Patent Publication Number: US-11033268-B2

Title: Surgical stapling loading unit with stroke counter and lockout

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation Application which claims that benefit of and priority to U.S. patent application Ser. No. 14/812,353, filed on Jul. 29, 2015, now U.S. Pat. No. 10,064,622, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a surgical stapling apparatus, and more particularly, relates to a surgical stapling loading unit having a firing stroke counter and a lockout which locks the loading unit upon completion of a predefined number of firing strokes. 
     2. Background of Related Art 
     Surgical staplers for stapling tissue are known in the art and are inclusive of both single use and multiple use devices. Single use devices are preloaded with one or more staples and are disposed after a single use. Multiple use devices are disposed upon exhaustion of the supply of staples or completion of the surgical procedure. If the supply of staples is exhausted prior to completion of a surgical procedure, a new surgical stapler may be required to complete the surgical procedure. The use of additional surgical staplers for a single surgical procedure can be expensive. 
     In order to address the high expense associated with the use of multiple surgical staplers for a single procedure, surgical staplers with replaceable staple cartridges have been developed. 
     Covidien, LP, has manufactured and marketed stapling systems having replaceable cartridges, such as the Multifire ENDO GIA™ 30 and Multifire ENDO GIA™ 60 systems, for a number of years. These systems include a surgical stapling handle assembly and a surgical loading unit. The loading unit may be a single use loading unit (SULU) or a multiple use loading unit (MULU). The loading unit includes a body and an end effector, and is attached to the handle assembly immediately prior to surgery. The end effector may include a cartridge which houses a plurality of staples. After use, the loading unit can be removed relative to the handle assembly and replaced with a new loading unit to perform additional stapling and/or cutting operations. A drive assembly is supported within the loading unit and is engagable with a control rod of the surgical handle assembly to control operation of the loading unit. 
     Although these systems have provided significant clinical benefits, improvements are still possible. For example, it would be desirable to provide an improved stapling loading unit for use in a surgical stapling system which tracts the staple firing sequence to assist the clinician in monitoring the staple supply. It also would be beneficial to provide a surgical stapling device having a lockout to prevent firing of the device after the staple supply has been depleted. 
     SUMMARY 
     Accordingly, the present disclosure is directed to a surgical loading unit for use with a handle assembly. The surgical loading unit includes an elongate outer frame defining a longitudinal axis and having proximal and distal ends, an end effector mounted to the distal end of the outer frame, a drive at least partially disposed within the outer frame and operatively coupled to the end effector and being adapted for longitudinal movement through a plurality of sequential firing strokes to operate the end effector, and a rotatable counter mounted to the outer frame. The rotatable counter is adapted for rotational movement through an arc segment of rotation upon movement of the drive through each firing stroke, and has visual indicators for providing visual indicia corresponding to a number of firing strokes completed by the drive. 
     In one embodiment, the outer frame defines a window through which a visual indicator of the rotatable counter is visible. In certain embodiments, the rotatable counter includes a stop which is positionable to engage the drive upon rotatable movement of the rotatable counter through a predetermined number of arc segments corresponding to a predetermined number of firing strokes completed by the drive. 
     In embodiments, a counter actuator is mounted to the drive. The counter actuator is dimensioned to engage the rotatable counter to cause rotational movement of the rotatable counter through each arc segment of rotation during each firing stroke of the drive. The rotatable counter may include a helical gear having internal helical grooves. The counter actuator is engageable with the helical grooves to cause rotational movement of the rotatable counter. In certain embodiments, the counter actuator is adapted for pivotal movement relative to the drive, and is dimensioned to pivot out of engagement with the helical grooves of the rotatable counter during a return stroke of the driver subsequent to each firing stroke. The counter actuator may be adapted to pivot between an initial position and first and second pivoted positions. The counter actuator is engageable with one helical groove when in the first pivoted position during movement of the drive through each drive stroke, and disengaged from the one helical groove when in the second pivoted position during movement of the drive through each return stroke. In embodiments, the counter actuator is normally biased toward the initial position, and pivots in a first direction to assume the first pivoted position and pivots in a second direction to assume the second pivoted position. 
     In some embodiments, the outer frame includes a cam having rear and forward cam surfaces. The rear cam surface is engaged by the counter actuator during movement of the drive through each firing stroke to orient the counter actuator in the first pivoted position. The forward cam surface is engaged by the counter actuator during movement of the drive through each return stroke to orient the counter actuator in the second pivoted position. 
     The surgical loading unit may include a detent mechanism having a detent member mounted relative to the outer frame and locking recesses associated with the rotatable counter. The detent member is engagable with a respective locking recess subsequent to each firing stroke of the drive to maintain the rotatable counter at a desired angular or rotational position, and is adapted to release the respective locking recess upon movement of the drive through a successive firing stroke. 
     In certain embodiments, the end effector may include a fastener assembly including a plurality of fasteners with at least one fastener being ejected upon movement of the drive through a firing stroke. 
     In accordance with one embodiment, a surgical loading unit for use with a handle assembly includes an elongate outer frame defining a longitudinal axis and having proximal and distal ends and a staple assembly mounted to the distal end of the outer frame. The staple assembly has a staple cartridge housing a plurality of staples and an anvil. The anvil is adapted for movement relative to the staple cartridge between an open position to receive tissue and an approximated position to clamp tissue. A drive is at least partially disposed within the outer frame and operatively couplable to the staple assembly. The drive is adapted for longitudinal movement through a plurality of sequential strokes to eject at least one staple from the staple cartridge for crimping by the anvil when in the approximated position thereof. The surgical loading unit further includes a rotatable counter and lockout mechanism. The mechanism includes a rotatable counter mounted to the outer frame and adapted for rotational movement through an arc segment of rotation upon movement of the drive through each firing stroke, at least one visual indicator associated with the rotatable counter for providing visual indicia corresponding to a number of firing strokes completed by the drive and a lock member positionable to engage the drive upon rotatable movement of the rotatable counter through a predetermined number of arc segments corresponding to a predetermined number of firing strokes completed by the drive. 
     In embodiments, a counter actuator is mounted to the drive, and adapted to engage the rotatable counter to cause rotational movement of the rotatable counter through each arc segment of rotation during each firing stroke of the drive. The counter actuator may be adapted to pivot between an initial position and first and second pivoted positions. The counter actuator is engageable with the rotatable counter when in the first pivoted position during movement of the drive through each drive stroke, and disengaged from the rotatable counter when in the second pivoted position during movement of the drive through each return stroke. In certain embodiments, the rotatable counter includes a helical gear having internal helical grooves. The counter actuator is engageable with one helical groove when in the first pivoted position to cause rotational movement of the rotatable counter during each drive stroke, and disengaged from the one helical groove when in the second pivoted position during each return stroke. 
     In an embodiment, the loading unit includes a detent mechanism having a detent member mounted relative to the outer frame and locking recesses associated with the rotatable counter. The detent member is engagable with a respective locking recess subsequent to each firing stroke of the drive to maintain the rotatable counter at a desired angular or rotational position, and is adapted to release the respective locking recess upon movement of the drive through a successive firing stroke. 
     Further details and advantages of the outer and inner elastic members will be appreciated from the following written description. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with a general description of the disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the disclosure, wherein: 
         FIG. 1  is a perspective view of a surgical loading unit for performing a surgical stapling procedure in accordance with the principles of the present disclosure; 
         FIG. 2  is a perspective view of the surgical loading unit mounted to a surgical handle assembly; 
         FIG. 3  a perspective view of the surgical loading unit with portions removed illustrating the central drive and the counter and lockout mechanism mounted relative to the central drive; 
         FIG. 4  is an enlarged isolated view of the area of detail identified in  FIG. 3  illustrating the rotatable counter and counter actuator of the counter and lockout mechanism; 
         FIG. 5  is an exploded perspective view of the loading unit; 
         FIGS. 6-7  are perspective views of the rotatable counter of the counter and lockout mechanism; 
         FIG. 8  is a side cross-sectional view of the counter and lockout mechanism mounted relative to the outer frame; 
         FIG. 9  is an enlarged isolated view of the area of detail identified in  FIG. 1  illustrating the window for viewing the visual indicators; 
         FIG. 10  is an enlarged isolated view of the area of detail identified in  FIG. 5  illustrating the actuator holder and the counter actuator of the counter and lockout mechanism; 
         FIG. 11  is an exploded perspective view illustrating the actuator holder, the counter actuator and the torsion spring of the counter and lockout mechanism; 
         FIG. 12  is a perspective view of a detent mechanism for releasably securing the rotatable counter at select positions; 
         FIG. 13  is a cross-sectional view of another embodiment of a detent mechanism associated with the rotatable counter; 
         FIGS. 14-16  are cross-sectional views illustrating a sequence of movement of the counter actuator and rotatable counter during a firing stroke of the central drive; 
         FIG. 17  is a perspective view illustrating rotation of the rotatable counter during movement of the central drive during the firing stroke; 
         FIGS. 18-19  are cross-sectional views similar to the views of  FIGS. 14-16  illustrating a sequence of movement of the counter actuator during a return stroke of the central drive; 
         FIG. 20  is a side cross-sectional view of the counter and lockout mechanism illustrating the rotatable counter in a lock position with an internal stop on the rotatable counter in engagement with a lock shelf of the central drive to lock the central drive; 
         FIG. 21  is a perspective view further illustrating the relationship of the internal stop of the rotatable counter and the central drive when in the locked position of the rotatable counter; 
         FIGS. 22-23  are cross-sectional views of the staple assembly with the staple cartridge and the anvil in respective open and approximated conditions; 
         FIG. 24  is an enlarged side cross sectional view of the staple assembly illustrating the staples fired from the staple cartridge during a firing stroke; and 
         FIG. 25  is a side cross-sectional view illustrating the staples fired upon completion of a firing stroke. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely examples of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present disclosure in virtually any appropriately detailed structure. 
     Referring now to the drawings where like reference numerals indicate similar components throughout the several views,  FIGS. 1-2  illustrate the surgical loading unit  10  in accordance with the principles of the present disclosure. In  FIG. 1 , the surgical loading unit  10  is depicted in isolation while in  FIG. 2  the surgical loading unit  10  is depicted connected to a surgical handle assembly  200 . The surgical loading unit  10  and the surgical handle assembly  200  form a surgical system adapted to perform a surgical procedure on tissue. The loading unit  10  includes an end effector  300  which, in one embodiment, is a stapling assembly adapted to staple tissue. The loading unit  10  may be a multi-use loading unit (MULU) adapted, e.g., for sequential or multiple firing of one or more staples in a linear arrangement. 
     The surgical handle assembly  200  may be any handle assembly having at least one actuator, and in some embodiments, two or more actuators adapted to control operation of the loading unit  10 . It is contemplated that the surgical handle assembly  200  may be reusable, i.e., it can be reused with a plurality of loading units  10 , and may be used with loading units having different stapling functions such as, e.g., circular stapling of tissue. The end effector  300  (shown in phantom in  FIG. 1 ) may include a staple cartridge  302  which houses a plurality of staples and an anvil  304 . The staple cartridge  302  and the anvil  304  are movable relative to each other between open and approximated positions. Staples are driven from the staple cartridge  302  through tissue and crimped by the anvil  304 . Further details of the handle assembly  200  and the end effector  300  will be discussed in greater detail hereinbelow. 
     Referring now to  FIGS. 3-5 , in conjunction with  FIG. 1 , the loading unit  10  includes an elongate outer member or frame  12  defining a longitudinal axis “k” and proximal and distal ends  14 ,  16 . In  FIGS. 3-4 , half of the outer frame  12  is removed for illustrative purposes. The proximal end  14  of the outer frame  12  includes a handle mount  18  ( FIG. 1 ) with at least one mounting tab  20  which couples with the handle assembly  200 . The distal end  16  of the outer frame  12  supports the end effector  300  (removed in  FIGS. 3-5 ). A central beam or drive  22  is at least partially disposed within the outer frame  12 . The central drive  22  is adapted for longitudinal movement within the outer frame  12  and is operatively couplable, at its proximal end, to an actuator of the handle assembly  200  and, at its distal end, to the end effector  300 . The central drive  22  advances or moves distally, during a firing stroke, to control the end effector  300 , e.g., by causing the firing of one or more staples. Subsequent to a firing stroke, the central drive  22  moves proximally, during a return stroke, to be in position for another firing sequence. The central drive  22  includes an actuation sled  24  at its distal end  16  and a knife  26  to sever tissue, e.g., during the stapling process. The knife  26  may be a component of, or coupled, to the actuation sled  24 . The outer frame  12  may include a translating rod  28  extending along the longitudinal axis “k”. The translating rod  28  may be coupled to an actuator of the handle assembly  200  and to the end effector  300 . The translating rod  28  may move in a longitudinal direction to control articulation (e.g., pivoting movement) of the end effector  300 . 
     Referring now to  FIGS. 3-7 , the loading unit  10  includes a counter and lockout mechanism  30  for tracking the number of firings or firing strokes completed by the central drive  22  and lock the loading unit  10  upon completion of a predetermined number of firing strokes. The counter and lockout mechanism  30  includes a rotatable counter  32  and an actuator assembly  34 . The rotatable counter  32  is adapted for rotational movement about the longitudinal axis “k” and within the outer frame  12 . In one embodiment, the outer frame  12  defines an internal annular recess  36  ( FIG. 5 ) which is dimensioned to receive the rotatable counter  32  in a manner permitting rotational movement of the rotatable counter  32  while restricting axial movement. As depicted in  FIG. 8 , the annular recess  36  may include a pair of annular ribs  38 , which are received within corresponding dimensioned annular grooves  40  ( FIG. 6 ) disposed on the external wall  32   e  of the rotatable counter  32 , to assist in securing the rotatable counter  32  from axial movement. 
     With particular reference to  FIGS. 6 and 7 , the rotatable counter  32  may include a helical gear defining a plurality of internal helical threads or grooves  42 . Each internal helical groove  42  longitudinally extends along the length of the rotatable counter  32  in oblique relation with respect to the longitudinal axis “k”. The internal helical grooves  42  may encompass one-half the inner diameter or dimension of the inner wall  32   i  of the rotatable counter  32  while the remaining portion of the inner wall  32   i  is mostly smooth. The rotatable counter  32  may have twelve internal helical grooves  42  although more or less than twelve internal helical grooves  42  are also envisioned. The helical grooves  42  may be identical such when engaged by the actuator assembly  34  the rotatable counter  32  rotates through the same incremental arc segment of rotation. 
     The rotatable counter  32  includes visual indicia or indicators  44  on its external wall  32   e . The indicators  44  may include a plurality of numbers, e.g., 1-12, corresponding to a number of times the central drive  22  completes a firing stroke. Alternatively, the number may correspond to the number of firing strokes remaining with the loading unit  10 . The indicators  44  are visible through a window  46  defined in the outer frame  12  ( FIGS. 1 and 9 ). Upon movement of the central drive  22  through a firing stroke, the rotatable counter  32  is rotated to present the next subsequent indicator  44  for visualization through the window  46 . 
     With continued reference to  FIGS. 6 and 7 , the rotatable counter  32  includes an internal stop  48  depending inwardly from the inner wall  32   i  of the rotatable counter  32  in diametrical opposed relation to the internal helical grooves  42 . The internal stop  48  is positionable to block advancement of the central drive  22  upon rotation of the rotatable counter  32  to a predefined angular orientation, e.g., to lockout the central drive  22  upon movement through a predefined number of firing strokes, which may correspond to depletion of, e.g., the staples in the end effector  300 . 
     Referring now to  FIGS. 4, 8 and 10-11 , the actuator assembly  34  of the counter and lockout mechanism  30  will be discussed. The actuator assembly  34  includes an actuator holder  50  and a counter actuator  52  at least partially disposed within a channel  54  of the actuator holder  50 . The actuator holder  50  is supported within a longitudinal opening  56  of the central drive  22  in fixed relation therewith (see also  FIG. 5 ). Any methodologies for securing the actuator holder  50  within the opening  56  of the central drive  22  are envisioned. In one embodiment, the actuator holder  50  includes spaced longitudinal grooves or rails  58  which receive mounting segments  22   m  of the central drive  22  (see  FIGS. 8 and 10 ). 
     As best depicted in  FIGS. 10 and 11 , the counter actuator  52  is pivotally mounted within the actuator holder  50  through pivot pin  60  which extends through respective openings  62 ,  64  of the actuator holder  50  and the counter actuator  52 . The counter actuator  52  may pivot in both a clockwise and counter clockwise direction about the pivot pin  60 . A biasing member  66 , e.g., a torsion spring, is mounted to the counter actuator  52  to normally bias the counter actuator  52  to an initial starting condition or stage of the counter actuator  52 . The starting or initial stage of the counter actuator  52  is depicted in  FIG. 10 . The torsion spring  66  has one end  68  secured in an opening  70  in the counter actuator  52  and a second end  72  secured in an opening  74  (shown in phantom) in the actuator holder  50 . 
     With reference again to  FIGS. 4 and 5 , the outer frame  12  includes a cam member  76  which cooperates with the counter actuator  52  to rotate the rotatable counter  32 . The cam member  76  may be a separate component secured to the outer frame  12  or be integrally formed with the outer frame  12 . The cam member  76  defines rear and forward cam surfaces  78 ,  80  and extends through the interior of the rotatable counter  32  in spaced relation therewith to not interfere with rotation of the rotatable counter  32 . The cam member  76  defines an interior surface  76   i.    
     Referring now to  FIG. 12 , the loading unit  10  may include a detent mechanism to permit rotational movement of the rotatable counter  32  in a first direction through actuation of the counter actuator  52  while preventing rotational movement in a second opposite direction. In the embodiment of  FIG. 12 , the detent mechanism may include a spring loaded plunger  84  which is adapted for reciprocal longitudinal movement in the direction of directional arrows “c 1 , c 2 ”. The plunger  84  may be mounted to the outer frame  12  by conventional means and defines a rounded plunger head  86 . The plunger head  86  may selectively engage corresponding openings or recesses  88  in the distal face  32   d  of the rotatable counter  32  during rotation of the rotatable counter  32  through each incremental arc segment of rotation. Each locking recess  88  may be in general alignment with a respective internal helical groove  42 . Upon rotation of the rotatable counter  32 , the plunger  84  is forced in a distal direction “c 1 ” such that the plunger head  86  is released from a select locking recess  88  and then returns under the influence of its spring bias in proximal direction “c 2 ” whereby the plunger head  86  is received within the next adjacent locking recess  88  in releasable secured relation therewith. In this position of the plunger  84 , the rotatable counter  32  is prevented from rotating, and the successive internal helical groove  42  is positioned to receive the counter actuator  52 . Upon movement of the central drive  22  and the counter actuator  52  through a successive firing stroke, the spring bias of the plunger  84  is overcome causing release of the plunger head  86  from the respective locking recess  88  permitting rotation of the rotatable counter  32  through a successive incremental arc segment of rotation. The plunger head  86  and the locking recesses  88  may have angled or cam surfaces to facilitate entry and exit of the plunger head  86  relative to the recesses  88 . 
       FIG. 13  illustrates an alternate detent mechanism to permit movement of the rotatable counter  32  in the first direction while preventing movement in the second direction. In this embodiment, the external wall  32   e  of the rotatable counter  32  includes a plurality of equi-distally spaced locking recesses  90  with each recess  90  in general alignment with a respective internal helical groove  42  of the rotatable counter  32 . The outer frame  12  has a ratchet pawl  92  mounted thereto. The ratchet pawl  92  is normally biased toward the external wall  32   e  of the rotatable counter  32  to engage a select locking recess  90 . Upon rotation of the rotatable counter  32 , the ratchet pawl  92  moves radially outwardly to release the select locking recess  90  and then returns under the influence of the spring bias to be received within the next adjacent locking recess  90 . 
     The operation of the loading unit  10  and the counter and lockout mechanism  30  now will be discussed. With reference to  FIG. 14 , the central drive  22  is in its proximal or initial position and the counter actuator  52  of the actuator assembly  34  is in its starting condition or first stage under the normal bias of the torsion spring  66  (e.g., biased in a counter-clockwise direction). The loading unit  10  is coupled to the handle assembly  200  whereby a coupler  202  (shown schematically) of the handle assembly  200  couples with the actuator holder  50  and/or the central drive  22 . An actuator of the handle assembly  200 , which is operatively connected to the coupler  202 , is actuated which initiates the first firing stroke of the central drive  22 . As the central drive  22  and the actuator assembly  34  (including the actuator holder  50  and the counter actuator  52 ) move distally through the firing stroke in the direction “t”, the upper leg  52   u  of the counter actuator  52  engages the rear cam surface  78  of the cam member  76 , causing the counter actuator  52  to pivot or rotate in a clockwise direction “m” to its second stage shown in  FIG. 15 . In this position, the lower leg  521  of the counter actuator  52  is orientated to engage a first internal helical groove  42  of the rotatable counter  32 . As depicted in  FIGS. 16-17 , during continued movement of the central drive  22  and the actuator assembly  34  through the firing stroke, the lower leg  521  of the counter actuator  32  traverses the internal helical groove  42  causing the rotatable counter  32  to rotate in the direction of directional arrow “b” through a predefined angular segment of rotation. The upper leg  52   u  traverses the inner surface  76   i  of the cam member  76  to maintain the counter actuator  52  in the engaged position. The central drive  22  is advanced (see arrow “t”) until the counter actuator  52  exits the internal helical groove  42  and clears the rotatable counter  32  as depicted in  FIG. 18 . In this position, the counter actuator  52  is reset or returns to its initial condition or first stage under the influence of the biasing member or torsion spring  66 . Simultaneously therewith, the ratchet or detent mechanism of either  FIG. 12  or  FIG. 13  selectively secures the rotatable counter  32  at this angular position. 
     Subsequent to completion of the firing stroke, the central drive  22  and the actuator assembly  34  are moved proximally via, e.g., one of the actuators of the handle assembly  200  or via a spring bias, to initiate its return stroke. During the return stroke, the upper segment  52   u  of the counter actuator  52  engages the forward cam surface  80  of the cam member  76  to rotate the counter actuator  52  in an opposite (e.g., counterclockwise) direction corresponding to a third stage of the counter actuator  52  depicted in  FIG. 19 . In the third stage, the lower segment  521  of the counter actuator  52  clears the internal helical grooves  42  of the rotatable counter  32  to permit the central drive  22  to complete the return stroke without engagement of the counter actuator  52  with the rotatable counter  32 . The upper segment  52   u  of the counter actuator  52  is in contact with the inner surface  76   i  of the cam member  76  to maintain the counter actuator in the disengaged position. 
     The central drive  22  and the actuator assembly  34  may undergo successive firing strokes to, e.g., deliver all of the staples. During each stroke, the counter actuator  52  engages a subsequent internal helical groove  42  to cause rotation, e.g., incremental, of the rotatable counter  32  with the corresponding indicator  44  being viewable by the clinician through the window  46  of the outer frame  12 . The ratchet or detent mechanism of  FIG. 12  or  FIG. 13  will secure the rotatable counter  32  at each incremental angular position, and then become released from the rotatable counter  32  during the next firing stroke and traversing movement of the counter actuator  52  through the successive internal helical groove  42 . 
     With reference now to  FIGS. 20-21 , upon movement of the rotatable counter  32  through a predefined number of arc segments corresponding to a predefined number of firing strokes of the central drive  22 , the rotatable counter  32  is eventually rotated to a position where the internal stop  48  is aligned with a lock shelf  82  of the central drive  22 . In this position, the central drive  22  is locked and prevented from moving in a distal direction, i.e., incapable of firing. The locked position may correspond to depletion of the staples, e.g., in the end effector or staple assembly  300 . 
     Thus, during use, the clinician can monitor the staple supply within the end effective  300  and anticipate when the supply will be exhausted. When the loading unit  10  is completed, the clinician can release the loading unit  10  from the handle assembly  200  and, if necessary, connect a new loading unit  10  to complete the procedure. 
     Referring now to  FIG. 2 , details of one exemplative handle assembly  200  for use with the loading unit  10  will be described. The handle assembly  200  includes a housing  204  and an elongated body  206  extending from the housing  204 . The housing  204  includes a stationary handle  208  and a movable handle  210  which is pivotally supported to the housing  204  and is operatively connected to a control rod  212  extending at least partially through the elongated body  206 . The control rod  212  is couplable to the central drive  22  of the loading unit  10  via, e.g., coupling  202 , upon mounting of the loading unit  10  to the handle assembly  200 . Pivotal movement of the movable handle  210  causes longitudinal translation of the control rod  212 , which also may approximate the staple cartridge  302  and the anvil  304 , and cause firing of the staples. A pair of retraction knobs  214  may be mounted to the housing  204  and also operatively coupled to the control rod  212 . The retraction knobs  214  may be utilized to retract the control rod  212  and the central drive  22  of the loading unit  10  subsequent to each firing stroke. The handle assembly  200  may further include an articulation lever  216  which is couplable to the translating rod  28  of the loading unit  10 . The articulation lever  216  may be manipulated to articulate the end effector or staple assembly  300 . A rotatable knob  218  may also be provided to cause rotation of the elongated body  206  and at least the end effector  300  of the loading unit  10 . 
     Other handle arrangements are also envisioned including single actuator handles, powered, electro-mechanical or the like. One example of a handle assembly  200  suitable for use with the loading unit  10  is disclosed in commonly assigned U.S. Pat. No. 8,070,033 to Millman et al., the entire contents of which are hereby incorporated by reference herein. 
     With reference now to  FIGS. 22-25 , further details of the end effector  300  of the loading unit will be discussed. In the embodiment of  FIG. 1 , the end effector  300  is a staple assembly including the staple cartridge  302  and the anvil  304  which are adapted to pivot relative to each other between open and approximated conditions depicted respectively in  FIGS. 22-23 . As best depicted in  FIGS. 24-25 , the staple cartridge  302  may include one or more staple magazines  306  with each magazine having a plurality of staples  308 . Each magazine  306  may further include a staple cam  310  which moves in a direction generally orthogonal to the axis “k” to eject the staples  308  toward the anvil  304 . At least one or more staple pushers  312  are at least partially disposed within the staple cartridge  302  and operatively coupled to the central drive  22  of the loading unit  10 . (see also  FIGS. 22-23 ) The staple pusher(s)  312  may be operatively couplable or engageable with, or a component of, the actuation sled  24  of the central drive  22 . Movement of the central drive  22  through a complete firing stroke, e.g., actuation of the movable handle  210  of the handle assembly  200 , will cause the staple pusher(s)  312  to engage the staple cams  310  to eject the staples  308  for passage through tissue to be crimped by the anvil  304 . In one embodiment, the staple cartridge  302  will deliver at least two or more linear rows of staples. Simultaneously therewith, the knife  26  of the actuation sled  24  may sever the tissue between the linear rows of staples  308 . Thereafter, the staple pusher  312  is returned through a return stoke to the initial position of  FIG. 22  via, e.g., retracting movement of the retraction knobs  214  of the handle assembly  200 . In this position, the movable handle  210  may be actuated to advance the control rod  212  and the central drive  22  of the loading unit  10  to deliver another set of staples  308  in sequence. 
     One exemplative staple assembly which may be incorporated with loading unit  10  is disclosed in commonly assigned U.S. patent application Ser. No. 14/279,781 to Kostrzewski, filed May 16, 2014, the entire contents of which disclosure are hereby incorporated by reference herein. 
     Although the end effector  300  is described as a stapling assembly, the loading unit  10  with the counter and lockout mechanism  30  may incorporate other types of end effectors with different functions. For example, the end effector  300  may be adapted to deliver any type of fasteners including clips, needles, medicant capsules or the like, and may be adapted to perform different stapling functions including end to end or circular fastening. 
     Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described.