WO2014139440A1

WO2014139440A1 - Surgical stapling apparatus

Info

Publication number: WO2014139440A1
Application number: PCT/CN2014/073334
Authority: WO
Inventors: Lin Chen
Original assignee: Covidien Lp; Covidien (China) Medical Devices Technology Co., Ltd.
Priority date: 2013-03-15
Filing date: 2014-03-13
Publication date: 2014-09-18
Also published as: CN104042288A

Abstract

A surgical stapling apparatus (10) is disclosed which includes a handle portion (20), an elongated body potion (30) extending distally from the handle portion (20) and a distal head portion (40) including an anvil assembly (400) and a replaceable stapling assembly (100). The replaceable stapling assembly (100) includes a pusher (112) and a plurality of staples (600). A firing assembly (300) extends between the handle portion (20) and the replaceable stapling assembly (100) and includes a pusher link (330) which is releasably engageable with the pusher (112) and is movable to effect movement of the pusher (112). An approximation assembly (200) extends between the handle portion (20) and the distal head portion (40) and includes an anvil retainer (260) configured to releasably support the anvil assembly (400). A first engagement collar (36a) is rotatably supported about a distal end of the elongated body portion (30) and is configured to releasably engage the replaceable stapling assembly (100). A housing of the handle portion (20) may releasably support one or more modular assemblies for assisting a clinician in using the apparatus. The modular assembly may include indicator assemblies or lockout assemblies.

Description

SURGICAL STAPLING APPARATUS

BACKGROUND

Technical Field

[0001] The present disclosure relates generally to a surgical stapling apparatus for applying surgical staples to body tissue and, more particularly, to a surgical stapling apparatus for performing circular anastomosis of hollow tissue structures.

Background of Related Art

[0002] Anastomosis refers to the surgical joining of separate hollow tissue sections.

Typically, an anastomosis procedure follows surgery in which a diseased or defective section of a hollow tissue structure is removed, thus requiring the joining of the remaining end sections of the tissue structure. Depending on the particular procedure being performed and/or other factors, the end sections of the tissue may be joined by circular anastomosis, e.g., end-to-end anastomosis, end-to-side anastomosis, or side-to-side anastomosis.

[0003] In a circular anastomosis procedure, the two end sections of a tubular organ are joined using a stapling apparatus that drives a circular array of staples through each of the end sections to join the end sections to one another in end-to-end relation and simultaneously cores any tissue within the newly joined hollow tissue structure to clear the passage defined by the hollow tissue structure. A typical circular anastomosis apparatus includes an elongated shaft having a handle portion at a proximal end and a staple holding component at a distal end. An anvil assembly including an anvil rod and an attached anvil head is mounted to the distal end of the elongated shaft adjacent the staple holding component. In use, the end portions to be joined are clamped between the anvil head and the staple holding component. The clamped end portions are then joined to one another by driving one or more staples from the staple holding component, through the tissue, and into the anvil head to form the staples about the tissue. Examples of such circular anastomosis apparatus are described in U.S. Patent Nos. 7,857,187 to Milliman ("the Ί87 patent"), 6,945,444 to Gresham et al. ("the '444 patent") the entire contents of which are hereby incorporated by reference herein in its entirety.

[0004] Typically, surgical stapling apparatus for performing circular anastomosis procedures are disposable after a single use. Due to the rising costs of health care, a need exists for a surgical stapling apparatus that includes reusable components and is configured to facilitate sterilization of the reusable components.

SUMMARY

[0005] A surgical stapling apparatus is disclosed which includes a handle portion, an elongated body portion extending distally from the handle portion and a distal head portion including an anvil assembly and a replaceable stapling assembly. The replaceable stapling assembly includes a pusher and a plurality of staples. The pusher is movable to eject the staples from the replaceable stapling assembly. A firing assembly extends between the handle portion and the replaceable stapling assembly and includes a pusher link which is releasably engageable with the pusher and is movable to effect movement of the pusher. An approximation assembly extends between the handle portion and the distal head portion. The approximation assembly includes an anvil retainer configured to releasably support the anvil assembly. The approximation assembly is actuable to move the anvil assembly in relation to the replaceable stapling assembly. A first engagement collar is rotatably supported about a distal end of the elongated body portion and is configured to releasably engage the replaceable stapling assembly. [0006] In an embodiment, the replaceable stapling assembly includes a shell which houses the pusher. The shell has a proximal end including external threads configured to releasably engage internal threads formed on the first engagement collar.

[0007] The elongated body portion may include an outer tube such that the first engagement collar is rotatably supported about the distal end of the outer tube.

[0008] In an embodiment, the outer tube includes an annular flange which is positioned to prevent the first engagement collar from sliding off of the distal end of the outer tube.

[0009] In an embodiment, a second engagement collar is rotatably supported about a proximal end of the outer tube and, the handle portion includes a housing. The second engagement collar is configured to releasably engage the housing to facilitate separation of the outer tube from the housing. The second engagement collar may include internal threads and the housing may include external threads which are configured to releasably engage the internal threads of the engagement collar to releasably secure the outer tube to the housing.

[0010] In an embodiment, the handle portion includes a housing supporting a proximal portion of the firing assembly and the approximation assembly. A modular indicator assembly may be releasably secured to the housing. The modular indicator assembly may be configured to provide an indication to a clinician of when the apparatus is in a fire-ready position and may be secured to the housing as a unit by at least one screw.

[0011] In an embodiment, the housing supports a modulator safety lockout assembly configured to block pivotal movement of a lockout member for preventing action of the firing assembly. The lockout assembly includes a mounting plate which is releasably secured to the housing by screws to facilitate easy attachment or removal of the safety lockout assembly to the housing, as an integral unit. [0012] In an embodiment, the approximation assembly includes a drive screw defining a helical channel, a rotatable sleeve assembly including a detent positioned within the helical channel, and a rotatable knob secured to the rotatable sleeve assembly. The rotatable sleeve assembly is rotatably secured to the housing and rotatable in relation to the drive screw to effect longitudinal translation of the drive screw within the housing.

[0013] The rotatable sleeve assembly may include a sleeve having an annular flange.

The apparatus may further include a first collar secured to the proximal end of the housing and a second collar secured to the first collar, wherein the first and second collars define an annular recess configured to rotatably receive the annular flange on the sleeve.

[0014] In an embodiment, the first collar is releasably secured to the proximal end of the housing such as threadably engaged with the housing.

[0015] In an embodiment, the pusher link includes an L-shaped slot and the pusher includes a finger which is rotatable into engagement with the L-shaped slot to releasably secure the pusher to the pusher link.

[0016] In an embodiment, the plurality of staples of the replaceable stapling assembly are supported in an annular staple guide cap.

[0017] A surgical stapling apparatus is also disclosed which includes, a handle portion; an elongated body portion extending distally from the handle portions, a distal head portion including an anvil assembly and a replaceable stapling assembly housing a plurality of staples, a firing assembly extending between the handle portion and the replaceable stapling assembly, and an approximation assembly extending between the handle portion and the distal head portion. The approximation assembly is actuable to move the anvil assembly in relation to the replaceable stapling assembly. In an embodiment, at least one modular assembly is secured to the housing and removable from the housing as a single unit to facilitate sterilization of the apparatus.

[0018] The modular assembly may be an indicator assembly for identifying to a clinician that the anvil assembly has been approximated and that the apparatus is in a fire-ready position. Alternately, the modular assembly may be safety lockout assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Various embodiments of the presently disclosed surgical stapling apparatus are described herein with reference to the drawings wherein:

[0020] FIG. 1 is a side perspective view from the distal end of an embodiment of the presently disclosed surgical stapling apparatus with an anvil assembly attached to the apparatus;

[0021] FIG. 2 is a side view of the surgical stapling apparatus shown in FIG. 1 with the anvil assembly removed;

[0022] FIG. 3 is a top perspective view from the proximal end of the surgical stapling apparatus shown in FIG. 2;

[0023] FIG. 4 is an enlarged, perspective view of a handle portion of the surgical stapling apparatus shown in FIG. 3;

[0024] FIG. 5 is an enlarged, side, perspective view of the handle portion shown in FIG.

4 with the housing removed;

[0025] FIG. 6 is a cross-sectional view taken along section lines 6-6 of FIG. 5;

[0026] FIG. 7 is a cross-sectional view taken along section lines 7-7 of FIG. 5;

[0027] FIG. 8 is an exploded, perspective view of the surgical stapling apparatus shown in FIG. 1; [0028] FIG. 9 is an exploded, perspective view of a replaceable stapling assembly of the surgical stapling apparatus shown in FIG. 1;

[0029] FIG. 10 is a side, perspective view of the distal end of the surgical stapling apparatus shown in FIG. 2 with the replaceable stapling assembly separated from the outer tube of the surgical stapling apparatus;

[0030] FIG. 11 is a side, perspective view of the pusher of the replaceable stapling assembly shown in FIG. 10;

[0031] FIG. 12 is a side, perspective view of the distal end of the surgical stapling apparatus shown in FIG. 2 with the replaceable stapling assembly separated from the outer tube and the outer tube partially cut away to expose the distal end of the pusher link;

[0032] FIG. 13 is a side perspective view of the distal end of the surgical stapling apparatus shown in FIG. 12 with the outer tube partially cut away to expose the pusher link as the replaceable stapling assembly is connected to the pusher link of the surgical stapling apparatus;

[0033] FIG. 14 is a side perspective view of the distal end of the surgical stapling apparatus shown in FIG. 13 after the pusher of the replaceable stapling assembly has been rotated into engagement with the pusher link of the surgical stapling apparatus;

[0034] FIG. 15 is a side perspective view of the distal end of the surgical stapling apparatus shown in FIG. 14 as the engagement collar is rotated to secure the replaceable stapling assembly to the outer tube;

[0035] FIG. 16 is a side perspective view of the firing assembly of the surgical stapling apparatus shown in FIG. 1; [0036] FIG. 17 is an exploded, side perspective view of the firing assembly shown in FIG.

16;

[0037] FIG. 18 is a side view of the pusher link of the firing assembly shown in FIG. 17;

[0038] FIG. 19 is a cross-sectional view along a longitudinal axis of the pusher link shown in FIG. 18;

[0039] FIG. 20 is a cross-sectional view along the longitudinal axis of the pusher link shown in FIG. 19 with the pusher link deformed to be received in the outer tube;

[0040] FIG. 21 is a side, perspective view of the approximation assembly of the surgical stapling apparatus shown in FIG. 1;

[0041] FIG. 22 is an enlarged perspective view of the indicated area of detail shown in

FIG. 21;

[0042] FIG. 23 is an enlarged, side, perspective view of a proximal end of the approximation assembly;

[0043] FIG. 24 is an exploded, side, perspective view of the approximation assembly shown in FIG. 1;

[0044] FIG. 25 is an enlarged view of the indicated area of detail shown in FIG. 24;

[0045] FIG. 26 is a cross-sectional view taken along section lines 26-26 of FIG. 25;

[0046] FIG. 27 is a side, perspective view of a safety lockout assembly of the handle portion of the surgical stapling apparatus shown in FIG. 1;

[0047] FIG. 28 is an exploded, side, perspective view of the safety lockout assembly shown in FIG. 27;

[0048] FIG. 29 is a top, perspective view of an indicator assembly of the handle portion of the surgical stapling apparatus shown in FIG. 1; [0049] FIG. 30 is a bottom perspective view of the indicator assembly shown in FIG. 29;

[0050] FIG. 31 is an exploded, top, perspective view of the indicator assembly shown in

FIG. 29;

[0051] FIG. 32 is an exploded, side, perspective view of the housing portion of the handle portion of the surgical stapling apparatus shown in FIG. 1;

[0052] FIG. 33 is a side, cross-sectional view of the surgical stapling apparatus shown in

FIG. 1 with the anvil assembly removed;

[0053] FIG. 34 is an enlarged view of the indicated area of detail shown in FIG. 33;

[0054] FIG. 35 is an enlarged view of the indicated area of detail shown in FIG. 33;

[0055] FIG. 36 is an enlarged view of the indicated area of detail shown in FIG. 35;

[0056] FIG. 37 is a side, cross-sectional view taken along section lines 37-37 of FIG. 35;

[0057] FIG. 38 is a side-cross-sectional view of the handle portion of the surgical stapling apparatus shown in FIG. 1 in a position corresponding to the approximated position of the anvil assembly;

[0058] FIG. 39 is an enlarged view of the indicated area of detail shown in FIG. 38;

[0059] FIG. 40 is a cross-sectional view of the distal end of the surgical stapling apparatus shown in FIG. 1 with the anvil assembly in the approximated position;

[0060] FIG. 41 is a cross-sectional view of the handle portion of the surgical stapling apparatus shown in FIG. 1 in a position corresponding to the fired position of the surgical stapling apparatus; and

[0061] FIG. 42 is a cross-sectional view of the distal end of the surgical stapling apparatus shown in FIG. 1 in the fired position. DETAILED DESCRIPTION OF EMBODIMENTS

[0062] Embodiments of the presently disclosed surgical stapling apparatus will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. Throughout this description, the term "proximal" will refer to the portion of the apparatus closest to the user and the term "distal" will refer to the portion of the apparatus farthest from the user.

[0063] FIGS. 1-42 illustrate an embodiment of the presently disclosed surgical stapling apparatus shown generally by reference numeral 10. Referring specifically to FIGS. 1-7, surgical stapling apparatus 10 includes a proximal handle portion 20, an elongated central body portion 30, and a distal head portion 40. Proximal handle portion 20 includes a housing 22, a firing trigger 24, a safety lockout assembly 25 a rotatable approximation knob 26 and an indicator assembly 27. Housing 22 supports the indicator assembly 27 and includes first and second housing covers 22a and 22b which will be discussed in further detail below.

[0064] Referring to FIGS. 1-3 and 8, elongated central body portion 30 of surgical stapling apparatus 10 includes a curved elongated outer tube 32 having an engagement collar 36a disposed at a distal end of outer tube 32 and an engagement collar 36b disposed at a proximal end of outer tube 32. Alternately, elongated outer tube 32 may be linear to suit a particular surgical procedure, e.g., a hemorrhoidectomy. Outer tube 32 is configured to slidably receive components of approximation assembly 200 (FIG. 8) and firing assembly 300, as will be discussed in detail below. In an embodiment, engagement collar 36a is rotatably supported on a distal end of outer tube 32 to facilitate connection to a replaceable stapling assembly 100. Similarly, engagement collar 36b may be rotatably supported on a proximal end of outer tube 32 to facilitate threaded securement of outer tube 32 to housing 22 of handle portion 20 as will be discussed in further detail below.

[0065] With particular reference to FIGS. 1 and 8-15, distal head portion 40 (FIG. 1) of surgical stapling apparatus 10 includes an anvil assembly 400 that is releasably engagable with the distal end of approximation assembly 200 (FIG. 8), and a replaceable stapling assembly 100 that is releasably engagable with engagement collar 36a of elongated central body portion 30 and the distal end of elongated pusher link 330 of firing assembly 300 (FIG. 8). Replaceable stapling assembly 100 (or portions thereof) may be configured as a disposable component that is to be replaced with a new replaceable stapling assembly 100 (or portions thereof) after each firing. The remaining components of surgical stapling apparatus 10 are configured as reusable, separable and sterilizable components, although one or more of these components may alternatively be configured as a disposable component. Distal head portion 40 will be described in greater detail below.

[0066] The various components of surgical stapling apparatus 10 described hereinbelow are configured to facilitate the assembly and disassembly of surgical stapling apparatus 10, thus facilitating the disposal and replacement of those components that are disposable and the sterilization and reassembly of those components that are reusable. The materials used to form the various components of surgical stapling apparatus 10 will depend upon the strength requirements of the particular component and the use requirements of the particular component, e.g., whether the component is reusable or disposable. For example, the reusable and/or high stress components of the apparatus including portions of the anvil assembly 400 and approximation mechanism may be formed of high strength materials capable of being repeatedly sterilized, such as materials including stainless steel and aluminum. The disposable and/or low stress components of the apparatus, such as portions of the stapling assembly 100 may be formed of thermoplastics including polycarbonates.

[0067] Referring to FIGS. 8, and 21-26, approximation assembly 200 of surgical stapling apparatus 10 includes approximation knob 26 (FIG. 21), a drive screw 220, a rotatable sleeve assembly 230, first and second screw extensions 240 and 250 (FIG. 24), respectively, and an anvil retainer 260. Rotatable sleeve assembly 230 includes a cylindrical hollow body portion 231 (FIG. 24), an inner sleeve 231a, a first collar 280 and a second collar 281. The hollow body portion 231 defines a bore 294 (FIG. 26) and includes a proximal flange 282 and a distal housing 283 (FIG. 25) defining a recess 283a for receiving a ball detent assembly 284 which will be described in detail below. Inner sleeve 231a is fixedly secured to an internal surface of hollow body portion 231 and includes a cutout 231b to facilitate passage of a ball 284a of the ball detent assembly 284. The second collar 281 defines a bore 281a dimensioned to slidably receive the sleeve assembly 230. Throughbore 281a includes a cutout 281b dimensioned to facilitate passage of distal housing 283 of body portion 231. A proximal side of second collar 281 is configured to releasably engage a distal side of first collar 280, such as by mating threads (not shown). When first collar 280 is engaged with second collar 281, the collars 280 and 281 define an annular cavity 285 (FIG. 38) which is dimensioned to rotatably receive flange 282 of body portion 231.

[0068] Referring to FIG. 25, the ball detent assembly 284 includes a detent member, e.g., ball 284a, a plug 284b and a pin 284c. The ball 284a is positioned within recess 283a of distal housing 283 to be received in a helical channel 222 (FIG. 24) of drive screw 220. Plug 284b defines a spherical concavity for receiving a side of the ball 284a opposite screw 220 to retain ball 284a within recess 283a of distal housing 283. Plug 284b defines a bore 286 for receiving pin 284c. Pin 284c extends through openings 287 in housing 283 and bore 286 of plug 284b to secure plug 284b and ball 284a within recess 283a of housing 283. Recess 283a includes a cutout 288 for receiving a rib 289 on plug 284b to properly align bore 286 of plug 284b with openings 287 in housing 283.

[0069] Approximation knob 26 includes a flat grip portion 26a and a cylindrical body portion 26b. Grip portion 26a is secured in slots 290 in body portion 26b and in slots 298 in a proximal end of body portion 231 using adhesives, welding or the like. By positioning grip 26a in slots 290 and 298, grip 26a is rotatably fixed to body portion 26b and body portion 231 of rotatable sleeve assembly 230. Body portion 26b defines a bore 291 (FIG. 38) dimensioned to receive the proximal end of hollow body portion 231. A set screw 292 is provided to secure body portion 26b of knob 26 to hollow body portion 231 of sleeve assembly 230 such that rotation of knob 26 effects rotation of sleeve assembly 230. Alternately, other fastening techniques may be used to rotatably fix knob 26 to sleeve assembly 230 including adhesion, welding, interlocking structure, interference fit, and snap-fit connectors.

[0070] In use, rotatable sleeve assembly 230 is secured to a proximal end of housing 22 by positioning hollow portion 231 of sleeve assembly 230 through bore 281a of second collar 281 and into housing 22 such that a proximal end of drive screw 220 is received in bore 294 of hollow body portion 231 and ball 284a is positioned in helical channel 222 of drive screw 220 (FIG. 26). As discussed above, flange 282 of hollow body portion 231 is positioned in annular cavity 285 between collars 280 and 281 such that hollow body portion 231 is rotatable in relation to housing 22 but is axially fixed in relation to housing 22. The distal end of the second collar 281 is releasably coupled to the proximal end of housing 22 by screw threads (not shown) or using other known fastening techniques, e.g., friction, snap-fit, etc. When approximation knob 26 is rotated, ball 284a of ball detent assembly 284 is rotated about drive screw 220 within helical channel 222. Since hollow body portion 231, and, thus ball detent assembly 284, are axially fixed in relation to housing 22, drive screw 220 is forced by ball 284a to translate within housing 22.

[0071] The distal end of screw 220 includes a transverse slot 226 (FIG. 24). First and second screw extensions 240 and 250 each include a flexible band portion 242 and 252, although other configurations are also contemplated. The flexibility of band portions 242 and 252 permits translation of screw extensions 240 and 250 through curved elongated outer tube 32 of elongated body portion 30. The proximal end of each band portion 242 and 252 includes a respective hole 244 and 254 dimensioned to receive a pin 246 for securing the proximal end of screw extensions 240 and 250, respectively, within transverse slot 226 of screw 220. The band portion 242 and 252 of each screw extension 240 and 250 is dimensioned to be received within a transverse slot 262 formed in a proximal end of anvil retainer 260 to fasten anvil retainer 260 to the distal end of screw extensions 240 and 250. More specifically, a pair of pins 264 extends through the proximal end of anvil retainer 260 and band portions 240 and 250 to secure screw extensions 240 and 250 to anvil retainer 260.

[0072] With reference to FIGS. 8, 21 and 24, anvil retainer 260 includes a trocar portion

265a (FIG. 24), a body portion 265b, and an attachment portion 265c. Trocar portion 265a includes a blunt trocar tip 267, although other less blunt or sharpened tip configurations are also contemplated. Body portion 265b is substantially cylindrical and has a diameter which is larger than the diameter of trocar portion 265a. An annular protrusion 268 defining a proximal shoulder is disposed about body portion 265b of anvil retainer 260 and is configured to engage anvil assembly 400 (FIG. 1) in a known manner to releasably secure anvil assembly 400 to anvil retainer 260.

[0073] Referring to FIGS. 8, and 21-26, in use, when approximation knob 26 is manually rotated, hollow body portion 231 is likewise rotated about the proximal end of drive screw 220. Since sleeve 230 is axially fixed with respect to housing 22, and ball 284a of ball detent assembly 284 is disposed within helical channel 222 and rotationally fixed relative to hollow body portion 231, axial rotation of hollow body portion 231 about screw 220 causes ball 284a to move along channel 222 of screw 220 to thereby urge screw 220 to translate axially within housing 22 relative to hollow body portion 231. Upon axial translation of screw 220, first and second screw extensions 240 and 250, which are fastened to the distal end of drive screw 220, and anvil retainer 260, which is fastened to the distal end of screw extensions 240 and 250, are moved axially through outer tube 32 of elongated body portion 30. Thus, with anvil assembly 400 (FIG. 1) releasably engaged about the distal end of anvil retainer 260, knob 26 may be rotated to effect movement of anvil assembly 400 (FIG. 1) relative to stapling assembly 100 (FIG. 1) between spaced-apart and approximated positions, i.e., to move anvil assembly 400 closer to or further from stapling assembly 100, depending on the direction of rotation of knob 26.

[0074] With reference to FIGS. 1, 6-8, and 21-24, approximation assembly 200 further includes a screw stop 270 which is fixedly secured to drive screw 220 and configured to function as a proximal stop for defining the minimum tissue receiving clearance between anvil assembly 400 and stapling assembly 100. More specifically, screw top 270 is positioned about drive screw 220 and will abut a distal end of hollow body portion 231 of rotatable sleeve assembly 230 when drive screw 220 has been retracted to its proximal-most position to define the approximated position or minimum tissue gap between the anvil assembly 400 and the stapling assembly 100 (FIG. 1). Screw stop 270 includes a cam adjustment member 272 that allows the minimum tissue gap defined between the stapling assembly 100 and the anvil assembly 400 to be selectively adjusted. Cam adjustment member 272 is described in detail in the Milliman Ί87 patent and the Gresham '444 patent which are incorporated herein in their entireties by reference.

[0075] Screw stop 270 further includes a pair of guide members 274 (FIG. 7) that extend radially outwardly from screw stop 270. Guide members 274 are dimensioned to slide along guides 29 (FIG. 7) formed along an interior wall of housing 22 to maintain proper alignment and guide translation of approximation assembly 200 through stationary handle 22. Screw stop 270 also defines a sloped backstop 270a which is positioned to engage a pivot member of firing assembly 300 after screw stop 270 has been retracted towards its proximal-most position as will be discussed in detail below.

[0076] Referring to FIGS. 6-8 and 16-17, firing assembly 300 includes firing trigger 24, a firing link 310, an elongated pusher link 330, and a coupling member 350. The distal end of firing trigger 24 is pivotally connected to coupling member 350 by a pivot member 352. Pivot member 352 includes a distal end 352a which may be threadably connected to an opening 24a in the distal end of trigger 24. See FIG. 17. Coupling member 350, in turn, is secured to the proximal end of elongated pusher link 330 using any known fastening technique and may be formed integrally with pusher link 330. Wings 358 extend radially outwardly from pusher link 330 adjacent coupling member 350 and are dimensioned to slide along channels 31 (FIG. 6) formed along the interior walls of housing 22 to maintain proper alignment and guide translation of coupling member 350 and pusher link 330 through housing 22 of handle portion 20. It is envisioned that wings 358 may be formed integrally with coupling member 350. [0077] Referring also to FIGS. 18-20, elongated pusher link 330 defines a generally tubular configuration having a hollow interior and includes a cut-out 332 that extends along a portion of the length of elongated pusher link 330. As such, elongated pusher link 330 defines a semi-tubular segment 334 adjacent cut-out 332. Elongated pusher link 330 also includes a plurality of alternating opposed transverse recesses 336 extending about the exterior surface of a distal end of pusher link 330 at spaced-apart locations along the length thereof. Recesses 336 facilitate the resilient flexion of elongated pusher link 330 within outer tube 32 during firing to reduce the force required to effect translation of pusher link 330 through outer tube 32.

[0078] The hollow interior of elongated pusher link 330 is configured to slidably receive the distal end of drive screw 220 and first and second screw extensions 240, 250 of the approximation assembly 200. Elongated pusher link 330 may define a slightly curved configuration when at-rest, as shown in FIGS. 18 and 19, and may be configured to resiliently flex from this at-rest position (FIG. 19) to a more curved configuration, as shown in FIG. 20, upon translation through curved outer tube 32 (FIG. 8). The flexed configuration of the resilient pusher link 330 may be such as to urge the elongated pusher link 330 to a retracted, unfired position after the apparatus has been fired. In addition, or in lieu thereof, a biasing member 359 (FIG. 8) is provided between a distal end of wings 358 and a proximal end of outer tube 32 to bias pusher link 330, and/or coupling member 350 proximally towards an unfired position (FIG. 35).

[0079] The proximal end of elongated pusher link 330, as mentioned above, is secured to coupling member 350. The distal end of elongated pusher link 330, as shown in FIGS. 8 and 16- 20, includes a hollow tubular neck 338 which defines a bayonet-like L-shaped recess 340 (FIG. 8). As discussed in detail below, the distal end of elongated pusher link 330 is configured to releasably engage a pusher 112 of stapling assembly 100.

[0080] Referring to FIGS. 8, and 16-17, firing link 310 has a distal end pivotally secured to firing trigger 24 by a pivot member 312 and a proximal end that is coupled to removable cover 22b of housing 22. More specifically, the proximal end of firing link 310 defines a bifurcated configuration having first and second flanges 313, 315 including openings that are configured to receive a pivot member 316. Pivot member 316 extends between and outwardly from each of first and second flanges 313, 315, such that each end of pivot member 316 is positioned for receipt within a triangular-shaped slot 28 (FIG. 4) formed within opposite sides of removable cover 22b (FIG. 38). Removable cover 22b is removably secured to housing 22 of handle portion 20 using any known fastening technique including screws, interlocking features, snap- fitting, etc. Triangular-shaped slots 28 are defined by a vertical proximal wall 28a, a horizontal bottom wall 28b, and an angled wall 28c interconnecting the vertical distal wall 28a and horizontal bottom wall 28b. As such, pivot member 316 is permitted to move slightly longitudinally and/or vertically within triangular-shaped slots 28 during actuation of firing trigger 24 to provide greater mechanical advantage to advance elongated pusher link 330 distally. Pivot member 316 is inhibited from substantial movement relative to housing 22, such that actuation of firing trigger 24 effects distal translation of elongated pusher link 330 in relation to housing 22. As shown in FIG. 35, a biasing member 381 may be provided to urge firing link 310 to a position in which pivot member 316 is positioned adjacent a bottom of proximal wall 28a. The biasing member 381, which may be in the form of a leaf spring, can be secured to an inner surface of firing trigger 24 by a fastener, screw, rivet 381a or other known fastening device or technique. [0081] Prior to actuation of firing trigger 24, anvil assembly 400 is approximated in relation to stapling assembly 100, using approximation assembly 200 as discussed above. When this occurs, sloped backstop 270a (FIG. 39) of screw stop 270 is moved to a position proximal of pivot member 316. When firing trigger 24 is actuated by pivoting firing trigger 24 towards housing 22, firing link 310 is pivoted about pivot member 316, which is supported by backstop 270a of screw stop 270, towards housing 22 to urge firing trigger 24 and pivot member 352 distally in relation to housing 22. Since pivot member 352 is pivotally secured to coupling member 350, distal movement of pivot member 352 effects distal movement of coupling member 350 to urge pusher link 330 distally. With the distal end of pusher link 330 coupled to pusher 112 of stapling assembly 100, as will be described below, distal translation of pusher link 330 may be effected to translate pusher 112 distally through cartridge assembly 110 to eject surgical staples 600 (FIG. 9) from stapling assembly 100.

[0082] The anvil assembly 400 may be any known anvil assembly including anvil assemblies having stationary heads or tiltable heads such as disclosed in the Milliman Ί87 and Gresham '444 patents which have been incorporated herein by reference in their entireties. Anvil assembly 400, as known in the art, includes an anvil head assembly 410 including anvil head 414 and an anvil center rod assembly 420. The anvil center rod 420 is configured to releasably engage the anvil retainer 260. In addition, anvil retainer 260 may be formed as a single piece or alternately, may be formed as a multi-part assembly and include a retractable trocar such as disclosed in the Ί87 patent which is incorporated herein by reference.

[0083] Turning to FIGS. 1 and 9-14, replaceable stapling assembly 100 includes a cartridge assembly 110 and an engagement assembly 140 (FIG. 9). Cartridge assembly 110 is configured to house a plurality of surgical staples 600 and, upon actuation of firing assembly 300 (FIG. 8), facilitate the ejection of surgical staples 600, through tissue, and into an anvil head 414 (FIG. 1) of anvil head assembly 410 (FIG. 42) for formation of the surgical staples 600 about tissue. Engagement assembly 140 is configured to facilitate operable engagement of stapling assembly 100 to engagement collar 36a at the distal end of outer tube 32 of elongated central body portion 30. Stapling assembly 100 (or component(s) thereof) may be formed as a disposable assembly that is configured to be replaced with a new stapling assembly after each firing.

[0084] Engagement assembly 140 includes an outer shell 142 that may be formed from any suitable material, e.g., polyethylene, and is configured as a disposable component. Outer shell 142 defines a generally hollow configuration and includes a distal cylindrical section 147, a central tapered section 148, and a proximal cylindrical section 149 that defines a slightly smaller diameter than distal cylindrical section 147. A plurality of openings 150 are formed in tapered section 148 to permit fluid and tissue passage during operation of surgical stapling apparatus 10. Proximal cylindrical section 149 of outer shell 142 is configured for releasable engagement with engagement collar 36a (FIG. 8) of elongated central body portion 30 about pusher link 330. More specifically, proximal cylindrical section 149 of outer shell 142 includes threading 149a disposed about its exterior annular surface. Threading 149a is configured to engage threading 37 (FIG. 34) disposed on the interior annular surface of engagement collar 36a. Engagement collar 36a is rotatably supported about a distal end of outer tube 32 such that it can be rotated in relation to outer shell 142 to secure outer shell 142 to outer tube 32. An annular flange 41 (FIG. 10) is formed about the distal end of outer tube 32 to prevent removal of collar 36a from outer tube 32. Although flange 41 is shown to be a separate bead formed about outer tube 32, flange 41 may be integrally formed with outer tube 32. Collar 36a is shown to have internal threading and shell 142 is shown to have external threading. However, it is envisioned that these surfaces may be reversed. Although the collar 36a is shown to be threadably connected to the shell 142, it is envisioned the other engagement structure may be used to secure the shell 142 to collar 36a or to the distal end of outer tube, such as snap-fit connectors, bayonet-type connectors, frictional connectors or the like.

[0085] With particular reference to FIGS. 9-15, cartridge assembly 110 is housed within outer shell 142 of engagement assembly 140 and includes a pusher 112 (FIG. 11), a cylindrical knife 114, and a staple guide cap 116. Outer shell 142 defines a central tubular bore 142a dimensioned to slidably receive the anvil retainer 260. A tubular bushing 142b is secured within a proximal end of tubular bore 142a to provide rigidity to bore 142a (FIG. 9). The central tubular bore 142a is secured to outer shell 142 by transverse flanges 142c (FIG. 34). As mentioned above, cartridge assembly 110 and outer shell 142 are configured as disposable components.

[0086] Pusher 112 of cartridge assembly 110 defines a central bore 118 and is configured to be received within outer shell 142. More specifically, pusher 112 includes a distal cylindrical section 119 that is slidably positioned within distal cylindrical section 147 of outer shell 142, a central tapered section 121 that is slidably positioned within central section 148 of outer shell 142, and a proximal cylindrical section 123 that has a smaller diameter than distal cylindrical section 119 and is slidably positioned within proximal section 149 of outer shell 142. Pusher 112 includes slots 113 which slidably receive flanges 142c of shell 142 to rotatably fix and axially guide movement of pusher 112 within outer shell 142.

[0087] Proximal section 123 of pusher 112 is configured to releasably engage pusher link

330. More specifically, pusher 112 includes a proximally extending arm 123a having an angled finger 123b. When shell 142 is positioned about a distal end of pusher link 330, as sequentially shown in FIGS. 12 to 14, shell 142 can be rotated to rotate pusher 112 and position finger 123b in slot 340 of pusher link 330 releasably to secure pusher 112 to pusher link 330. After pusher 112 has been secured to pusher link 330 as discussed above, engagement collar 36a can be advanced about outer tube 32 as shown in FIG. 15 to move threads 37 (FIG. 34) formed on an internal surface of collar 36a into engagement with threads 149a formed about outer shell 142. Thereafter, engagement collar 36a can be rotated to selectively secure replaceable stapling assembly 100 onto outer tube 32.

[0088] Referring in particular to FIGS. 9 and 11, the distal end of pusher 112 includes a plurality of distally- extending pusher fingers 129 dimensioned to be slidably received within slots 131 formed in staple guide cap 116. Staple guide cap 116 is engaged about the distal end of outer shell 142 via the engagement of tabs 133 and recesses 135, e.g., via snap-fit, welding, adhesion, etc. Each slot 131 formed within staple guide cap 116 is configured to retain a surgical staple 600. Upon advancement of pusher 112 in response to actuation of firing trigger 24, surgical staples 600 are ejected from slots 131 of staple guide cap 116, through tissue, and into pockets (not shown) formed in anvil head 414 of anvil assembly 400 (FIG. 1). Cylindrical knife 114 (FIG. 9) is pinned within bore 118 of pusher 112 to fixedly secure knife 114 in relation to pusher fingers 129 such that advancement of pusher 112 effects simultaneous advancement of knife 114 through tissue. The distal end of knife 114 includes a circular cutting edge 115 to facilitate the cutting of tissue.

[0089] Referring to FIGS. 4, 27, 28 and 32, a safety lockout assembly 25 is supported on a bottom of removable housing cover 22b (FIG. 32). Safety lockout assembly 25 includes a base plate 700 defining a channel 702 dimensioned to slidably receive a locking plate 704. Base plate 700 includes an integral mounting block 706 defining a bore 708. Locking plate 704 is slidably mounted in channel 702 and includes a proximally extending finger 710 which extends through bore 708. A biasing member, e.g., coil spring 712, is positioned about finger 710 between mounting block 706 and abutments 714 supported on a proximal end of locking plate 704 to urge the locking plate 704 distally.

[0090] Locking plate 704 includes a pair of distal tabs 716 which are positioned to engage projections 275 (FIG. 22) on screw stop 270 as the drive screw 220 is moved to approximate the anvil assembly 400 with the replaceable stapling assembly 100 (FIG. 1). A blocking member 720 is formed on the distal end of the locking plate 704.

[0091] A firing trigger lockout member 722 is pivotally supported on removable housing cover 22b (FIG. 32) and operates in association with safety lockout assembly 25. More specifically, cover 22b defines a pair of spaced openings 726 for pivotally receiving a pivot member 718. Pivot member 718 is positioned through a bore 730 in pivot member 728 to pivotally secure the lockout member 722 to cover 22b.

[0092] Lockout member 722 is pivotally positioned between housing 22 and firing trigger 24 to prevent actuation of firing trigger 724 until the anvil assembly 400 and the replaceable stapling assembly 100 have been approximated. More specifically, a shelf 732 is formed on lockout member 722 and is positioned to engage blocking member 720 when the locking plate 704 is in its distal most position (FIG. 27) to prevent pivotal movement of lockout member 722 towards housing 22. As the anvil assembly 400 and replaceable stapling assembly 100 are approximated, projections 275 (FIG. 23) of screw stop 270 engage distal tabs 716 on locking plate 704 to pull locking plate 704 proximally and disengage blocking member 720 from shelf 732. When this occurs, lockout member 722 can be pivoted towards housing 22 to a position aligned with base plate 700 (FIG. 41) to facilitate actuation of firing trigger 24.

[0093] Base plate 700 includes mounting bores 740 which receive screws 794 (FIG. 8).

The screws are also received within openings 790 formed in housing cover 22b (FIG. 32) to releasably secure safety lockout assembly 25 and cover 22b to housing 22. Removal of screws 794 facilitate separation of safety lockout assembly 722 and housing cover 22b from housing 22 to allow for more effective sterilization of the reusable components of the stapling apparatus 10, as will be discussed in detail below. By removing screws 794, the safety lockout assembly 25 can be removed as a module or single unit from the housing 22.

[0094] Referring to FIGS. 1 and 29-32, the indicator assembly 27 includes a support plate 802 which is removably supported on housing 22 by screws 803. Support plate 802 supports a bulbous indicator 824, lens cover 824a and slide assembly 830. Indicator 824 is pivotally supported about a pivot members 832 which extend through openings 834 in the support plate 802. Lens cover 824a is positioned above indicator 824 and, in an embodiment, is formed of magnification material to facilitate easy visualization of indicator 824. Slide assembly 830 includes a distal plate 836 having a distal abutment member or upturned lip portion 840. A proximal plate 839 abuts the proximal end of distal plate 836 and includes a downwardly extending projection 841. The proximal plate 839 includes an extension 842 which supports a biasing member 844, e.g., a coil spring. The biasing member 844 is positioned in compression about proximal extension 842 between support structure 816 formed on support plate 802 and proximal plate 839 of slide assembly 830 to urge slide assembly 830 distally within a longitudinal recess 850 defined along an inner wall of support plate 802. Indicator 824 includes a pair of downwardly extending projections 852a and 852b (FIG. 39). Upturned lip portion 840 of distal plate 836 is positioned between projections 852a and 852b.

[0095] In the unfired position of device 10, biasing member 844 urges slide assembly

830 distally to move lip portion 840 into engagement with projection 852a to pivot indicator 824 to a first position, which provides an indication to a surgeon that the apparatus 10 has not been approximated and is not in a fire-ready condition. Referring also to FIG. 39, screw stop 270 is fixedly attached to drive screw 220 (FIG. 22). Screw stop 270 includes a first abutment or engagement member 862 which is positioned to travel beneath slide assembly 830 and engage the downwardly extending projection 841 supported on proximal plate 839 to move the proximal plate 839 proximally. Movement of proximal plate 839 effects corresponding proximal movement of distal plate 836 such that upturned lip portion 840 of distal plate 836 engages the projection 852b during approximation of the apparatus 10. When upturned lip 840 of distal plate 836 engages the projection 852b of indicator 824, lip 840 causes indicator 824 to pivot about pivot members 832 to a second position. In the second position, indicator 824 provides indication to a surgeon that the apparatus 10 has been approximated and is now in a fire-ready position. See FIG. 41.

[0096] By supporting the indicator assembly 27 on a support plate 802, the indicator assembly 27 can be easily and quickly removed from the handle portion 20 of the apparatus 10 as a single unit or module by removing screws 803. This modular design allows for easy separation of the components of the handle portion 20 to facilitate sterilization and reuse of the surgical stapling apparatus 10. Alternatively, other types of indicators may be used with the surgical stapling apparatus 10 including those described in the Milliman Ί87 and Gresham '444 patents. [0097] FIGS. 33-38 illustrate the surgical stapling apparatus 10 prior to attachment of an anvil assembly 400 (FIG. 1) to anvil retainer 260 (FIG. 34) with the anvil retainer 260 in a fully advanced or unapproximated position. As shown in FIG. 34, stapling assembly 100 is secured to engagement collar 36a to secure stapling assembly 100 to elongated central body portion 30. In addition, screw stop 270 is positioned in a distal end of stationary handle 22 such that locking plate 704 is positioned to prevent pivotal movement of lockout member 722 (FIG. 36) and indicator 834 is pivoted to its counter-clockwise position as shown in FIG. 36.

[0098] The use, disassembly and assembly of surgical stapling apparatus 10, for subsequent reuse will now be described in detail. With reference to FIGS. 38-40, in use, distal head portion 40 (FIG. 1) of surgical stapling apparatus 10 is inserted into an internal surgical site such that anvil assembly 400 and stapling assembly 100 are positioned adjacent tissue to be stapled. Once positioned as desired, anvil assembly 400 may be approximated relative to stapling assembly 100 to clamp tissue therebetween by manipulating approximation assembly 200 (FIG. 8). More specifically, anvil assembly 400 is moved to the approximated or closed position to grasp tissue between anvil assembly 400 and stapling assembly 100 by rotating rotation knob 26 in a first direction. Rotation of knob 26 in the first direction causes sleeve assembly 230 to rotate about drive screw 220 to move ball 284a along helical channel 222 of screw 220 such that screw 220 is translated proximally in the direction indicated by arrow "A" in FIG. 39. The distal end of screw 220 is connected to screw extensions 240 and 250 which, in turn, are fastened at their distal ends to anvil retainer 260, such that anvil retainer 260 is likewise translated proximally to approximate anvil assembly 400 relative to stapling assembly 100. Knob 26 may be rotated to approximate anvil assembly 400 relative to stapling assembly 100 to a desired position to clamp tissue therebetween. [0099] As shown in FIG. 39, when the drive screw 220 is moved to its proximal-most position, projections 275 of screw stop 270 engage tabs 716 on locking plate 704 of safety lockout assembly 25 (FIG. 27) and retract plate 704 proximally to disengage blocking member 720 from shelf 732 on lockout member 722. When this occurs, lockout member 722 can be pivoted to a position aligned with base plate 700 of safety lockout assembly 25 (FIG. 39) to facilitate actuation of firing trigger 24.

[00100] In addition, when screw 220 is moved to its proximal-most position, engagement member 862 (FIG. 22) of screw stop 270, engages projection 841 of proximal plate 839 to retract plate 839 and distal plate 836 proximally. As distal plate 836 moves proximally, lip portion projection 852b on indicator 824 to pivot indicator 824 to its second position wherein an indication is provided to a surgeon that the stapling apparatus has been approximated and is in a fire-ready position.

[00101] Referring to FIGS. 40-42, with anvil assembly 400 disposed in the approximated position clamping tissue between anvil head 414 and staple guide cap 116 of stapling assembly 100, firing assembly 300 may be actuated to staple and core the clamped tissue. More specifically, in order to fire surgical stapling apparatus 10, trigger 24 (FIG. 41) is compressed towards housing 22. As described above, the distal end of firing trigger 24 is connected through coupling member 350 to the proximal end of pusher link 330. Accordingly, as firing trigger 24 is actuated, pivot member 316 engages backstop 270a of screw stop 270 such that trigger 24 is advanced distally as trigger 24 is compressed towards housing 22. As this occurs, pusher link 330 is also moved distally to urge pusher 112 (FIG. 40) of cartridge assembly 110 distally. Upon distal translation of pusher 112 relative to staple guide cap 116, which houses the surgical staples 60, fingers 129 of pusher 112 engage and eject staples 600 from staple guide cap 116. As staples 600 exit guide cap 116 and pass through tissue, the staples 600 are received in pockets formed in the anvil head 414 of anvil assembly 400 and are formed about the tissue. Cylindrical knife 114 is moved concurrently with pusher 112 such that knife 114 is likewise advanced distally to core tissue.

[00102] The surgical stapling apparatus 10 (FIG. l) is used to perform circular anastomoses. Typically, circular anastomoses are required during procedures for removing a portion of a diseased vessel such as the colon or the intestine. During such a procedure, the diseased portion of the vessel is removed from the diseased vessel and the end portions of the remaining first and second vessel sections are joined together using the surgical stapling apparatus 10. Circular anastomoses are also required in a variety of other surgical procedures such as in gastric bypass procedures.

[00103] Prior to removing a diseased vessel portion from a diseased vessel, the anvil assembly 400 (FIG. l) with a removable trocar (not shown) attached thereto is positioned in the first vessel section on a first side of the diseased portion. A removable trocar which is suitable for use with the anvil assembly 400 is disclosed in the Gresham '444 patent which, as discussed above, is incorporated herein by reference in its entirety. After the diseased vessel portion is removed and open ends of the first and second vessel sections have been sutured, the distal end of apparatus 10 is positioned in the second vessel section on the other side of the diseased portion which has been removed. At this time, the removable trocar is pushed through the suture line in the end of the first vessel section and removed from the anvil assembly. Next, trocar tip 267 (FIG. 2) of anvil retainer 260 is pushed through the suture line in the second vessel section and is joined to the center rod of the anvil assembly 400. The surgical stapling apparatus 10 can now be approximated and fired in the manner discussed above to join the ends of the first and second vessel sections and core out any tissue obstructing the vessel lumen. (See ,e.g, FIG. 42). See, e.g, the Gresham '444 patent which has been incorporated herein by reference.

[00104] At the completion of the stapling operation, surgical stapling apparatus 10 may be removed from the internal surgical site. Although not shown, anvil assembly 400 may be configured to pivot to a low-profile configuration to facilitate removal of surgical stapling apparatus 10 from the internal surgical site. Alternatively, anvil assembly 400 need not have a pivotal head and may be removed from the surgical site in the same orientation as it was advanced into the surgical site.

[00105] After surgical stapling apparatus 10 has been fired, the used stapling assembly

100 may be removed from the distal end of outer tube 32 by rotating the engagement collar 36a in relation to stapling assembly 100 to disengage threads 37 of collar 36a from threads 149a of outer shell 142 (FIG. 15) and rotating outer shell 142 in relation to pusher 112 to disengage angled finger 123b of pusher 112. from slot 340 of pusher link 330 (FIG. 14). When stapling assembly 100 is separated from outer tube 32, a new stapling assembly 100 can be secured to outer tube 32, in the manner discussed above, to perform an additional procedure on the same patient. The used stapling assembly 100 can be disposed of by the surgeon. If no further stapling procedures are required on the patient, the stapling apparatus 10 can be disassembled further to facilitate sterilization of apparatus 10 for reuse.

[00106] In order to disassemble stapling apparatus 10 for sterilization, the proximal end of outer tube 32 can be separated from housing 22 by disengaging proximal engagement collar 36b from outer tube 32. As shown in FIG. 37, collar 36b is rotatably supported on the proximal end of outer tube 32. A flange 43 is formed about the proximal end of outer tube 32 to prevent collar 36b from sliding off the outer tube 32. Although not shown, the inner surface of collar 36b and the outer surface of housing 22 may include threads for releasably securing collar 36b to housing 22. Alternately, it is envisioned that other know re leasable engagement structure can be used to secure the proximal end of outer tube 32 to the distal end of housing 22.

[00107] Once outer tube 32 is separated from stapling assembly 100 and from housing 200, the housing 22 can be disassembled to provide access to the internal components of the apparatus. More specifically, the firing trigger 24 can be removed from the housing 22 by disengaging housing cover 22b from housing 22 and removing pivot member 352 from firing trigger opening 24a and coupling member 350. Pivot member 352 can be accessed through openings 23 (FIG. 2) formed in cover 22a and safety lockout assembly 25 can be removed from housing 22 by removing screws 794 (FIG. 4) from base plate 700 of safety lockout assembly 25 and cover 22b. The indicator assembly 27 can also be removed from housing 22 by removing screws 832 from housing 822 (FIG. 1). Indicator assembly 27 and safety lockout assembly 25 are in modular form and can be separated from housing 22 as individual units. Next, rotation knob 26 can be separated from the proximal end of assembly 230 by unscrewing set screw 292. Finally, the collar 281 can be separated from housing 22 by unscrewing collar 281 from housing 22. Thereafter, the firing assembly 200 and the approximation assembly 300 can be withdrawn proximally through outer tube 32 and housing 22 for sterilization, e.g., autoclaving. After sterilization, the apparatus 10 can be reassembled by reversing the disassembly steps described above. It is noted that the steps for assembly and disassembly need not be performed in any specific order.

[00108] 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, except as indicated by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A surgical stapling apparatus comprising:

a handle portion;

an elongated body portion extending distally from the handle portion;

a distal head portion including an anvil assembly and a replaceable stapling assembly, the replaceable stapling assembly including a pusher and a plurality of staples, the pusher being movable to eject the staples from the replaceable stapling assembly;

a firing assembly extending between the handle portion and the replaceable stapling assembly, the firing assembly including a pusher link which is releasably engageable with the pusher and movable to effect movement of the pusher;

an approximation assembly extending between the handle portion and the distal head portion, the approximation assembly including an anvil retainer configured to releasably support the anvil assembly and being actuable to move the anvil assembly in relation to the replaceable stapling assembly; and

a first engagement collar rotatably supported about a distal end of the elongated body portion, the engagement collar being configured to releasably engage the replaceable stapling assembly.

2. The surgical stapling apparatus of claim 1, wherein the replaceable stapling assembly includes a shell which houses the pusher, the shell having a proximal end including external threads configured to releasably engage internal threads formed on the first engagement collar.

3. The surgical stapling apparatus of claim 1, wherein the elongated body portion includes an outer tube and the first engagement collar is rotatably supported about a distal end of the outer tube.

4. The surgical stapling apparatus of claim 3, wherein the outer tube includes an annular flange which is positioned to prevent the first engagement collar from sliding off of the distal end of the outer tube.

5. The surgical stapling apparatus according to claim 3, further including a second engagement collar rotatably supported about a proximal end of the outer tube, wherein the handle portion includes a housing, and the second engagement collar is configured to releasably engage the housing to facilitate separation of the outer tube from the housing.

6. The surgical stapling apparatus according to claim 5, wherein the second engagement collar includes internal threads and the housing includes external threads which are configured to releasably engage the internal threads of the engagement collar.

7. The surgical stapling apparatus of claim 1, wherein the handle portion includes a housing supporting a proximal portion of the firing assembly and a proximal portion of the approximation assembly.

8. The surgical stapling apparatus of claim 7, further including a modular indicator assembly releasably secured to the housing, the indicator assembly being configured to provide an indication to a clinician of when the apparatus is in a fire-ready position.

9. The surgical stapling apparatus of claim 8, wherein the modular indicator assembly is secured to the housing by at least one fastener.

10. The surgical stapling apparatus of claim 7, wherein the housing supports a modular safety lockout assembly configured to block pivotal movement of a lockout member, the lockout assembly including a mounting plate which is releasably secured to the housing.

11. The surgical stapling apparatus of claim 10, wherein the modular safety lockout assembly is secured to the housing by at least one fastener extending through the mounting plate.

12. The surgical stapling apparatus of claim 7, wherein the approximation assembly includes a drive screw defining a helical channel, a rotatable sleeve assembly including a detent positioned within the helical channel, and a rotatable knob secured to the rotatable sleeve assembly, the rotatable sleeve assembly being rotatably secured to the housing and rotatable in relation to the drive screw to effect longitudinal translation of the drive screw within the housing.

13. The surgical stapling apparatus of claim 12, wherein the rotatable sleeve assembly includes a sleeve having an annular flange and the apparatus further includes a first collar secured to the proximal end of the housing and a second collar secured to the first collar, wherein the first and second collars define an annular recess configured to rotatably receive the annular flange of the sleeve.

14. The surgical stapling apparatus of claim 13, wherein the first collar is releasably secured to the proximal end of the housing.

15. The surgical stapling apparatus of claim 14, wherein the first collar is threadably engaged with the housing.

16. The surgical stapling apparatus of claim 1, wherein the pusher link includes an L-shaped slot and the pusher includes a finger which is rotatable into engagement with the L-shaped slot to releasably secure the pusher to the pusher link.

17. The surgical stapling apparatus of claim 1, wherein the plurality of staplers of the replaceable stapling assembly are supported in an annular array.

18. A surgical stapling apparatus comprising:

an elongated body portion extending having a proximal end and a distal end;

a distal head portion positioned adjacent the distal end of the elongated body portion, the distal head portion including an anvil assembly and a replaceable stapling assembly housing a plurality of staples;

a firing assembly extending between the handle portion and the replaceable stapling assembly; an approximation assembly extending between the handle portion and the distal head portion, the approximation assembly being actuable to move the anvil assembly in relation to the replaceable stapling assembly; and

at least one of a modular lockout assembly and a safety lockout assembly removably secured to the housing.

19. The surgical stapling apparatus of claim 18, further comprising an engagement collar removably attached to the distal end of the elongated body portion.

20. The surgical stapling apparatus of claim 18, wherein the replaceable stapling assembly is releasably secured to the engagement collar.