Patent Publication Number: US-7721933-B2

Title: Surgical fastener applying apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   The present application is a continuation of U.S. patent application Ser. No. 12/011,419, filed on Jan. 24, 2008; which is a continuation of U.S. patent application Ser. No. 11/699,620, filed on Jan. 29, 2007 now U.S. Pat. No. 7,419,081; which is a continuation of U.S. patent application Ser. No. 11/356,912, filed on Feb. 16, 2006 now U.S. Pat. No. 7,293,685; which is a divisional of U.S. patent application Ser. No. 11/292,736, filed on Dec. 2, 2005 now U.S. Pat. No. 7,140,527; which is a divisional of U.S. patent application Ser. No. 10/399,071, filed on Apr. 10, 2003 now U.S. Pat. No. 7,055,730; which is a 35 U.S.C. §371 National Filing of International Application Serial Number PCT/US01/32213, filed on Oct. 15, 2001; which claims priority of U.S. provisional application Ser. No. 60/240,461 filed on Oct. 13, 2000, the entire contents of which are hereby incorporated by reference. 

   BACKGROUND 
   1. Technical Field 
   The present disclosure relates to surgical fastener applying apparatus and more particularly to surgical fastener appliers for sequentially applying a plurality of surgical fasteners to body tissue. 
   2. Discussion of Related Art 
   Surgical devices wherein tissue is first grasped or clamped between opposing jaw structures and then joined by means of surgical fasteners are well known in the art. In some such instruments a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners are typically in the form of surgical staples however, other surgical fasteners may also be utilized, for example, clips or two part polymeric surgical fasteners. 
   Instruments for applying surgical fasteners typically include two elongated beam members which are respectively used to capture or clamp tissue therebetween. Typically, one of the beam members carries a disposable cartridge which houses a plurality of staples arranged in at least two lateral rows while the other beam member comprises an anvil which defines a surface for forming the staple legs as the staples are driven from the cartridge. Where two part fasteners are used, this beam member carries the mating part, e.g. the receiver, to the fasteners driven from the cartridge. Generally, the staple formation process is effected by the interaction between a longitudinally moving camming surface and a series of individual staple pusher member. As the camming surface travels longitudinally through the cartridge carrying member, the individual pusher members are biased laterally acting upon the staples to sequentially eject them from the cartridge. A knife may travel with the pusher between the staple rows to longitudinally cut the tissue between the rows of formed staples. Examples of such instruments are disclosed in U.S. Pat. No. 3,079,606 and U.S. Pat. No. 3,490,675. 
   A later stapler disclosed in U.S. Pat. No. 3,499,591 applies a double row of staples on each side of the incision. This is accomplished by providing a cartridge assembly in which a cam member moves through an elongate guide path between two sets of staggered staple carrying grooves. Staple drive members are located within the grooves and are positioned in such a manner so as to be contacted by the longitudinally moving cam to effect ejection of the staples. 
   SUMMARY 
   It is an object of the present invention to provide a surgical fastener applying apparatus which apparatus will not fire if a disposable staple cartridge is not properly loaded within the apparatus or is not loaded in the apparatus at all. 
   It is another object of the present invention to provide a surgical fastener applying apparatus which will not open during the firing stroke of the apparatus. 
   It is a further object of the present invention surgical fastener applying apparatus which will not accept a completely fired or a partially fired disposable staple cartridge therein. 
   It is yet another object of the present invention to provide a surgical fastener applying apparatus which will not fire while in an unclamped state. 
   The presently disclosed apparatus includes a cartridge half-section and an anvil half-section with the cartridge and anvil half-sections being relatively movable from an unclamped position to a fully clamped position. The apparatus further includes a replaceable staple cartridge assembly receivable in the cartridge half-section. The cartridge assembly includes a plurality of surgical staples abutting a plurality of staple pusher members and a pivotably mounted safety lock-out. The safety lock-out is pivotable between an initial position, which permits a relative movement of the cartridge and anvil half-sections to the fully clamped position, and a blocking position, which prevents a relative movement of the cartridge and anvil half-sections from returning to the fully clamped position after the plurality of staples have been at least partially fired. The apparatus further includes a pair of camming surface extensions extending from a cam bar channel and positioned within the cartridge half-section and a pivotably mounted firing lever operatively associated with the pair of camming surfaces to move the pair of camming surfaces longitudinally, thereby sequentially firing the plurality of surgical staples in a direction transverse to a direction of travel of the pair of camming surfaces. 
   In addition, each of the presently disclosed cartridge and anvil half-sections of the fastener applying apparatus includes a clamping lever, which clamping levers are configured and adapted to enable the applying apparatus to be opened by either one of the cartridge half-section and the anvil half-section. The apparatus including a clamp latch configured and adapted to retain the clamp levers in a clamped orientation and a safety interlock assembly configured and adapted to prevent opening of either of the clamping levers after the firing lever has been moved distally. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the presently disclosed surgical fastener applying apparatus will be described herein with reference to the accompanying drawing figures wherein: 
       FIG. 1  is a perspective view of one embodiment of a surgical fastener apparatus constructed in accordance with the present disclosure; 
       FIG. 2  is a top plan view of the embodiment of  FIG. 1 ; 
       FIG. 3  is a side elevation view of the embodiment of  FIG. 1 ; 
       FIG. 4  is a side elevation view of the embodiment of  FIG. 1  taken from the opposite side of that shown in  FIG. 3 ; 
       FIG. 5  is a bottom plan view of the embodiment of  FIG. 1 ; 
       FIG. 6  is a front elevation view of the embodiment of  FIG. 1 ; 
       FIG. 7  is a rear elevation view of the embodiment of  FIG. 1 ; 
       FIG. 8  is a perspective view of a disposable staple cartridge assembly of the presently disclosed surgical fastener applying apparatus; 
       FIG. 9  is a perspective view with parts separated of the disposable staple cartridge assembly of  FIG. 8 ; 
       FIG. 10  is a schematic view of a staple pusher pair; 
       FIG. 11  is an enlarged left distal perspective view of a staple cartridge loading and lockout mechanism; 
       FIG. 12  is an enlarged right side proximal perspective view of the loading and lockout mechanism of  FIG. 11 ; 
       FIG. 13  is a perspective view with parts separated showing installation of a staple cartridge assembly on a cartridge half-section of the presently disclosed surgical fastener applying apparatus; 
       FIG. 14  is an enlarged perspective view from the bottom of the loading and lockout mechanism with a staple cartridge in place thereon; 
       FIG. 15  is an enlarged perspective view similar to  FIG. 12 , with a staple cartridge in place; 
       FIG. 16  is an enlarged side perspective view which shows the relative positioning of the loading and lockout mechanism with a staple cartridge installed and with an anvil half-section in place in a clamped condition; 
       FIG. 17  is a perspective view which shows a surgical stapler apparatus after partial or complete firing in an unclamped condition with a staple cartridge safety lockout in a locked out position; 
       FIG. 18  is an enlarged view of the indicated area of detail of  FIG. 17 ; 
       FIG. 19  is a perspective view of the surgical stapler apparatus opened from an anvil half-section side with an anvil half-section clamp lever opened and a cartridge half-section clamp lever closed; 
       FIG. 20  is a perspective view of the surgical stapler apparatus opened from a cartridge half-section side with a cartridge half-section clamp lever opened and an anvil half-section clamp lever closed; 
       FIG. 21  is a perspective view with parts separated which shows the structural relationship of the various components of a clamp lever lockout and safety interlock mechanism; 
       FIG. 22  is a plan view looking down on the anvil half-section of the surgical stapler apparatus with a firing lever in the proximal-most position; 
       FIG. 23  is a cross-sectional view taken along section line  23 - 23  of  FIG. 22 ; 
       FIG. 24  is an enlarged view of the indicated area of detail of  FIG. 23 ; 
       FIG. 25  is an enlarged view of the indicated area of detail of  FIG. 23 ; 
       FIG. 26  is a plan view similar to  FIG. 22 , which shows the firing lever advanced distally a short distance; 
       FIG. 27  is a cross-sectional view taken along section line  27 - 27  of  FIG. 26 ; 
       FIG. 28  is an enlarged view of the indicated area of detail of  FIG. 27 ; 
       FIG. 29  is an enlarged view of the indicated area of detail of  FIG. 27 ; 
       FIG. 30  is a perspective view of the cartridge half-section of the surgical stapler apparatus; 
       FIG. 31  is a perspective view of a disposable staple cartridge assembly according to an alternative embodiment of the present invention; 
       FIG. 32  is a perspective view, with parts separated, of the disposable staple cartridge assembly of  FIG. 31 ; 
       FIG. 33  is a perspective view of the disposable staple cartridge assembly as shown in  FIG. 31  with the shipping wedge removed therefrom; 
       FIG. 34  is a perspective view of a cartridge half-section according to the alternative embodiment of the present invention; 
       FIG. 35  is an enlarged left distal perspective view of a staple cartridge loading and lockout mechanism; 
       FIG. 36  is an enlarged right side proximal perspective view of the loading and lockout mechanism of  FIG. 35 ; 
       FIG. 37  is an enlarged perspective view, as seen from the bottom of the loading and lock out mechanism, according to the alternative embodiment of the present invention, with a staple cartridge in place thereon; 
       FIG. 38  is a partially exploded enlarged perspective view, as seen from the bottom of the loading and lock out mechanism shown in  FIG. 38 ; 
       FIG. 39  is an enlarged perspective view similar to  FIG. 36 , with a staple cartridge in place; 
       FIG. 40  is an enlarged side perspective view which shows the relative positioning of the loading and lockout mechanism with a staple cartridge installed and with an anvil half-section in place in a clamped condition; 
       FIG. 41  is a perspective view of the surgical stapler apparatus opened from an anvil half-section side with an anvil half-section clamp lever opened and a cartridge half-section clamp lever closed; 
       FIG. 42  is a perspective view of the surgical stapler apparatus opened from a cartridge half-section side with a cartridge half-section clamp lever opened and an anvil half-section clamp lever closed; 
       FIG. 43  is a perspective view with parts separated which shows the structural relationship of the various components of a clamp lever lockout and safety interlock mechanism; 
       FIG. 44  is a cross-sectional view of the surgical stapler taken along the longitudinal center line thereof; 
       FIG. 45  is an enlarged view of the indicated area of detail of  FIG. 44 ; 
       FIG. 46  is an enlarged view of the indicated area of detail of  FIG. 44 ; 
       FIG. 47  is a cross-sectional view of the surgical stapler taken along the longitudinal center line thereof; 
       FIG. 48  is an enlarged view of the indicated area of detail of  FIG. 47 ; 
       FIG. 49  is an enlarged view of the indicated area of detail of  FIG. 47 ; 
       FIG. 50  is a perspective view of the cartridge half-section of the surgical stapler apparatus after partial or complete firing with a staple cartridge safety lockout in a locked out position; and 
       FIG. 51  is a perspective view of the surgical stapler apparatus opened from both the cartridge half-section side with the cartridge half-section clamp lever opened and from the anvil half-section side with the anvil half-section clamp lever opened. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Preferred embodiments of the presently disclosed surgical fastener apparatus will now be described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical structural elements. As shown in the drawings and described throughout the following description, as is traditional when referring to relative positioning on a surgical instrument the term “proximal” refers to the end of the apparatus which is closer to the user and the term “distal” refers to the end of the apparatus which is further away from the user. 
   Referring initially to  FIG. 1 , an illustrative embodiment of the presently disclosed surgical fastener apparatus is illustrated therein and designated generally as surgical stapler  10 . Surgical stapler  10  is particularly adapted to apply a plurality of adjacent rows of staples to body tissue clamped in between the instrument&#39;s two principle sections, a cartridge receiving half-section  12  and an anvil half-section  14 . Typical applications of the presently disclosed surgical fastener apparatus are, for example, creating a hemostatic seal in general, thoracic, and urologic surgery for resection, transection and creation of anastomoses. Specific tissue structures in which the instrument may be used are, for example, the stomach, the large and small bowels, lungs and the esophagus. 
     FIGS. 1-7  illustrate one preferred overall ornamental design for the presently disclosed surgical fastener applying apparatus wherein. Each of these various figures illustrates surgical stapler  10  with an anvil tip removed to illustrate the end cross-section profile of the anvil half-section. The anvil tip is the same as the tip on the distal end of the staple cartridge. 
   Referring to  FIGS. 8-10 , surgical stapler  10  is designed for use with a disposable staple cartridge assembly such as single use disposable loading unit (“SULU”)  16  includes a cartridge body  18 , a plurality of staple pusher members  20 , a bottom cover  22 , a knife  24  having an angled sharpened leading edge  24   a , a plurality of staples  26 , a pivotably mounted safety lockout  28  and a removable shipping wedge  30 . As with known staple cartridge designs, cartridge body  18  has a plurality of rows of staple retaining slots  32  formed therein. Surgical stapler  10  may be manufactured and assembled in different sizes to receive different size SULUs  16 . For example, surgical stapler  10  can be made in different sizes to accept SULUs having staple line lengths of 60 mm, 80 mm, and 100 mm. 
   Alternatively, SULUs  16  may be adapted such that one common surgical stapler  10  will accept multiple different staple count SULUs. For example, SULUs  16  may be configured such that each different staple count SULU shares a common size cartridge body  18  to facilitate mounting on surgical stapler  10 . 
   In the illustrated embodiment, there are two staggered rows of slots  32  formed on either side of a linear slotted track  34  which guides knife  24  during its longitudinal movement. A single staple  26  is positioned in each of slots  32 . The staple rows preferably extend a distance distally beyond the distal end of knife track  34  to facilitate staple formation beyond the stroke length of knife  24 . 
   Staple pushers  20  are aligned one each with slots  32  such that a single staple pusher  20  is positioned under the staple  26  retained in slot  32 . Staple pushers  20  are formed such that they are attached to each other in groups of two offset oriented pusher pairs, shown schematically in  FIG. 10 , and have an actuating surface connecting each pair of two pushers  20 . 
   The pusher pairs are arranged in two series, one on each side of slotted track  34 , such that the actuating surfaces of each series of pusher pairs forms a line centered between the staggered row of staples  26 . The actuating surfaces act as cam followers and interact with a pair of staggered camming surfaces  36 ,  38  (see  FIG. 11 ) extending from a cam bar channel  40  to expel the pairs of staples  26  on each side of the knife track  34 . As illustrated, camming surfaces  36 ,  38  form a single angle relative to horizontal. In certain application, for example, with staples having an unformed leg height of about 4.5 mm, camming surfaces  36 ,  38  may be formed of a plurality of angles to facilitate optimal staple deformation with a given firing force. As cam bar channel  40  is moved distally this sequence is repeated until the distal movement of cam bar channel  40  is either stopped intentionally by the user to form less than all of staples  26  or until all of staples  26  are expelled from SULU  16 . 
   Bottom cover  22  partially encloses the bottom of a channel formed by the upper surface and side walls of cartridge body  18 . A longitudinal ridge  22   a  is formed on the upper surface of bottom cover  22  and serves as a bearing surface for knife bearing channel  42  secured to the bottom edge of knife  24  as it travels in knife track  34 . A pair of slots are formed one on either side of longitudinal ridge  22   a . The outer limit of each slot being defined by the outer wall of cartridge body  18  on the respective side of ridge  22   a . These slots facilitate reciprocating longitudinal movement of the camming surface extensions  36 ,  38  of cam bar channel  40 . Knife bearing channel  42  which is wider than knife track  34 , is secured to the bottom surface of the knife such that knife bearing channel member  42  rides between knife track  34  and longitudinal ridge  22   a  of bottom cover  22 . In this manner, knife  24  is prevented from undergoing substantial vertical movement during longitudinal translation in knife track  34 . 
   Safety lockout  28  is pivotably disposed on the upper proximal end of cartridge body  18  and is movable from a locked orientation to an unlocked orientation. Preferably, safety lockout  28  is biased away from the locked orientation towards an orientation substantially perpendicular to the longitudinal axis of cartridge body  18 . Any suitable bias member may be utilized such as, for example, springs  44 ,  46 . To overcome the bias towards the perpendicular orientation, safety lockout  28  includes a transverse horizontal surface  28   a  (see  FIG. 24 ) formed on the underside thereof which engages a hook  24   b  formed on the upper edge surface of knife  24 . This cooperative engagement serves to retain safety lockout  28  in the locked orientation wherein safety lockout  28  covers knife  24 . 
   When surgical stapler  10  has been unclamped, as will be described in greater detail further herein, after either partial or complete firing, safety lockout  28  is biased to the perpendicular orientation (see  FIGS. 17 and 18 ), extending upwardly away from cartridge half-section  12 . In this manner, surgical stapler  10  cannot be re-clamped until the partial or completely fired SULU  16  is removed and replaced with a new SULU  16 . Safety lockout  28  also provides a cut-out grasping surface  28   b  with which SULU  16  may readily be removed from surgical stapler  10 . 
   As previously noted, shipping wedge  30  is removably attachable to cartridge body  18 . When installed on SULU  16 , shipping wedge  30  covers the entire surface area of the staple rows  26  and knife track  34 . Additionally, shipping wedge  30  includes an abutment  30   a  extending upwardly and proximally from the upper proximal surface of shipping wedge  30 . Abutment  30   a  in cooperation with safety lockout  28  covers sharpened distal edge  24   a  of knife  24 . This feature prevents the knife from being exposed to the user during handling of SULU  16 . Additionally, abutment  30   a  prevents pivotal movement of safety lockout  28  from the locked orientation. Thus, even if SULU  16  is properly loaded on surgical stapler  10 , staples  26  cannot be fired until shipping wedge  30  is first removed. 
   Shipping wedge  30  also includes a post  30   b  extending downwardly from the underside near the proximal end. Post  30   b  fits into a complementary shaped opening  18   c  formed in cartridge body  18  at the proximal end of knife track  34 . With shipping wedge  30  in place, post  30   b  blocks potential distal movement of knife  26 . In an alternative embodiment, SULUs  16  may also be provided without a knife in applications where it is desirable to perform stapling without transection. In such an embodiment, knife  26  is replaced with a blank element to substitute for the knife to interact with safety lockout  28 . 
   Cartridge body  18  is provided with several molded surfaces to facilitate mounting and alignment of SULU  16  with respect to cartridge half-section  12  of surgical stapler  10 . Such alignment facilitating surfaces may be formed at any suitable location on the various components of cartridge body  18  to correspond with complementary surfaces on cartridge half-section  12 . In the illustrated embodiment, locating/alignment feature surfaces  18   a  are formed extending downwardly on either side of SULU  16  near the proximal end thereof and molded surfaces  18   b  are formed on either side of cartridge body  18  near the distal end thereof. When SULU  16  is properly installed on surgical stapler  10 , surfaces  18   a  seat in a pair of notches  48 ,  50  (see  FIG. 13 ) formed in cartridge half-section  12 . 
   Referring to  FIGS. 11-16 , a loading and lockout mechanism for SULU  16  will now be described in detail. In these figures, a channel frame  12   a  (see  FIG. 21 ) of cartridge half-section  12  is not shown so that the loading and lockout mechanism can be illustrated more clearly. The loading and lockout mechanism facilitates loading of SULU  16  and prevents firing of surgical stapler  10  until SULU  16  is properly loaded on cartridge half-section  12  and surgical stapler  10  is properly clamped shut. The loading and lockout mechanism includes a rocker  52  which is pivotably mounted to channel frame  12   a  (see  FIG. 21 ) of cartridge half-section  12  by way of transversely extending post portions  52   a  seating in openings formed through the sidewalls of channel frame  12   a . Post portions  52   a  are provided with angled downwardly oriented surfaces to facilitate assembly of rocker  52  with channel frame  12   a . Rocker  52  is preferably a molded plastic component and is provided with three slots, namely an open bottomed slots  52   b ,  52   c  to permit longitudinal movement of cam bar channel  40  and a closed slot  52   d  to permit passage of a center bar  54 . 
   As best shown in  FIGS. 12 and 14 , rocker  52  is further provided with a downwardly extending blocking surface  52   e  which is in vertical alignment with an opening formed through the bottom surface of cam bar channel  40  when cam bar channel  40  is in its proximal-most position. Rocker  52  is biased, by way of a spring  56  being disposed between downwardly extending leg  52   f  and an end wall  58   a  of a beam member  58 , toward a locked-out position wherein blocking surface  52   e  extends through opening  40   a . In this manner, cam bar channel  40  is prevented from distal longitudinal movement. In versions of surgical stapler  10  using shorter SULUs  16 , beam  58  may be eliminated. 
   Upon loading of SULU  16  on cartridge half-section as shown in  FIGS. 15 and 16 , the spring bias maintains rocker  52  in the locked-out position. It is only when anvil half-section  14  is joined with cartridge half-section  12  and the half-sections clamped together thereby causing downwardly extending leg portions  60   a  formed on either side of anvil half-section channel member  60  to bias against SULU  16 , that rocker  52  is urged to rotate by the camming action of proximal end surface of SULU  16  against the distal end surface of rocker  52 . In this manner, blocking surface  52   e  is moved out of longitudinal alignment with opening  40   a  of cam bar channel  40  thereby permitting distal longitudinal movement thereof. 
   Referring to  FIGS. 17 and 18 , once surgical stapler  10  has been at least partially fired, if the instrument is opened, safety lockout  28  of SULU  16  automatically moves to the perpendicular orientation due to the spring bias mounting thereof. In this orientation, surgical stapler  10  cannot be re-clamped. Thus, if the user desires to apply further staples, SULU  16  must first be removed and replaced with a non-fired SULU  16 . 
   Referring to  FIGS. 19-21 , surgical stapler  10  is provided with dual selectable clamping levers  62 ,  64  and a pivotably mounted firing lever  65 . Clamping levers  62 ,  64  provide the user with the uniquely novel option of opening surgical stapler  10  from either half-section  12  or  14 . Additionally, firing lever  65  provides the user with the ability to fire surgical stapler  10  from either the left or right side. 
   Clamping levers  62 ,  64  are pivotably mounted to cartridge half-section  12  and anvil half-section  14 , respectively. A pair of ergonomic contoured handles  66 ,  68  are secured to clamping levers  62 ,  64 , respectively to provide the user with a convenient gripping handle. To further enhance the gripping of surgical stapler  10  by the user, a pair of friction enhancing inserts  70 ,  72  are secured to handles  66 ,  68 . Inserts  70 ,  72  may be formed of any suitable friction enhancing materials, for example, rubber. Half-sections  12  and  14  are preferably configured and dimensioned to provide the ability for the user to reach around both halves and comfortably close surgical stapler  10  with a one-handed operation to approximate the captured tissue. 
   Referring to  FIGS. 21-23 ,  25 - 27  and  29 , a clamp latch and safety interlock mechanism is provided at the proximal end of surgical stapler  10 . The clamp latch and safety interlock mechanism serves to retain clamp levers  62 ,  64  in a clamped orientation as well as to provide a safety interlock which prevents opening of either clamp lever  62   64  once firing lever  65  is moved distally. Each half section  12  and  14  is provided with a clamp latch and safety interlock assembly which is essentially the same and which work to latch clamp levers  62 ,  64  in a clamped configuration upon squeezing the clamp levers  62 ,  64  to the closed position. Accordingly, the following description of the various components which make up the assembly will be directed to that for the cartridge half-section  12  as shown in  FIG. 21 . 
   The clamp latch and safety interlock mechanism includes a distal clamp lever latch  74  and a proximal interlock latch  76  which is spring biased distally toward a latched position. When surgical stapler  10  is in the clamped configuration with firing lever  65  in the proximal-most position, a firing slide block  78  biases latch  76  proximally to overcome the distal spring bias, as shown in  FIG. 25 , to position ledge  76   a  of latch  76  out of lateral alignment with proximal ledge  74   a  formed on latch  74  thereby positioning latch  76  in an unlatched position. In this position, the user may unclamp either clamp lever  62 ,  64  by squeezing spring biased finger pad portions  80   a ,  80   b  of latch handle release member  80  which urges latch  74  proximally such that distal ledge  74   b  is moved out of lateral alignment with the blocking structure formed on cartridge half-section  12   a  or anvil half-section  14   a  (not shown). 
   Once firing lever  65  is moved distally to begin the firing sequence of surgical stapler  10 , as shown in  FIGS. 26 ,  27  and  29 , slide block  78  also moves distally thereby removing the biasing force which overcame the distal spring bias of latch  76 . Thus, ledge  76   a  moves in to lateral alignment with ledge  74   a  of latch  74  thereby preventing clamp lever  62  from being opened until firing lever  65  is once again moved to the proximal-most position. The instrument is thereby prevented from opening during the firing stroke. 
   Upon initial distal movement, firing lever  65  becomes locked-out from pivotal movement by way of firing lever  65  being cammed downwardly to overcome an upward spring bias, as shown in the operationally progressive views of  FIGS. 25 and 29 . In particular, as best shown in  FIG. 30 , recessed notches  65   a ,  65   b  are formed as keyways which engage a key  78   a  formed on slide block  78 , respectively depending upon which side firing lever  65  is rotated to during firing. Firing lever  65  can be returned to the proximal-most position at any time during the firing stroke. Firing lever  65  must be returned to the proximal-most position before the levers can be released and the instrument unclamped. As described previously, if the instrument is opened after firing either partially or completely, safety lockout  28  on SULU  16  is configured to prevent the user from re-clamping the instrument. 
   Turning now to  FIGS. 31-51 , an alternative embodiment of a disposable staple cartridge assembly is generally shown as  116 . Staple cartridge assembly  116  includes a cartridge body  118 , a plurality of staple pusher members  120 , a bottom cover  122 , a knife  124  having an angled sharpened leading edge  124   a , a plurality of staples  126 , a pivotably mounted safety lockout  128  and a removable shipping wedge  130 . As with known staple cartridge designs, cartridge body  118  has a plurality of rows of staple retaining slots  132  formed therein. 
   Alternatively, cartridge assembly  116  may be adapted such that one common surgical stapler  100  (see  FIGS. 41 and 42 ) will accept multiple different staple count cartridge assemblies  116 . For example, cartridge assembly  116  may be configured such that each different staple count cartridge assembly  116  shares a common size cartridge body  118  to facilitate mounting on surgical stapler  100 . 
   In the present illustrated embodiment, there are two staggered rows of slots  132  formed on either side of a linear slotted track  134  which guides knife  124  during its longitudinal movement. A single staple  126  is positioned in each of slots  132 . The staple rows preferably extend a distance distally beyond the distal end of knife track  134  to facilitate staple formation beyond the stroke length of knife  124 . Staple pushers  120  are formed such that they are attached to each other in groups of two offset oriented pusher pairs. 
   The pusher pairs are arranged in two series, one on each side of slotted track  134 , such that the actuating surfaces of each series of pusher pairs forms a line centered between the staggered row of staples  126 . The actuating surfaces act as cam followers and interact with a pair of staggered camming surfaces  136  and  138  (see  FIGS. 34-36 ) extending from a pair of cam bars  140  to expel the pairs of staples  126  on each side of the knife track  134 . As illustrated, camming surfaces  136  and  138  form a single angle relative to horizontal. As each cam bar  140  is moved distally this sequence is repeated until the distal movement of each cam bar  140  is either stopped intentionally by the user to form less than all of staples  126  or until all of staples  126  are expelled from cartridge assembly  116 . 
   Bottom cover  122  partially encloses the bottom of a channel formed by the upper surface and side walls of cartridge body  118 . A longitudinal ridge  122   a  is formed on the upper surface of bottom cover  122  and serves as bearing surface for knife bearing channel  142 , secured to the bottom edge of knife  124 , as knife  124  travels in knife track  134 . A pair of slots are formed one on either side of longitudinal ridge  122   a . The outer limit of each slot being defined by the outer wall of cartridge body  118  on the respective side of ridge  122   a . These slots facilitate reciprocating longitudinal movement of the camming surface extensions  136 ,  138  of each cam bar  140 . Knife bearing channel  142  which is wider than knife track  134 , is secured to the bottom surface of the knife such that knife bearing channel member  142  rides between knife track  134  and longitudinal ridge  122   a  of bottom cover  122 . In this manner, knife  124  is prevented from undergoing substantial vertical movement during longitudinal translation in knife track  134 . 
   Safety lockout  128  is pivotably disposed on the upper proximal end of cartridge body  118  and is movable from a locked orientation to an unlocked orientation. Preferably, safety lockout  128  is biased away from the locked orientation towards an orientation substantially perpendicular to the longitudinal axis of cartridge body  118 . Any suitable bias member may be utilized such as, for example, spring  144 . To overcome the bias towards the perpendicular orientation, safety lockout  128  includes a transverse horizontal surface  128   a  (see  FIG. 45 ) formed on the underside thereof which engages a hook  124   b  formed on the upper edge surface of knife  124 . This cooperative engagement serves to retain safety lockout  128  in the locked orientation when safety lockout  128  covers knife  124 . 
   When surgical stapler  100  has been unclamped, as will be described in greater detail further herein, after either partial or complete firing, safety lockout  128  is biased to the perpendicular orientation (see  FIG. 50 ), extending upwardly away from cartridge half-section  112 . In this manner, surgical stapler  100  cannot be re-clamped until the partial or completely fired cartridge assembly  116  is removed and replaced with a new cartridge assembly  116 . Safety lockout  128  also provides a cut-out grasping surface  128   b  with which cartridge assembly  116  may readily be removed from surgical stapler  100 . 
   As previously noted, shipping wedge  130  is removably attachable to cartridge body  118 . When installed on cartridge assembly  116 , shipping wedge  130  covers the entire surface area of the staple rows  126  and knife track  134 . Shipping wedge  130  includes a post  130   b  extending downwardly from the underside near the proximal end thereof. Post  130   b  fits into a complementary shaped opening  118   c  formed in cartridge body  118  at the proximal end of knife track  134 . With shipping wedge  130  in place, post  130   b  blocks potential distal movement of knife  126 . Post  130   b  maintains knife  134  retained within safety lockout  128  thereby ensuring that the sharpened distal edge  124   a  of knife  124  is covered. Once again, cartridge assembly  116  may be provided without a knife in applications where it is desirable to perform stapling without transection. In such an embodiment, knife  126  is replaced with a blank element to substitute for the knife to interact with safety lockout  128 . 
   Cartridge body  118  includes a series of finger grips  127  formed along the upper sides of the body  118  near a proximal end thereof. The finger grips  127  assist the user in gripping the cartridge assembly  116  for both installation and removal of the cartridge assembly  116  from the cartridge half-section  112 . Cartridge body  118  also includes a pair of resilient friction fingers  129  disposed on either side near a proximal end thereof. Friction fingers  129  are configured and adapted to project outwardly from the cartridge body  118  and to frictionally engage the inner surface of the cartridge half-section  112 . In this manner, the friction fingers  129  prevent the cartridge assembly  116  from falling out of the cartridge half-section  112 . 
   Referring to  FIGS. 35-40 , a loading and lockout mechanism for cartridge assembly  116  will now be described in detail. The loading and lockout mechanism facilitates loading of cartridge assembly  116  and prevents firing of surgical stapler  100  until cartridge assembly  116  is properly loaded on cartridge half-section  112  and surgical stapler  100  is properly clamped shut. The loading and lockout mechanism includes a rocker  152  which is pivotably mounted to a channel frame  112   a  (see  FIG. 43 ) of cartridge half-section  112  by way of transversely extending post portions  152   a  seating in openings formed through the sidewalls of channel frame  112   a . Post portions  152   a  are provided with angled downwardly oriented surfaces to facilitate assembly of rocker  152  with channel frame  112   a . Rocker  152  is preferably a molded plastic component and is provided with three slots, namely an open bottomed slots  152   b ,  152   c  to permit longitudinal movement of cam bar channel  140  and a closed slot  152   d  to permit passage of a center bar  154 . 
   As best shown in  FIGS. 37 and 39 , rocker  152  is further provided with a downwardly extending blocking surface  152   e  which is in vertical alignment with an opening  140   a  formed through the bottom surface of each cam bar  140  when each cam bar  140  is in its proximal-most position. Rocker  152  is biased, by way of a spring  156  which is disposed on transversely extending post portion  152   a  and between a ridge  152   f  formed on a side of the rocker  152  and upper surface of the cartridge half section  112  (see  FIG. 35 ), toward a locked-out position wherein blocking surface  152   e  extends through opening  140   a . In this manner, each cam bar  140  is prevented from distal longitudinal movement. 
   Upon loading cartridge assembly  116  on cartridge half-section  112  as shown in  FIGS. 37-40  and, the spring bias maintains rocker  152  in the locked-out position. It is only when anvil half-section  114  is joined with cartridge half-section  112  and the half-sections clamped together thereby causing downwardly extending leg portions  160   a  formed on either side of anvil half-section channel member  160  to bias against cartridge assembly  116 , that rocker  152  is urged to rotate by the camming action of proximal end surface of cartridge assembly  116  against the distal end surface of rocker  152 . In this manner, blocking surface  152   e  is moved out of longitudinal alignment with opening  140   a  of each cam bar  140  thereby permitting distal longitudinal movement thereof. 
   Similar to the first embodiment once surgical stapler  100  has been at least partially fired, if the instrument is opened, safety lockout  128  of cartridge assembly  116  automatically moves to the perpendicular orientation due to the spring bias mounting thereof. In this orientation, surgical stapler  100  cannot be re-clamped. Thus, if the user desires to apply further staples, fired or partially fired cartridge assemblies  116  must first be removed and replaced with a non-fired cartridge assembly  116 . 
   Referring to  FIGS. 41 and 42 , surgical stapler  100  is provided with dual selectable clamping levers  162  and  164  and a pivotably mounted firing lever  165 . Like clamping levers  62  and  64  of the first embodiment, clamping levers  162  and  164  of the present embodiment provide the user with the uniquely novel option of opening surgical stapler  100  from either half-section  112  or  114 . Additionally, firing lever  165  provides the user with the ability to fire surgical stapler  100  from either the left or right side. 
   Clamping levers  162  and  164  are pivotably mounted to cartridge half-section  112  and anvil half-section  114 , respectively. Clamping levers  162  and  164  provide the user with the ability to open the surgical stapler from either the anvil half-section  114 , as seen in  FIG. 41 , the cartridge half-section  112 , as seen in  FIG. 42 , or simultaneously from both the cartridge half-section  112  and the anvil half-section  114 , as seen in  FIG. 51 . A pair of ergonomic contoured handles  166  and  168  are secured to clamping levers  162  and  164 , respectively to provide the user with a convenient gripping handle. To further enhance the gripping of surgical stapler  100  by the user, a pair of friction enhancing inserts  170  and  172  are secured to handles  166  and  168 . 
   Unlike the first embodiment, the surgical stapler  100  according to the alternative embodiment does not have a safety interlock mechanism. In this manner, the user can open the surgical stapler  100  after a complete or partial firing of the cartridge assembly  116 . Referring now to  FIGS. 43-49 , a clamp latch mechanism, according to the alternative embodiment, is provided at the proximal end of surgical stapler  100  which serves to retain clamp levers  162  and  164  in a clamped orientation. Each half section  112  and  114  is provided with a clamp latch mechanism which is essentially the same and which works to latch clamp levers  162  and  164  in a clamped configuration upon squeezing the clamp levers  162  and  164  to the closed position. Accordingly, the following description of the various components which make up the clamp latch mechanism will be directed to that for the cartridge half-section  112 . 
   As shown in  FIG. 43 , the clamp latch mechanism includes a distal clamp lever latch  174  formed at a proximal end of the cartridge half-section  112  and latch handle release member  180  operatively coupled to a proximal end of clamp lever  162 . Latch handle release member  180  is spring biased proximally toward a latched position and is provided with a catch  182  for engaging clamp lever latch  174 . In order to release clamp lever  162 , the user presses release member  180  in the distal direction, thereby disengaging catch  182  from latch  174 . 
   In order to prevent inadvertent opening of the clamp lever  162 , release member  180  is provided with a projection  184  extending downwardly from a proximal end thereof, which projection  184  is seated within a guard  186  formed at the proximal end of the lever  162 . It is envisioned that the guard  186  can be integral with the handles  166  and  168  and made of a resilient material to enable the user to more easily move the guard  186  and thereby depress the release member  180 . 
   Further, as seen in  FIG. 43 , surgical stapler  100  is provided with a firing lever slide block  188 . Slide block  188  included a hub  190  projecting therefrom and configured and adapted to be received in a pivot hole  192  formed in firing lever  165 . Slide block  188  is configured and adapted to be slidably received in either the cartridge half-section  112  or the anvil half-section  114 . In use, the firing lever  165  is pivotable about hub  190  thereby providing the user with the ability to manipulate the firing lever  165  from either side of the surgical stapler  100 . 
   As seen in  FIGS. 41-43  and  50 , surgical stapler  100  is provided with a staple gap adjustment mechanism  200  which enables each stapler  100  to be manufactured and assembled with a very precise staple gap between the cartridge assembly and the anvil structure of the surgical stapler. The staple gap adjustment mechanism  200  is the subject of commonly owned and co-pending U.S. provisional patent application Ser. No. 60/327,369, filed on Oct. 5, 2001, entitled “Surgical Stapling Apparatus”, the entire contents of which are incorporated herein by reference. According to the present embodiment gap adjustment mechanism  200  includes a pair of upstanding hinge plates  202  formed along the sides of the cartridge half-section  112  and an eccentric cam  206 . Each hinge plate  202  is provided with a coaxial through hole  204  formed therein and is configured and adapted to receive the eccentric cam  206  therein. In use, as the eccentric cam  206  is rotated, the eccentric cam  206  presses against the anvil half-section  114  until the desired staple gap between the anvil half-section  114  and the cartridge half section  112  is achieved. At which point the eccentric cam  206  is fixedly secured in the through holes  204 . 
   It will be understood that various modifications may be made to the embodiments of the surgical fastener applying apparatus disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.