Abstract:
The present disclosure is directed to an endoscopic surgical instrument and methods for performing a diverticulum treatment. The surgical instrument includes a handle assembly, an elongated member and a jaw assembly. The elongated member is operably coupled to the distal end of the handle assembly, while the jaw assembly is operably coupled to a distal end of the elongated member. The jaw assembly includes a knife slot that is defined therewithin and is adapted to receive a knife blade to thereby cut tissue that is disposed between the jaw assembly. The jaw assembly is configured to approximate an esophageal tract and a diverticulum.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to an apparatus and method of performing a surgical procedure. More particularly, the present disclosure relates to an apparatus and method for performing a minimally invasive surgical procedure utilizing a motor driven instrument. 
         [0003]    2. Background of Related Art 
         [0004]    In certain conventional surgical procedures, surgeons have direct access to the operative site. However, laparoscopic surgery, a type of minimally invasive surgery, has been developed, in which the surgical site is viewed through a laparoscope or endoscope and the instruments are introduced through a trocar cannula. The benefits of laparoscopic surgery include reduced hospital stay, speedier recovery, and less pain. 
         [0005]    One of the instruments utilized in laparoscopic surgery, as well as other types of minimally invasive surgery, is the surgical stapler. Surgical stapling devices are employed by surgeons to sequentially or simultaneously apply one or more rows of fasteners, e.g., staples or two-part fasteners, to body tissue for the purpose of joining segments of body tissue together. Such devices generally consist of a pair of jaws or finger-like structures between which the body tissue to be joined is placed. When the stapling device is actuated, or “fired”, a firing member or members contact staple drive members in one of the jaws. The staple drive members push the surgical staples through the body tissue and into an anvil in an opposite jaw which crimps the staples closed. If tissue is to be removed or separated, a knife blade can be provided in the jaws of the device to cut the tissue between the lines of staples. 
         [0006]    Certain surgical device manufacturers have developed surgical instruments that are not manually actuated by, for example, a pivotable, manually graspable handle part, but are driven by a motor either provided in a separate housing, or provided in the handle of the instrument. Certain electromechanical surgical devices include a handle assembly, which is reusable and connectable with a replaceable loading unit prior to use. Then, following the use of the instrument, the loading unit is disconnected from the handle assembly, in order to be disposed of. A system including reusable portions has the potential advantage of reducing the cost of the instrument, as a portion of the instrument is reused over time. In addition, the replaceable parts can be offered in multiple different configurations, which can include, for surgical staplers, staples lines of various lengths, staple sizes of various lengths, etc. 
         [0007]    Many of these electromechanical surgical devices are relatively expensive to manufacture, purchase and/or operate. There is a desire by manufactures and end users to develop electromechanical surgical devices that are relatively inexpensive to manufacture, purchase and/or operate. 
         [0008]    Accordingly, a need exists for electromechanical surgical apparatus, devices and/or systems that are relatively economical to develop and manufacture, to store and ship, as well as economical and convenient to purchase and use from the end user&#39;s perspective. 
         [0009]    There is also a need to provide flexibility for the user of such instruments, so as to provide the user with various parts that can be replaced, and various configurations to choose from. 
       SUMMARY 
       [0010]    The present disclosure relates to an endoscopic surgical instrument, which includes various types of instrumentation. 
         [0011]    In an aspect of the present application, a surgical instrument comprises a handle assembly including a housing; an elongated body extending distally from the handle assembly; and a jaw assembly adjacent a distal end of the elongated body. The jaw assembly includes a cartridge assembly including a plurality of fasteners and a longitudinal slot defined therein; an anvil having a fastener forming surface thereon, the cartridge assembly and anvil being mounted for movement with respect to one another between an open position and a closed position in close cooperative alignment for clamping tissue; an actuation sled supported within the cartridge assembly, the actuation sled being movable to urge the plurality of fasteners from the cartridge; and a knife blade mounted to the actuation sled. The jaw assembly further includes a drive beam including a vertical support strut and a cam member supported on the vertical support strut, the cam member being positioned to translate relative to the anvil to maintain the anvil in the closed position during firing of the fasteners, the vertical support strut being positioned to abut the actuation sled; and a drive screw supported within the cartridge assembly, the drive screw having a threaded portion, wherein the drive beam is threadably coupled to the threaded portion of the drive screw such that rotation of the drive screw imparts longitudinal movement of the drive beam. 
         [0012]    The surgical instrument may have a the knife blade that is pivotably mounted to the actuation sled for pivotable movement in relation to the sled between a concealed position in which the knife blade is disposed within the actuation sled and a raised position in which the knife blade extends through the longitudinal slot. The knife blade may have an actuating surface that is arranged to be contacted by the vertical support strut. 
         [0013]    The drive screw may define a longitudinal axis and the drive shaft may be disposed off-axis in relation to the drive screw. 
         [0014]    The jaw assembly may further include a mounting portion coupled to the cartridge assembly and the anvil, the anvil being pivotally mounted to the mounting portion for pivotal movement in relation to the cartridge. 
         [0015]    The anvil may include a pair of actuating shoulders disposed at a proximal end thereof. The mounting portion may include a pair of biasing members biased against the actuating shoulders for pushing the anvil into the open position. 
         [0016]    In certain preferred embodiments, the instrument further comprises a camera mounted on the at least one of the cartridge assembly and the anvil. The camera may be mounted on the anvil. 
         [0017]    The jaw assembly of the instrument may be configured to be removably attached to a shaft. The shaft may be selected from the group consisting of: a rigid shaft, a flexible shaft, and a shaft having a rigid portion and an articulating portion. 
         [0018]    In a further aspect of the present disclosure, a surgical instrument comprises a handle assembly including a housing and an actuator; an elongated body extending distally from the handle assembly; a motor disposed at least partially within the housing; an actuation shaft mechanically engaged with the motor; a jaw assembly adjacent a distal end of the elongated body. The jaw assembly includes a cartridge assembly including a plurality of fasteners and a longitudinal slot defined therein; an anvil having a fastener forming surface thereon, the cartridge assembly and anvil being mounted for pivotal movement with respect to one another between an open position and a closed position for clamping tissue; an actuation sled supported within the cartridge assembly, the actuation sled being movable to urge the plurality of fasteners from the cartridge; and a knife blade mounted to the actuation sled. The jaw assembly further includes a drive beam including a vertical support strut and a cam member supported on the vertical support strut, the cam member being positioned to translate relative to the anvil to maintain the anvil in the closed position during firing of the fasteners and the vertical support strut being positioned to abut the actuation sled to translate the actuation sled; and a drive screw supported within the cartridge assembly, the drive screw having a threaded portion, wherein the drive beam is threadably coupled to the threaded portion of the drive screw such that rotation of the drive screw imparts longitudinal movement of the drive beam. 
         [0019]    The knife blade may be is pivotally mounted to the sled for movement in relation to the sled between a concealed position in which the knife blade is disposed within the actuation sled and a raised position in which the knife blade extends through the longitudinal slot 
         [0020]    The jaw assembly may further include a mounting portion coupled to the cartridge assembly and the anvil, the anvil being pivotally mounted to the mounting portion for pivotal movement in relation to the cartridge. The anvil may include a pair of actuating shoulders disposed at a proximal end thereof. The mounting portion may include a pair of biasing members biased against the actuating shoulders for pushing the anvil into the open position. 
         [0021]    The jaw assembly may further include a drive shaft disposed within the mounting portion, the drive shaft mechanically coupling the drive screw to the actuation shaft, wherein the drive shaft transfers rotational motion of the actuation shaft to the drive screw., and the drive shaft may be is coupled off-axis to the drive screw. 
         [0022]    In certain preferred embodiments, a camera is mounted on the at least one of the cartridge assembly and the anvil. The camera may be mounted on the anvil. 
         [0023]    The jaw assembly of the surgical instrument may be configured to be removably attached to a shaft. The shaft may be selected from the group consisting of: a rigid shaft, a flexible shaft, and a shaft having a rigid portion and an articulating portion. 
         [0024]    In another aspect of the present disclosure, a jaw assembly comprises a cartridge assembly including a plurality of fasteners and a longitudinal slot defined therein; an anvil having a fastener forming surface thereon and pivotally mounted in relation to the cartridge assembly for pivotal movement between an open position having a distal end spaced from the cartridge assembly and a closed position in close cooperative alignment with the fastener cartridge; an actuation sled supported within the cartridge assembly, the actuation sled being movable to urge the plurality of fasteners from the cartridge; a knife blade pivotally mounted to the actuation sled for pivotal movement in relation to the sled between a closed position in which the knife blade is disposed within the actuation sled and a deployed position in which the knife blade extends through the longitudinal slot. The jaw assembly may also include a drive beam including a vertical support strut and a cam member supported on the vertical support strut, the cam member being positioned to translate relative to the anvil to maintain the anvil in the closed position during firing of the fasteners and the vertical support strut being positioned to abut the actuation sled and the knife blade to translate the actuation sled and to pivot the knife blade from the closed position into the deployed position. 
         [0025]    The jaw assembly may further comprise a drive screw supported within the cartridge assembly, the drive screw having a threaded portion, wherein the drive beam is threadably coupled to the threaded portion of the drive screw such that rotation of the drive screw imparts longitudinal movement of the drive beam, or may further comprise a drive shaft mechanically coupling the drive screw to an actuation shaft, wherein the drive shaft transfers rotational motion of the actuation shaft to the drive screw. 
         [0026]    The drive shaft may be coupled off-axis to the drive screw. 
         [0027]    The jaw assembly may further comprise a mounting portion coupled to the cartridge assembly and the anvil, the anvil being pivotally mounted to the mounting portion for pivotal movement in relation to the cartridge. The anvil may include a pair of actuating wings disposed at a proximal end thereof, the mounting portion includes a pair of biasing members biased against the actuating wings for pushing the anvil into the open position. 
         [0028]    The jaw assembly may be configured to be removably attached to a shaft. The shaft may be selected from the group consisting of: a rigid shaft, a flexible shaft, and a shaft having a rigid portion and an articulating portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    The above and other aspects, features, and advantages of the present disclosure will become more apparent in light of the following detailed description when taken in conjunction with the accompanying drawings in which: 
           [0030]      FIG. 1  is an exploded, perspective view of a jaw assembly for a surgical instrument in accordance with an embodiment of the present disclosure; 
           [0031]      FIG. 2  is a side, perspective view of a jaw assembly in accordance with the embodiment of  FIG. 1 ; 
           [0032]      FIG. 3  is a top, perspective view of a jaw assembly in accordance with the embodiment of  FIGS. 1 and 2 ; 
           [0033]      FIG. 4  is a rear, perspective view of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 3 ; 
           [0034]      FIG. 5  is a front, perspective view of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 4 ; 
           [0035]      FIG. 6  is a bottom perspective view, with parts removed, of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 5 ; 
           [0036]      FIG. 7  is a bottom cross-sectional perspective view, with parts removed, of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 6 ; 
           [0037]      FIG. 8  is a perspective cross-sectional view of a portion of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 7 ; 
           [0038]      FIG. 9  is a side cross-sectional view of a portion of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 8 ; 
           [0039]      FIG. 10  is a side cross-sectional view of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 9 ; 
           [0040]      FIG. 11  is a perspective view of an actuation sled of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 10 ; 
           [0041]      FIG. 12  is a perspective cross-sectional view of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 11 ; 
           [0042]      FIG. 13  is a side cross-sectional view of a portion of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 12 ; and 
           [0043]      FIG. 14  is a side cross-sectional view of a portion of a jaw assembly in accordance with the embodiment of  FIGS. 1 through 13 . 
       
    
    
       [0044]    Other features of the present disclosure will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the present disclosure. 
       DETAILED DESCRIPTION 
       [0045]    Embodiments of the presently disclosed surgical devices are 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 “distal” refers to that portion of the devices, or component thereof, that is farther from the user of the device, while the term “proximal” refers to that portion of the devices or component thereof, that is closer to the user. 
         [0046]    Referring now to  FIG. 1 , a jaw assembly for an endoscopic instrument is shown. The jaw assembly, in certain embodiments disclosed herein, removably attached to an elongated shaft member that is integral with, or attached to the handle assembly of a surgical instrument. The elongated shaft member may be rigid, or flexible, or have rigid and flexible portions, or include one or more pivotable pivot members. 
         [0047]    The elongated member may be articulated by the user of the instrument. In embodiments, the handle assembly and elongated member may include any suitable articulating mechanisms known in the art to manipulate (e.g., rotate and articulate) elongated member, which include, but not limited to gears, wires, cables, linkages, tubular shafts, drive rods, and combinations thereof. 
         [0048]    The jaw assembly  30  includes a pair of jaw members. In certain embodiments, the jaw members include a staple cartridge assembly  32  and an anvil  34 . Cartridge assembly  32  houses one or more staples or fasteners  33  that are disposed within the cartridge assembly, and is configured to deploy the one or more staples or fasteners  33  upon actuation of an actuator on the handle assembly. The cartridge assembly and the anvil are mounted so that they are movable with respect to one another. Anvil  34  in  FIG. 1 , for example, is movably (e.g., pivotally) mounted on the cartridge assembly and is movable between an open position, spaced apart from cartridge assembly  32 , to a closed position wherein anvil  34  is in close cooperative alignment with cartridge assembly  32 , to thereby clamp tissue. Alternatively, the cartridge assembly  32  may pivot with respect to the anvil member. The anvil  34  includes an inner fastener forming surface  39  having a plurality of fastener pockets (not shown) that are configured to receive fasteners  33  and to form fasteners  33  in a closed configuration when the fasteners are driven against the anvil  34 . 
         [0049]    During use, anvil  34  is moved between the open and closed positions by actuator. In embodiments, the actuator controls the rotational movement of an actuation shaft in the elongated shaft member, and the actuation shaft operates to rotate a drive screw  160  (see  FIG. 1 ). The drive screw will interact with other members of the jaw assembly to move the anvil  34  between the open and closed positions. In this way, the jaw assembly can be operated to clamp onto tissue. Then, the drive screw  160  continues to rotate to move an actuation sled  140  ( FIG. 1 ) provided in the jaw assembly. The sled moves distally through the cartridge assembly  32  to eject the fasteners  33  as described in more detail below. 
         [0050]    The fasteners  33  are released from the cartridge assembly and they are configured to penetrate tissue that has been clamped between the jaw assembly, i.e., the cartridge assembly  32  and anvil  34  that have been approximated with one another. In certain preferred embodiments, cartridge assembly  32  is a replaceable cartridge so that when all of fasteners  33  have been expelled, cartridge assembly  32  may be replaced with a replacement cartridge (not shown), in order to continue a surgical procedure. In another alternative, the jaw assembly  30  is incorporated into a loading unit that can be replaced after the fasteners are fired. The loading unit may have an elongated body portion that attaches to the elongated member  20 . 
         [0051]    In other embodiments, jaw assembly  30  may include a pair of jaw members that are configured to utilize laser energy, radio-frequency energy or any other suitable techniques to treat or join tissue. The laser and/or radio frequency energy may be used in combination with cartridge assembly  32  and anvil  34 . 
         [0052]      FIGS. 1-14  illustrate the components and operation the jaw assembly  30 . Referring to  FIG. 1 , an exploded view of the jaw assembly  30  is shown. The jaw assembly  30  is adapted to apply a plurality of linear rows of staples or fasteners  33 , which in embodiments may be of various sizes, e.g., about 30 mm in length. The jaw assembly  30  and/or the cartridge assembly can be replaceable so that 30 mm, 45 mm, or 60 mm long staple lines can be applied to tissue. Replaceable units for applying staples of different sizes are contemplated as well. 
         [0053]    The jaw assembly  30  includes a carrier  31  having an elongate channel  110  having a base  112  and two parallel upstanding walls  114  and  116  which include several mounting structures, such as notches  139 , for supporting the cartridge assembly  32  and the anvil  34 . A longitudinal slot  111  extends through the elongate channel  110 . 
         [0054]    The carrier  31  also includes a plate cover  115  disposed on a bottom surface thereof. The plate cover  115  includes a plurality of knobs  117  configured to frictionally engage with corresponding apertures  119  disposed within the channel  112  of the carrier  31 . The carrier  31  also includes a pair of tabs  107  and  109  disposed at a distal end thereof for coupling to a mounting portion  120 . 
         [0055]    With continuing reference to  FIG. 1 , the distal portion of channel  110  supports cartridge assembly  32  which contains a plurality of surgical staples or fasteners  33  and a plurality of corresponding ejectors or pushers  134 . Actuation sled  140  having upstanding cam wedges  144 , exerts a fastener driving force on the pushers  134 , which drive the fasteners  33  from cartridge assembly  32 , as described in more detail below. Cartridge assembly  32  is maintained within channel  110  by lateral struts  136  which frictionally engage the upper surfaces of channel walls  114  and  116 , and the frictional engagement of housing tabs, such as tab  138 , within notches  139 . These structures serve to restrict lateral, longitudinal, and elevational movement of the cartridge assembly  32  within channel  110 . 
         [0056]    A plurality of spaced apart longitudinal slots  142  extend through cartridge assembly  32  to accommodate the upstanding cam wedges  144  of actuation sled  140 . Slots  142  communicate with a plurality of transverse retention slots  146  within which the plurality of fasteners  33  and pushers  134  are respectively supported. The pushers  134  are secured by a pusher retainer  135  disposed below the cartridge assembly  32 . The pusher retainer  135  supports and aligns the pushers  134  prior to engagement thereof by the actuation sled  140 . During operation, as actuation sled  140  translates through cartridge assembly  32 , the angled leading edges of cam wedges  144  sequentially contact pushers  136 , causing the pushers to translate vertically within slots  146 , urging the fasteners  134  therefrom. The cartridge assembly  32  also includes a longitudinal slot  185  to allow for the knife blade  174  to travel therethrough, as described in more detail below. 
         [0057]    In certain embodiments, the cartridge  32  is removable from the jaw assembly. The pushers  134  are held in place by the retainer  135  and the retainer, which is attached to the cartridge by at least one proximal feature  201  and at least one distal feature  202 , is removable with the cartridge. Hook shaped features on the retainer  135  are shown in  FIG. 1 , which illustrates a pair of distal features and a pair of proximal features. In use, the drive beam is refracted to a position proximal of the proximal ends of the cartridge and retainer, so that the removable assembly (the cartridge, pushers, and retainer) can be lifted out of the channel  110 . In certain embodiments, the cartridge and channel form a detent connection so that the removable assembly is removable. 
         [0058]    With continuing reference to  FIG. 1 , the jaw assembly  30  includes an anvil cover  35  disposed over the anvil  34 . The anvil cover  35  protects tissue from moving parts along the exterior of anvil  34 . The anvil cover  35  includes opposed mounting wings  150  and  152  which are dimensioned and configured to engage detents  154  and  156  of the anvil  34 , respectively. The mounting wings  150  and  152  also align the anvil  34  with the cartridge assembly  32  during closure as shown in  FIGS. 7 and 8 . The anvil  34  along with the cover  35  is configured to remain in an open configuration until closed, as described in more detail below. As shown in  FIG. 1 , the cover  35  includes a pair of actuating shoulders  157  and  159 . 
         [0059]    The anvil  34  and the carrier  31 , including the cartridge assembly  32 , are coupled to a mounting portion  120 . The mounting portion  120  includes a pair of extensions  123  and  125 , each having depressions  127  and  129 , respectively. The depressions  127  and  129  are dimensioned and configured for insertion (e.g., frictionally fit) of a proximal portion of the carrier  31 , including the tabs  107  and  109 . 
         [0060]    The mounting portion  120  includes a pair of openings  121  and  122  within the depressions  127  and  129 . Each of the actuating shoulders  157  and  159  and the tabs  107  and  109  of the carrier  31  also include openings  157   a ,  159   a ,  107   a , and  109   a , respectively. A pivot pin  117 , or a pair of pins, passes through the openings  121 ,  122 ,  157   a ,  159   a ,  107   a , and  109   a.    
         [0061]    As shown in  FIGS. 6 ,  18  and  19 , biasing members  158   a  and  158   b , which are shown as coil springs, are secured within the mounting portion  120 . The biasing members  158   a  and  158   b  bear against internal bearing surfaces defined within mounting portion  120  to bias anvil  34  into a normally open position wherein the interior fastener forming surface  39  thereof is spaced from cartridge assembly  32 . In particular, as described above, the anvil  34  includes actuating shoulders  157  and  159  disposed at a proximal end thereof. Each of the actuating shoulders  157  and  159  includes contact surfaces  157   b  and  159   b , respectively. The contact surfaces  157   b  and  159   b  abut the biasing members  158   a  and  158   b , respectively, pushing the anvil  34  into the open position as shown in  FIG. 5 . As the anvil  34  is closed, the biasing members  158   a  and  158   b  are compressed within the mounting portion  120 . 
         [0062]    With reference to  FIGS. 1 and 8 , a coupling member  128  is coupled to the proximal end of the mounting portion  120 . The coupling member  128  includes an axial bore  131  defined therethrough. The mounting portion  120  also includes an axial bore  133  defined therein, which is aligned with the axial bore  131  of coupling member  128  when the coupling member  128  is coupled thereto. The bores  131  and  133  are threaded and are dimensioned and configured to be interconnected by a bolt  135 . 
         [0063]    With continued reference to  FIGS. 2 , the coupling member  128  includes a J-shaped slot  137 , and one or more alignment shafts  129   a  and  129   b . The alignment shafts  129   a  and  129   b  along with the slot  137  are used to align and couple the jaw assembly  30  to the distal end  24  of the elongated member  20 . The shafts  129   a  and  129   b  may align the elongated member  20  with the jaw assembly  30  and the slot  137  may define a conventional bayonet-type coupling which facilitates quick and easy engagement and removal of the jaw assembly  30  from the instrument  10  during a surgical procedure. Once engaged in the distal end  24  of the elongated portion  20 , the drive mechanism, e.g., actuation shaft  55 , of the instrument  10  is coupled to a drive shaft  64  of the jaw assembly  30 . 
         [0064]    As seen in  FIG. 1 , jaw assembly  30  further includes an axial drive screw  160  for transmitting the rotational drive forces exerted by the drive shaft in the handle assembly to actuation sled  140  during a stapling procedure. The drive shaft  64  is disposed within the mounting portion  120  and includes a proximal portion  65  and a distal portion  67 . The proximal portion  65  is configured to be engaged by the actuation shaft extending from the instrument  10 , and the distal portion  67  is dimensioned and configured to engage the drive screw  160 . The actuation shaft includes a distal engagement portion. The engagement portion includes a multi-faceted or non-circular female connection (e.g., hexagonal) which is dimensioned and configured to engage the proximal portion  65  of the drive shaft  64 . 
         [0065]    The proximal and distal portions  65  and  67  are shaped as multi-faceted or non-circular male connections. The drive shaft  64  also includes a bushing  69  disposed centrally thereon. The bushing  69  allows the drive shaft  64  to rotate about its longitudinal axis A-A. The drive shaft  64  is secured within the mounting portion  120  via a frictionally fit washer  71 , which prevents the drive shaft  64  from sliding out of the mounting portion  120 . 
         [0066]    Drive screw  160  includes a threaded portion  160   a  and a proximal engagement portion  166 . Engagement portion  166  includes a multi-faceted or non-circular female connection  164  (e.g., hexagonal) which is dimensioned and configured to engage the distal portion  67  of the drive shaft  64 . The drive screw  160  is disposed within the longitudinal slot  111  of the carrier  31  as shown in  FIGS. 6 and 10 . The drive screw  160  is rotatably secured at its engagement portion  166  via a thrust plate  141 . The thrust plate  141  is disposed between the coupling member  128  and the mounting portion  120  and is fitted over a portion of the coupling member  128 , as shown in  FIG. 9 . In particular, the thrust plate  141  includes a pair of teeth  143   a  and  145   a  that engage the drive screw  160  between the engagement portion  166  and a protrusion  167 , thereby preventing lateral, longitudinal, and elevational movement and allowing only for rotation of the drive screw  160  about a longitudinal axis B-B. As described above, the drive shaft  64  is disposed within the mounting portion  120  off-axis with respect to the drive screw  160 . The longitudinal axis A-A defined by the drive shaft  64  is at a non-parallel (e.g., non-zero angle) angle with respect to the longitudinal axis B-B defined by the drive screw  160 . 
         [0067]    With reference to  FIGS. 1 and 9 , a drive beam  162  is also disposed within the jaw assembly  30 . The drive beam  162  includes a vertical support strut  172  and an abutment surface  176  which engages the central support wedge  145  ( FIG. 1 ) of actuation sled  140 . The drive beam  162  also includes a cam member  180  disposed on top of the vertical support strut  172 . Cam member  180  is dimensioned and configured to engage and translate with respect to an exterior camming surface  182  of anvil  34  to progressively clamp the anvil against body tissue during firing. 
         [0068]    A longitudinal slot  184  extends through the anvil  34  to accommodate the translation of the vertical strut  172 . In embodiments, the anvil cover  35  is secured to an upper surface of anvil  34  to form a channel therebetween. This allows the cam member  180  to travel in between the cover  35  and anvil  34  during firing. 
         [0069]    The drive beam  162  includes a retention foot  188  having a threaded bore  189  defined therethrough. The drive screw  160  is threadably coupled to the drive beam  162  through the bore  189 , such that as the drive screw  160  is rotated, the drive beam  162  travels in a longitudinal direction along the axis B-B. 
         [0070]    As the drive screw  160  is rotated in a clock-wise direction, the drive beam  162  travels in a distal direction closing the anvil  34  as the cam member  180  pushes down on the camming surface  182  thereof. The drive beam  162  also pushes the sled  140  in the distal direction, which then engages the pushers  134  via the cam wedges  144  to eject the fasteners  33 . 
         [0071]    The sled  140  also includes a knife blade  174  for transecting the fastened tissue. The knife blade  174  travels slightly behind actuation sled  140  during a stapling procedure to form an incision between the rows of fastener body tissue. As shown in  FIG. 11 , the sled  140  includes a centrally disposed slit  190  for housing the knife blade  174 , which is pivotally coupled to the sled  140  via a pin  191 . The knife blade  174  includes a blade portion  192  at a distal end and an actuating surface  193  disposed at a proximal end (see  FIG. 12 ). The knife blade  174  pivots about the pin  191  from a concealed position in which the knife blade  174  is fully submerged within the slit  190 , as shown in  FIGS. 9 and 12 , and a raised position in which the knife blade  174  is in a deployed upright position extending through the longitudinal slot  185 , as shown in  FIG. 10 . 
         [0072]    As the drive beam  162  is driven in the distal direction, the abutment surface  176  of the vertical strut  172  comes in contact with a actuating surface  193  of knife body  174 , thereby pivoting the knife blade  174  about the pin  191  and raising the blade portion  192  from the slit  190  and into the longitudinal slot  185 , as shown in  FIGS. 9 and 10 . As the drive beam  162  is continually driven in the distal direction, the abutment surface  176  maintains contact with the knife blade  174 , thereby pushing the sled  140  in the distal direction to eject the fasteners  33  and simultaneously dissect tissue with the blade portion  192 . The knife blade  174  and the drive beam  162  travel through the knife slot  38  thereby fastening and severing tissue. In particular, the knife slot  38  is formed by the longitudinal slots  184  and  185  defined in the anvil  34 , the anvil cover  35 , and the cartridge assembly  32 , respectively. The drive beam  162  closes the anvil as it is driven in the distal direction and also pushes the sled  140 , which, in turn, ejects the fasteners  33  ahead of the knife blade  174  that is pivoted into the upright position. 
         [0073]    The jaw assembly may be removably attached to a elongated shaft member that is flexible, or rigid, or has rigid and flexible portions. In this way, the user of the surgical instrument can select the type of elongated shaft member for the particular procedure to be performed. In addition, the handle assembly is removably attached to the elongated shaft member so that the shaft members can be interchanged. The handle assembly desirably has a housing, a motor, a drive shaft, and a controller. The controller may be configured to interact with the shaft and/or jaw assembly to modify the operation of the handle assembly to correspond to the particular jaw assembly and/or shaft member attached to the handle assembly. 
         [0074]    Each of the embodiments described above are provided for illustrative purposes only and it is within the concept of the present disclosure to include modifications and varying configurations without departing from the scope of the disclosure that is limited only by the claims included herewith.