by lifting knife support bar cut out  224  against guide block  200  after firing, to prevent re-firing of a used cartridge. A second spring  252  is integrated into module pan bottom wall  176  near the proximal end of the pan. This second spring  252  is a detent spring that interacts with a notch on pusher block  180  to prevent forward movement of actuator knob  182  during shipping, and to provide audible and tactile feedback when the actuator knob is returned to the proximal-most position in the module pan following firing.  FIGS. 28 and 29  illustrate the operation of detent spring  252  in greater detail. In  FIG. 28 , spring  252  is shown engaging a notch  254  on pusher block  180  to prevent unintentional distal movement of the pusher block.  FIG. 29  shows detent spring  252  disengaged from notch  254  by the application of an intentional, distally directed force on actuator knob  182 . Pusher bars  190  and knife support bar  214  are advanced distally by applying sufficient force to actuator knob  182  to overcome the force of spring  252  against notch  254 . After spring  252  is disengaged from notch  254 , pusher block  180  can slide distally through module pan  172  to first advance pusher bars  190  and then advance knife support bar  214  from guide block  200  into staple cartridge  90 . 
         [0057]    In an initial firing position, shown in  FIG. 28 , a downwardly directed edge of pusher block  180  is in contact with knife support bar  214  at the proximal end point  232  of offset section  226 . Actuating knob  182  is retracted to a fully proximal position within guide slot  186 , thereby placing pusher bars  190  and knife blade  222  within slots  194  and  220  of guide block  200 . When a distal pushing force is applied to actuating knob  182 , spring  252  disengages from notch  254 , enabling pusher block  180  to advance longitudinally within module pan  172 . As pusher block  180  moves, the block advances pusher bars  190  distally, causing the inclined tips of the bars to advance into cartridge driver slots  100 . During the initial movement of pusher block  180 , the distal edge of the block moves through knife support bar offset  226 , as shown in  FIG. 29 , thereby not making contact with the support bar itself. Knife support bar  214  thus remains stationary during the initial distal movement of the pusher bars  190  and block  180 . 
         [0058]    After pusher block  180  advances through knife offset section  226 , the distal edge of the block contacts the distal end point  230  of knife support bar  214 . This contact between pusher block  180  and knife support bar  214  causes the knife support bar to begin advancing distally, along with the pusher block and pusher bars  190 , as knob  182  is advanced. As knife support bar  214  moves distally, knife blade  222  is guided by central slot  220  and rear cartridge extension  116  into central longitudinal slot  94  of staple cartridge  90  and central longitudinal slot  46  of anvil  44 . As knife blade  222  advances through cartridge extension  116 , the blade deflects lock out pin  106  out of the path of the advancing support bar. Knife blade  222  and pusher bar tips  206  advance simultaneously through staple cartridge  90  driving staples through openings  96  and cutting tissue. Knife blade  222  is advanced into staple cartridge  90  slightly behind pusher bars  190  so that staples are formed into the tissue gripped between the anvil and cartridge prior to the knife blade advancing and cutting the tissue between the staple rows. 
         [0059]    After the knife and pusher bars have been fully advanced by knob  182  (or advanced to the desired forward position), pusher block  180  is retracted within module pan  172  by drawing the actuating knob back proximally through jaw guide slot  186 . Initially, as pusher block  180  is drawn proximally, pusher bars  190  are drawn proximally while knife support bar  214  remains in a distal, stationary position due to the offset section  226  in the support bar. As the distal pusher block edge retracts into contact with proximal knife bar offset point  232 , the knife support bar  214  begins to retract proximally with the pusher block and bars. As knife support bar  214  retracts within guide block  200 , the support bar is lifted up by leaf spring  250  into contact with the guide block, until the knife locking cut out  224  catches a center post  256  ( FIG. 23 ) of the guide block. Once knife cut out  224  engages guide block post  256 , knife support bar  214  is prevented from further movement in conjunction with pusher block  180 . Preferably, knife support bar  214  engages locking cut out section  224  as pusher block  180  and pusher bars  190  are reaching the fully proximal position. 
         [0060]    After actuator knob  182  is fully retracted, as shown in  FIG. 28 , latching member  30  is pivoted relative to jaw members  22 ,  24  to separate the upper and lower jaws, as described above. With the jaw members separated, staple cartridge  90  can be removed and replaced with a new cartridge. The used cartridge can be removed by pulling up on cartridge wings  114  to dislodge cartridge legs  110  from lower jaw opening  76 . As the proximal end of the staple cartridge is lifted out of lower jaw opening  76 , cartridge leg notches  112  ( FIG. 7 ) are drawn out of engagement with latch pin  122 . After the proximal end of staple cartridge  90  is dislodged, the cartridge can be slid distally out of cartridge channel  70  and discarded. 
         [0061]    A new staple cartridge  90  can be loaded into lower jaw  24  by pushing the flanged, distal end of the cartridge against the distal end of the lower jaw cartridge channel  70 , and pushing down on wings  114  to lower legs  110  through jaw opening  76 . Cartridge legs  110  are pushed through lower jaw opening  76  until leg notches  112  snap onto latch pin  122 . As the proximal end of staple cartridge  90  is pushed down, lockout pin  106  on the cartridge depresses knife support bar  214  at locking notch  228  against the counter force of leaf spring  250 . The force of lockout pin  106  pushes knife support bar cutout  224  down and out of contact with guide block center post  256 . As knife support bar  214  is pushed down, the support bar is realigned with guide block center slot  220  to enable the support bar to pass distally through the slot and into the new cartridge. The safety lockout feature is thus reset during loading of a new staple cartridge. With a new cartridge loaded, the stapler can be reassembled by placing upper jaw  22  over lower jaw  24  and reinserting upper jaw pins  54  into lower jaw alignment slots  56 . Latching hook members  140  are pivoted back over the opening of slots  56  until pins  54  are lodged within notches  142 . With pins  54  locked within hook member notches  142 , and latching member  30  pivoted into position about lower jaw  24 , the stapler is closed and ready to fire staples from the new cartridge. 
         [0062]    The reusable upper and lower jaw and latching member components described above are provided to a user in a non-sterile package. Prior to assembly of stapler  20 , the components are cleaned with pH neutral enzymatic cleaners, and then steam autoclaved to sterilize the components. This conditioning procedure is also followed prior to each subsequent reuse of the components. Actuator module  170 , due to it multiple movable components, is designed for single patient use to eliminate the complexity of cleaning the module. The actuator module is provided to the user in a sterile disposable package which is opened in the sterile field. Staple cartridge  90  is also delivered as a sterile disposable package that is opened in the sterile field. 
         [0063]    To assemble stapler  20 , actuator module  170  is removed from its packaging and inserted proximal end first into the proximal channel of lower jaw member  24 . Actuator module  170  snaps into place when proximal detent bumps  178  engage lower jaw retention features  86 . The distal end of the actuator module is then rotated down into the channel shaped frame of lower jaw  24 . With actuator module  170  within the lower jaw channel, protector cap  234  is pushed down to snap cap lips  240  into indentations  74  on the lower jaw sidewalls  64   a ,  64   b . Pushing down on protector cap  234  pushes guide block center section  212  through lower jaw opening  76 , aligning guide block slot  212  with lower jaw slot  82 , and locking the actuator module in place within the lower jaw member  24 . With actuator module  170  loaded into lower jaw member  24 , latching member  30  is attached to the lower jaw by inserting latch pin  122  into slots  82  and  212 , as described above. Latching member  30  is rotated relative to lower jaw member  24  to the partial locked-in position shown in  FIG. 14 . In this position, latching member  30  is attached to lower jaw member  24 , but upper jaw  22  is separable from the lower jaw. Protector cap  234  is removed from actuator module  170  by moving the cap in the distal direction, as indicated by the arrow on the cap shown in the Figures. 
         [0064]    A new staple cartridge  90  is next inserted into lower jaw cartridge channel  70  in the manner described above. After a staple cartridge is loaded, upper jaw member  22  is placed over lower jaw member  24 , with pins  54  inserted into alignment slots  56 . Latching member  30  is pivoted relative to the upper and lower jaw members  22 ,  24  to place the stapler into the pre-close position (shown in  FIG. 15 ), in which the hook member cam surfaces  144  extend over the openings to alignment slots  56  to prevent pins  54  from disengaging from the slots. The tissue to be transected is placed between the anvil  44  and staple cartridge  90  and adjusted to the desired position. Tissue stops  52  prevent the tissue from being positioned too far back into the stapler. With the tissue properly situated, the stapler is closed in preparation for firing by rotating latching member  30  into contact with lower jaw  24  to place hook member  140  over slots  56 , and lock pins  54  inside hook member notches  142 . In this state, the tissue is clamped within the device. If additional tissue adjustment is required, the stapler can be returned to the pre-close state, as shown in  FIG. 16 , in which the distal ends of the upper and lower jaw members can move slightly relative to each other to accommodate tissue repositioning. With the tissue properly clamped between the jaw members, and latching member  30  pivoted to the closed, operative position, the stapler can be fired by pushing actuator knob  182  forward through guide slot  186  until the knob stops. As the knob advances, the clamped tissue is stapled and cut. After actuator knob  182  reaches its distal stop, the knob is drawn back proximally through guide slot  186 . At the proximal end of the knob path, the interaction of detent spring  252  and push block notch  254  provides tactile and audible feedback that the knob is fully retracted, signaling that the actuating components have been withdrawn from staple cartridge  90  back into module pan  172 . 
         [0065]    If additional stapling and cutting is desired to complete the procedure, latching member  30  is pivoted back to the partially locked-in state so that upper jaw  22  can be removed, and the used staple cartridge discarded and replaced with a new staple cartridge. After the new cartridge is in place, latching member  30  can be pivoted back through the pre-close and closed states to enable tissue to again be positioned, clamped and stapled using the new cartridge. Once all the required tissue is transected, latching member  30  is removed by rotating the member back to the open state (shown in  FIG. 13 ), and sliding latch pin  122  out of slots  82  and  212 . The actuating module  170  and staple cartridge  90  can then be removed from lower jaw member  24  and discarded. The remaining components (upper jaw, lower jaw, and latching member) can be cleaned and sterilized as separate components in preparation for reuse. 
         [0066]    In the present invention, actuator module  170  is a separate component from staple cartridge  90 , enabling spent staple cartridges to be replaced during a single patient procedure without replacing the actuator module. Accordingly, the actuator module may be used multiple times in the same patient with different staple cartridges. Using the single piece module pan  172  as a supporting structure for the actuator module components enables the actuator module to be easily assembled into and disassembled from the lower jaw channel. The reusable stapler components have a simple, single piece design to facilitate repeated reconditioning and reuse of the parts. The detachable design of the latching member facilitates easy disassembly and reassembly of the reusable components of the stapler. Further, once the stapler is assembled, the retaining and locking features of the latching and lower jaw members prevent accidental disassembly during a procedure. 
         [0067]    The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment was chosen and described in order to best illustrate the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.