Patent Publication Number: US-2022225985-A1

Title: Multi-use loading unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/600,865, filed Oct. 14, 2019, which is a continuation of U.S. patent application Ser. No. 15/376,979, filed Dec. 13, 2016, now U.S. Pat. No. 10,463,367, which is a continuation of U.S. patent application Ser. No. 14/691,906, filed Apr. 21, 2015, now U.S. Pat. No. 9,526,499, which is a division of U.S. patent application Ser. No. 13/280,880, filed Oct. 25, 2011, now U.S. Pat. No. 9,016,539, the entire contents of each of these prior applications are incorporated by reference herein. 
    
    
     BACKGROUND 
     The present disclosure relates generally to instruments for surgically joining tissue and, more specifically, to a multi-use loading unit for use with surgical instruments. 
     Various types of surgical instruments used to surgically join tissue are known in the art, and are commonly used, for example, for closure of tissue or organs in transection, resection, anastomoses, for occlusion of organs in thoracic and abdominal procedures, and for electrosurgically fusing or sealing tissue. 
     One example of such a surgical instrument is a surgical stapling instrument, which may include an anvil assembly, a cartridge assembly for supporting an array of surgical staples, an approximation mechanism for approximating the cartridge and anvil assemblies, and a firing mechanism for ejecting the surgical staples from the cartridge assembly. 
     Using a surgical stapling instrument, it is common for a surgeon to approximate the anvil and cartridge members. Next, the surgeon can fire the instrument to emplace staples in tissue. Additionally, the surgeon may use the same instrument or a separate instrument to cut the tissue adjacent or between the row(s) of staples. 
     SUMMARY 
     The present disclosure relates to a surgical instrument having a channel and a removable assembly disposed in releasable engagement with the channel. The removable assembly includes a cartridge body and a support plate. The cartridge body is configured to house a plurality of fasteners or staples therein and includes an engagement structure disposed adjacent a proximal end thereof. The support plate is configured to mechanically engage the cartridge body and includes an engagement structure disposed adjacent a proximal end thereof. The engagement structure of the cartridge body is configured for longitudinal alignment with the engagement structure of the support plate. The engagement structure of the cartridge body and the engagement structure of the support plate are configured to mechanically engage engagement structure of the channel when the removable assembly is engaged with the channel. 
     In disclosed embodiments, the engagement structure of the channel includes raised bosses, the engagement structure of the cartridge body includes a U-shaped recess, and/or the engagement structure of the support plate includes a U-shaped recess. In disclosed embodiments, the U-shaped recesses of the cartridge body and the support plate include a proximally-facing opening. 
     In disclosed embodiments, the channel includes a longitudinally-extending slot disposed adjacent a distal end thereof, and the support plate includes an outwardly-extending finger configured to releasably engage the longitudinally-extending slot of the channel. 
     In disclosed embodiments, the support plate includes an inwardly-extending finger disposed on a distal portion thereof. Here, the inwardly-extending finger is configured to releasably engage a groove disposed on a distal portion of the cartridge body. 
     In disclosed embodiments, the support plate includes a proximal protrusion disposed adjacent a proximal end thereof. The proximal protrusion is configured to help prevent an actuation sled from prematurely translating distally with respect to the cartridge body. 
     In certain embodiments, the channel is part of a removable loading unit that includes an anvil assembly. 
     In a further aspect of the present disclosure, a loading unit for a surgical instrument has an anvil assembly, a channel, and a cartridge assembly. The channel has a boss disposed adjacent a proximal end thereof. The cartridge assembly and anvil assembly are pivotable with respect to one another. The cartridge assembly includes a support plate, and a cartridge body. The support plate is configured to releasably engage the channel and includes a recess disposed adjacent a proximal end thereof. The cartridge body is configured to releasably engage the support plate and is configured to house a plurality of fasteners or staples therein. The cartridge body includes a recess disposed adjacent a proximal end thereof. The recess of the cartridge body is configured for longitudinal alignment with the recess of the support plate. At least one of the recesses of the cartridge body and the support plate is configured to mechanically engage the boss of the channel when the support plate is engaged with the channel. 
     In disclosed embodiments, the recess of the cartridge body includes a U-shaped recess and/or the recess of the support plate includes a U-shaped recess. In such embodiments, the U-shaped recesses of the cartridge body and the support plate include a proximally-facing opening. 
     In disclosed embodiments, the channel includes a longitudinally-extending slot disposed adjacent a distal end thereof, and the support plate includes an outwardly-extending finger configured to releasably engage the longitudinally-extending slot of the channel. 
     In disclosed embodiments, the support plate includes an inwardly-extending finger disposed on a distal portion thereof. The inwardly-extending finger is configured to releasably engage a groove disposed on a distal portion of the cartridge body. 
     In disclosed embodiments, the support plate includes a proximal protrusion disposed adjacent a proximal end thereof. The proximal protrusion is configured to help prevent an actuation sled from prematurely translating distally with respect to the cartridge body. 
     In certain embodiments, the loading unit includes a body portion to which the cartridge assembly and anvil assembly are attached the body portion being attachable to the elongate member of a surgical instrument. 
     The present disclosure also relates to a surgical instrument having a channel and comprising a cartridge assembly, a drive member and a lockout mechanism. The drive member is configured to travel in a distal direction. The lockout mechanism is configured to prevent longitudinal translation of the drive member. The lockout mechanism comprises a latch and a spring. The latch is disposed in mechanical cooperation with the channel and is laterally movable from an initial position to a blocking position. The spring is configured to bias the latch into the blocking position in which a shaped surface of the latch obstructs the distal movement of the drive member when the latch is in the blocking position. 
     In disclosed embodiments, the latch is pivotable with respect to the cartridge assembly. 
     In disclosed embodiments, the latch includes a hook configured to engage a portion of the drive member to prevent distal translation of the drive member. 
     In disclosed embodiments, the latch includes a camming surface, and wherein when the drive member translates proximally into contact with the camming surface, the latch pivots away from its blocking position. 
     In disclosed embodiments, the surgical instrument comprises a sled configured for longitudinal translation with respect to at least a portion of the cartridge assembly. The sled includes a tail portion that is configured to abut a portion of the latch when the sled is adjacent its proximal-most position. The tail portion of the sled is configured to prevent the latch from moving into its blocking position. 
     The cartridge assembly may include a cartridge body defining a longitudinal slot. The drive member travels along the longitudinal slot in the distal direction. The shaped surface of the latch is substantially aligned with the longitudinal slot when the latch is in the blocking position. 
    
    
     
       BRIEF DESCRIPTION OF FIGURES 
       Various embodiments of the presently disclosed surgical instrument are disclosed herein with reference to the drawings, wherein: 
         FIG. 1  is a perspective view of a surgical stapling instrument without a loading unit connected thereto in accordance with the present disclosure; 
         FIG. 1A  is a perspective view of a loading unit in accordance with the present disclosure; 
         FIG. 1B  is a perspective view of a tool assembly of the loading unit of  FIG. 1A ; 
         FIG. 1C  is a perspective view of a cartridge assembly of the loading unit of  FIG. 1A ; 
         FIG. 1D  is an assembly view of the tool assembly of  FIG. 1B ; 
         FIG. 2  is a bottom perspective view of a portion of the tool assembly of  FIG. 1B ; 
         FIG. 3  is a perspective view of a portion of the tool assembly of  FIG. 1B ; 
         FIGS. 4 and 5  are transverse cross-sectional views of portions of the tool assembly of  FIG. 1B ; 
         FIG. 6  is a perspective view of a proximal portion of a channel of the tool assembly of  FIG. 1B ; 
         FIG. 7  is a perspective view of a distal portion of the channel of the tool assembly of  FIG. 1B ; 
         FIG. 8  is a transverse cross-sectional view of portion of the tool assembly of  FIG. 1B ; 
         FIG. 9  is a perspective view of the tool assembly of  FIG. 1B ; 
         FIG. 10  is a perspective view of a support plate of the tool assembly of  FIG. 1B ; 
         FIG. 11  is a perspective view of a distal portion of a cartridge body of the tool assembly of  FIG. 1B ; 
         FIG. 12  is a perspective view of a proximal portion of the cartridge body of the tool assembly of  FIG. 1B ; 
         FIG. 13  is a perspective view of a portion of a tool assembly of the present disclosure including another embodiment of a channel; 
         FIGS. 14 and 15  are perspective views of the channel of  FIG. 13 ; 
         FIGS. 16 and 17  are perspective views of different portions of the channel of  FIG. 13 ; 
         FIG. 18  is a perspective view of a tool assembly of the present disclosure including a lockout mechanism; 
         FIG. 19  is an enlarged perspective view of the lockout mechanism of the present disclosure engaged with a portion of the tool assembly; 
         FIG. 20  is a perspective assembly view of portions of the tool assembly includes the lockout assembly; 
         FIG. 21  is a perspective view of the lockout mechanism engaged with the channel; 
         FIG. 22  is a perspective assembly view of the lockout mechanism and a portion of the channel; 
         FIG. 23  is an assembly view of the removable assembly of an embodiment of the present disclosure; 
         FIG. 24  is a perspective view of a latch of the lockout mechanism of the present disclosure; 
         FIG. 25  is a perspective view of a sled of the present disclosure; 
         FIG. 26  is a top view of the cartridge assembly taken along line  26 - 26  of  FIG. 18  and illustrating the lockout mechanism, and the drive member and sled in their original positions; 
         FIG. 27  is an enlarged view of the area indicated in  FIG. 26 ; 
         FIGS. 28-31  are top views of a portion of the cartridge assembly showing the drive member, sled, and latch in various positions; and 
         FIGS. 32-35  are perspective views of a second embodiment of a lockout mechanism in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the presently disclosed surgical instrument, loading unit and tool assembly for use therewith, are described in detail with reference to the drawings, wherein like reference numerals designate corresponding elements in each of the several views. As is common in the art, the term ‘proximal” refers to that part or component closer to the user or operator, e.g., surgeon or physician, while the term “distal” refers to that part or component farther away from the user. 
     A surgical stapling instrument of the present disclosure is indicated as reference numeral  10  in  FIG. 1 . Additionally, the depicted surgical instrument fires staples, but it may be adapted to fire any other suitable fastener such as clips and two-part fasteners. A loading unit for use with surgical instrument  10  is shown in the accompanying figures and is indicated as reference number  500 . A tool assembly of the loading unit  500  is shown in the accompanying figures and is indicated as reference number  1000 . 
     Loading unit  500  is attachable to an elongated or endoscopic portion  18  of surgical instrument  10 , e.g., to allow surgical instrument  10  to have greater versatility. Loading unit  500  of the present disclosure is configured for to be used more than once. In particular, the loading unit has a removable assembly  1600  that includes the cartridge assembly  1200 . The cartridge assembly  1200  forms a part of the tool assembly  1000 , and the tool assembly  1000  forms a portion of the loading unit  500 . The removable assembly is configured to be removed and replaced (e.g., after firing fasteners therefrom). Examples of loading units for use with a surgical stapling instrument are disclosed in commonly-owned U.S. Pat. No. 5,752,644 to Bolanos et al., the entire contents of which are hereby incorporated by reference herein. The loading unit  500  shown includes a proximal body portion  502  that is attachable to an endoscopic portion or an elongated portion  18  of a surgical instrument  10  having a handle assembly  12 . However, the features of the loading units  500  of the present disclosure, including the tool assembly  1000 , can be incorporated in a surgical instrument in which does not include a detachable portion of the elongated portion of the instrument. 
     Loading unit  500  includes a proximal body portion  502  and a tool assembly  1000 . Proximal body portion  502  defines a longitudinal axis “A-A,” and is releasably attachable to a distal end of elongated portion  18  of surgical instrument  10 . Tool assembly  1000  includes a pair of jaw members including an anvil assembly  1100  and a cartridge assembly  1200 . One jaw member is pivotal in relation to the other to enable the clamping of tissue between the jaw members. In the illustrated embodiments, cartridge assembly  1200  is pivotal in relation to anvil assembly  1100  and is movable between an open or unclamped position and a closed or approximated position. However, the anvil assembly, or both the cartridge assembly and the anvil assembly, can be movable. 
     With reference to  FIG. 1D , for example, anvil assembly  1100  includes an anvil cover  1110  and an anvil plate  1112 , which includes a plurality of staple forming depressions  1113 . Anvil plate  1112  is secured to an underside of anvil cover  1110  and defines a channel  1114  (see  FIG. 8 , for example) therebetween. When tool assembly  1000  is in the approximated position, staple forming depressions  1113  are positioned in juxtaposed alignment with staple receiving slots of the cartridge assembly  1200 . 
     The tool assembly includes a channel or carrier  1300  which receives and supports a cartridge assembly and a support plate  1500 . The cartridge assembly has a cartridge body  1400 . The cartridge body and support plate  1500  are attached to the channel or carrier  1300  by a snap-fit connection, as discussed below, a detent, latch, or by another type of connection. The cartridge assembly includes fasteners or staples  1414 . Cartridge body  1400  defines a plurality of laterally spaced staple retention slots  1410 , which are configured as openings in tissue contacting surface  1412  (see  FIG. 11 ). Each slot  1410  is configured to receive a fastener or staple  1414  therein. Cartridge assembly  1200  also defines a plurality of cam wedge slots which accommodate staple pushers  1416  and which are open on the bottom (i.e., away from tissue-contacting surface  1412 ) to allow an actuation sled  1418  to pass longitudinally therethrough. 
     Further details of the various components of cartridge assembly  1200 , including the connection between its various components, and the removability and replaceability of cartridge body  1400  and support plate  1500  with respect to channel  1300 , are discussed below. Generally, the removable assembly  1600  includes cartridge assembly  1200  and support plate  1500 . The removable assembly  1600  is removable from channel  1300 , e.g., after staples  1414  has been fired from cartridge body  1400 . Another removable assembly is capable of being loaded onto channel  1300 , such that surgical instrument  10  can be actuated again to fire additional fasteners or staples  1414 , for instance. 
     Channel  1300 , which may be machined (e.g., e.g.,  1300   a  in  FIGS. 13-17 ) or made of sheet metal (e.g.,  1300   b  in  FIG. 9 ), includes one or a pair of engagement structures or proximal bosses  1310  (e.g.,  1300   b  in  FIG. 6 ), a pair of cut-outs  1320  disposed adjacent a distal end, a pair of distal slots  1330 , a central slot  1340 , a pair of proximal holes  1350 , and a ramped surface  1360 . Proximal holes  1350  are configured to align with/mechanically engage a pair of corresponding holes  1120  (e.g., with a pin or protrusion extending through holes  1350  and holes  1120 ) on anvil cover  1110  to facilitate a pivotal relationship between anvil assembly  1100  and cartridge assembly  1200 . It is envisioned that engagement structures  1310  may be pins, protrusions, or similar structure. 
     Cartridge body  1400  includes a central slot  1420 , and rows of staple retention slots  1410  positioned on each side of slot  1420  (see  FIG. 11 ). In the illustrated embodiment, three rows of retention slots  1410  are shown. More specifically, cartridge body  1400  is configured such that actuation sled  1418  can pass through the cam wedge slots and force staple pushers  1416  towards anvil plate  1112 . The staples  1414 , which are supported on the pushers, are then forced out of their respective staple retention slots  1410 . Cartridge body  1400  also includes a pair of engagement structures or U-shaped recesses  1430  (which may, in other embodiments, be slots or openings) adjacent its proximal end, a pair of central bosses  1440 , a pair of distal protrusions  1450 , and a pair of distal grooves  1460 . Pairs of upper and lower mounting surfaces  1470 ,  1480 , respectively, are disposed adjacent a proximal end of cartridge body  1400 , and are disposed adjacent respective upper and lower mounting slots  1472 ,  1482 . 
     With particular reference to  FIG. 10 , support plate  1500  includes a base surface  1510 , a longitudinal slot  1520  extending through base surface  1510 , a pair of proximal fingers  1530  disposed and extending substantially perpendicularly from a proximal end of base surface  1510 , a pair of intermediate fingers  1550  extending substantially perpendicularly from a middle portion of base surface  1510 , a pair of inwardly-extending fingers  1560  and outwardly-extending bosses  1570  disposed adjacent a distal end of base surface  1510 , and a pair of proximal protrusions  1580  disposed adjacent the proximal end of base surface  1510 . Each proximal finger  1530  includes an engagement structure or proximal-facing U-shaped recesses  1532 , an upper mounting flange  1534 , and a lower mounting flange  1536 . As can be appreciated, support plate  1500  helps maintain pushers  1416  in place with respect to cartridge body  1400 . Additionally, longitudinal slot  1520  allows a portion of a drive member to pass through the support plate  1500 . The drive member may be a dynamic clamping member  1402 . The dynamic clamping member or drive member  1402  drives the actuation sled  1418  through the cartridge body  140 . The central slot of the cartridge body, the central slot of the channel, and the longitudinal slot of the support plate are all configured to align with one another to allow the passage of the drive member. 
     In use, to connect cartridge body  1400  and support plate  1500 , cartridge body  1400  and support plate  1500  are assembled or brought together such that the proximal-most end of cartridge is positioned between proximal fingers  1530  of support plate  1500  and in contact with base surface  1510  thereof. Support plate  1500  is then longitudinally translated (e.g., slid distally) with respect to cartridge body  1400  such that upper mounting flanges  1534  and lower mounting flanges  1536  engage upper mounting slots  1472  and lower mounting slots  1482 , respectively. The longitudinal translation between cartridge body  1400  and support plate  1500  continues until a distal-most end of proximal fingers  1530  contact a respective vertical wall  1490  ( FIG. 12 ) of cartridge body  1400 . At this stage, U-shaped recesses  1430  are laterally adjacent and aligned with U-shaped recesses  1532  (see  FIG. 3 ), and continued proximal movement of cartridge body  1400  with respect to support plate  1500  is prevented. Next, or concomitantly with the relative longitudinal translation between cartridge body  1400  and support plate  1500 , cut-outs  1552  within intermediate fingers  1550  of support plate  1500  are positioned around central bosses  1440  of cartridge, and inwardly-extending fingers  1560  are moved into engagement with distal grooves  1460  of cartridge. Cartridge assembly  1200  and support plate  1500  comprise a removable assembly  1600 , which is removable from and replaceable onto channel  1300  by the user of the surgical instrument  10  and/or loading unit  500 . 
     Removable assembly  1600  is insertable onto channel  1300  by approximating removable assembly  1600  and channel  1300  such that proximal bosses  1310  are positioned proximally of U-shaped recesses  1430  and  1532 , and such that distal ends of distal slots  1330  are positioned proximally of proximal ends of outwardly-extending bosses  1570 . Next, removable assembly  1600  is translated longitudinally (e.g., proximally) with respect to channel  1300  such that outwardly-extending bosses  1570  translate proximally within distal slots  1330  until proximal bosses  1310  contact U-shaped recesses  1430  and  1532 . Next, or concomitantly with the relative longitudinal translation between removable assembly  1600  and channel  1300 , cut-outs  1320  of channel  1300  are moved into engagement with distal protrusions  1450  of cartridge body  1400 . Ramped surface  1360  is engaged by the dynamic clamping member  1402  in order to move the anvil assembly  1100  and the cartridge assembly  1200  with respect to one another. A similar surface could be provided on the anvil assembly  1100 , in other embodiments. It is envisioned that ramped surface  1360  may also facilitate the alignment and/or engagement between channel  1300  and support plate  1300  and/or cartridge body  1400 . 
     Once assembled, a user is able to actuate movable handle  22  to eject staples  1414  from cartridge body  1400  and into tissue, as described below. It is envisioned that proximal protrusions  1580 , which extend from base surface  1510 , help maintain actuation sled  1418  in its relative position with respect to support plate  1500  before actuation of instrument  10 . That is, it is envisioned that actuation sled  1418 , or a portion thereof, is positioned proximally of proximal protrusions  1580 , and that proximal protrusions  1580  form a physically barrier to hinder any premature distal advancement of actuation sled  1418 . Once a user intends to actuate instrument  10  and distally advance actuation sled  1418  beyond proximal protrusions  1580 , the force used to advance actuation sled  1418  is sufficient to force a lower surface or portion of actuation sled  1418  over proximal protrusions  1580 . 
     After staples  1414  have been ejected from cartridge body  1400 , and a user wishes to use the same instrument  10  to fire additional staples  1414  (or another type of fastener or knife), the user can remove the removable assembly  1600  by sliding removable assembly  1600  distally with respect to channel  1300 . Next, a user removes the removable assembly  1600  from the channel  1300 . Another removable assembly with unfired staples can be loaded into the channel  1300 . In other embodiments, a cartridge body of a cartridge assembly can be removable from a support plate after the removable assembly is removed from the channel  1300 . The cartridge body is removed by sliding support plate  1500  proximally with respect to cartridge body  1400 . Another cartridge body, if desired, may be coupled to the support plate and inserted into the channel. 
     In certain embodiments, the removable assembly is part of a loading unit  500  that is removably attached to the elongated portion of a surgical stapling instrument, such as elongated portion  18 . This enables the user to choose a staple line length that is shorter or longer. It is also contemplated that the removable assembly can be used with a surgical instrument that does not have a loading unit that is removable and instead has jaws permanently attached to the elongated portion  18 . 
     During operation of stapler  10 , actuation of its movable handle  22  will fire the staples. The handle assembly  12  has an elongate actuation shaft that is translated distally when the movable handle  22  is pivotally moved by the user. The actuation shaft of the handle assembly can include teeth that are engaged by the movable handle  22 , or the handle assembly  12  can include a series of gears for moving the actuation shaft. Alternatively, the handle assembly can include a motorized driver for moving the actuation shaft, or the handle assembly can be attachable to a separate motorized driver. 
     In certain embodiments, through successive strokes of the movable handle, a drive rod  30  (a distal portion of which is illustrated in  FIGS. 1 and 27-31 )) is advanced distally, such that drive rod  30  pushes a portion of the drive assembly (which includes the dynamic clamping member  1402 ) to translate distally through cartridge body  1400 . (Further details of how actuation of movable handle  22  causes distal advancement of drive rod  30  are explained in U.S. Pat. No. 6,953,139 to Milliman et al., which is hereby incorporated by reference herein.) Distal movement of the drive assembly, and in particular, the dynamic clamping member or drive member  1402 , causes approximation of one jaw member with respect to the other. That is, an upper portion of the dynamic clamping member  1402  travels through the channel  1114  between the anvil plate  1112  and the anvil cover  1110 , and a lower portion of the dynamic clamping member  1402  travels below the carrier  1300  of the cartridge assembly  1200 , which causes approximation of the anvil assembly  1100  and the cartridge assembly  1200  to clamp tissue therebetween. For example, the channel  1300  may have a lower surface defining a camming surface and the lower portion of the dynamic clamping member  1402  engages the camming surface to pivot the cartridge assembly  1200  toward the anvil assembly  1100 . 
     Additionally, distal translation of the dynamic clamping member  1402  causes the actuation sled  1418  to move distally through cartridge body  1400 , which causes cam wedges  1419  of actuation sled  1418  to sequentially engage pushers  1416  to move pushers  1416  vertically within staple retention slots  1410  and eject staples  1414  into staple forming depressions  1113  of anvil plate  1112 . Subsequent to the ejection of staples  1414  from retention slots  1410  (and into tissue), a cutting edge of the dynamic clamping member  1402  severs the stapled tissue as the cutting edge travels distally through central slot  1420  of cartridge body  1400 . 
     It is also envisioned, in further embodiments, that an end effector or tool assembly like the end effector or tool assembly  1000  is arranged for articulating between a first position where tool assembly  1000  is aligned with longitudinal axis “A-A,” and a second position where tool assembly  1000  is disposed at an angle with respect to longitudinal axis “A-A.” For example, the anvil assembly  110  may be pivotably attached to the proximal body portion  502  of a loading unit  500 , or pivotably attached to the elongated portion of the instrument. The loading unit includes one or more cables or linkages disposed in the proximal body portion  502  and attached at the tool assembly  1000 . When the cable or linkage is displaced, the tool assembly pivots and articulates with respect to the instrument. Further details of providing articulation are described in detail in commonly-owned U.S. Pat. No. 6,953,139 to Milliman et al., the contents of which has previously been incorporated by reference in their entirety. Further, the tool assembly can be configured not to articulate. 
     Additionally, it is envisioned that instrument  10  is powered by a power source and/or motor. Further details of such a powered surgical instrument are included in U.S. Pat. No. 8,800,837, the entire contents of which are hereby incorporated by reference herein. 
     Further, and as illustrated in  FIG. 11 , for example, the present disclosure includes a cartridge body  1400  having a stepped tissue-contacting surface  1412 . In such an embodiment, different sized staples  1414 , or all the same sized staples, may be used. Further details of a staple cartridge having multiple staple sizes are included in U.S. Pat. No. 7,407,075 to Holsten et al., the entire contents of which are hereby incorporated by reference herein. 
     The present disclosure also relates to methods of using the described surgical instrument  10 , loading unit  500 , and tool assembly  100  to perform a surgical procedure and to methods of assembling the various components thereof, as described above. 
     With reference to  FIGS. 18-35 , two embodiments of a lockout mechanism  2000 ,  2000   a  of the present disclosure are shown. For each of these embodiments, a surgical instrument having the lockout may have a channel, removable assembly, cartridge body, support plate, and the engagement structures discussed above. Furthermore, the present disclosure is directed to a removable assembly having the lockout, or a loading unit having the lockout. 
     With reference to  FIGS. 18-31 , the first embodiment of lockout mechanism  2000  includes a latch  2010  and a spring  2030 , and is configured to prevent re-firing of cartridge body  1400  of removable assembly  1600 , and also prevent distal translation of dynamic clamping member  1402  after an initial distal translation of knife and prior to another removable assembly  1600  being loaded onto channel  1300 . 
     With particular reference to  FIGS. 22 and 24 , latch  2010  includes a body  2012  having an upper surface  2014  and a lower surface  2016 , a lower protrusion  2018  depending downwardly from lower surface  2016 , a spring stop  2019  extending upwardly from upper surface  2014 , and a shaped surface  2020  on a first lateral side  2022 . The body  2012  also has a second lateral side  2024 . The shaped surface  2020  has two sides. The first side  2020   a  is angled with respect to the central slot  1340  when the latch  2010  is in a blocking position in which the latch obstructs the passage of the dynamic clamping member  1402 . The second side  2020   b  of the shaped surface  2020  extends transversely to the central slot  1340  when the latch is in the blocking position. (See  FIG. 30 ). 
     Referring now to  FIGS. 19-24 , latch  2010  is mechanically engaged with channel  1300  so that the latch  2010  can pivot with respect to the channel  1300 . In particular, lower protrusion  2018  of latch  2010  ( FIG. 24 ) extends through an opening  1380  ( FIG. 22 ) in channel  1300 , such that latch  2010  is pivotable with respect to channel  1300 . Lower protrusion  2018  is maintained in mechanical engagement with channel  1300  by a lock pin  2050  ( FIG. 22 ). Alternatively, the protrusion can be omitted and a separate pivot pin in engagement with the body  2012  and the channel  1300  can be used. 
     With regard to  FIGS. 21-22 , spring  2030  includes a first leg  2032 , a second leg  2034 , and an intermediate portion  2036  interconnecting first leg  2032  and second leg  2034 . First leg  2032  is in contact with a portion of channel  1300 . For example, the channel  1300  may have a slot  1301 , a notch, or some other feature for restricting the movement of the first leg  2032 . Second leg  2034  is disposed in contact with spring stop  2018  of latch  2010 . Intermediate portion  2036  is disposed between first leg  2032  and second leg  2034 . For example, the spring may have a U-shaped configuration (see  FIG. 27 ), or some other shape, such as L-shaped. 
     Spring  2030  is in mechanical cooperation with a portion of the cartridge assembly  1200 . The spring is configured to bias latch  2010  towards its blocking position. In the initial position of the dynamic clamping member  1402  and the sled  1418  (e.g., prior to distal advancement thereof to fire staples and incise tissue), a tail portion  1417  of sled  1418  ( FIG. 25 ) physically prevents the shaped surface  2020  of latch  2010  from moving from its initial position into its blocking position, and thus allows distal translation of dynamic clamping member  1402  and sled  1418  (see  FIGS. 26 and 27 ). After translation of the dynamic clamping member and sled, the spring moves the latch  2010  to the blocking position, where the shaped surface  2020  of latch  2010  obstructs the central slot  1340  of channel  1300  and the longitudinal slot  1520  extending through base surface  1510  of support plate  1500  (see  FIGS. 30 and 31 ), such that shaped surface  2020  would block distal translation of dynamic clamping member  1402  when the dynamic clamping member  1402  has been retracted after firing staples and cutting tissue. 
     The latch  2010  is laterally movable from an initial position to a blocking position. The latch moves laterally, which enables the shaped surface of the latch to obstruct the slot and move away from a position that obstructs the slot of the cartridge assembly. 
     During retraction of the dynamic clamping member, the dynamic clamping member slides along the shaped surface first side  2020   a , keeping the latch  2010  away from the dynamic clamping member and pivoting the latch against the bias of the spring. In the retracted position of the dynamic clamping member, it is disposed proximally of shaped surface  2020  and the sled  1418  and/or tail portion  1417  is not abutting the shaped surface  2020 . The latch  2010  pivots to the blocking position, so that the second side  2020   b  obstructs and/or prevents distal movement of the dynamic clamping member. 
     During distal advancement of dynamic clamping member  1402  and sled  1418 , and after sled  1418  distally passes latch  2010  such that shaped surface  2020  is no longer in contact with tail portion of sled  1418 , dynamic clamping member  1402  abuts the shaped surface  2020 , which physically blocks latch  2010  from moving into its blocking position, and thus permits distal translation of dynamic clamping member  1402  (see  FIG. 28 ). 
     When cartridge assembly  1200  or removable assembly  1600  is removed from channel  1300 , latch  2010  continues to block dynamic clamping member  1402  (see  FIG. 31 ). When a new cartridge assembly  1200  or removable assembly  1600  is loaded onto channel  1300 , tail portion  1417  of the new sled  1418  engages shaped surface first side  2020   a  of latch  2010  and pivots latch  2010  away from its blocking position. Without a sled having the correct configuration, the latch remains in the blocking position. 
     With reference to  FIGS. 32-35 , a second embodiment of lockout mechanism  2000   a  is shown. A surgical instrument having the lockout may have a channel, removable assembly, cartridge body, support plate, and the engagement structures discussed above. Furthermore, the present disclosure is directed to a removable assembly having the lockout, or a loading unit having the lockout. Lockout mechanism  2000   a  includes a latch  2010   a , and a spring. The spring is not shown for clarity, but may be as discussed above. Unlike the embodiment of lockout mechanism  2000  discussed above, this embodiment of lockout mechanism  2000   a  does not include a lock pin  2050 . Here, to maintain latch  2010   a  in engagement with channel  1300   a , lower surface  2016   a  of latch  2010   a  includes a locking member  2018   a  depending therefrom. 
     In the illustrated embodiment, locking member  2018   a  includes a pair of parallel walls that are interconnected by a pair of arcuate walls. The opening  1380   a  of channel  1300   a  includes similar, but slightly larger shape with respect to locking member  2018   a  and also includes a circular recess  1381   a , around which locking member  2018   a  can rotate (see  FIGS. 34 and 35 ). 
     To engage latch  2010   a  with channel  1300   a , locking member  2018   a  is inserted through opening  1380   a  and latch  2010   a  is then rotated a predetermined amount (e.g., about 40 degrees to about 130 degrees) such that latch  2010   a  does not fall through opening  1380   a  of channel  1300   a . The spring (not shown in this embodiment for clarity) may then be positioned between spring stop  2018   a  of latch  2010   a  and a portion of channel  1300   a , as described above. 
     As can be appreciated, use of surgical instrument including the second embodiment of lockout mechanism  2000   a  is similar to, or that same as use of the surgical instrument including the first embodiment of lockout mechanism  2000 , as described above. 
     While the above description contains many specifics, these specifics should not be construed as limitations on the scope of the present disclosure, but merely as illustrations of various embodiments thereof. Therefore, the above description should not be construed as limiting, but merely as exemplifications of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.