Patent Description:
Stapling devices for suturing body tissue during surgical procedures are well known. The stapling devices include a tool assembly having an anvil and a staple cartridge that supports a plurality of surgical staples. The staples can be driven from the staple cartridge into the anvil to staple tissue clamped between the staple cartridge and the anvil. Some stapling devices include a knife member that is adapted to cut body the tissue clamped between the anvil and the staple cartridge as the tissue is being stapled. These stapling devices have reduced the amount of time required to perform surgical procedures by reducing the time required to join tissue segments during the surgical procedure.

In order to minimize costs associated with performing surgical procedures, known stapling devices include a loading unit or reload that is removably attached to an adapter assembly of the stapling device. After the staples are fired from the staple cartridge into the anvil through the tissue, the loading unit can be replaced to facilitate reuse of the stapling device.

Generally, a loading unit includes a proximal body portion and a tool assembly pivotally supported on a distal end of the proximal body portion. The proximal body portion of the loading unit supports a drive assembly and an articulation link and includes a proximal end that is adapted to engage an adapter or body of a stapling device such that the drive assembly of the loading unit is coupled with a drive member of the stapling device and the articulation link of the loading unit is coupled to an articulation mechanism of the stapling device.

In some instances, if the drive assembly of the loading unit is not properly coupled to the drive member of the surgical stapling device, the tool assembly can be locked in a clamped position after the stapling device is fired. In addition, coupling of the articulation link of the loading unit to the articulation mechanism of the stapling device generally requires multiple components with clearances that cause the tool assembly to wobble during firing and retraction of the drive assembly.

<CIT> discloses a surgical instrument comprising a connector assembly for connecting an end effector to a flexible shaft portion.

A continuing need exists in the stapling arts for a stapling device including a loading unit that can be selectively coupled to a body of the stapling device in a manner to ensure proper engagement of the components of the reload with the components of the stapling device to provide a reliable and stable device.

The present invention is defined by the features of the independent claims. Further embodiments are provided by the dependent claims.

One aspect of the disclosure is directed to a surgical stapling device including a body portion and a tool assembly. The body portion includes a housing, a base member positioned on the housing, and a drive assembly supported within the housing. The base member defines a longitudinal slot and spaced keyways. The drive assembly includes a proximal portion having a connector and a distal portion including a working end. The drive assembly is movable within the housing between a retracted position in which the working end of the drive assembly is positioned within the longitudinal slot of the base member and an advanced position. The tool assembly includes a first jaw, a second jaw, and a mounting member. The first jaw and the second jaw are secured to the mounting member such that the first jaw is movable in relation to the second jaw between an open position and an unclamped position. The mounting member defines a channel having an open end that is dimensioned to receive the base member of the body portion. The mounting member includes locking tabs positioned within the channel. Each of the locking tabs is configured to be received within one of the spaced keyways of the base member to releasably secure the tool assembly to the body portion.

Each of the spaced keyways includes an axial portion and a radial portion, wherein axial movement of the tool assembly in relation to the body portion moves the locking tabs through the axial portions of the keyways and rotatable movement of the tool assembly in relation to the body portion moves the locking tabs through the radial portions of the spaced keyways to secure the tool assembly to the body portion.

In certain embodiments, the working end of the drive assembly is configured to be movable through the tool assembly when the drive assembly is moved from the retracted position to the advanced position to move the tool assembly from the open position to the clamped position and to fire the tool assembly.

In embodiments, the body portion includes a lead screw and an inner tube, and the lead screw is rotatable to axially advance the inner tube within the housing, wherein the inner tube engages the connector of the drive assembly to axially advance the drive member within the housing from the retracted position to the advanced position.

In some embodiments, the body portion includes a biasing member that is positioned between a distal portion of the inner tube and the connector to urge the drive assembly distally within the housing in relation to the inner shaft.

In certain embodiments, the first jaw includes an anvil and the second jaw includes a channel member that supports a staple cartridge.

In embodiments, the working end of the drive member includes a vertical strut having a knife edge and the channel member and staple cartridge define longitudinal slots that receive the vertical strut when the tool assembly is secured to the body portion.

In some embodiments, when the locking tabs are in the axial portions of the spaced keyways, the vertical strut of the working end of the drive assembly is misaligned with the longitudinal slot in the channel member such that when the tool assembly is moved towards the base member to move the locking tabs through the axial portions of the spaced keyways, the working end of the drive assembly abuts the channel member to prevent axial movement of the drive assembly in relation to the tool assembly.

In certain embodiments, axial advancement of the base member within the channel of the mounting member when the working end of the drive assembly is in abutment with the channel member causes the drive assembly to move axially in relation to the inner tube to compress the biasing member.

In embodiments, when the tool assembly is rotated in relation to body portion to move the locking tabs through the radial portions of the spaced keyways, the vertical strut of the drive assembly is moved into alignment with the longitudinal slots of the channel member and the staple cartridge.

In some embodiments, when the vertical strut is rotated into alignment with the longitudinal slots of the channel member and the staple cartridge, the biasing member urges the working end of the drive assembly into a proximal portion of the tool assembly.

The housing includes a distal portion, and the base member is pivotally supported on the distal portion of the housing.

The body portion includes a platform that is supported on the distal portion of the housing.

The base member defines a transverse slot and the platform includes a flange that is pivotably received within the transverse slot of the base member.

The platform defines upper and lower recesses that diverge outwardly in a distal direction.

In embodiments, the drive assembly includes an elongate flexible body having an upper body portion and a lower body portion, and the platform is positioned between the upper and lower body portions.

In some embodiments, the stapling device includes upper and lower U-shaped guides, wherein the upper guide is positioned in the upper recess of the platform and receives the upper body portion of the flexible body of the drive assembly and the lower guide is positioned in the lower recess of the platform and receives the lower body portion of the flexible body of the drive assembly.

In certain embodiments, each of the upper and lower U-shaped guides has a proximal portion including a pivot member, wherein the pivot members pivotably support the upper and lower U-shaped guides within the upper and lower recesses.

In embodiments, the stapling device includes an upper blowout plate assembly positioned within the upper guide on opposite sides of the upper body portion of the flexible body and a lower blowout plate assembly positioned within the lower guide on opposite sides of the lower body portion of the flexible body.

In some embodiments, the stapling device includes an articulation assembly having an articulation drive member, a first articulation link secured to the articulation drive member, a second articulation link pivotably coupled to the first articulation link and to the base member.

Various embodiments of the presently disclosed loading unit and adapter assembly are described herein below with reference to the drawings, wherein:.

The presently disclosed stapling device including a loading unit and an adapter assembly 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. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.

In this description, the term "proximal" is used generally to refer to that portion of the device that is closer to a clinician, while the term "distal" is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term "endoscopic" is used generally used to refer to endoscopic, laparoscopic, arthroscopic, and/or any other procedure conducted through a small diameter incision or cannula. Further, the term "clinician" is used generally to refer to medical personnel including doctors, nurses, and support personnel.

<FIG> and <FIG> illustrate a surgical stapling device shown generally as stapling device <NUM> including a handle assembly <NUM>, and exemplary embodiments of the presently disclosed tool assembly <NUM> (e.g., an end effector, multiple or single use tool assembly) and adapter assembly <NUM>. The adapter assembly <NUM> includes an elongate body <NUM> having a distal portion that supports the tool assembly <NUM>. The handle assembly <NUM> is configured for releasable connection to the adapter assembly <NUM>, and, in turn, the adapter assembly <NUM> is configured for releasable connection to the tool assembly <NUM>. Together, the handle assembly <NUM> and the adapter assembly <NUM> cooperate to actuate the tool assembly <NUM>. The stapling device <NUM> may be an electromechanically powered system and the handle assembly <NUM> may support a power source, e.g., a battery pack. Alternatively, the stapling device <NUM> may be manually actuated and the adapter assembly <NUM> may be fixedly secured to the handle assembly <NUM>.

In embodiments, the handle assembly <NUM> includes a stationary handle <NUM> and a plurality of actuation switches <NUM>. The actuation switches <NUM> are provided to control various functions of the stapling device <NUM> including approximation of the tool assembly <NUM>, and cutting, and firing of tissue.

<FIG> illustrates an exemplary embodiment of the presently disclosed tool assembly <NUM> of the stapling device <NUM> (<FIG>) which includes an anvil assembly <NUM>, and a cartridge assembly <NUM>. The cartridge assembly <NUM> includes a cartridge channel member <NUM>, and a staple cartridge <NUM>. The anvil assembly <NUM> includes an anvil cover <NUM> and an anvil plate <NUM>. The anvil cover <NUM> includes a mounting portion <NUM> that defines a proximal cutout <NUM>, and a cover portion <NUM> that extends along the distal portion of the anvil plate <NUM>. The mounting portion <NUM> includes spaced proximal extensions 224a that define the cutout <NUM> and bores <NUM>. The tool assembly <NUM> also includes a mounting member <NUM> that is secured to the proximal portions of the anvil assembly <NUM> and the cartridge assembly <NUM>.

The anvil plate <NUM> includes a tissue engaging surface <NUM> that is in opposed relation to the staple cartridge <NUM> and defines a plurality of staple deforming recesses (not shown). The anvil plate <NUM> has a side opposite to the tissue engaging surface <NUM> that defines an elongated recess <NUM> that is configured to receive an upper beam <NUM> (<FIG>) of a drive assembly <NUM> (<FIG>) of the adapter assembly <NUM> as described in further detail below. The anvil cover <NUM> is secured to the anvil plate <NUM>, e.g., by welding or crimping, such that the cover portion <NUM> encloses the elongated recess <NUM>. The anvil plate <NUM> also defines an elongated knife slot <NUM> that extends through the tissue engaging surface <NUM> of the anvil plate <NUM> into the elongated recess <NUM>.

The cartridge channel member <NUM> includes a bottom wall <NUM> and a pair of spaced side walls <NUM> that define a channel <NUM>. The channel <NUM> is dimensioned to receive the staple cartridge <NUM>. The side walls <NUM> of the channel member <NUM> each include a proximal extension <NUM> that defines a bore 246a. The bottom wall <NUM> defines a longitudinal slot <NUM> (<FIG>) that is open at its proximal end to receive a working end <NUM> (<FIG>) of the drive assembly <NUM> as described in detail below. The staple cartridge <NUM> also defines a longitudinal slot 214a that is aligned with the longitudinal slot <NUM> of the channel member <NUM>.

Referring also to <FIG>, the mounting member <NUM> includes a substantially cylindrical proximal portion <NUM> and a distal portion <NUM>. The distal portion <NUM> of the mounting member <NUM> defines an I-shaped slot <NUM> (<FIG>) and includes flat outer side walls <NUM> that define bores 254a. The side walls <NUM> are received between the pair of proximal extensions 224a of the mounting portion <NUM> of the anvil cover <NUM> within the cutout <NUM> such that the bores <NUM> of the proximal extensions 224a are aligned with the bores 254a of the mounting member <NUM>. The extensions <NUM> of the side walls <NUM> of the channel member <NUM> are also positioned between the flat side walls <NUM> of the mounting member <NUM> and the proximal extensions 224a of the anvil cover <NUM> such that the bores 246a are aligned with the bores <NUM> of the anvil cover and with the bores 254a of the mounting member <NUM>.

A pivot pin <NUM> is positioned through each of the bores <NUM> of the anvil cover <NUM>, the bores 246a of the channel member <NUM>, and the bores 254a of the mounting member <NUM> on each side of the anvil assembly <NUM> to fixedly secure the anvil assembly <NUM> to the mounting member <NUM>, and to pivotably secure the cartridge channel member <NUM> in relation to the mounting member <NUM> and the anvil assembly <NUM>. The channel member <NUM> is pivotal about the pivot pins <NUM> from an open position (<FIG>) to a clamped position (<FIG>).

Referring to <FIG>, a distal portion of the adapter assembly <NUM> (<FIG>) is dimensioned to be received in the proximal portion <NUM> (<FIG>) of the mounting member <NUM> to releasably couple the tool assembly <NUM> to the adapter assembly <NUM>. More specifically, the proximal portion <NUM> of the mounting member <NUM> defines a channel <NUM> that is configured to receive a pivot base <NUM> (<FIG>) of the adapter assembly <NUM> which is described in further detail below. The mounting member <NUM> includes locking tabs <NUM> (<FIG>) that project inwardly from an inner surface of the mounting member <NUM> into the channel <NUM>. In embodiments, an outer surface of the mounting member <NUM> includes a pair of arrows <NUM>, <NUM> that extend in directions perpendicular to each other. A first arrow <NUM> of the pair of arrows points in a direction that is parallel to a longitudinal axis "X" of the tool assembly <NUM> and the second arrow <NUM> of the pair of arrows points in a direction that is perpendicular to the longitudinal axis "X" of the tool assembly <NUM>. The arrows <NUM>, <NUM> assist a clinician with coupling the tool assembly <NUM> to the adapter assembly <NUM> as described in detail below.

Referring to <FIG>, the adapter assembly <NUM> includes a housing <NUM> (<FIG>) that includes an upper housing portion 304a and a lower housing portion 304b. The upper and lower housing portions 304a, 304b are secured together using any of a variety of known fastening technique, e.g., welding, interlocking structure, etc., to define a cavity <NUM> (<FIG>) that receives other components of the adapter assembly <NUM>. A distal portion of each of the upper and lower housing portions 304a, 304b defines a recess <NUM> and a cutout <NUM> (<FIG>). The recesses <NUM> of the upper and lower housing portions 304a, 304b diverge outwardly in the distal direction. The upper and lower housing portions 304a, 304b are supported within an outer cylindrical housing <NUM> to prevent separation of the upper housing portion 304a from the lower housing portion 304b.

The cutouts <NUM> of the upper and lower housing portions 304a, 304b define a slot in the distal end of the housing <NUM> that receives a platform <NUM> (<FIG>) when the upper and lower housing portions 304a, and 304b are assembled. The platform <NUM> can be secured between the upper and lower housing portions 304a, 304b using any known fastening technique including screws, welding or the like. The platform <NUM> defines upper and lower recesses <NUM> (<FIG>) that have shapes that correspond to the shapes of the recesses <NUM> in the upper and lower housing portions 304a, 304b. When the platform <NUM> is secured between the upper and lower housing portions 304a, 304b, the recesses <NUM> of the upper and lower housing portions 304a, 304b and the recesses <NUM> of the platform <NUM> define upper and lower cavities <NUM> (<FIG>) at the distal portion of the housing <NUM> that diverge outwardly in the distal direction.

The adapter assembly <NUM> includes the pivot base <NUM>, a drive assembly <NUM>, a lead screw <NUM>, a firing nut <NUM>, and an inner tube <NUM>. The pivot base <NUM> defines a longitudinal slot 302a and the lead screw <NUM> includes a threaded outer wall 322a. The drive assembly <NUM> is positioned within the housing <NUM> (<FIG>) and includes a distal working end <NUM>, a proximal connector <NUM>, and an elongate flexible body <NUM> positioned between the working end <NUM> and the connector <NUM>. The flexible body <NUM> includes an upper body portion 332a and a lower body portion 332b. The working end <NUM> includes an upper beam <NUM>, a lower beam <NUM>, and a vertical strut <NUM>. The vertical strut <NUM> includes a knife edge <NUM>. When the drive assembly <NUM> is in a retracted position, the vertical strut <NUM> is positioned within the longitudinal slot 302a of the pivot base <NUM>. The upper and lower beams <NUM>, <NUM> are positioned to engage the anvil assembly <NUM> and the cartridge channel member <NUM> to move the anvil assembly <NUM> and the cartridge channel member <NUM> between open and clamped positions as is known in the art. For a more detailed description of the working end <NUM> of the drive assembly <NUM>, see <CIT>("'<NUM> Patent").

Referring briefly to <FIG>, the connector <NUM> extends proximally from the flexible body <NUM> of the drive assembly <NUM> and includes a distal portion <NUM> and a proximal portion <NUM>. The distal portion <NUM> of the connector <NUM> is secured to a proximal end of the flexible body <NUM> between the upper body portion 332a and a lower body portion 332b of the flexible body <NUM>. The proximal portion <NUM> of the connector <NUM> includes an annular recess <NUM> (<FIG>) and is configured to be received within a distal end of the firing nut <NUM>. Pins <NUM> extend through a distal portion of the firing nut <NUM> through the annular recess <NUM> of the connector <NUM> to secure the distal portion of the firing nut <NUM> to the connector <NUM>. The annular recess <NUM> has a length that is greater than the diameter of the pins <NUM> such that the connector <NUM> is axially movable within the firing nut <NUM> independently of the firing nut <NUM>. More specifically, the connector <NUM> is axially movable in relation to the firing nut <NUM> between an advanced position (<FIG>) in which the pins <NUM> engage a proximal wall 350a defining the proximal end of the annular recess <NUM> and a retracted position (<FIG>) in which the pins <NUM> engage a distal wall 350b defining the distal end of the annular recess <NUM>. The connector <NUM> translates movement of the firing nut <NUM> into movement of the drive assembly <NUM> when the pins <NUM> are engaged with the walls 350a and 350b defining the annular recess <NUM>.

Referring again to <FIG>, the firing nut <NUM> includes an inner wall having a threaded portion <NUM> (<FIG>) and an outer side wall defining a flat <NUM> (<FIG>). The threaded portion <NUM> is positioned to engage the threaded outer wall 322a of the lead screw <NUM> such that rotation of the lead screw <NUM> within the firing nut <NUM> causes longitudinal movement of the firing nut <NUM> within the housing <NUM> (<FIG>). The inner tube <NUM> includes an inner wall having a flat surface portion (not shown) that defines an axial bore <NUM> (<FIG>). The flat surface portion of the inner wall of the inner tube <NUM> is positioned to engage the flat <NUM> (<FIG>) on the outer side wall of the firing nut <NUM> to prevent rotation of the firing nut <NUM> within the inner tube <NUM> of the adapter assembly <NUM>. The inner tube <NUM> also has an outer wall that defines a flat <NUM>. The flat <NUM> of the inner tube <NUM> is positioned within the housing <NUM> to prevent rotation of the inner tube <NUM> within the housing <NUM>.

In use, when the lead screw <NUM> is rotated within the firing nut <NUM>, engagement between the threaded outer wall 322a of the lead screw <NUM> and the threaded portion <NUM> (<FIG>) of the inner wall of the firing nut <NUM> causes axial movement of the firing nut <NUM> within the inner tube <NUM> of the adapter assembly <NUM>. As discussed above, engagement between the flat <NUM> of the firing nut <NUM> and the flat surface portion (not shown) on the inner wall of the inner tube <NUM> prevents the firing nut <NUM> from rotating and, thus, limits the firing nut <NUM> to axial movement within the inner tube <NUM> of the adapter assembly <NUM>. As the firing nut <NUM> is moved axially within the inner tube <NUM>, the pins <NUM> are moved within the annular recess <NUM> of the connector <NUM> until the pins <NUM> engage one of the ends 350a, 350b of the wall defining the annular recess <NUM>. When this occurs, axial movement of the firing nut <NUM> will cause axial movement of the connector <NUM> and corresponding axial movement of the drive assembly <NUM>. Axial movement of the drive assembly <NUM> causes the working end <NUM> of the drive assembly <NUM> to move within the tool assembly <NUM> to actuate the tool assembly <NUM> as is known in the art.

As discussed above, the platform <NUM> (<FIG>) is secured between a distal portion of the upper and lower housing portions 304a, 304b and defines upper and lower cavities <NUM> (<FIG>) (only the upper cavity is shown). A distal end of the platform <NUM> includes a flange <NUM> (<FIG>) that extends distally from the housing <NUM> of the adapter <NUM>. The flange <NUM> defines a bore <NUM>.

Referring to <FIG> and <FIG>, the pivot base <NUM> includes a body <NUM> (<FIG>) having a distal portion <NUM> that defines the longitudinal slot 302a and a proximal portion <NUM>. The distal portion <NUM> of the body <NUM> is dimensioned to be received in the channel <NUM> (<FIG>) defined in the proximal portion <NUM> (<FIG>) of the mounting member <NUM> and defines spaced keyway slots <NUM>. Each of the keyway slots <NUM> is dimensioned to receive one of the locking tabs <NUM> (<FIG>) of the mounting member <NUM> when the tool assembly <NUM> is secured to the adapter assembly <NUM>. The keyway slots <NUM> are substantially J-shaped and have an axial portion <NUM> and a transverse portion <NUM>.

The proximal portion <NUM> of the body <NUM> of the pivot base <NUM> has a radiused proximal end <NUM> and defines a transverse through slot <NUM> and a vertical opening <NUM> (<FIG>). The slot <NUM> receives the flange <NUM> (<FIG>) of the platform <NUM>. A pivot member <NUM> is received through the opening <NUM> in the proximal portion <NUM> of the pivot base <NUM> and the vertical bore <NUM> in the flange <NUM> of the platform <NUM> to pivotably secure the pivot base <NUM> to the platform <NUM>. In embodiments, top and bottom surfaces of the proximal portion <NUM> of the body <NUM> of the pivot base <NUM> define annular guide channels <NUM> (<FIG>).

Referring to <FIG> and <FIG>, the adapter <NUM> (<FIG>) includes upper and lower drive assembly guides <NUM>. Each of the guides <NUM> (<FIG>) is substantially U-shaped and includes side walls <NUM>, a base wall <NUM>, and an open end <NUM> opposite to the base wall <NUM> that define a channel 392a that has a divergent distal portion <NUM>. The open end <NUM> of the guides <NUM> is dimensioned to receive one of the upper and lower body portions 332a, 332b of the flexible body <NUM> of the drive assembly <NUM>. The base wall <NUM> defines spaced elongated slots <NUM> (<FIG>) and includes a proximal circular pivot member <NUM>. The pivot member <NUM> is received within an opening <NUM> (<FIG>) that is formed in a proximal end of the platform <NUM> to pivotably secure each of the drive assembly guides <NUM> within one of the cavities <NUM> of the platform <NUM> (<FIG>) in the distal end of the housing <NUM>.

The adapter <NUM> also includes an upper and a lower blow out plate assemblies <NUM>. Each of the upper and lower blow-out plate assemblies <NUM> includes a pair of blow-out plates <NUM> and a support block <NUM>. One blow-out plate <NUM> is positioned on each side of the upper body portion 332a of the flexible body <NUM> within a respective one of the channels 392a of the drive assembly guides <NUM>. In addition, one blow-out plate <NUM> is positioned on each side of the lower body portion 332b of the flexible body <NUM> within a respective one of the channels 392a of the drive assembly guides <NUM>. Each of the blow-out plates <NUM> includes a distal end having a transverse portion <NUM> (<FIG>) and a central vertical extension <NUM> (<FIG>). The transverse portion <NUM> (<FIG>) is received within a slot <NUM> (<FIG>) formed in the pivot base <NUM> distally of the pivot member <NUM> to axially fix the distal ends of the blow-out plates <NUM> to the pivot base <NUM>. The vertical extensions <NUM> of the blow-out plates <NUM> are each received within one of the spaced elongated slots <NUM> formed in the guides <NUM> to properly position the blow-out plates <NUM> about the flexible body <NUM> of the drive assembly <NUM>. Proximal ends of the blow-out plates <NUM> are free to move axially along the flexible body <NUM> when the tool assembly <NUM> is articulated in relation to the adapter assembly <NUM> to prevent binding of the flexible body <NUM> when the tool assembly <NUM> is articulated.

The blow-out plate assemblies <NUM> are positioned on opposite sides of the flexible body <NUM> of the drive assembly <NUM> and extend from a position proximal of the pivot axis of the tool assembly <NUM> defined by the pivot member <NUM> (<FIG>) to stabilize the flexible body <NUM> of the drive assembly <NUM> and minimize the likelihood of outward buckling of the flexible body <NUM> of the drive assembly <NUM> during approximation and firing of the stapling device <NUM> (<FIG>).

Referring to <FIG>, the adapter assembly <NUM> includes an articulation assembly <NUM> including an articulation drive member <NUM>, a first articulation link <NUM>, and a second articulation link <NUM>. The articulation drive member <NUM> is supported on the housing <NUM> and is movable between a retracted position and an advanced position. The articulation drive member <NUM> includes a distal end <NUM> that is coupled to a proximal end of the first articulation link <NUM>. In embodiments, the distal end of the articulation drive member <NUM> defines a slot <NUM> and the proximal end of the first articulation link <NUM> includes a rib <NUM> that is received in the slot <NUM> to couple the articulation drive member <NUM> to the first articulation link <NUM>. Alternately, other coupling mechanisms may be used to secure the articulation drive member <NUM> to the first articulation link <NUM>. In embodiments, the distal end of the first articulation link <NUM> is coupled to a proximal end of the second articulation link <NUM> by a pivot pin <NUM> (<FIG>) and the distal end of the second articulation link <NUM> is pivotably secured to the pivot base <NUM> by a pivot pin <NUM> (<FIG>). The pivot pin <NUM> is laterally offset from the pivot axis of the tool assembly <NUM> defined by the pivot member <NUM>.

In use, axial movement of the articulation drive member <NUM> within the housing <NUM> causes corresponding movement of the first and second articulation links <NUM>, <NUM>, respectively. As the second articulation link <NUM> moves axially, the tool assembly <NUM> is articulated about the pivot axis defined by the pivot member <NUM> from a position in which a longitudinal axis of the tool assembly <NUM> is aligned with a longitudinal axis of the adapter assembly <NUM> to a position in which the longitudinal axis of the loading unit defines an acute angle with the longitudinal axis of the adapter assembly <NUM>. By providing two pivotally coupled articulation links <NUM>, <NUM>, a greater range of articulation of the tool assembly <NUM> can be achieved.

Referring to <FIG>, the proximal connector <NUM> of the drive assembly <NUM> defines channels <NUM> that are closed by a radial flange <NUM> that extends transversely across a proximal end of the channels <NUM>. The channels <NUM> receive the upper and lower body portions 332a, 332b of the flexible body <NUM> of the drive assembly <NUM>. The radial flange <NUM> is positioned to engage a biasing member <NUM> that is supported between a distal end of the firing nut <NUM> and a proximal surface of the radial flange <NUM>. The biasing member <NUM> is positioned to urge the drive assembly <NUM> in relation to the firing nut <NUM> towards an advanced position (<FIG>). In the advanced position, the pins <NUM> supported on the distal end of the firing nut <NUM> engage the proximal wall 350a of the annular recess <NUM> in the connector <NUM>. In embodiments, the biasing member <NUM> is a coil spring and the distal end of the firing nut <NUM> defines an annular recess <NUM> that receives the coil spring <NUM> to align the coil spring <NUM> with the flange <NUM> of the connector <NUM>.

<FIG> illustrate the stapling device <NUM> as the tool assembly <NUM> is releasably coupled to the distal portion of the adapter assembly <NUM>. Referring initially to <FIG>, in order to attach the tool assembly <NUM> to the adapter assembly <NUM>, a proximal end of the tool assembly <NUM> is moved towards the distal end of the adapter assembly <NUM> in the direction indicated by arrows "A" in <FIG> to position the distal portion <NUM> of the body <NUM> of the pivot base <NUM> and the working end <NUM> of the drive assembly <NUM> positioned in the longitudinal slot <NUM> of the pivot base <NUM> into the channel <NUM> (<FIG>) of the mounting member <NUM> of the tool assembly <NUM>. When the distal portion <NUM> of the pivot base <NUM> is received within the channel <NUM> of the mounting member <NUM>, the locking tabs <NUM> of the mounting member are received within the axial portion <NUM> of the keyway slots <NUM>. When the locking tabs <NUM> are positioned within the axial portion <NUM> of the keyway slots <NUM>, the vertical strut <NUM> of the working end <NUM> of the drive assembly <NUM> is misaligned with the slot <NUM> (<FIG>) in the distal end of the mounting member <NUM> and with the knife slot <NUM> (<FIG>) in the channel member <NUM>. As such, the working end <NUM> of the drive assembly <NUM> presses against the proximal end of the channel member <NUM>. Thus, as the pivot base <NUM> is advanced into the channel <NUM> of the mounting member <NUM>, the drive assembly <NUM> is urged from its advanced position (<FIG>) towards its retracted position (<FIG>) and the biasing member <NUM> is compressed.

Referring to <FIG>, as the locking tabs <NUM> of the mounting member <NUM> are moved through the axial portion <NUM> of the keyway slots <NUM> in the direction indicated by arrows "A" in <FIG>, the drive assembly <NUM> is pressed rearward by the channel member <NUM> to move the drive assembly <NUM> including the connector <NUM> proximally in relation to the firing nut <NUM> in the direction indicated by arrow "B" in <FIG> from its advanced position (<FIG>) to its retracted position (<FIG>). As shown in <FIG>, in the retracted position of the drive assembly <NUM>, the pins <NUM> on the distal end of the firing nut <NUM> are engaged with the distal wall 350b defining the annular recess <NUM> of the proximal connector <NUM> (<FIG>) and the locking tabs <NUM> are positioned in the distal ends of the axial portion <NUM> of the keyway slots <NUM>.

Referring to <FIG>, in order to secure the tool assembly <NUM> to the pivot base <NUM> of the adapter assembly <NUM>, the tool assembly <NUM> is rotated in relation to the adapter assembly <NUM> in the direction indicated by arrows "C" to move the locking tabs <NUM> in the direction indicated by arrow "D" in <FIG> into and through the transverse portion <NUM> of the keyway slots <NUM>. As the tool assembly <NUM> is rotated in relation to the adapter assembly <NUM>, the working end <NUM> of the drive assembly <NUM> moves into alignment with the slot <NUM> (<FIG>) in the distal end of the mounting member <NUM> and with the knife slot <NUM> in the channel member <NUM>. Once the working end <NUM> of the of the drive assembly <NUM> is aligned with the slot <NUM> (<FIG>) in the distal end of the mounting member <NUM> and with the knife slot <NUM> in the channel member <NUM>, the biasing member <NUM> urges the drive assembly <NUM> back to the advanced position in the direction indicated by arrows "E" in <FIG> to move the working end <NUM> of the drive assembly <NUM> into the knife slot <NUM> of the channel member <NUM>. In this position, the tool assembly <NUM> is secured to the adapter assembly <NUM>, and the stapling device <NUM> is ready for use. For a detailed description of the operation of a stapling device, see the '<NUM> Patent.

In the presently described stapling device <NUM>, the tool assembly <NUM> forms a loading unit that does not include an articulation assembly or a drive assembly that must be coupled to the different mechanisms in the adapter assembly to operate. As such, drawbacks associated with known loading units or reloads are minimized to provide a more reliable tool assembly.

Claim 1:
A surgical stapling device comprising:
a body portion (<NUM>) including a housing (<NUM>), a base member (<NUM>) supported by the housing, and a drive assembly (<NUM>) supported within the housing, the base member defining a longitudinal slot (302a) and spaced keyways (<NUM>), the drive assembly including a proximal portion having a connector (<NUM>) and a distal portion including a working end (<NUM>), the drive assembly being movable within the housing between a retracted position in which the working end of the drive assembly is positioned within the longitudinal slot (302a) of the base member and an advanced position; and
a tool assembly (<NUM>) including a first jaw, a second jaw, and a mounting member (<NUM>), the first jaw and the second jaw being secured to the mounting member such that the first jaw is movable in relation to the second jaw between an open position and an unclamped position, the mounting member defining a channel (<NUM>) having an open end that is dimensioned to receive the base member (<NUM>) of the body portion, the mounting member including locking tabs (<NUM>), each of the locking tabs being configured to be received within one of the spaced keyways (<NUM>) of the base member to releasably secure the tool assembly to the body portion,
wherein each of the spaced keyways includes an axial portion (<NUM>) and a transverse portion (<NUM>) and axial movement of the tool assembly in relation to the body portion moves the locking tabs (<NUM>) through the axial portions of the keyways and rotatable movement of the tool assembly in relation to the body portion moves the locking tabs through the radial portions of the spaced keyways to secure the tool assembly to the body portion, and wherein the housing (<NUM>) includes a distal portion, the base member (<NUM>) being pivotally supported on the distal portion of the housing
characterised by the body portion including a platform (<NUM>) that is supported on the distal portion of the housing, the base member defining a transverse slot (<NUM>) and the platform including a flange (<NUM>) that is pivotably received within the transverse slot (<NUM>) of the base member, the platform defining upper and lower recesses (<NUM>) that diverge outwardly in a distal direction.