Abstract:
A surgical stapling device comprises a housing and a plurality of cartridges that are coupled together to form a barrel that is rotatably supported within the housing. Each of the cartridges defines a plurality of staple pockets that support a plurality of staples. An anvil is pivotally coupled to the housing and is movable in relation to the barrel between an open position and a clamped position. A drive shaft extends through the housing and through the barrel and a pusher operatively connected to the drive shaft. The pusher is configured to translate through the barrel to eject the staples from the plurality of cartridges in response to actuation of the drive shaft. The barrel is positioned within the housing to align a first one of the plurality of cartridges with the anvil to eject the staples from the first cartridge upon movement of the pusher within the barrel through a first firing stroke and subsequently rotatable within the housing to align a second one of the plurality of cartridges with the anvil to eject the staples from the second cartridge upon movement of the pusher within the barrel through a second firing stroke.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Patent Application No. 62/166,979 filed May 27, 2015, the entire disclosure of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    Technical Field 
         [0003]    The present disclosure relates generally to a surgical stapling device for applying surgical fasteners to body tissue. More particularly, the present disclosure relates to a endoscopic surgical stapling device having a plurality of staple cartridges that are sequentially moved into alignment with an anvil assembly to allow a clinician to fire the stapling device a plurality of times without removing the stapling device from the surgical site. 
         [0004]    Background of Related Art 
         [0005]    Surgical stapling devices for joining tissue sections are commonly used in surgical procedures. The use of surgical stapling devices as compared to traditional stitching techniques reduces the time required to join and/or cut tissue, thus, reducing the time required to perform a surgical procedure. Reducing the time required to perform a surgical procedure minimizes the time a patient must be anesthetized and, thus minimizes trauma to the patient. 
         [0006]    During endoscopic or laparoscopic procedures in which surgery is performed through small incisions or through narrow cannulas inserted through the small incisions in the skin, replacement of the staple cartridge or the loading unit after firing requires removal of the surgical stapling device from the incision or cannula, replacement of the staple cartridge and/or loading unit and reinsertion of the surgical stapling device into the incision or cannula. Removal of the surgical stapling device from the incision for cartridge or loading unit replacement increases the time required to perform the surgical procedure. 
         [0007]    It would be advantageous to provide a staple cartridge or loading unit that is capable of being fired a plurality of times before replacement of the staple cartridge or loading unit is required. 
       SUMMARY 
       [0008]    The present disclosure provides, in one aspect, a surgical stapling device including a housing and a plurality of cartridges which are coupled together to form a barrel that is rotatably supported within the housing. Each of the cartridges defines a plurality of staple pockets that support a plurality of staples. An anvil is pivotally coupled to the housing and is movable in relation to the barrel between an open position and a clamped position. A drive shaft extends through the housing and through the barrel. A pusher is operatively connected to the drive shaft and is configured to translate through the barrel to eject the plurality of staples from the plurality of cartridges in response to actuation of the drive shaft. The barrel is positioned within the housing to align a first one of the plurality of cartridges with the anvil to eject the staples from the first cartridge upon movement of the pusher through a first firing stroke and subsequently rotatable within the housing to align a second one of the plurality of cartridges with the anvil to eject the plurality staples from the second cartridge upon movement of the pusher through a second firing stroke. 
         [0009]    In some embodiments, the plurality of cartridges includes three cartridges. 
         [0010]    In certain embodiments, the drive shaft defines a helical thread and the pusher defines a threaded bore. The drive shaft extends through the threaded bore of the pusher such that rotatable movement of the drive shaft causes longitudinal movement of the pusher about the drive shaft and through the barrel. 
         [0011]    In embodiments, an indexer is supported about the drive shaft at a position distal of the pusher. The indexer is operatively engaged with the barrel and adapted to rotate the barrel after the first firing stroke of the pusher to align the second one of the plurality of cartridges with the anvil. 
         [0012]    In some embodiments, the indexer includes a body having a plurality of fins and each of the plurality of cartridges defines a longitudinal channel. Each of the longitudinal channels receives one of the plurality of fins of the indexer to rotatably couple the indexer to the barrel such that rotation of the indexer about the drive shaft causes corresponding rotation of the barrel about the drive shaft. 
         [0013]    In certain embodiments, a distal end of the pusher is positioned to engage the indexer such that distal movement of the pusher within the barrel causes distal movement of the indexer within the barrel. 
         [0014]    In embodiments, the pusher includes a hub and a plurality of flexible arms that extend distally from the hub. The distal end of each of the flexible arms is positioned to engage the indexer to translate distal movement of the pusher into distal movement of the indexer. 
         [0015]    In some embodiments, the indexer includes a body defining an annular rib and the distal end of each of the plurality of flexible arms of the pusher is positioned to engage the annular rib as the pusher is moved distally through the barrel to translate distal movement of the pusher into distal movement of the indexer. 
         [0016]    In certain embodiments, each of the flexible arms includes an inwardly extending protrusion. The inwardly extending protrusion is configured to engage and pass over the annular rib when the indexer reaches its distal-most position within the housing as the pusher is moved independently of the indexer to its distal-most position to releasably couple the pusher and the indexer such that proximal movement of the pusher through a retraction stroke causes corresponding proximal movement of the indexer. 
         [0017]    In embodiments, the indexer body defines a cam slot and the drive shaft includes a shaft pin. The shaft pin is rotatable with the drive shaft and moves within the cam slot of the indexer during the retraction stroke of the pusher to cause rotation of the indexer and the barrel within the housing. 
         [0018]    In some embodiments, the plurality of cartridges is coupled together using dove-tail connectors. 
         [0019]    In certain embodiments, the surgical stapling device includes an annular end cap having a plurality of posts and each of the plurality of cartridges includes a distal end defining a blind bore. The blind bores of the plurality of cartridges receive the posts of the end cap to secure the distal ends of the plurality of cartridges together. 
         [0020]    In embodiments, a ratchet is supported adjacent to the barrel and is configured to permit rotation of the barrel within the housing in a first direction and prevent rotation of the barrel within the housing in a second direction. 
         [0021]    In some embodiments, each of the plurality of cartridges defines a notch that is positioned to receive the ratchet. 
         [0022]    In certain embodiments, the pusher includes a clamping member that is positioned to engage the anvil to move the anvil from the open position to the clamped position. 
         [0023]    In embodiments, the clamp member includes a vertical strut and a beam. The vertical strut extends radially from a hub of the pusher and the beam is positioned transversely to the vertical strut. 
         [0024]    In some embodiments, the vertical strut supports a knife. 
         [0025]    In certain embodiments, the pusher includes a plurality of pusher fingers. Each of the plurality of pusher fingers is positioned to translate through respective slots defined by the plurality of cartridges to engage and eject the plurality of staples from the plurality of cartridges. 
         [0026]    The present disclosure provides, in another aspect, a surgical staple including a backspan, a first leg having a first length extending from one end of the backspan, and a second leg having a second length extending from the other end of the backspan, wherein the first length is greater than the second length. The first and second legs are positioned within a common plane and the backspan has a central portion offset from the common plane. 
         [0027]    In embodiments, the backspan is V-shaped. 
         [0028]    In embodiments, the first length is between 2 and 10 times the second length. 
         [0029]    In some embodiments, the first length is between 4 and 8 times the second length. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Various embodiments of the presently disclosed surgical stapling device are described herein with reference to the drawings, wherein: 
           [0031]      FIG. 1  is a side perspective view from the distal end of one embodiment of the presently disclosed surgical stapling device with the anvil assembly in an clamped position; 
           [0032]      FIG. 2  is a side perspective view from the proximal end of the surgical stapling device shown in  FIG. 1 ; 
           [0033]      FIG. 3  is a side perspective view of the surgical stapling device shown in  FIG. 1  with the housing removed and the anvil assembly in the open position; 
           [0034]      FIG. 4  is a side perspective view of the surgical stapling device shown in  FIG. 3  with the housing and barrel removed and the anvil assembly in the open position; 
           [0035]      FIG. 5  is an exploded perspective view of the surgical stapling device shown in  FIG. 1 ; 
           [0036]      FIG. 6  is a side perspective view from the proximal end of the surgical stapling device shown in  FIG. 1  in an articulated position in relation to a supporting shaft; 
           [0037]      FIG. 7  is a side, exploded, perspective view of the universal joint of the surgical stapling device shown in  FIG. 6 ; 
           [0038]      FIG. 8  is a side exploded, perspective view of one of the cartridges of the surgical stapling device shown in  FIG. 1 ; 
           [0039]      FIG. 9  is a side cross-sectional view through a portion of the cartridge shown in  FIG. 8  with the staples positioned in the staple pockets of the cartridge; 
           [0040]      FIG. 9A  is a cross-sectional view taken along sectionline  9 A- 9 A of  FIG. 8 ; 
           [0041]      FIG. 10  is a side perspective view of one of the staples of the cartridge assembly shown in  FIG. 8 ; 
           [0042]      FIG. 11  is a side exploded, perspective view of the drive shaft, indexer and pusher of the surgical stapling device shown in  FIG. 1 ; 
           [0043]      FIG. 12  is a side perspective view of the drive shaft, indexer and pusher of the surgical stapling device shown in  FIG. 11  with the components assembled; 
           [0044]      FIG. 13  is a perspective view from the distal end of the pusher of the surgical stapling device shown in  FIG. 1 ; 
           [0045]      FIG. 14  is a side perspective view of the indexer of the surgical stapling device shown in  FIG. 1 ; 
           [0046]      FIG. 15  is a side perspective view of the drive shaft, end cap, and bearing and barrel of the surgical stapling device shown in  FIG. 1  with the barrel separated from the other components; 
           [0047]      FIG. 16  is a cross-sectional view taken along section line  16 - 16  of  FIG. 1 ; 
           [0048]      FIG. 17  is a cross-sectional view taken along section line  17 - 17  of  FIG. 1 ; 
           [0049]      FIG. 18  is a side perspective view of the surgical stapling device shown in  FIG. 1  in the open position; 
           [0050]      FIG. 19  is a cross-sectional view taken along section line  19 - 19  of  FIG. 18 ; 
           [0051]      FIG. 20  is an enlarged view of the indicated area of detail shown in  FIG. 19 ; 
           [0052]      FIG. 21  is a side perspective view of the drive shaft, pusher and indexer of the surgical stapling device shown in  FIG. 1  assembled in the start position; 
           [0053]      FIG. 22  is a cross-sectional view taken along section line  22 - 22  of  FIG. 18 ; 
           [0054]      FIG. 23  is a side perspective view of the surgical stapling device shown in  FIG. 1  in the clamped position; 
           [0055]      FIG. 24  is a side cross-sectional view taken along section line  24 - 24  of  FIG. 23 ; 
           [0056]      FIG. 25  is a side perspective view of the surgical stapling device shown in  FIG. 1  as the surgical stapling device is being fired; 
           [0057]      FIG. 26  is a cross-sectional view taken along section line  26 - 26  of  FIG. 25 ; 
           [0058]      FIG. 27  is an enlarged view of the indicated area of detail shown in  FIG. 26 ; 
           [0059]      FIG. 28  is a cross-sectional view taken along section line  28 - 28  of  FIG. 26 ; 
           [0060]      FIG. 29  is a cross-sectional view taken along section line  29 - 29  of  FIG. 26 ; 
           [0061]      FIG. 30  is a side view of the distal end of the surgical stapling device shown in  FIG. 1  after the pusher has been moved to the fully advanced position and the staples from one of the plurality of cartridges have been fired; 
           [0062]      FIG. 31  is a side cross-sectional view of the distal end of the surgical stapling device shown in  FIG. 30  after the pusher has been moved to the fully advanced position and the staples from one of the plurality of cartridges have been fired; 
           [0063]      FIG. 32  is a perspective view of the drive shaft, pusher, indexer and anvil assembly in the position as shown in  FIG. 31 ; 
           [0064]      FIG. 33  is a perspective view of the surgical stapling device shown in  FIG. 26  with the housing and barrel removed and the pusher and indexer being moved towards the retracted position; 
           [0065]      FIG. 34  is a side perspective view of the drive shaft, pusher and indexer as the indexer is rotating the barrel; 
           [0066]      FIG. 35  is a cross-sectional view taken through the surgical stapling device and the indexer as the indexer rotates the barrel; and 
           [0067]      FIG. 36  is a top view of the proximal end of the surgical stapling device shown in  FIG. 1  with the housing removed illustrating the locking ratchet; 
           [0068]      FIG. 37  is a side cross-sectional view of the surgical stapling device shown in  FIG. 25  after the device has been fired and the pusher has been moved to its proximal-most position; 
           [0069]      FIG. 38  is a side perspective view of the drive shaft, pusher and indexer after the indexer has rotated the barrel; and 
           [0070]      FIG. 39  is a side perspective view of the drive shaft, pusher and indexer after the indexer has rotated the barrel and the pusher is being moved from its proximal-most position to uncouple the indexer from the pusher. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0071]    Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term “clinician” refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term “proximal” refers to the portion of the device or component thereof that is closest to the clinician and the term “distal” refers to the portion of the device or component thereof that is farthest from the clinician. In addition, the term “endoscopic procedure”, as used herein, refers to any procedure performed through a small incision in the skin or through one or more cannulas and encompasses laparoscopic procedures, arthroscopic procedures, etc. 
         [0072]    As described in detail below, the presently disclosed surgical stapling device includes a barrel formed by a plurality of cartridges connected to each other that is rotatably supported within a cartridge housing or channel. Each cartridge is sequentially movable into alignment with an anvil and supports an array of staples. A pusher includes a clamping member, a knife and a plurality of pusher fingers that is positioned to engage the staples supported within each cartridge to eject the staples from each of the cartridges. An indexer is provided to rotate the barrel after each use of the surgical stapling device to position a fresh cartridge in alignment with the anvil to facilitate refiring of the stapling device. 
         [0073]      FIGS. 1-4  illustrate one embodiment of the presently disclosed surgical stapling device shown generally as  10 . The surgical stapling device  10  includes a channel or housing  12 , an anvil  14 , and a first clevis  16 . The housing  12  defines a chamber  18  ( FIG. 16 ) which is dimensioned to rotatably receive a cylindrical barrel  20  as described in detail below. The first clevis  16  has a distal end secured within a proximal end of the chamber  18  and a proximal end adapted to engage a drive mechanism  21  ( FIG. 7 ), such as a manually powered handle assembly, or a powered or robotic drive mechanism. The proximal end of the first clevis  16  defines slots  17  ( FIG. 3 ) that are described in further detail below. In one embodiment, the first clevis  16  is secured to the housing  12  with rivets or pins (not shown). Alternately, other fastening techniques can be used to connect the first clevis  16  to the housing  12 , e.g., welding, crimping, etc. The first clevis  16  defines a proximally facing opening  16   a  ( FIG. 2 ) that receives a proximal end  24   a  of a drive shaft  24  ( FIG. 5 ). 
         [0074]    The anvil  14  has a proximal end defining cam surface  14   a  and a pair of spaced flanges  22 . The cam surface  14   a  is provided to facilitate movement of the anvil  14  from an open position to a clamped position as described in detail below. Each of the spaced flanges  22  defines an opening  22   a  that receives a pivot pin (not shown) to pivotally secure the anvil  14  to the housing  12 . The anvil  14  also defines a knife slot  22   b.    
         [0075]    Referring also to  FIG. 5 , the cylindrical barrel  20  ( FIG. 3 ) is formed from a plurality of cartridges  26  that are connected together to define a bore  28  ( FIG. 15 ) that extends the length of the cylindrical barrel  20 . Although three cartridges  26  are shown, it is envisioned that the barrel  20  can be formed from two or more cartridges  26 , e.g., 2, 4, 5, etc. The drive shaft  24  defines a helical thread  30  and has a distal end  24   b  ( FIG. 5 ) positioned adjacent the distal end of the housing  12 . A bearing  32  is supported in the distal end of the housing  12  and supports the distal end  24   b  of the drive shaft  24 . The proximal end  24   a  of the drive shaft  24  is unthreaded and is configured to engage the drive mechanism  21  ( FIG. 7 ). 
         [0076]    Referring to  FIGS. 3-5 , the drive shaft  24  supports a pusher  36  and an indexer  38 . The pusher  36  defines a threaded longitudinally extending bore  40  ( FIG. 5 ) that is dimensioned to engage the helical thread  30  of the drive shaft  24  such that rotational movement of the drive shaft  24  causes linear movement of the pusher  36  as described in detail below. The indexer  38  is positioned distally of the pusher  36  and also defines a longitudinally extending bore  42  ( FIG. 5 ) that is dimensioned to receive the drive shaft  24 . The indexer  38  is positioned distally of the pusher  36  such that distal movement of the pusher  36  causes the indexer  38  to be advanced distally along the drive shaft  24  as described in detail below. 
         [0077]    Referring to  FIGS. 6 and 7 , the first clevis  16  forms a distal portion of the universal joint  46  including a second clevis  48  that is coupled to the first clevis  16  by a swivel mount  50 . The first clevis  16  includes a first pair of spaced fingers  52  each defining an opening  54 . Similarly, the second clevis  48  includes a second pair of spaced fingers  58  each defining an opening  60 . The swivel mount  50  has a first pair of coaxial pivot members  62  and a second pair of coaxial pivot members  64  which are offset ninety degrees from each adjacent one of the first pair of coaxial pivot members  62 . The first pair of coaxial pivot members  62  are received in the openings  54  of the first clevis  16  to pivotally secure the surgical stapling device  10  to the swivel mount  50  about a first axis and the second pair of coaxial pivot members  64  are received in the openings  60  of the second clevis  48  to pivotally secure the second clevis  48  to the swivel mount  50  about a second axis transverse to the first axis. The swivel mount  50  of the universal joint  46  can be secured to the drive mechanism by four cables (not shown) that have distal ends connected to the swivel mount  50  at positions ninety degrees offset from each other. The cables can be selectively retracted to pivot the surgical stapling device about the first and/or second axes. 
         [0078]    Although a universal joint  46  is described herein to connect the surgical stapling device  10  to the drive mechanism  21 , it is envisioned that the surgical stapling device  10  can be coupled to a drive mechanism  21  using a variety a coupling techniques including, e.g., single axis pivot members, ball joints, etc. 
         [0079]    Referring to  FIGS. 8-10 , each cartridge  26  includes a cartridge body  70  defining a plurality of rows of staple pockets  72  and a knife slot  74 . In embodiments, the body  70  defines three linear rows of staple pockets  72  on each side of the knife slot  74 . Alternately, the body may define one or more rows of staple pockets  72  on each side of the knife slot  74 . Each cartridge body  70  also has a distal end defining two spaced blind bores  76 , a longitudinal channel  78  that is aligned with the knife slot  74  and a coupling member  80  positioned on each of the side edges of the cartridge body  70 . In embodiments, the coupling member  80  includes a dove-tail projection  80   a  positioned along one side edge of the cartridge body  70  and a dove-tail groove  80   b  positioned along an opposite side edge of the cartridge body  70  ( FIG. 16 ). The dove-tail projections  80   a  and grooves  80   b  facilitate attachment of each cartridge  26  to adjacent cartridges  26  to define the cylindrical barrel  20  ( FIG. 16 ). The blind bores  76  at the distal end of each cartridge  26  receive the legs  84   a  of an end cap  84  to further secure the cartridges  26  in a radial and axially fixed position in relation to each other. 
         [0080]    Each cartridge body  70  defines a slot  88  ( FIG. 9 ) that is aligned with each row of staples  90 . As described above, the staples  90  are supported in one or more rows of staple pockets  72  located on each side of the knife slot  74 . In the illustrated embodiment, each cartridge body  70  defines three rows of staples  90  on each side of the knife slot  74  and, thus, defines three slots  88  on each side of the knife slot  74 . 
         [0081]    Each staple pocket  72  has a curved distal wall  92 , a curved proximal wall  94  and angled shelf  96  that extends between the distal and proximal walls  92 ,  94 . Each of the staples  90  includes the backspan  90   a , a first leg  90   b  and a second leg  90   c . The shelf  96  supports the backspan  90   a  of the staple  90 . The first leg  90   b  extends from one end of the backspan  90   a  and is elongated and curved. When a staple  90  is supported in the staple pocket  72 , the first leg  90   b  is positioned adjacent to the curved distal wall  92  of a respective staple pocket  72 . The second leg  90   c  has a length that is substantially shorter than the length of the first leg  90   b  and is positioned adjacent the proximal wall  94  of the staple pocket  72 . In embodiments, the first leg  90   b  has a length between 2 and 10 times greater than the length of the second leg  90   c . In certain embodiments, the first leg  90   b  has a length between 4 and 8 times greater than the length of the second leg  90   c . The backspan  90   a  of each staple  90  has a triangular or V-shaped configuration and includes a central portion that is offset from a common plane defined by the first and second legs  90   b ,  90   c  of the staple  90 . The backspan  90   a  is configured to extend off the shelf  96  and into a respective slot  88  defined by the cartridge body  70  such that movement of the pusher  36  through the slots  88  of the cartridge body  70  causes the staples  90  to be ejected from the staple pockets  72 . 
         [0082]    The presently disclosed staple geometry facilitates deformation of the staple  90  from a non-deformed configuration to a deformed or closed configuration ( FIG. 27 ) by deforming only the first, elongated leg  90   b  towards the shorter leg  90   c . This eliminates the need for pushers that engage the backspan of staples, as are conventional in the prior art, to deform the staples. It is envisioned that the second leg  90   c  may be completely removed from the staple  90 . 
         [0083]    Referring to  FIGS. 11-15 , the pusher  36  includes a hub  100  defining the threaded longitudinally extending bore  40 , a clamping member  101 , wings  102  and a plurality of pusher fingers  103  extending radially outward from the hub  100 , and a plurality of flexible arms  104  extending distally from the hub  100 . The clamping member  101  has a vertical strut  106  and a horizontal beam  108 . A cutting edge or knife  110  is formed or supported on a distal face of the vertical strut  106 . The wings  102  and the vertical strut  106  are positioned about the hub  100  of the pusher  36  such that the each of the wings  102  and the vertical strut  106  is slidably received within the knife slot  74  ( FIG. 8 ) of a respective cartridge  26 . In addition, each of the wings  102  is dimensioned to extend through an elongated slot  110  ( FIG. 1 ) defined in the housing  12  ( FIG. 1 ) and the slot  17  ( FIG. 3 ) defined in the first clevis  16  ( FIG. 5 ) and the vertical strut  106  of the clamping member  101  is positioned to extend through the knife slot  22   b  ( FIG. 5 ) of the anvil  14  to prevent the pusher  36  from rotating in relation to the housing  12 . 
         [0084]    Each of the flexible arms  104  extends distally from the hub  100  of the pusher  36  towards the indexer  38  and includes an inwardly extending projection  104   a . The inwardly extending projections  104   a  are positioned to engage an annular rib  112  formed on the indexer  38  as described in further detail below. Each of the pusher fingers  103  extends radially outward from the hub  100  of the pusher  36  and is slidably received within a respective slot  88  ( FIG. 9 ) of the cartridge body  70 . The pusher fingers  103  are positioned to engage the staples  90  to eject the staples  90  from the cartridge body  70  as the pusher  36  is moved through the barrel  20  ( FIG. 15 ) as described in detail below. 
         [0085]    The indexer  38  includes a body  114  defining the longitudinally extending bore  42 , the annular rib  112  and cam slots  116 . The indexer  38  also includes a plurality of fins  118  that extend radially outward from the body  114 . The annular rib  112  is positioned distally of and in contact with the projections  104   a  of the flexible arms  104  of pusher  36  such that distal movement of the pusher  36  within the barrel  20  about the drive shaft  24  causes distal movement of the indexer  38  about the drive shaft  24 . When the indexer  38  is advanced to its distal-most position ( FIG. 31 ), the indexer  38  engages the bearing  32  supported at the distal end of the housing  12 , to prevent further distal movement of the indexer  38 . Further distal movement of the pusher  36  causes the flexible arms  104  of pusher  36  to flex outwardly as the pusher  36  moves distally independently of the indexer  38  such that projections  104   a  snap over and engage the annular rib  112  formed on the indexer  38  to releasably couple the pusher  36  to the indexer  38 . In the coupled position, the indexer body  114  is positioned further proximally in relation to the hub  100  of the pusher  36  such that, upon retraction, the indexer  38  is able to move further proximal within the barrel  20  about the drive shaft  24  as described in further detail below. With the projections  104   a  of the flexible arms  104  of the pusher  36  engaged with the annular rib  112  of the indexer  38 , proximal movement or retraction of the pusher  36  within the barrel  20  will cause corresponding proximal movement of the indexer  38  within the barrel  20 . 
         [0086]    Each of the plurality of fins  118  of the indexer  38  is received within a longitudinal channel  78  ( FIG. 15 ) of a respective one of the cartridges  26  to rotatably fix the barrel  20  to the indexer  38 . As such, rotational movement of the indexer  38  about the drive shaft  24  is translated through the fins  118  to the barrel  20  such that rotational movement of the indexer  38  about the drive shaft  24  effects rotational movement of the barrel  20  about the drive shaft  24 . 
         [0087]    The cam slot  116  ( FIG. 14 ) of the indexer  38  is positioned to receive a shaft pin  120  formed on a proximal portion of the drive shaft  24  as the indexer  38  nears its retracted or proximal-most position within the housing  12 . The shaft pin  120  is positioned to be received within and engage a wall  122  defining the cam slot  116  when the indexer  38  is coupled to the pusher  36  and the pusher  36  and indexer  38  are moved to their proximal-most position to rotate the barrel  120  within the housing  12  as described in detail below. 
         [0088]    Referring to  FIGS. 18-22 , in the open, pre-fired position of the surgical stapling device  10 , the anvil  14  is in the open position in relation to the cartridge  26  that is aligned with the anvil  14 , i.e., the active cartridge, the pusher  36  is in its proximal-most position located within the first clevis  16 , and the annular rib  112  of the indexer  38  is positioned distally of the protrusions  104   a  of the flexible arms  104  of the pusher  36 . In the proximal-most position of the pusher  36 , the wings  102  of the pusher  36  are received in the slots  17  ( FIG. 3 ) of the first clevis  16  proximally of the knife slots  74  of the cartridges  26 , the beam  108  of the clamping member  101  is positioned proximally of the cam surface  14   a  formed on the proximal end of the anvil  14  ( FIG. 20 ), and the pusher fingers  103  are positioned proximally of the slots  88  defined in each of the cartridge bodies  70 . 
         [0089]    Referring to  FIGS. 23 and 24 , as discussed above, the threaded drive shaft  24  is engaged with the threaded bore  40  of the pusher  36 . When the drive mechanism  21  ( FIG. 6 ) is actuated to rotate the drive shaft  24 , the pusher  36  is driven by the drive shaft  24  distally from within the first clevis  16  into the barrel  20 . As the pusher  36  moves distally into the barrel  20 , the beam  108  of the pusher  36  moves in the direction indicated by arrow “A” into engagement with the cam surface  14   a  of the anvil  14  to pivot the anvil  14  in the direction indicated by arrow “B” ( FIG. 24 ) from the open position to the clamped position. As the pusher  36  moves distally within the barrel  20 , the wings  102  and vertical strut  106  ( FIG. 21 ) of the pusher  36  move through the knife slots  74  of the cartridge  26  and the slots  110  ( FIG. 18 ) of the housing  12  to cofine the pusher  36  to linear movement within the housing  12 . The pusher fingers  103  of the pusher  36  also move into the slots  88  of the active cartridge  26  that is aligned with the rows of staples  90 . 
         [0090]    Referring to  FIGS. 25-30 , as the pusher  36  is driven distally in the direction indicated by arrow “C” through the barrel  20  by rotation of the drive shaft  24 , the pusher fingers  103  of the pusher  36  translate through the cartridge slots  88  and sequentially engage the staples  90  in the active cartridge  26  to eject the staples  90  into anvil pockets  14   b  of the anvil  14 . As discussed above, the pusher fingers  103  engage an offset portion of the backspan  90   a  of each of the staples  90  to drive the first leg  90   b  of each staple  90  into a respective anvil pocket  14   b  to deform the staple  90  into a substantially D-shape ( FIG. 27 ). As illustrated, the vertical strut  106  ( FIG. 28 ) of the clamp member  101  of the pusher  36  travels through the knife slot  22   b  of the anvil  14  such that the beam  108  moves along an outer surface of the anvil  14  in the direction indicated by arrow “C” to maintain a maximum tissue gap in the area where tissue is being stapled. As discussed above, the vertical strut  106  supports a knife  110  that moves between the cartridge  26  and the anvil  14  to transect tissue positioned between the cartridge  26  and the anvil  14 . 
         [0091]    Referring to  FIGS. 30-32 , when the indexer  38  is advanced to its distal-most position in which the indexer  38  abuts the bearing  32 , distal movement of the pusher  36  continues independently of the indexer  38  until the flexible arms  104  of the pusher  36  pass over the annular rib  112  on the indexer  38  to position the protrusions  104   a  of the flexible arms  104  at a location distally of the annular rib  112  to releasably couple the pusher  36  with the indexer  38 . In this position, the wings  102  of the pusher  36  reach the distal end of the slots  110  of the housing  12  ( FIG. 30 ) to define the distal-most position of the pusher  36 . 
         [0092]    Referring to  FIGS. 33-37 , when the direction of rotation of the drive screw  24  is reversed to rotate in a direction indicated by arrow “D” in  FIG. 33 , the pusher  36  is retracted within the barrel  20 , in the direction indicated by arrow “E” in  FIGS. 33 and 34  to cause proximal movement of the indexer  38 . As the pusher  36  moves towards its proximal-most position, the wings  102  and vertical strut  106  of the pusher  36  exit the knife slots  74  of the cartridges  26  and pass back into the slots  17  ( FIG. 33 ) of the first clevis  16 . Removal of the wings  102  and vertical strut  106  of the pusher  36  from the knife slots  74  frees the barrel  20  for rotation within the housing  12 . As the pusher  36  and the indexer  38  are retracted within the housing  12 , the shaft pin  120  on the drive shaft  24  engages the inner profile of the cam slot  116  in the indexer  38  ( FIG. 34 ) to effect rotation of the indexer  38  in the direction indicated by arrow “F” in  FIG. 34 . As noted above, the fins  118  ( FIG. 35 ) of the indexer  38  are positioned within the longitudinal channels  78  of the cartridges  26  such that rotation of the indexer  38  in the direction indicated by arrow “F” in  FIG. 35  causes rotation of the barrel  20  within the housing  12  in the direction indicated by arrow “G” in  FIG. 36  to reposition a fresh, i.e., unfired, cartridge  26  in opposition to the anvil  14 . As shown in  FIG. 36 , the distal end of the first clevis  16  supports a ratchet  160  that is received within a notch  162  formed at the proximal end of each cartridge  26  to limit rotation of the barrel  20  to rotation in the direction indicated by arrow “G” to prevent the barrel  20  from rotating back to its original position. Movement of the pusher  36  to its proximal-most position moves the beam  108  to a position proximally of the cam surface  14   a  on the anvil  14  to allow the anvil  14  to move back to the open position ( FIG. 37 ). 
         [0093]    Referring to  FIGS. 38 and 39 , when the drive shaft  24  is actuated again to advance the pusher  36  distally in the direction indicated by arrow “H”, the shaft pin  120  engages the angled profile of the cam slot  116  of the indexer  38  in a direction to advance the indexer  38  distally and to rotate the indexer  38  and, thus, the barrel  20 , in a direction opposite to direction “G” ( FIG. 36 ). Since rotation of the barrel  20  in a direction opposite to direction “G” is prevented by the ratchet  160 , the indexer  38  is pushed distally by the shaft pin  120  to move the indexer  38  distally in relation to the pusher  36 . This relative movement between the pusher  36  and the indexer  38  causes the flexible arms  104  to flex outwardly as the protrusions  104   a  pass back to a position proximally of the annular rib  112 . As the pusher  36  is advanced distally to fire staples  90  from the second cartridge  26 , the surgical stapling device  10  will function as described above until all of the plurality of cartridges  26  have been fired. 
         [0094]    While several embodiments of the disclosure have been described, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Any combination of the above embodiments is also envisioned and is within the scope of the appended claims. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope of the claims appended hereto.