Patent Publication Number: US-2022211369-A1

Title: Surgical stapling device with firing lockout mechanism

Description:
FIELD 
     The disclosure is directed to surgical stapling devices and, more particularly, to surgical stapling devices with lockout mechanisms to prevent firing of the stapling device with a spent staple cartridge. 
     BACKGROUND 
     Surgical stapling devices for simultaneously stapling and cutting tissue are well known in the art. Typically, these stapling devices include a tool assembly and a drive assembly. The tool assembly includes an anvil assembly and a cartridge assembly having a staple cartridge including a knife and an actuation sled. The drive assembly is movable in relation to the anvil and cartridge assemblies to move the tool assembly between open and clamped positions and to advance the knife and actuation sled to eject staples from the staple cartridge and cut tissue clamped between the anvil and cartridge assemblies. After the stapling device is fired, the actuation sled remains in an advanced position within the tool assembly. 
     In some stapling devices, the staple cartridge is received within a channel member of the cartridge assembly and is replaceable to facilitate reuse of the stapling device. In order to prevent advancement of the knife of the tool assembly after the staples have been fired from the staple cartridge, the tool assembly may include a lockout assembly. The lockout assembly is movable from an unlocked position to a locked position into engagement with the drive assembly when the sled is in its advanced position to prevent readvancement of the drive assembly. In some stapling devices, the lockout assembly is movable to the unlocked position in response to insertion of a new staple cartridge into the channel member. 
     A continuing need exists for a lock mechanism of simple construction that can prevent advancement of a drive assembly of a stapling device when a spent staple cartridge is positioned within the channel member of the cartridge assembly. 
     SUMMARY 
     This disclosure is directed to a surgical stapling device having a tool assembly that includes an anvil and a cartridge assembly that are movable in relation to each other between open and clamped positions. The cartridge assembly includes a staple cartridge that can be replaced after each firing of the stapling device to facilitate reuse of the stapling device. The anvil includes a lockout mechanism that prevents operation of the stapling device when the staple cartridge has been previously fired. The lockout mechanism moves from a locked position to an unlocked position when the staple cartridge is replaced and the tool assembly is moved from the open position to the clamped position. 
     One aspect of the disclosure is directed to a surgical stapling device including an elongate body, a tool assembly, a lock mechanism, and a drive assembly. The elongate body has a proximal portion and a distal portion. The tool assembly is supported on the distal portion of the elongate body and includes an anvil and a cartridge assembly. The cartridge assembly includes a channel member and a staple cartridge that is removably received within the channel member. The staple cartridge includes a cartridge body, staples, and an actuation sled assembly including an actuation sled and a knife supported on the actuation sled. The actuation sled assembly is movable through the cartridge body between retracted and advanced positions. The anvil includes an anvil body and is coupled to the cartridge assembly such that the tool assembly is movable between open and clamped positions. The lock mechanism is supported on the anvil and includes a lock member that is movable between a locked position and an unlocked position in response to movement of the tool assembly from the open position to the clamped position. The drive assembly includes a clamp member that is movable in relation to the tool assembly between retracted and advanced positions. The lock member is positioned to prevent movement of the clamp member from the retracted position to the advanced position in the locked position. 
     Another aspect of the disclosure is directed to an anvil assembly that includes an anvil and a lock mechanism. The anvil includes an anvil body having a staple forming surface that defines a plurality of staple forming pockets and a central knife slot. The staple forming pockets are positioned on opposite sides of the central knife slot. The lock mechanism is supported on the anvil body and includes a lock member that is movable between a locked position and an unlocked position. 
     In aspects of the disclosure, the lock member is biased to the locked position. 
     In some aspects of the disclosure, the lock member engages the actuation sled assembly when the actuation sled assembly is in its retracted position to retain the lock member in the unlocked position. 
     In certain aspects of the disclosure, the lock mechanism includes a pivot member that pivotably secures the lock member to the anvil body. 
     In aspects of the disclosure, the lock mechanism includes a biasing member for urging the lock member towards the locked position. 
     In some aspects of the disclosure, the biasing member includes a torsion spring. 
     In certain aspects of the disclosure, the lock mechanism includes a dowel that extends through the anvil body and engages the lock member to prevent outward movement of the lock member. 
     In aspects of the disclosure, the lock member is secured to the anvil body in cantilevered fashion and includes a resilient arm that is deformable to move the lock member from the locked position to the unlocked position. 
     In some aspects of the disclosure, the lock mechanism includes a biasing mechanism that is supported on the anvil body and is positioned to urge the arm of the lock member towards the locked position. 
     In certain aspects of the disclosure, the biasing mechanism includes a post and a coil spring that is positioned about the post and is engaged with the arm of the lock member to urge the lock member towards the locked position. 
     In aspects of the disclosure, the lock mechanism includes a lock plate and the lock member, and the anvil body defines first and second through bores. 
     In some aspects of the disclosure, the lock plate includes a clevis and a guide member, and the clevis extends through the first through bore and is pivotably coupled to the lock member and the guide member extends through the second through bore. 
     In certain aspects of the disclosure, the lock member is pivotable between the locked and unlocked positions. 
     In aspects of the disclosure, the anvil body includes an outer surface that defines a recess and the lock plate is received within the recess and is movable between raised and lowered positions. 
     In some aspects of the disclosure, the raised position corresponds to the locked position of the lock member and the lowered position corresponds to the unlocked position of the lock plate. 
     In certain aspects of the disclosure, the lock mechanism includes a first biasing member that is positioned to urge the lock plate towards the lowered position. 
     In aspects of the disclosure, the lock mechanism includes a second biasing member that is positioned to urge the lock member towards the locked position. 
     Other features of the disclosure will be appreciated from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of the disclosure are described herein below with reference to the drawings, wherein: 
         FIG. 1  is side perspective view of a surgical stapling device including a tool assembly having a locking mechanism according to aspects of the disclosure with the tool assembly in an open position; 
         FIG. 2  is an enlarged view of the indicated area of detail shown in  FIG. 1 ; 
         FIG. 3  is a side perspective view the tool assembly shown in  FIG. 2  with the tool assembly in a clamped position; 
         FIG. 4  is a side perspective view of a clamp member of a drive assembly of the stapling device shown in  FIG. 1 ; 
         FIG. 5  is a side perspective view of a knife and actuation sled of the tool assembly shown in  FIG. 3 ; 
         FIG. 6  is a side perspective view of the clamp member, actuation sled, and knife shown in  FIGS. 4 and 5  with the clamp member engaged with the actuation sled; 
         FIG. 7  is a perspective view of the anvil of the tool assembly shown in  FIG. 3  with a lock mechanism secured to the anvil; 
         FIG. 8  is a perspective view of the anvil and lock mechanism shown in  FIG. 7  with the lock mechanism separated from the anvil; 
         FIG. 9  is a cross-sectional view taken along section line  9 - 9  of  FIG. 3  with the lock mechanism in an unlocked position; 
         FIG. 10  is a side perspective view of the clamp member, the actuation sled, and the lock mechanism of the tool assembly shown in  FIG. 9  with the lock mechanism in an unlocked position; 
         FIG. 11  is a cross-sectional view taken along section line  11 - 11  of  FIG. 9 ; 
         FIG. 12  is a cross-sectional view taken through the tool assembly with the lock mechanism in an unlocked position; 
         FIG. 13  is a side perspective view of the clamp member, the actuation sled, and the lock mechanism of the tool assembly shown in  FIG. 12  with the lock mechanism in a locked position; 
         FIG. 14  is a cross-sectional view taken along section line  14 - 14  of  FIG. 12 ; 
         FIG. 15  is a perspective view of an alternate version of the anvil and lock mechanism of the tool assembly of the stapling device shown in  FIG. 1 ; 
         FIG. 16  is a perspective view of the anvil and lock mechanism shown in  FIG. 15  with the lock mechanism separated from the anvil; 
         FIG. 17  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 1  and the lock mechanism shown in  FIG. 16  with the lock mechanism in an unlocked position; 
         FIG. 18  is a cross-sectional view taken through the tool assembly with the lock mechanism shown in  FIG. 17  in an unlocked position; 
         FIG. 19  is a side perspective view of the tool assembly shown in  FIG. 1 , and the lock mechanism shown in  FIG. 15  with the lock mechanism in the locked position; 
         FIG. 20  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 1  and the lock mechanism shown in  FIG. 19  with the lock mechanism in the locked position; 
         FIG. 21  is a perspective view of another alternate version of the anvil and lock mechanism of the tool assembly of the stapling device shown in  FIG. 1 ; 
         FIG. 22  is a perspective view of the anvil and lock mechanism shown in  FIG. 21  with the lock mechanism separated from the anvil; 
         FIG. 23  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 1  and the lock mechanism shown in  FIG. 22  with the lock mechanism in an unlocked position; 
         FIG. 24  is a cross-sectional view taken through the tool assembly with the lock mechanism shown in  FIG. 23  in the unlocked position; 
         FIG. 25  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 1  and the lock mechanism shown in  FIG. 23  with the lock mechanism in the locked position; 
         FIG. 26  is a side perspective view of the tool assembly shown in  FIG. 1 , and the lock mechanism shown in  FIG. 25  with the lock mechanism in the locked position; 
         FIG. 27  is a perspective view of yet another alternate version of the anvil and lock mechanism of the tool assembly of the stapling device shown in  FIG. 1 ; 
         FIG. 28  is a perspective view of the anvil and lock mechanism shown in  FIG. 27  with the lock mechanism separated from the anvil; 
         FIG. 29  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 1  and the lock mechanism shown in  FIG. 28  with the lock mechanism in an unlocked position; 
         FIG. 30  is a side perspective view taken of an alternate version of the tool assembly of the stapling device shown in  FIG. 1  including the lock mechanism of  FIG. 29 ; 
         FIG. 31  is a cross-sectional view taken along section line  31 - 31  of  FIG. 30 ; 
         FIG. 32  is a side perspective view of the clamp member and the actuation sled of the tool assembly shown in  FIG. 30  with the lock mechanism shown in  FIG. 29  with the lock mechanism in the locked position; 
         FIG. 33  is a side perspective view of the tool assembly of the stapling device shown in  FIG. 30  including the lock mechanism of  FIG. 29  in the locked position; and 
         FIG. 34  is a cross-sectional view taken along section line  34 - 34  of  FIG. 33 . 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed stapling device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the aspects of the disclosure are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the disclosure in virtually any appropriately detailed structure. In addition, directional terms such as front, rear, upper, lower, top, bottom, distal, proximal, and similar terms are used to assist in understanding the description and are not intended to limit the disclosure. 
     In this description, the term “proximal” is used generally to refer to that portion of the device that is closer to a clinician, while the term “distal” is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term “endoscopic” is used generally to refer to endoscopic, laparoscopic, arthroscopic, and/or any other procedure conducted through a small diameter incision or cannula. Further, the term “clinician” is used generally to refer to medical personnel including doctors, nurses, and support personnel. 
     The disclosed surgical stapling device includes a tool assembly and a drive assembly for actuating the tool assembly. The tool assembly includes an anvil and a cartridge assembly that are movable in relation to each other between open and clamped positions. The cartridge assembly includes a channel member and a staple cartridge that is releasably received within the channel member and replaceable to facilitate reuse of the stapling device. The staple cartridge includes a clamp member, a knife, and an actuation sled that are movable through a body of the staple cartridge in response to movement of the drive assembly from a retracted position to an advanced position to move the tool assembly from the open position to the clamped position, to eject staples from the staple cartridge, and to cut tissue clamped between the anvil and the cartridge assembly. The anvil supports a lock mechanism that is movable from a locked position to an unlocked position in response to movement of the tool assembly from the open position to the clamped position. In the locked position, the lock mechanism obstructs movement of the drive assembly from its retracted to its advanced position to prevent operation of the stapling device. In the unlocked position, the lock mechanism is positioned to allow the drive assembly to move from the retracted position to the advanced position to operate the stapling device. 
       FIGS. 1-3  illustrate a surgical stapling device according to aspects of the disclosure shown generally as stapling device  10  which includes a handle assembly  12 , an elongate body  14 , and a tool assembly  100 . The elongate body  14  defines a longitudinal axis “X”. The handle assembly  12  includes a body  18  that defines a hand grip  18   a , a plurality of actuator buttons  20 , a rotation knob  22 , and an articulation lever  24 . The rotation knob  22  is rotatably supported on a distal portion of the body  18  of the handle assembly  12  and supports the elongate body  14  to facilitate rotation of the elongate body  14  and the tool assembly  100  in relation to the handle assembly  12  about the longitudinal axis “X”. The actuator buttons  20  control operation of the various functions of the stapling device  10  including approximation, firing and cutting. The articulation lever  24  is rotatably supported on the rotation knob  22  and is pivotable to effect articulation of the tool assembly  100  in relation to the elongate body  14  about an axis transverse to the longitudinal axis “X” of the elongate body  14 . Although the stapling device  10  is illustrated as an electrically powered stapling device, it is envisioned that the disclosed tool assembly  100  would also be suitable for use with manually powered surgical stapling devices or with a robotic system for robotically controlling a stapling device. U.S. Pat. No. 9,055,943 discloses a surgical stapling device including a powered handle assembly and U.S. Pat. No. 6,241,139 discloses a surgical stapling device including a manually actuated handle assembly. U.S. Pat. No. 9,962,159 discloses a stapling device that is configured for use with a robotic system. 
       FIGS. 2 and 3  illustrate the tool assembly  100  which includes an anvil  102  and a cartridge assembly  104 . The cartridge assembly  104  includes a staple cartridge  106  and a channel member  108  that receives the staple cartridge  106 . In aspects of the disclosure, the staple cartridge  106  is releasably supported within the channel member  108  and is replaceable to facilitate reuse of the tool assembly  100 . The staple cartridge  106  includes a cartridge body  110 , an actuation sled  112  ( FIG. 5 ), and a plurality of staples  114  ( FIG. 9 ). The cartridge body  110  defines a central knife slot  116  and staple receiving pockets  118 . In aspects of the disclosure, the staple receiving pockets  118  are aligned in rows positioned on each side of the central knife slot  116 . Although three rows of staple receiving pockets  118  on each side of the central knife slot  116  are shown in  FIG. 2 , it is envisioned that the cartridge body  110  may define one or more rows of staple receiving pockets  118  on each side of the central knife slot  116 . Each of the staple receiving pockets  118  receives a staple  114 . Although not shown, the staple cartridge  104  also includes pushers that support the staples  114  and are engaged by the actuation sled  112  ( FIG. 5 ) as the actuation sled  112  is advanced through the cartridge body  110  to eject the staples  114  from the cartridge body  110 . More specifically, the actuation sled  112  includes angled cam surfaces  112   a  ( FIG. 5 ) that engage and lift the pushers within the cartridge body  110  of the staple cartridge  104  to eject the staples  114  from the cartridge body  110 . 
       FIGS. 4-7  illustrate the actuation sled  112  of the staple cartridge  106 . In aspects of the disclosure, the actuation sled  112  supports a knife  120  to form an assembly that is movable through the cartridge body  110  from a retracted position to an advanced position. The knife  120  includes a longitudinal body portion  122  and a vertically positioned cutting member  124  that extends from the body  122  through the central knife slot  116  in the cartridge body  110  towards the anvil  102 . 
       FIGS. 7 and 8  illustrate the anvil  102  of the tool assembly  100  which includes an anvil body  130  that has a proximal portion  132  and a distal portion  134 . The distal portion  134  of the anvil body  130  has a staple forming surface  136  that defines staple forming pockets  136   a . The staple forming surface  136  is movable into juxtaposed alignment with the staple cartridge  106  when the tool assembly  100  is moved from the open position to the clamped position to position the staple forming pockets  136   a  in alignment with the staple receiving pockets  118  of the staple cartridge  106 . The anvil body  130  defines a channel  138  and a central knife slot  140  that communicates with the channel  138 . The channel  138  has a proximal portion that is defined by ramped surfaces  142  that are positioned on each side of the central knife slot  140 . The proximal portion  132  of the anvil body  130  includes side flanges  144  that define openings  146 . Each of the openings  146  receives a pivot member  148  ( FIG. 3 ) to pivotably couple the anvil  102  to the channel member  108  of the cartridge assembly  104 . 
     The stapling device  10  ( FIG. 1 ) includes a drive assembly including a drive screw  150  ( FIG. 9 ) and a clamp member  152 . As known in the art, the drive screw  150  is axially fixed but rotatably supported within the cartridge assembly  104 . 
       FIGS. 4-6  illustrate the clamp member  152  which includes a body  154  having a first beam  156 , a second beam  158 , and a central portion  160  that interconnects the first beam  156  and the second beam  158 . The central portion  160  includes a vertical strut  162  and a hub  164 . The vertical strut  162  defines a distal stop surface  172  and has a first end that is secured to the first beam  156  and a second end that is secured to a first side of the hub  164 . The hub  164  has a second side that is connected to the second beam  158 . The hub  164  defines a threaded through bore  166  that receives the drive screw  150 . When the drive screw  150  is rotated within the cartridge assembly  104 , the clamp member  152  is driven longitudinally along the drive screw  150  within the staple cartridge  106  between retracted and advanced positions. 
     The first beam  156  is received within the channel  138  defined within the anvil body  130  of the anvil  102 . When the clamp member  152  moves from its retracted position to its advanced position, the first beam  156  of the clamp member  152  engages the ramped surfaces  142  of the anvil body  130  to pivot the anvil  102  in relation to the cartridge assembly  104  from the open position to the clamped position. The first beam  156  of the clamp member  152  includes a distally extending finger  156   a  that has a downwardly extending projection  170  that slides along the central knife slot  140  ( FIG. 7 ) of the anvil  102  to push tissue from within the knife slot  140 . 
     The second beam  158  is positioned to move within a channel  108   a  ( FIG. 11 ) that extends along the channel member  108  ( FIG. 2 ) of the cartridge assembly  104  as the clamp member  152  moves between its retracted and advanced positions. Engagement of the first and second beams  156  and  158  with the anvil  102  and the cartridge assembly  104 , respectively, sets a maximum tissue gap between the staple forming surface  136  of the anvil  102  and the staple cartridge  106  ( FIG. 2 ) as the clamp member  152  moves through the tool assembly  100 . 
     When the staple cartridge  106  is received within the channel member  108  of the cartridge assembly  104 , the clamp member  152  is positioned proximally of and adjacent to the actuation sled  112 . In this position, the cutting member  124  of the knife  120  is positioned adjacent to the distal stop surface  172  ( FIG. 4 ) of the vertical strut  162  of the clamp member  152 . 
       FIGS. 7 and 8  illustrate a lock mechanism  180  of the tool assembly  100  which includes a lock member  182 , a biasing member  184 , and a pivot member  186 . The lock member  182  includes a circular hub portion  188 , an arm  190  that extends proximally from the hub portion  188 , and a central tab  189 . The central hub  189  includes an angled side wall  189   a . The arm  190  includes a proximal abutment surface  192 . The hub portion  188  is pivotably secured within a circular recess  194  defined in the anvil body  130  ( FIG. 8 ) by the pivot member  186  such that the lock member  182  is pivotable about an axis “Z” ( FIG. 8 ) that is transverse to the longitudinal axis “X” of the tool assembly  100 . The biasing member  184  includes a central hub portion  196  that is received about the pivot member  186  and first and second spring arms  198  and  200 . The first spring arm  198  is secured to the lock member  182  and the second spring arm  200  is received with the circular recess  194  of the anvil body  130  to urge the lock member  182  to a locked position. In the locked position, the proximal abutment surface  192  of the lock arm  182  is axially aligned with the distal stop surface  172  of the clamp member  152  to prevent movement of the clamp member  152  within the tool assembly  100  from the retracted position towards the advanced position. 
     A pin or dowel  204  is inserted through an opening  206  in the anvil body  130 . The dowel  204  defines a flat  208  that engages the arm  190  of the lock member  182  to obstruct outward movement of the lock member  182  towards the anvil body  130  of the anvil  102 . 
       FIGS. 9-11  illustrate the tool assembly  100  in the clamped position with the lock mechanism  180  in the unlocked position. When a new staple cartridge  106 , i.e., unfired, is positioned within the channel member  108  of the cartridge assembly  104  and the tool assembly  100  is moved to the clamped position, the staple forming surface  136  ( FIG. 8 ) of the anvil  102  moves into juxtaposed alignment with the staple cartridge  106 . The cartridge body  110  of the staple cartridge  106  defines a cutout  110   a  ( FIG. 11 ) that receives a portion of the lock member  182  when the tool assembly  100  is moved to the clamped position. As the anvil  102  pivots in relation to the staple cartridge  106 , the angled side wall  189   a  ( FIG. 11 ) of the central tab  189  of the lock member  182  engages the knife  120  to urge the lock member  182  of the lock mechanism  180  against the urging of the biasing member  184  from the locked position ( FIG. 12 ) to the unlocked position ( FIG. 9 ). In the unlocked position, the lock member  182  is engaged with the knife  120  and the proximal abutment surface  192  of the lock arm  182  is maintained in a position outwardly of the distal stop surface  172  of the clamp member  152 . In this position, the stapling device  10  ( FIG. 1 ) can be fired. 
       FIGS. 12-14  illustrate the tool assembly  100  with the lock mechanism  180  in the locked position. When the stapling device  10  is fired, the clamp member  152  is advanced through the tool assembly  100  from a retracted position to an advanced position. As the clamp member  152  moves through the tool assembly  100 , the clamp member  152  abuts and advances the actuation sled  112  and the knife  120  (which is supported on the actuation sled  112 ) through the staple cartridge  106 . Since the actuation sled  112  is only in abutting relationship with the clamp member  152 , when the clamp member  152  is moved from the advanced position back to the retracted position, the actuation sled  112  and the knife  120  remain in the distal end of the staple cartridge  106 . As such, after the stapling device  10  ( FIG. 1 ) is fired and the clamp member  152  is returned to the retracted position, the knife  120  and/or actuation sled  112  are no longer positioned to obstruct movement of the lock member  182  of the lock mechanism  180  from the unlocked position to the locked position. Thus, after the stapling device  10  ( FIG. 1 ) is fired and the clamp member  152  is retracted, the lock member  182  is moved by the biasing member  184  from the unlocked position ( FIG. 9 ) to the locked position ( FIG. 12 ) in which the proximal abutment surface  192  of the lock member  182  is positioned in alignment with the distal stop surface  172  of the clamp member  152  to prevent distal movement (or readvancement) of the clamp member  152 . 
       FIGS. 15-19  illustrate a tool assembly  300  ( FIG. 18 ) including an alternate version of the anvil and lock mechanism of the stapling device  10  ( FIG. 1 ) which are shown generally as anvil  302  and lock mechanism  380 . The anvil  302  is substantially like the anvil  102  ( FIG. 7 ) except that the anvil  302  defines a cutout  304  and a through bore  306 . The anvil  302  includes side flanges  344 . The lock mechanism  380  includes a lock member  382  and a securement member  386 . In aspects of the disclosure, the securement member  386  includes a screw although other securement members are envisioned. The lock member  382  has a resilient arm  390  that includes a proximal portion  390   a  and a distal portion  390   b . The proximal portion  390   a  defines a bore  392  and the distal portion  390   b  includes an abutment member  394  that has an abutment surface  394   a . The proximal portion  390   a  of the lock member  382  is secured to an inner wall of one of the side flanges  344  of the anvil  302  in cantilevered fashion by inserting the screw  386  through the through bore  306  in the side flange  344  of the anvil  302  and the through the bore  392  in the proximal portion  390   a  of the lock member  382  and securing the screw  386  to an inner surface of the anvil  302 . The arm  390  includes a central portion  390   c  of reduced thickness that allows the arm  390  to flex outward from a non-deformed locked position ( FIG. 18 ) to a deformed unlocked position ( FIG. 20 ). 
       FIGS. 17 and 18  illustrate the tool assembly  300  with the anvil  302  in a clamped position and the lock mechanism  380  in an unlocked position. When the anvil  302  is moved to the clamped position ( FIG. 18 ) prior to firing of the stapling device  10 , the abutment member  394  engages the cutting member  124  of the knife  120  to deflect the abutment member  394  outwardly of the distal stop surface  172  of the clamp member  152 . In this position, the clamp member  152  can move along the drive screw  150  from its retracted position towards its advanced position to move the actuation sled  112  and the knife  120  through the staple cartridge  106  to eject staples  114  from the staple cartridge  106  and cut tissue clamped between the anvil  302  and the staple cartridge  106 . 
       FIGS. 19 and 20  illustrate the tool assembly  300  with the anvil  302  in the clamped position and the lock mechanism  380  in the locked position. After the stapling device  10  ( FIG. 1 ) is fired, the actuation sled  112  and the knife  120  ( FIG. 18 ) remain in the distal portion of the staple cartridge  106 . When the clamp member  152  is returned to its retracted position, the resilient arm  390  of the lock member  382  flexes inwardly to its non-deformed position to position the abutment surface  394   a  in alignment with the distal stop surface  172  of the clamp member  152 . In this position, the lock member  382  prevents readvancement of the clamp member  152  within the tool assembly  300 . 
       FIGS. 21-26  illustrate a tool assembly  400  ( FIG. 24 ) including an alternate version of the anvil and lock mechanism of the stapling device  10  ( FIG. 1 ) which are shown generally as anvil  402  and lock mechanism  480 . The anvil  402  is substantially like the anvil  302  ( FIG. 16 ) except that the anvil  402  includes a second through bore  408  that receives a biasing mechanism  484  as described below. The lock mechanism  480  includes a lock member  482 , the biasing mechanism  484 , and a securement member  486 . In aspects of the disclosure, the securement member  486  includes a screw although other securement members are envisioned. The lock member  482  has a resilient arm  490  that includes a proximal portion  490   a  and a distal portion  490   b . The proximal portion  490   a  defines a first bore  492  and the distal portion  490   b  includes an abutment member  494  that has an abutment surface  494   a . The proximal portion  490   a  of the lock member  482  is secured to an inner wall of one of the side flanges  444  of the anvil  402  in cantilevered fashion by inserting the screw  486  through the through bore  406  in the side flange  444  of the anvil  402  and the through the bore  492  in the proximal portion  490   a  of the lock member  482  and securing the screw  486  to an inner surface of the anvil  402 . The arm  490  includes a central portion  490   c  of reduced thickness that allows the arm  490  to flex outward from a non-deformed locked position ( FIG. 24 ) to a deformed unlocked position ( FIG. 26 ). 
     The biasing mechanism  484  includes a post  484   a  and a biasing member  484   b . The post  484   a  extends through the second through bore  408  in the anvil  402  and supports the biasing member  484   b . In aspects of the disclosure, the biasing member  484   b  includes a coil spring that is positioned about the post  484   a  and is engaged with the abutment member  494  of the lock member  482  to urge the arm  490  of the lock member  482  towards the locked position. 
       FIGS. 23 and 24  illustrate the tool assembly  400  with the anvil  402  in a clamped position and the lock mechanism  480  in an unlocked position. When the anvil  402  is moved to the clamped position ( FIG. 24 ) prior to firing of the stapling device  10 , the abutment member  494  engages the cutting member  124  of the knife  120  to deflect the abutment member  494  against the urging of the biasing member  484   b  outwardly of the distal stop surface  172  of the clamp member  152 . In this position, the clamp member  152  can move along the drive screw  150  from its retracted position towards its advanced position to move the actuation sled  112  and the knife  120  through the staple cartridge  106  to eject staples  114  from the staple cartridge  106  and cut tissue clamped between the anvil  402  and the staple cartridge  106 . 
       FIGS. 25 and 26  illustrate the tool assembly  400  with the anvil  402  in the clamped position and the lock mechanism  480  in the locked position. After the stapling device  10  ( FIG. 1 ) is fired, the actuation sled  112  and the knife  120  ( FIG. 26 ) remain in the distal portion of the staple cartridge  106 . When the clamp member  152  is returned to its retracted position, the arm  490  of the lock member  482 , which is urged by the biasing member  484   b , flexes inwardly to its non-deformed position to position the abutment surface  494   a  in alignment with the distal stop surface  172  of the clamp member  152 . In this position, the lock member  482  prevents readvancement of the clamp member  152  within the tool assembly  400 . 
       FIGS. 27-34  illustrate a tool assembly  500  ( FIG. 30 ) including an alternate version of the anvil and lock mechanism of the stapling device  10  ( FIG. 1 ) which are shown generally as anvil  502  and lock mechanism  580 .  FIGS. 27 and 28  illustrate the anvil  502  and the lock mechanism  580 . The anvil  502  is substantially like the anvil  102  ( FIG. 7 ) except that the anvil  502  defines first and second through bores  510  and  512  ( FIG. 28 ) that are positioned on opposite sides of a central knife slot  516  of the anvil  502 . Each of the through bores  510  and  512  is substantially rectangular. In some aspects of the disclosure, the anvil  502  defines circular recesses  514  on each side of the first through bore  510 . 
     The lock mechanism  580  includes a lock member  582 , a lock plate  584 , a first biasing member  586 , a second biasing member  588 , and a pivot member  590 . The lock plate  584  includes a body  584   a  that includes a clevis  592  that extends through the first through bore  510  of the anvil  502  and a guide member  594  that extends through the second through bore  512 . The body  584   a  is received within a recess  596  ( FIG. 30 ) defined in an outer surface of the anvil  502  and is movable between a raised position and a lowered position. 
     The lock member  582 , which may be in the form of a lever, has a first end that is pivotably coupled to the clevis  592  of the lock plate  584  and a second end that defines an abutment member  598  having an abutment surface  598   a . The lock member  582  is movable between an unlocked position ( FIG. 31 ) in which the abutment member  598  is spaced outwardly of the clamp member  152  and a locked position ( FIG. 34 ) in which the abutment member  598  is aligned with the distal stop surface  172  of the clamp member  152  to obstruct advancement of the clamp member  152 . The second biasing member  588  is received in the circular recesses  514  ( FIG. 27 ) in the anvil  502  and engages the pivot member  590  to urge the lock plate  584  towards its lowered position ( FIG. 34 ) within the recess  596  ( FIG. 30 ) in the outer surface of the anvil  502 . In aspects of the disclosure, the second biasing member  588  includes a coil spring. The first biasing member  586  includes a torsion spring and is engaged with the lock member  582  to pivot the lock member  582  about the pivot member  590  towards its locked position. 
       FIGS. 29-31  illustrate the tool assembly  500  with the anvil  502  in the clamped position and the lock mechanism  580  in the unlocked position. In the unlocked position, the abutment  598  of the lock member  582  is engaged with the knife  120  to prevent the lock member  582  from moving to the locked position. Engagement of the abutment member  594  of the lock member  582  with the knife  120  also prevents the second biasing member  588  from moving the lock plate  584  of the lock mechanism to its lowered position. When the lock plate  584  is in its raised position, a clinician is given notice that the knife  120  and the actuation sled  112  ( FIG. 29 ) of the staple cartridge  106  are in their retracted positions and the staple cartridge has yet to be fired. 
       FIGS. 32-34  illustrate the tool assembly  500  with the anvil  502  in the clamped position and the lock mechanism  580  in the locked position. After the stapling device  10  ( FIG. 1 ) is fired, the actuation sled  112  and the knife  120  ( FIG. 29 ) remain in the distal portion of the staple cartridge  106 . As such, when the clamp member  152  is retracted to a position proximally of the abutment member  598  of the lock member  582 , the lock member  582  is urged to its locked position in which the abutment surface  598   a  of the abutment member  598  is aligned with and positioned distally of the distal stop surface  172  of the clamp member  152  to prevent distal movement of the clamp member  152  within the tool assembly  500 . The biasing member  588  also moves the lock plate  584  downwardly in the direction of arrow “A” in  FIG. 32  to the lowered position to indicate to a clinician that the actuation sled  112  and knife  120  ( FIG. 29 ) are not positioned in the proximal portion of the staple cartridge  506  and the stapling device  10  ( FIG. 1 ) is not ready to fire. 
     As described above, each of the lock mechanisms disclosed is supported on the anvil of the tool assembly of the stapling device. By positioning the lock mechanism on the anvil, the lock mechanism remains in a locked position until the tool assembly is moved to the clamped position rather than upon insertion of the staple cartridge into the cartridge assembly of the stapling device. 
     Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims.