Patent Publication Number: US-2022218331-A1

Title: Surgical Stapler Having Shaft Recognition Mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and benefit of U.S. Provisional Patent Application Ser. No. 63/137,652 entitled “Surgical Stapler Having Shaft Recognition Mechanism” filed on Jan. 14, 2021 which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present application relates generally to surgical occlusion instruments and, more particularly, to surgical staplers. 
     Description of the Related Art 
     Surgical staplers are used to approximate or clamp tissue and to staple the clamped tissue together. As such, surgical staplers have mechanisms to ensure that tissue is properly positioned and captured and to drive staples through the tissue. As a result, this has produced, for example, multiple triggers and handles in conjunction with complex mechanisms to provide proper stapling of the clamped tissue. With these complex mechanisms, surgical staplers can have increased manufacturing burdens, as well as potential sources for device failure and confusion for the user. Thus, reliable stapling of clamped tissue without complex mechanisms is desired. 
     SUMMARY OF THE INVENTION 
     In certain embodiments, a handle assembly for a surgical stapler is provided herein. The handle assembly comprises a handle body, an actuation shaft, and a shaft coupling firing lockout mechanism. The handle body comprises a stationary handle and a movable handle pivotably coupled to the handle body. The handle body comprises a coupler configured to removably couple to an instrument shaft having a stapler jaw assembly. The actuation shaft is mechanically coupled to the movable handle for manual actuation thereof. The actuation shaft is slidable within the handle body along a longitudinal axis. The actuation shaft is selectively positionable in a first orientation wherein movement of the movable handle relative to the stationary handle distally advances the actuation shaft and a second orientation wherein movement of the movable handle relative to the stationary handle proximally retracts the actuation shaft. The shaft coupling firing lockout mechanism prevents selective positioning of the actuation shaft in the first orientation when no instrument shaft is coupled to the coupler and allows selective positioning of the actuation shaft in the first orientation when the instrument shaft is coupled to the coupler. 
     In certain embodiments, a handle assembly for a surgical stapler is provided. The handle assembly comprises a handle body, an actuation shaft, an articulation mechanism, an articulation lockout mechanism, and a shaft coupling firing lockout mechanism. The handle body comprises a stationary handle and a movable handle pivotably coupled to the handle body. The handle body comprises a coupler configured to removably couple to an instrument shaft having a stapler jaw assembly. The actuation shaft is mechanically coupled to the movable handle for manual actuation thereof. The actuation shaft is slidable within the handle body along a longitudinal axis. The actuation shaft is selectively positionable in a firing orientation and a reverse orientation. The articulation mechanism is configured to articulate the stapler jaw assembly relative to the instrument shaft when the instrument shaft is coupled to the handle body. The articulation lockout mechanism prevents operation of the articulation mechanism when no instrument shaft is coupled to the coupler and allows operation of the articulation mechanism when the instrument shaft is coupled to the coupler. The shaft coupling firing lockout mechanism, the shaft coupling firing lockout mechanism prevents selective positioning of the actuation shaft in the first orientation when no instrument shaft is coupled to the coupler and allows selective positioning of the actuation shaft in the first orientation when the instrument shaft is coupled to the coupler. 
     In certain embodiments, a handle assembly for a surgical stapler is provided. The handle assembly comprises a handle body, an actuation shaft, a rotation mechanism, and a shaft coupling firing lockout mechanism. The handle body comprises a stationary handle and a movable handle pivotably coupled to the handle body. The handle body having a coupler configured to removably couple to an instrument shaft. The actuation shaft is mechanically coupled to the movable handle for manual actuation thereof. The actuation shaft is slidable within the handle body along a longitudinal axis and rotatable relative to the longitudinal axis to selectively position the actuation shaft in one of a firing orientation and a reverse orientation. The rotation mechanism selectively rotates the actuation shaft. The shaft coupling firing lockout mechanism comprises a lockout sleeve and at least one lockout arm. The lockout sleeve is positioned adjacent the coupler. The at least one lockout arm is coupled to the lockout sleeve and extends proximally from the lockout sleeve. The lockout arm comprises a lockout tab protruding therefrom. The shaft coupling firing lockout mechanism is positioned in a locked out configuration when no instrument shaft is coupled to the coupler such that the lockout tab interferes with operation of the rotation mechanism to position the actuation shaft in a firing orientation. The shaft coupling firing lockout mechanism is positioned in an unlocked configuration when the instrument shaft is coupled to the coupler such that the lockout tab is spaced apart from the rotation mechanism. 
     In certain embodiments, a surgical stapler is provided. The surgical stapler comprises an instrument shaft and a handle assembly. The instrument shaft has a proximal end and a distal end. The instrument shaft comprises an end effector at the distal end and a lockout keyway at the proximal end. The handle assembly comprises a handle body, an actuation shaft, an articulation mechanism, and an integrated articulation lockout and shaft coupling firing lockout mechanism. The handle body comprises a stationary handle and a movable handle pivotably coupled to the handle body. The handle body has a coupler configured to removably couple to the instrument shaft. The actuation shaft is mechanically coupled to the movable handle for manual actuation thereof. The actuation shaft is slidable within the handle body along a longitudinal axis and selectively positionable in one of a firing orientation and a reverse orientation. The articulation mechanism is operable to articulate the end effector relative to the instrument shaft when the instrument shaft is coupled to the coupler. The integrated mechanism comprises a lockout sleeve positioned adjacent the coupler; at least one lockout arm coupled to the lockout sleeve; and a locking sleeve. The at least one lockout arm extends proximally from the lockout sleeve to a proximal end. The lockout arm comprises a lockout tab protruding therefrom. The locking sleeve is coupled to the proximal end of the at least one lockout arm. The lockout keyway of the shaft is engageable with the lockout sleeve such that integrated mechanism is positioned in a locked out configuration when no instrument shaft is coupled to the coupler such that the lockout tab interferes with positioning the actuation shaft in a firing orientation and the locking sleeve prevents operation of the articulation mechanism. The integrated mechanism is positioned in an unlocked configuration when the instrument shaft is coupled to the coupler such that the lockout tab is positioned to allow positioning of the actuation shaft in the firing orientation and the locking sleeve is positioned to allow operation of the articulation mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an embodiment of surgical stapling device with the jaws in an open configuration; 
         FIG. 2  is a perspective view of an embodiment of a reload shaft for the surgical stapling device of  FIG. 1  with the jaws in a closed configuration; 
         FIG. 3  is a perspective view of an embodiment of a handle assembly having an articulation mechanism for a surgical stapling device; 
         FIG. 4  is a perspective view of the handle assembly of  FIG. 3  with a movable handle in a closed configuration; 
         FIG. 5  is a top view of the handle assembly of  FIG. 3  with a selector in a first configuration; 
         FIG. 6  is a top view of the handle assembly of  FIG. 3  with a selector in a second configuration; 
         FIG. 7A  is a side view of the handle assembly of  FIG. 3 ; 
         FIG. 7B  is a cross-sectional side view of the handle assembly of  FIG. 3 ; 
         FIG. 8A  is a cross-sectional side view of the handle assembly of  FIG. 1  in an initial configuration; 
         FIG. 8B  is a cross-sectional perspective view of the handle assembly of  FIG. 8A ; 
         FIG. 9A  is a cross-sectional side view of the handle assembly of  FIG. 1  actuated to a closed configuration; 
         FIG. 9B  is a cross-sectional perspective view of the handle assembly of  FIG. 9A ; 
         FIG. 10A  is a cross-sectional side view of the handle assembly of  FIG. 1  in a forward drive configuration; 
         FIG. 10B  is a cross-sectional perspective view of the handle assembly of  FIG. 10A ; 
         FIG. 11A  is a cross-sectional side view of the handle assembly of  FIG. 1  in the forward drive configuration; 
         FIG. 11B  is a cross-sectional perspective view of the handle assembly of  FIG. 11A ; 
         FIG. 12A  is a cross-sectional side view of handle assembly of  FIG. 1  in a fully driven forward configuration; 
         FIG. 12B  is a cross-sectional perspective view of the handle assembly of  FIG. 12A ; 
         FIG. 13A  is a cross-sectional side view of the handle assembly of  FIG. 1  in a reverse drive configuration; 
         FIG. 13B  is a cross-sectional perspective view of the handle assembly of  FIG. 13A ; 
         FIG. 14A  is a cross-sectional side view of the handle assembly of  FIG. 1  in a fully driven reverse configuration; 
         FIG. 14B  is a cross-sectional perspective view of the handle assembly of  FIG. 14A ; 
         FIG. 15  is a cut-away side view of an embodiment of articulation mechanism of the handle assembly of  FIG. 3 ; 
         FIG. 16  is a perspective view of the articulation mechanism of  FIG. 15  in an articulated position; 
         FIG. 17A  is a cut-away side view of the articulation mechanism of  FIG. 15 ; 
         FIG. 17B  is a cut-away side view of the articulation mechanism of  FIG. 15  with a release button depressed; 
         FIG. 17C  is a cut-away side view of the articulation mechanism of  FIG. 15  with the release button depressed and partially returned to a centered position; 
         FIG. 17D  is a cut-away side view of the articulation mechanism of  FIG. 15  with the release button depressed and returned to a centered position; 
         FIG. 17E  is a cut-away side view of the articulation mechanism of  FIG. 15  in the centered position with the release button partially released; 
         FIG. 17F  is a cut-away side view of the articulation mechanism of  FIG. 15 ; 
         FIG. 18A  is a perspective view of an articulation lockout mechanism and a shaft coupling firing lockout mechanism of the handle assembly of  FIG. 3  in a locked out configuration; 
         FIG. 18B  is a perspective view of an articulation lockout mechanism and a shaft coupling firing lockout mechanism of the handle assembly of  FIG. 3  in an unlocked configuration; 
         FIG. 19A  is a perspective view of a shaft coupling firing lockout mechanism of the handle assembly of  FIG. 3  in a locked out configuration; 
         FIG. 19B  is a perspective view of a shaft coupling firing lockout mechanism of the handle assembly of  FIG. 3  in an unlocked configuration; 
         FIG. 20A  is a cut away top view of an articulation lockout mechanism of the handle assembly of  FIG. 3  in a locked out configuration; 
         FIG. 20B  is a cut away top view of an articulation lockout mechanism of the handle assembly of  FIG. 3  in an unlocked configuration; 
         FIG. 21A  is a side view of an embodiment of reload shaft for the surgical stapling system of  FIG. 1 ; 
         FIG. 21B  is a perspective end view of a proximal end of the reload shaft of  FIG. 21A ; 
         FIG. 21C  is a side view of an embodiment of lockout keyway for a reload shaft of  FIG. 21A ; 
         FIG. 21D  is perspective view of a lockout sleeve of the handle assembly of  FIG. 3 ; 
         FIG. 21E  is a schematic view illustrating a coupling operation of an embodiment of lockout keyway of a reload shaft with a lockout sleeve of a handle assembly; 
         FIG. 21F  is a cut away top view of a shaft coupling firing lockout mechanism of the handle assembly of  FIG. 3  in an engagement configuration; and 
         FIG. 21G  is a view of the shaft coupling firing lockout mechanism of  FIG. 21F  in an unlocked configuration. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIGS. 1-2 , an embodiment of surgical stapling device is illustrated. The illustrated embodiment of surgical stapler  10  comprises an elongate shaft  20 , a jaw assembly  30 , and a handle assembly  40 .  FIG. 1  illustrates the surgical stapler  10  with the jaw assembly  30  in an open configuration.  FIG. 2  illustrates a removable reload shaft assembly comprising the elongate shaft  20  and jaw assembly  30  of the surgical stapler  10  with the jaw assembly  30  in a closed configuration. 
     With continued reference to  FIGS. 1 and 2 , the illustrated embodiment of surgical stapler  10  can be sized and configured for use in laparoscopic surgical procedures. For example, the elongate shaft  20  and jaw assembly  30  can be sized and configured to be introduced into a surgical field through an access port or trocar cannula. In some embodiments, the elongate shaft  20  and jaw assembly  30  can be sized and configured to be inserted through a trocar cannula having a relatively small working channel diameter, such as, for example, less than 8 mm. In other embodiments, elongate shaft  20  and jaw assembly  30  can be sized and configured to be inserted through a trocar cannula having a larger working channel diameter, such as, for example, 10 mm, 11 mm, 12 mm, or 15 mm. In other embodiments, it is contemplated that certain aspects of the surgical staplers described herein can be incorporated into a surgical stapling device for use in open surgical procedures. 
     With continued reference to  FIGS. 1 and 2 , as illustrated, the elongate shaft  20  comprises a generally tubular member. The elongate shaft  20  extends from a proximal end  22  to a distal end  24 . The elongate shaft  20  defines a central longitudinal axis, L. of the surgical stapler  10  extending between the proximal end  22  and the distal end  24 . 
     With continued reference to  FIGS. 1 and 2 , in the illustrated embodiment, the jaw assembly  30  is coupled to the elongate shaft  20  at the distal end  24  of the elongate shaft  20 . The jaw assembly  30  comprises a first jaw  32  and a second jaw  34  pivotally coupled to the first jaw  32 . In the illustrated embodiment of  FIGS. 3 and 15-17 , the jaw assembly  30  is articulable with respect to the elongate shaft  20  responsive to an articulation mechanism in the handle.  FIG. 1  and  FIGS. 8-14  illustrate a handle assembly that are configured to fire a centrally-fixed jaw assembly to further illustrate an actuation mechanism of the handle assembly in a staple firing sequence. In an initial configuration, the first jaw  32  includes a plurality of staples  36  disposed therein. 
     With continued reference to  FIGS. 1 and 2 , in the illustrated embodiment, the jaw assembly  30  can be actuated from an open configuration ( FIG. 1 ) to a closed configuration ( FIG. 2 ) to a stapling configuration by an actuation member or beam that is longitudinally slideable within the elongate shaft. In an initial position, the beam can be positioned at the distal end  24  of the elongate shaft  20 . With the beam in the initial position, the second jaw  34  is pivoted away from the first jaw  32  such that the jaw assembly  30  is in the open configuration. The actuation beam engages the second jaw  34  upon translation of the actuation member or beam distally along the longitudinal axis L. Translation of the actuation beam distally from the initial position a first distance can actuate the jaw assembly from the open configuration to the closed configuration. With the jaw assembly  30  in the closed configuration, the actuation beam can be returned proximally the first distance to return the jaw assembly  30  to the open configuration. A distal end of the actuation beam can advance a staple slider configured to deploy staples from the first jaw  32  such that further translation of the actuation beam distally past the first distance deploys the plurality of staples  36  from the first jaw  32 . 
     With continued reference to  FIGS. 1 and 2 , in the illustrated embodiment, the handle assembly is coupled to the elongate shaft  20  at the proximal end  22  of the elongate shaft  20 . As illustrated, the handle assembly  40  has a pistol grip configuration with a housing defining a stationary handle  42  and a movable handle  44  or trigger pivotably coupled to the stationary handle  42 . It is contemplated that in other embodiments, surgical stapler devices including aspects described herein can have handle assemblies with other configurations such as, for example, scissors-grip configurations, or in-line configurations. As further described in greater detail below, the handle assembly  40  houses an actuation mechanism configured to selectively advance an actuation shaft responsive to movement of the movable handle  44 . 
     In some embodiments, the surgical stapler  10  can include the plurality of staples  36  positioned in a disposable cartridge while the handle assembly  40  is configured to be reused with multiple staple cartridges. In the illustrated embodiment, the elongate shaft  20  and jaw assembly  30  define a disposable cartridge that is removably couplable to the handle assembly  40 . Accordingly, in the illustrated embodiment the handle assembly  40  includes a coupler  46  at the distal end thereof. The coupler  46  is adapted to engage the elongate shaft  20  of the surgical stapler  10  The coupler  46  can have a bayonet connection having an outer connector that can removably couple the handle assembly  40  to the elongate shaft  20 , and an inner connector that can removably couple the actuation shaft of the handle assembly  42  to the actuation member of the elongate shaft  20 . Accordingly, the surgical stapler  10  can be configured such that the handle assembly  40  can be reused with multiple disposable cartridges during a surgical procedure. It is contemplated that in other embodiments, the handle assembly and some portion of the elongate shaft can be reusable while a remainder of the elongate shaft and the jaw assembly define a disposable cartridge. In certain other embodiments, the handle assembly and the elongate shaft can be reusable while the jaw assembly defines a disposable cartridge. In still other embodiments, a jaw insert housing a plurality of staples can define a disposable cartridge while the remainder of the surgical stapler is reusable. 
       FIGS. 3-7  illustrate various views of an embodiment of handle assembly  40  having an articulation mechanism for a surgical stapler  10 . The articulation mechanism can be positioned at the proximal end of the handle assembly  40  and have an articulation knob  190  for articulation of the jaw assembly. In  FIG. 3 , a perspective view of the handle assembly  40  as illustrated with the movable handle  44  in an open position spaced apart from the stationary handle  42 . The illustrated handle assembly  40  further comprises a selector  72  operably coupled to the actuation mechanism housed within the handle assembly  40  as further discussed herein. As illustrated in  FIG. 3 , the selector  72  is in a first position. 
     With reference to  FIG. 4 , another perspective view of the handle assembly  40  of  FIG. 3  is illustrated. As illustrated, the movable handle  44  is in the open position positioned adjacent the stationary handle  42 , and the selector  72  is in a second position.  FIGS. 5 and 6  illustrate a top view of the handle assembly of  FIG. 3  with the selector  72 , such as a slider  74 , in the first position ( FIG. 5 ), and in the second position ( FIG. 6 ).  FIG. 7A  illustrates a side view of the handle assembly  40  of  FIG. 3 , and  FIG. 7B  illustrates a cross-sectional side view of the handle assembly  40  of  FIG. 3 . 
       FIGS. 8A and 8B  illustrate cross-sectional views of the handle assembly  40  in an initial configuration, revealing operation of the actuation mechanism  50 . In the illustrated embodiment, the actuation mechanism  50  is configured to selectively translate the actuation shaft  60  from a first position corresponding to the jaw assembly  30  being in the open configuration to a second position corresponding to the jaw assembly  30  being in the closed configuration and from the second position to a third position to position the jaw assembly  30  in a stapling configuration and deploy the plurality of staples  36 . In the initial configuration illustrated in  FIGS. 8A and 8B , actuation mechanism  50  can repeatedly translate the actuation shaft  60  between the first position and the second position responsive to movement of the movable handle  44  or trigger without deploying the staples to provide an open and close functionality. This open and close functionality allows a user to position, clamp tissue, and reposition the stapler  10  to find a desirable staple placement location before deploying the staples. 
     With reference to  FIGS. 8-14 , in the illustrated embodiment, the actuation mechanism comprises an advancing or forward driver  52 , a reverse driver  54 , an opening driver  58 , an advancing surface  62 , a reversing surface  64 , and an opening surface  66 . The forward driver  52  can be operably coupled to the movable handle  44  such that movement of the movable handle  44  from the open position to the closed position advances the forward driver  52  in a first direction such as for example distally within the handle assembly  40 . The forward driver  52  can comprise a pawl or tooth configured to engage a recess or slot. 
     The reverse driver  54  can be operably coupled to movable handle  44  such that movement of the movable handle  44  from the open position to the closed position advances the reverse driver  54  in a second direction opposite the first direction such as, for example proximally within the handle assembly  40 . In some embodiments, the movable handle  44  can be operably coupled with the reverse driver  54  with a geared connection including an idler gear  56 . The reverse driver  54  can comprise a pawl or tooth configured to engage a recess or slot. 
     The opening driver  58  can be operably coupled to the movable handle  44  such that movement of the movable handle  44  from the open position to the closed position advances the opening driver  58  in a first direction such as for example distally within the handle assembly  40 . In the illustrated embodiment, the opening driver  58  is coupled to the idler  56  with a pin and slot connection to operably couple the opening driver  58  to the movable handle  44 . The opening driver  58  can comprise a pawl or tooth configured to engage a recess or slot. 
     The actuation shaft  60  includes advancing surface  62 , reversing surface  64 , and opening surface  66  formed thereon. In the illustrated embodiment, the advancing surface  62  comprises a rack, or plurality of spaced recesses or teeth formed longitudinally along the actuation shaft  60 . As illustrated, reversing surface  64  comprises a rack or plurality of space recesses or teeth formed longitudinally along the actuation shaft  60  and angularly offset from the advancing surface  62 . In the illustrated embodiment, the opening surface  66  comprises a recess formed in the actuation shaft  60 . 
     In certain embodiments, the actuation shaft  60  is rotatable within the handle assembly  40  about the longitudinal axis of the stapler  10 . The handle assembly  40  can comprise a rotation mechanism  70  to provide selective rotation of the actuation shaft  60  within the handle assembly  40 . The actuation shaft  60  can be rotatable between a first orientation in which the forward driver  52  is engageable with the advancing surface  62  and a second orientation in which the reverse driver  54  is engageable with the reversing surface  64 . With the angular offset of the advancing surface  52  from the reversing surface  54  with respect to the actuation shaft  60 , with the actuation shaft in the first orientation, the reverse driver  54  is disengaged from the reversing surface  64 , and with the actuation shaft in the second orientation, the forward driver  52  is disengaged from the advancing surface  62 . 
     With continued reference to  FIGS. 8-14 , in certain embodiments, the rotation mechanism  70  comprises a selector  72 , such as a slider. The slider can extend transversely through the housing of the handle assembly  40 . The slider can be operably coupled to the actuation shaft  60  such that positioning the slider in the first position extending from one side of the handle assembly  40  positions the actuation shaft  60  in the first orientation, and positioning the slider in the second position extending from an opposite side of the handle assembly  40  rotates the actuation shaft  60  to the second orientation. In the illustrated embodiment, the slider is coupled to a rack  76  in meshing engagement with a gear  78  that is rotatably fixed to the actuation shaft  60  and longitudinally slideable along the actuation shaft  60  (such as, for example, with a keyed connection). Desirably, the illustrated rotation mechanism  70  including a slider discretely positions the actuation shaft  60  in a desired orientation, reducing the incidence of the mismeshed gearing within the actuation mechanism  50 . In some embodiments the slider can include visual indicators, such as arrows, to indicate the orientation of the actuation shaft  60 , and thus, the actuation mode of the stapler to a user. In other embodiments, the rotation mechanism  70 ″ ( FIG. 1 ) can include another mechanism such as a rotatable knob directly rotationally coupled to the actuation shaft, rather than the slider selector  72 . 
     In the illustrated embodiment, the advancing surface  62  and the reverse surface  64  are angularly offset by approximately 90 degrees about the actuation shaft. Thus, the rotation mechanism  70  is configured to rotate the actuation shaft approximately 90 degrees between the first orientation and the second orientation. In other embodiments, the actuation surface  62  and the reverse surface  64  can have a different angular offset, such as, for example 120 degrees, and the rotation mechanism  70  can be configured to rotate the actuation shaft  60  correspondingly. Moreover, as described in further detail herein with respect to an open/close mode of the handle assembly  40  operation, in the illustrated embodiment, the opening driver  58  engages with the actuation shaft in the second orientation, in other embodiments, the actuation shaft can be rotatable to a third orientation in which the opening driver  58  engages with the actuation shaft. 
     With reference to  FIGS. 8-14 , a typical operation sequence of the actuation mechanism  50  of the handle assembly  40  is illustrated.  FIGS. 8A-8B and 9A-9B  illustrate operation of the handle assembly  40  in an initial configuration providing an open/close functionality to the jaw assembly  30 . In  FIG. 8A , the movable trigger  44  is at an open position, and the actuation shaft  60  is at a first position, corresponding to the first position of the actuation beam at the distal end of the elongate shaft  20 . In the initial position, the actuation shaft  60  is positioned at the second orientation such that the reverse driver  54  is angularly aligned with the reversing surface  64 . With actuation shaft  60  in the second orientation, the opening driver  58  is positioned within the opening surface  66  or recess. Movement of the movable handle  44  from the open position ( FIG. 8A-8B ) to the closed position ( FIG. 9A-9B ), advances the forward driver  52  distally along the actuation shaft  60  to engage an advancing recess  63  formed in the actuation shaft  60  and drive the actuation shaft  60  distally in the handle assembly  40  to a second position. The second position of the actuation shaft  60  within the handle assembly  40  corresponds to the second position of the actuation beam, which positions the jaw assembly  30  in a closed configuration. 
     The movable handle  44  can be biased to the open position by a biasing member, such as a coil spring  68  ( FIG. 11A ). Thus, releasing the movable handle  44  from the closed position illustrated in  FIG. 9A-9B  would return it to the open position of  FIGS. 8A-8B . Operable coupling of the movable handle  44  to the opening driver  58  would likewise translate the opening driver  58  proximally within the handle assembly  40  as the movable handle  44  returns to the open position. In the second orientation of the actuation shaft  60 , the opening driver  58  engages opening surface  66  such that the proximal movement of the opening driver  58  returns the actuation shaft  60  from the second position to the first position, returning the jaw assembly  30  to the open configuration. 
     A user can seek a desired stapling position within a surgical field by repeatedly opening and closing the jaws to clamp tissue in various locations. Once a desired stapling position has been selected, the actuation mechanism  50  can be configured in a stapling or firing mode by rotating the actuation shaft  60  to the first orientation. With the jaw assembly a closed configuration at a desired stapling position (as illustrated in  FIGS. 9A-9B ), a user can reposition the selector  72  by sliding the slider to the first position, corresponding to the first orientation of the actuation shaft  60  (as illustrated in  FIGS. 10A-10B ). In the first orientation of the actuation shaft  60 , the forward driver  52  is engageable with the advancing surface  62 , the reversing driver  54  is angularly misaligned with the reversing surface  64 , and the opening driver  58  angularly misaligned with the opening surface  66 . With the actuation shaft  60  in the first orientation, the movable handle  44  can be released into the open position ( FIG. 11A-11B ), engaging the forward driver  52  with the advancing surface  62 . 
     With reference to  FIGS. 11A-11B and 12A-12B , with the actuation shaft  60  in the first orientation, and the forward driver  52  engaging the advancing surface  62 , the actuation mechanism  50  is in a stapling or firing mode. Several cycles of movable handle  44  movement from the open position to the closed position and back to the open position advance the actuation shaft  60  from the second position ( FIGS. 11A-11B ), to a third position in which the actuation shaft  60  is moved to its distal-most limit with respect to the handle assembly  40  ( FIGS. 12A-12B ). In some embodiments, the actuation mechanism can include a stop to interfere with distal travel of the actuation shaft  60  at the third position. The second position of the actuation shaft corresponds to the second position of the actuation beam in the jaw assembly  30 . The third position of the actuation shaft corresponds to the third position of the actuation beam in the jaw assembly  30  in which the plurality of staples have been deployed from the first jaw. With movement of the movable handle  44  or trigger in the firing mode to advance the actuation shaft from the second position to the third position, the forward driver  52  is sequentially advanced over the adjacent teeth or grooves of the actuating surface  62  in a ratchet-like advancement. 
     With reference to  FIGS. 13A-13B , once the actuation shaft  60  has been advanced to the third position and the staples have been fired from the jaw assembly, the actuation mechanism  50  can be configured in a reverse mode. Accordingly, the rotation mechanism  70  can rotate the actuation shaft  60  to the second orientation to position the reversing surface  64  in angular alignment with the reverse driver  54 . The slider can be slid to the second position to rotate the actuation shaft from the first orientation ( FIGS. 12A-12B ) to the second orientation ( FIGS. 13A-13B ). With the actuation shaft  60  in the second orientation, repeated cycles of the movable handle  44  from the open position to the closed position and back to the open position engage the reverse driver  54  with the reversing surface  64  in a ratchet-like advancement while retracting the actuation shaft  60  proximally in the handle assembly  40 . Once the reverse driver  54  has driven the actuation shaft  60  proximally to the second position (illustrated in  FIGS. 14A-14B ), the opening driver  58  engages the opening surface  66 . The opening driver  58  returns the actuation shaft  60  to the first position when the movable handle  44  is released to the open position. (Returning the handle assembly to the configuration illustrated in  FIGS. 8A-8B ). With the actuation shaft  60  in the first position, the cartridge, emptied of staples, can be decoupled from the handle assembly  40  and a new cartridge can be coupled to the handle assembly to begin another stapling operation. 
     With reference to  FIGS. 15, 16, and 17A-17F , an embodiment of articulation mechanism for the handle assembly  40  is illustrated. In the illustrated embodiment, the handle can articulate the jaw assembly at the distal end of the shaft up to 45° in a fully articulated position in either direction relative to a longitudinally centered position. In some embodiments, the handle assembly uses a manual articulation mechanism including a series of components coupled to the manually actuated articulation knob  190  at the proximal end of the handle. It is contemplated that in other embodiments, the articulation knob and certain components of the articulation mechanism can be disposed at other locations on the handle assembly such as, for example, the distal end, an upper surface thereof, or on the stationary handle. 
     With reference to  FIGS. 15 and 16 , the articulation mechanism is coupled to an articulation member  206  extending longitudinally within the reload shaft when the reload shaft is coupled to the handle. Actuation of the articulation mechanism longitudinally translates the articulation member  206  proximally or distally relative to the shaft to articulate the jaw assembly at the distal end of the shaft. 
     With reference to  FIG. 15 , the articulation mechanism comprises a ball screw  192  having at least one helical groove or thread  195  in which one or more ball bearing  194  can ride. In the illustrated embodiment, the articulation mechanism comprises two ball bearings  194  that are engageable in two threads  195 . The ball bearings  194  are positioned in ball bearing apertures  189  in a ball sleeve  191  positioned radially outwardly of the ball screw  192 . The ball bearings  194  are maintained in the threads  195  by a release sleeve  196  positioned radially outward of the ball bearings  194 . Rotation of the articulation knob  190 , which is coupled to the ball sleeve  191  such as by connecting pins  193 , rotates the ball sleeve  191  about an axis of rotation, causing the ball bearings  194  to travel within the threads  195  and correspondingly longitudinally translate the ball screw  192 . Articulation of the jaw assembly is accomplished by rotating the articulation knob  190  to correspondingly rotate the ball sleeve  191  and the ball bearings  194  about the axis of rotation while their longitudinal position is fixed along the axis of rotation. The ball bearings  194 , which are engaged in the threads  195  of the ball screw  192  will then translate the ball screw  192  forward and reverse along the axis of rotation. In the illustrated embodiment, the ball sleeve  191  is generally tubular, having a cavity formed therein, and a portion of the ball screw  192  is positioned within the cavity and translates longitudinally within the cavity. While the illustrated embodiment of articulation mechanism includes two ball bearings engageable threads in a ball screw, it is contemplated that in other embodiments, the articulation mechanism can have fewer or more than two ball bearings such as, for example, a single ball bearing positioned in a single helical screw or three or more ball bearings in a corresponding number of helical threads. 
     With reference to  FIGS. 15 and 16 , the ball screw  192  extends to a distal end  200  coupled to a pair of articulation links  202 . The articulation links  202  are spaced apart from one another, which desirably allows them to be positioned radially outwardly of the actuation mechanism and actuation shaft within the handle. As illustrated in  FIG. 16 , the articulation links  202  can comprise a mating feature such as a slot formed therein to allow them to be keyed into a corresponding mating feature such as a post extending radially inwardly from the handle body. The slots can stabilize the articulation links relative to the handle and interaction of the handle posts with ends of the slots can define a range of articulation for the articulation mechanism. The distal ends of the articulation links  202  can be rotatably coupled to the articulation adapter  204 , which can be positioned coaxially radially outwardly of the actuation adapter at the distal end of the handle. This rotational coupling can include an articulation bearing  205  having relatively low friction properties. This articulation bearing  205  can facilitate rotation of a coupled reload shaft relative to the handle assembly and longitudinal movement of the articulation adapter  204  during operation of the articulation mechanism. While the illustrated embodiment of articulation mechanism includes two articulation links laterally offset from the actuation mechanism within the handle, it is contemplated that in other embodiments, the articulation mechanism can have fewer or more than two articulation links such as, for example, an articulation link or three or more articulation links. 
     With continued reference to  FIG. 16 , the articulation adapter  204  can be connected to the articulation member  206  in the shaft by a bayonet connection when the shaft is coupled to the handle. The articulation member  206  extends distally within the shaft and is coupled to an end effector or jaw assembly articulably coupled to the shaft. The threads  195  can be configured such that moving the ball screw proximally will articulate the jaw assembly to the left when viewed from the handle relative to a longitudinally centered position and moving the ball screw  192  distally will articulate the jaw assembly to the right when viewed from the handle relative to the centered position. 
     Advantageously, since the helical threads  195  of the ball screw  192  are continuous, the articulation mechanism can allow the jaw assembly to be articulated to virtually infinite angular positions between a desired operational range. In some embodiments, the articulation mechanism can be configured to provide an articulation operational range from −45° to +45° of the jaw assembly relative to a longitudinally centered position defined by the longitudinal axis of the shaft. In other embodiments, the articulation mechanism can be configured to provide other operative articulation ranges including ranges providing more than +/−45° of articulation or those providing less than +/−45° of articulation. In some embodiments, the articulation mechanism can be configured to provide articulation in a single direction relative to a longitudinally centered position. 
     In some embodiments, the pitch of the threads  195  on the ball screw  192  is variable. For example, the threads  195  can include a relatively low pitch towards an end of the threads to advantageously provide a larger mechanical advantage when the jaw assembly can require more force to articulate. The threads  195  can include a relatively higher pitch towards a center of the threads to allow rapid movement with a relatively lower mechanical advantage where the jaw assembly can require a lower force to articulate. In other embodiments, the threads  195  include a constant pitch such that rotation of the articulation knob results in a proportional amount of articulation of a jaw assembly of the stapler that does not vary over the articulation range of the articulation mechanism. Desirably, such a constant pitch thread ball screw can result in an easily predictable response during operation of the actuation mechanism. 
     With reference to  FIGS. 17A-17F , the articulation mechanism can comprise a release mechanism that allows the articulation mechanism to advantageously be reset to the longitudinally centered position from any articulated position. The release mechanism is operated by user pressing a release button  198 . In the illustrated embodiment, the release button  198  is positioned radially nested within the articulation knob  190 . 
     With reference to  FIG. 17B , operation of the release button  198  will distally advance the release sleeve  196 . A radially inner surface of the release sleeve  196  is stepped to include an engagement surface  186  having a relatively small inner diameter and a release surface  188  having a relatively larger inner diameter with a smooth ramp between the engagement surface and the release surface. In operation, the engagement surface of the release sleeve maintains the ball bearings  194  in the threads  195  of the ball screw  192 . Once the release button  198  is pushed, the engagement surface is distally advanced, allowing the ball bearings  194  to disengage from the threads  195  and advance radially outward through the ball bearing apertures  189  in the ball sleeve  191  ( FIG. 15 ) against the release surface. 
     With reference to  FIGS. 17C and 17D , with the ball bearings  194  disengaged from the threads  195 , the articulation mechanism can be biased to a centered position. In some embodiments, the ball screw  192  is biased to a centered position by a biasing member such as two springs  197  and spring force from the shaft. The ball bearings  194  positioned in the centered position ( FIG. 17D ) along the threads  195  corresponds to a longitudinally centered position of the jaw assembly. 
     With reference to  FIGS. 17E-17F , once the release button  198  is allowed to return to an undisturbed configuration, release sleeve  196  is retracted proximally (indicated by arrows  199 ) by a spring. Proximal movement of the release spring  196  forces the ball bearings  194  into engagement with the threads  195  of the ball screw. Thus, the articulation mechanism can then be used to articulate the jaw assembly from the longitudinally centered position, or the stapler can be used with the jaw assembly in the longitudinally centered position. 
     In certain embodiments, the handle assemblies described herein can further comprise an articulation lockout mechanism and a shaft coupling firing lockout mechanism. The articulation lockout mechanism can be configured to prevent operation of the articulation mechanism with no reload shaft coupled to the handle assembly and allow operation of the articulation mechanism as described above with respect to  FIGS. 15-17A  when a reload shaft is coupled to the handle assembly. Desirably, this articulation lockout mechanism facilitates coupling the articulation mechanism as described with respect to  FIG. 16  as the reload shaft is coupled to the handle assembly. If the articulation mechanism were maintained in an engaged configuration even when no instrument shaft were coupled to the handle assembly, it could be difficult to align the articulation member within the instrument shaft with the articulation adapter  204  in an attempt to couple the instrument shaft with the handle assembly. 
     The shaft coupling firing lockout mechanism can be configured to prevent a user from selecting a firing mode of the handle assembly unless a reload shaft is coupled to the handle assembly. Thus, desirably, a user is prevented from initiating a firing operation if the reload shaft is not secured to the handle assembly. In the illustrated embodiment, the articulation lockout mechanism and shaft firing lockout mechanism are integrated and share certain components. This integrated mechanism can desirably present manufacturing and packaging efficiencies. It is contemplated that in other embodiments a handle assembly can include an articulation lockout mechanism that is distinct from a shaft coupling firing lockout mechanism. Moreover, in other embodiments, a handle assembly can include only one of an articulation lockout mechanism and a shaft coupling firing lockout mechanism. 
     With reference to  FIGS. 18A-18B , a perspective view of an embodiment of handle assembly having an articulation lockout mechanism and a shaft coupling firing lockout mechanism are illustrated with a portion of a housing of the handle assembly removed to illustrate the mechanisms therein. As illustrated in  FIG. 18A , the articulation lockout mechanism and shaft coupling firing lockout mechanism are in a locked out configuration corresponding to no reload shaft coupled to the handle assembly. As illustrated in  FIG. 18B , the articulation lockout mechanism and shaft coupling firing lockout mechanism are in an unlocked configuration corresponding to a reload shaft coupled to the handle assembly. 
     With continued reference to  FIGS. 18A-18B , the articulation lockout mechanism comprises a lockout sleeve  302  at the distal end of the handle assembly and at least one lockout arm  304  coupled to the lockout sleeve. In the illustrated embodiment, the lockout sleeve  302  can be positioned radially outwardly of the articulation adapter  204 . In the illustrated embodiment, the articulation lockout mechanism comprises two lockout arms  304  extending longitudinally within the handle assembly from a proximal end coupled to a locking sleeve  306  positioned around the release sleeve  196  of the articulation mechanism to a distal end coupled to the lockout sleeve  302 . The lockout arms  304  can extend parallel to and offset from the articulation links  202  of the articulation mechanism. The lockout arms can be positioned laterally outwardly of the actuation shaft  60  and other actuation mechanism components. In other embodiments, one or more than two lockout arms  304  can couple the lockout sleeve  302  to the release sleeve  196 , and the lockout arms  304  can be disposed in a different lateral position than in the illustrated embodiment. 
     With continued reference to  FIGS. 18A-18B , in the illustrated embodiment, the shaft coupling firing mechanism comprises the lockout sleeve  302  at the distal end of the handle assembly and the at least one lockout arm  304  coupled to the lockout sleeve  302  and extending proximally therefrom. The at least one lockout arm  304  comprises at least one lockout tab  350  extending radially inwardly therefrom. In the illustrated embodiment, the articulation lockout mechanism comprises two lockout arms  304 , on laterally opposed sides of the actuation shaft  60 , and one of the two lockout arms  304  comprises one lockout tab  350 . As further discussed with reference to  FIGS. 21F  and  21 G, in certain embodiments to provide lock out functionality during engagement of an instrument shaft with the handle assembly, a lockout arm  304  can comprise two lockout tabs: a proximal lockout tab  351  and a distal lockout tab  353  with a lockout recess  352  therebetween. 
     With reference to  FIGS. 19A-19B , perspective views of the shaft coupling firing lockout mechanism are illustrated. As illustrated in  FIG. 19A , the shaft coupling firing lockout mechanism is in a locked out configuration corresponding to no reload shaft being coupled to the handle assembly. As illustrated in  FIG. 19B , the shaft coupling firing lockout mechanism is in an unlocked configuration corresponding to a reload shaft being coupled to the handle assembly. 
     With reference to  FIG. 19A , the shaft coupling firing lockout mechanism is biased longitudinally distally. For example, in some embodiments a coil spring can bias the lockout sleeve  302  distally relative to the handle assembly. With no reload shaft coupled to the handle assembly, the lockout sleeve  302  and lockout arm  304  are biased to a distal position corresponding to the locked out configuration of the shaft coupling firing lockout configuration. With the lockout arm  304  in the distal position, the lockout tab  350  is longitudinally aligned with the gear  78  of the rotation mechanism. In this position, the lockout tab  350  prevents rotation of the gear  78  such that a user is unable to rotate the actuation shaft  60  to a firing orientation. In certain embodiments, the gear  78  can comprise a slot  79  positioned to receive the lockout tab of the lockout arm  304   
     With reference to  FIG. 19B , as a reload shaft is coupled to the handle assembly, a lockout keyway  312  ( FIG. 21A-21B ) engages the lockout sleeve  302  and advances the lockout sleeve  302  and lockout arm  304  longitudinally proximally a predetermined distance to a proximal position. In the proximal position, as illustrated, the lockout tab  350  is misaligned with the gear  78  of the rotation mechanism such that the rotation mechanism can be actuated by the selector  72  as described with respect to  FIGS. 8-14 . 
     Thus, desirably, the shaft coupling firing lockout mechanism prevents initiating a firing actuation of the handle assembly without a reload shaft fully coupled to the handle assembly. Desirably, this lockout mechanism can facilitate proper alignment of the bayonet coupling features of the handle assembly and reload shaft during an initial coupling of the reload shaft to the handle assembly. Furthermore, the lockout mechanism can desirably prevent an inadvertent attempt to fire a reload shaft that is not securely, fully coupled to the handle assembly. 
     With reference to  FIGS. 20A-20B , cut away top views of the articulation lockout mechanism are illustrated. As illustrated in  FIG. 20A , the articulation lockout mechanism is in a locked out configuration corresponding to no reload shaft being coupled to the handle assembly. As illustrated in  FIG. 20B , the articulation lockout is in an unlocked configuration corresponding to a reload shaft being coupled to the handle assembly. 
     With reference to  FIG. 20A , with no reload shaft coupled to the handle assembly, the lockout sleeve at the distal end of the handle assembly is biased to the distal position, advancing the lockout arms  304  and locking sleeve  306  to a distal position. As illustrated, the locking sleeve  306  is positioned around the release sleeve of the articulation mechanism. In embodiments of handle assembly having an articulation lockout, the release sleeve  196  can comprise a flange  308  protruding radially outwardly at a distal end of the release sleeve. As the locking sleeve  306  is biased to the distal position corresponding to a locked out configuration of the articulation lockout mechanism, the locking sleeve  306  engages the flange  308  of the release sleeve  196 , moving the release sleeve distally to release ball bearings  194  from the ball screw as described above with reference to  FIGS. 17B-17D . Accordingly, with no reload shaft coupled to the handle assembly, the articulation knob may be rotated without actuating the articulation mechanism because the ball bearings  194  are disengaged from the threads of the ball screw. 
     Thus, in certain embodiments, the articulation lockout mechanism can maintain the articulation mechanism in a centered position if no instrument shaft is coupled to the handle assembly. This centered position of the articulation adapter can facilitate the bayonet coupling of instrument shaft and handle assembly previously discussed above. If the articulation mechanism were maintained in an engaged configuration even when no instrument shaft were coupled to the handle assembly, it could be difficult to align the articulation member within the instrument shaft with the articulation adapter  204  in an attempt to couple the instrument shaft with the handle assembly. 
     With reference to  FIG. 20B , once a reload shaft has been coupled to the handle assembly, the lockout sleeve at the distal end of the handle assembly is advanced to the proximal position, advancing the lockout arms  304  and locking sleeve  306  to a proximal position. As illustrated, with the locking sleeve  306  in the proximal position, the locking sleeve  306  is spaced apart from the flange  308  of the release sleeve.  196  Accordingly, with the articulation lockout mechanism in the unlocked configuration, ball bearings  194  are engaged with the ball screw, as described above with respect to  FIG. 17F , and the articulation mechanism and its release button are operable as described above with respect to  FIGS. 15-17F . Thus, with an instrument shaft attached, rotation of the articulation knob results in translation of the articulation adapter to articulate an end effector coupled to the instrument shaft. 
     While in certain embodiments, the shaft coupling firing lockout mechanism can have a locked out configuration in which the lockout sleeve is biased to the distal position and an unlocked configuration in which a shaft has been coupled to the handle assembly, as discussed above with respect to  FIGS. 19A-19B , in certain embodiments, the reload shaft and shaft coupling firing lockout mechanism can be configured to further comprise an engagement position of the lockout mechanism in which the reload shaft is being coupled to the handle assembly but not yet fully seated. It can be desirable that the reload shaft is securely coupled to the handle assembly before a firing operation is initiated to facilitate the reliable firing of staples. Thus, in certain embodiments, the shaft coupling firing lockout mechanism can be configured to position the lockout sleeve and lockout arm in a locked out configuration while the reload shaft is being coupled to the handle assembly. In certain embodiments, a lockout keyway on the reload shaft can be sized and configured to engage the lockout sleeve of the handle assembly to initially position the lockout sleeve and the shaft coupling firing lockout mechanism in the engagement position during coupling of the shaft with the handle assembly, then position the lockout sleeve and the shaft coupling firing lockout mechanism in the proximal position once the reload shaft is securely coupled to the handle assembly. 
     With reference to  FIGS. 21A-21C , an embodiment of reload shaft for use with a handle assembly having a shaft coupling firing lockout mechanism and an articulation lockout mechanism is illustrated.  FIG. 21A  illustrates a side view of the reload shaft  20  having a proximal end  22  configured to couple to the coupler  46  of the handle assembly. ( FIGS. 1-2 ).  FIG. 21B  is a detail perspective view of the proximal end  22  of the reload shaft  20  having a lockout keyway  310  therein. The lockout keyway  310  comprises at least one notch  312  formed therein that is engageable with the lockout sleeve to sequentially position the shaft coupling firing lockout mechanism initially in the engagement position corresponding to a locked out configuration of the mechanism, then to the proximal position, corresponding to an unlocked configuration of the mechanism. 
     With reference to  FIG. 21C , an exemplary embodiment of lockout keyway  310  is illustrated. The illustrated lockout keyway  310  has a height H to a proximal edge, a notch  312  recessed from the height H. The lockout keyway comprises a ramped edge  314  extending between the proximal edge and at least one side of the notch  312 . Each of the lockout keyways further comprise a key, such as a rib  322  to restrict rotation of the lockout keyway relative to the reload shaft as the reload shaft is coupled with the handle assembly. 
     With reference to  FIG. 21D , an exemplary lockout sleeve  302  of the handle assembly is illustrated. In the illustrated embodiment, the lockout sleeve  302  comprises an engagement feature such as a flange  332  at a proximal end and at least one rib  334  or other key element protruding from the outer surface thereof to maintain an orientation of the lockout sleeve  302  relative to a longitudinal axis of the actuation shaft. As illustrated, the lockout sleeve  302  further comprises at least one mating protrusion such as a tooth  336  extending distally from the distal end thereof positioned to engage a corresponding notch of a lockout keyway of a connected reload shaft. The at least one tooth  336  can have a ramped edge  338  such that it can matingly engage a notch of a lockout keyway that likewise has a ramped edge. In the illustrated embodiment, the lockout sleeve  302  comprises two teeth  336  positioned diametrically opposed on a distal end of the lockout sleeve  302  to engage a corresponding two identification notches. In other embodiments, it is contemplated that the number and locations of mating features included the lockout keyways and lockout sleeves can be varied. 
     With reference to  FIG. 21E , an exemplary sequence of interaction between a lockout sleeve  302  and a lockout keyway  310  is illustrated as a reload shaft is installed on a handle assembly. As illustrated, the shaft installation sequence proceeds from left to right. In the left panel, as the shaft is positioned in the coupler  46  ( FIG. 1 ) of the handle assembly, the lockout sleeve  302  is oriented such that the teeth  336  are misaligned with the notches  312 . The coupler  46  and shaft engage in a bayonet connection in which the shaft is advanced longitudinally proximally relative to the handle, then rotated relative to the longitudinal axis. The center panel illustrates the proximal longitudinal movement longitudinally proximally displacing the lockout sleeve  302  relative to the handle as the rotational movement of the shaft moves the teeth  336  closer to alignment with the notches  312 . The right panel illustrates completion of rotation of the shaft relative to the handle assembly to secure the bayonet coupling. As illustrated, once the shaft is coupled to the handle assembly, the teeth  336  of the lockout sleeve  302  engage and are positioned within the notches  312  of the lockout keyway  310 . Thus, during a coupling operation, the lockout sleeve  302  is initially displaced proximally by installation of the shaft with the teeth misaligned with the notches, then returns distally as the teeth  336  engage the notches  312 . Thus, in the illustrated embodiment as a bayonet coupling is initiated, the lockout sleeve is advanced longitudinally proximally to the engagement position of the shaft coupling firing lockout mechanism. Once the reload shaft has been rotated with respect to the handle assembly to complete the bayonet coupling, the lockout sleeve is biased distally to the proximal position corresponding to an unlocked configuration of the shaft coupling firing lockout mechanism. 
     With reference to  FIG. 21F , a side view of the shaft coupling firing lockout mechanism is illustrated in the engagement position. In the illustrated embodiment, the lockout arm  304  comprises two lockout tabs  351 ,  353  separated by a lockout recess  352  to provide a locked out configuration with the lockout arm  304  in the engagement position. Initially with no reload shaft coupled to the handle assembly, the shaft coupling firing lockout mechanism is positioned in a locked out configuration similar to  FIG. 19A . In this locked out configuration, the lockout sleeve  302  and lockout arm  304  are biased to a distal position such that the proximal lockout tab  351  is positioned to prevent rotation of the gear  78  of the rotation mechanism. As the reload shaft is advanced proximally in a bayonet coupling operation with the handle assembly, the lockout sleeve  302  and lockout arm  304  are advanced proximally to the engagement position of the shaft coupling firing lockout mechanism in which the distal lockout tab  353  is positioned to prevent rotation of the gear  78  of the rotation mechanism. 
     With reference to  FIG. 21G , a side view of the shaft coupling firing lockout mechanism of  FIG. 21F  is illustrated in the proximal position corresponding to an unlocked configuration of the lockout mechanism. Once the reload shaft is rotated to securely couple the reload shaft to the handle assembly, the lockout sleeve  302  and lockout arm  304  are biased distally to the proximal position of the shaft coupling firing lockout mechanism in which the lockout recess  352  is positioned to allow rotation of the gear  78  of the rotation mechanism. Thus, with the lockout arm  304  in the proximal position as illustrated, the shaft coupling firing lockout mechanism is in the unlocked configuration. 
     Although this application discloses certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Further, the various features of these inventions can be used alone, or in combination with other features of these inventions other than as expressly described above. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims.