Patent Description:
Some circular staplers may include a motorized actuation mechanism. Examples of circular staplers with motorized actuation mechanisms are described in <CIT>, now abandoned; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>.

<CIT> describes a surgical stapling device including a handle assembly, an adapter assembly removably and selectively attachable to the handle assembly, and a loading unit removably and selectively attachable to the adapter assembly. The adapter assembly extends from the handle assembly to transmit actuating forces from the handle assembly to the loading unit. The adapter assembly includes a connector assembly. The loading unit includes a shell member and a housing extending from an inner surface of the shell member. The surgical stapling device further includes a chip assembly disposed within the housing and moveable relative to the shell member to facilitate connection with the connector assembly of the adapter assembly. A proximal end of the shell member includes a housing formed on its inner surface and defines a cut-out and a notch. The housing defines a recess configured to receive the chip assembly and includes first and second longitudinal side walls and a distal end wall. A proximal end of the housing is open to permit axial loading of the chip assembly within the recess. The notch is positioned adjacent the recess of the housing and is configured to facilitate loading of the chip assembly within the recess. A lip extending about the first and second side walls and the distal wall of the housing is provided for retaining the chip assembly within the recess. The lip defines an opening providing access to the chip assembly from within the shell member when the chip assembly is received within the housing. The housing is positioned within the shell member such that upon attachment of the shell member to the distal end of the adapter assembly, the chip assembly aligns with a connector assembly mounted within the distal end of the adapter assembly. The cut-out formed in the shell member adjacent the housing is configured to receive a flanged portion of a spring member of the chip assembly. The chip assembly includes a chip member and the spring member. The chip member includes a base portion and a chip. The base portion forms a planar member configured to be received within the recess of the housing. The base portion permits the radial movement of the chip member within the recess to facilitate connection between the chip assembly and the connector assembly. The chip includes a plurality of connection protrusions. The spring member includes a flanged portion and a biasing portion. A first end of the flanged portion is received within the cut-out of the shell member and a second end of the flanged portion engages the lip of the housing. The flanged portion of the spring member secures the chip member and the biasing portion of the spring member within the recess of the housing. The biasing portion forms a curved member to provide a biasing force against the chip member. The biasing force provided by biasing portion against the chip member positions the chip of the chip member within the opening formed by the lip of the housing.

<CIT> describes an interlock assembly for attaching a loading unit to a surgical stapling instrument. The interlock assembly is formed on the proximal end of the loading unit and the distal end of an adapter assembly. The loading unit includes a shell member having a proximal end received about the distal end of the adapter assembly. The proximal end of the shell member defines a pair of openings. The distal end of the adapter assembly is received within the proximal end of the shell member and includes a shelf to engage a proximal surface of the proximal end of the shell member. The distal end of the adapter assembly also includes legs flexibly attached to it. Protrusions are formed on the free end of each leg. The distal end of the adapter assembly is aligned with the proximal end of the shell member of the loading unit. Advancement of the adapter assembly relative to the loading unit causes the legs on the distal end of the adapter assembly to flex radially inward, thereby permitting continued advancement of the adapter assembly relative to the shell member of the loading unit. Engagement of a proximal surface of the shell member of the loading unit with the shelf of the adapter assembly aligns the protrusions on the free ends of the legs of the adapter assembly with the openings formed in the proximal end of the shell member of the loading unit. This permits the free ends of the legs to return to an unflexed condition, in which the protrusions of the adapter assembly are received within the openings of the shell member of the loading unit, thereby securing the loading unit to the adapter assembly.

Patent Publication No.: <CIT> describes a loading unit for a surgical stapler that includes a shell assembly and a locking collar. The shell assembly has an annular ring that defines a locking slot and a proximal opening. The proximal opening receives a distal end portion of the surgical instrument. The locking collar is rotatably disposed about the annular ring. The locking collar has a body including a flexible tab that has an inwardly extending lock. The locking collar is moveable about the annular ring between a locked and unlocked configuration. In the locked configuration, the lock passes through the locking slot and into a lock window of the annular ring. In the unlocked configuration, the body of the locking collar is rotated about the annular ring from the locked configuration to move the lock from within the proximal opening. To secure the loading unit to the distal end portion of an adapter of a surgical instrument, the assembled loading unit is aligned with the distal end portion of the adapter such that the longitudinal axis of the loading unit is aligned with the longitudinal axis of the adapter. The loading unit is then radially aligned with the distal end portion of the adapter such that a key of the shell assembly is aligned with a keyway of the distal end portion. When the key and the keyway are radially aligned, a locking slot of the shell assembly is radially aligned with the lock window of the distal end portion of the adapter. With the loading unit and the distal end portion of the adapter aligned with one another, the loading unit is slid over the distal end portion of the adapter such that the distal end portion of the adapter is at least partially disposed within the proximal opening of the shell assembly. As the distal end portion of the adapter slides into the proximal opening, the key slides in the keyway of the distal end portion. As the distal end portion of the adapter slides into the proximal opening, the distal end of the adapter adjacent the locking slot engages a lateral cam surface of the lock to urge the lock and the flexible tab outward. The loading unit is slid over the distal end portion of the adapter until the lock window of the adapter is longitudinally aligned with the locking slot of the annular ring of the shell assembly. When the lock window and the locking slot are aligned, the resilience of the flexible tab urges or snaps the lock through the lock window of the adapter and into the locked configuration.

A surgical stapling instrument as set out in claim <NUM> is provided. The surgical stapling instrument comprises a body member and a shaft assembly. The body member has a distal end configured to be fixedly secured to an annular deck member having a plurality of staple openings. The body member is configured to slidably house a staple driver member, and includes a collar having at least one latching feature. The shaft assembly comprises a proximal sheath portion, a distal sheath portion, and at least one protrusion extending radially outwardly from the distal sheath portion. The protrusion includes at least one abutment surface configured to engage the at least one latching feature of the collar. The collar is defined by a plurality of circumferentially-arranged flexible tabs configured to flex radially outwardly and spaced apart from each other by a plurality of longitudinal slots, and the latching feature is defined on the flexible tabs and configured to be engaged by the at least one protrusion to mechanically couple the body member to the shaft assembly.

A method according to claim <NUM> is provided, of manufacturing a surgical stapling instrument including a body member including a collar having at least one latching feature, the body member being configured to slidably house a staple driver member, and a shaft assembly having a sheath portion and at least one protrusion extending radially outwardly from the sheath portion, the at least one protrusion including at least one abutment surface. The method comprises slidably positioning the sheath portion within the collar, advancing a proximal portion of the collar proximally over the at least one protrusion, including transitioning the collar from a radially unexpanded state to a radially expanded state, and after the act of advancing, transitioning the collar from the radially expanded state toward the radially unexpanded state to engage the at least one latching feature with the at least one abutment surface for coupling the body member to the shaft assembly.

The accompanying drawings, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention in <FIG>, and the remaining drawings are included for background and context, as follows.

The drawings and the following description should be regarded as illustrative in nature and not restrictive.

For clarity of disclosure, the terms "proximal" and "distal" are defined herein relative to a surgeon, or other operator, grasping a surgical instrument having a distal surgical end effector. The term "proximal" refers to the position of an element arranged closer to the surgeon, and the term "distal" refers to the position of an element arranged closer to the surgical end effector of the surgical instrument and further away from the surgeon. Moreover, to the extent that spatial terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "clockwise," "counterclockwise," or the like are used herein with reference to the drawings, it will be appreciated that such terms are used for exemplary description purposes only and are not intended to be limiting or absolute. In that regard, it will be understood that surgical instruments such as those disclosed herein may be used in a variety of orientations and positions not limited to those shown and described herein.

Furthermore, the terms "about," "approximately," and the like as used herein in connection with any numerical values or ranges of values are intended to encompass the exact value(s) referenced as well as a suitable tolerance that enables the referenced feature or combination of features to function for the intended purpose described herein.

<FIG> depict an exemplary circular surgical stapling instrument (<NUM>) that may be used to provide an end-to-end, side-to-side, or end-to-side anastomosis between two sections of an anatomical lumen such as a portion of a patient's digestive tract. Instrument (<NUM>) of this example includes a body assembly in the form of a handle assembly (<NUM>), a shaft assembly (<NUM>) extending distally from handle assembly (<NUM>), a stapling head assembly (<NUM>) at a distal end of shaft assembly (<NUM>), and an anvil (<NUM>) configured to releasably couple and cooperate with stapling head assembly (<NUM>) to clamp, staple, and cut tissue. Instrument (<NUM>) further includes a removable battery pack (<NUM>) operable to provide electrical power to a motor (<NUM>) housed within handle assembly (<NUM>), as will be described in greater detail below.

As shown in <FIG> and as will be described in greater detail below, anvil (<NUM>) is configured to removably couple with shaft assembly (<NUM>), adjacent to stapling head assembly (<NUM>). As will also be described in greater detail below, anvil (<NUM>) and stapling head assembly (<NUM>) are configured to cooperate to manipulate tissue in three ways, including clamping the tissue, cutting the tissue, and stapling the tissue. A rotatable knob (<NUM>) at the proximal end of handle assembly (<NUM>) is rotatable to provide precise clamping of the tissue between anvil (<NUM>) and stapling head assembly (<NUM>). When a safety trigger (<NUM>) of handle assembly (<NUM>) is pivoted away from a firing trigger (<NUM>) of handle assembly (<NUM>), firing trigger (<NUM>) may be actuated to thereby provide cutting and stapling of the clamped tissue.

As best seen in <FIG>, anvil (<NUM>) of the present example comprises a head (<NUM>) and a shank (<NUM>). Head (<NUM>) includes a proximal stapling surface (<NUM>) that defines a plurality of staple forming pockets (<NUM>). Staple forming pockets (<NUM>) are arranged in two concentric annular arrays in the present example. Staple forming pockets (<NUM>) are configured to deform staples as the staples are driven into staple forming pockets (<NUM>). Proximal stapling surface (<NUM>) terminates at an inner edge (<NUM>), which defines an outer boundary of an annular recess (<NUM>) surrounding shank (<NUM>). A breakable washer (<NUM>) is positioned within annular recess (<NUM>) and is configured to provide the operator with a tactile and audible indication that a distal firing stroke has been completed, in addition to serving as a cutting board, as described in greater detail below.

Shank (<NUM>) defines a bore (<NUM>) and includes a pair of pivoting latch members (<NUM>). Latch members (<NUM>) are positioned within bore (<NUM>) such that distal ends (<NUM>) are positioned at the proximal ends of lateral openings (<NUM>), which are formed through the sidewall of shank (<NUM>). Latch members (<NUM>) thus act as retaining clips. This allows anvil (<NUM>) to be removably secured to an actuatable closure member in the form of a trocar (<NUM>) of stapling head assembly (<NUM>), as will be described in greater detail below. Shank (<NUM>) of anvil (<NUM>) and trocar (<NUM>) of stapling head assembly (<NUM>) thus cooperate with one another as coupling members.

As best seen in <FIG> and <FIG>, stapling head assembly (<NUM>) of the present example is coupled to a distal end of shaft assembly (<NUM>) and comprises a tubular body member (<NUM>) and a staple driver member (<NUM>) slidably housed therein. Body member (<NUM>) includes a distally extending cylindraceous inner core member (<NUM>) positioned coaxially therein. Body member (<NUM>) is fixedly secured to an outer sheath (<NUM>) of shaft assembly (<NUM>), and body member (<NUM>) and outer sheath (<NUM>) thus serve together as a mechanical ground for stapling head assembly (<NUM>).

Trocar (<NUM>) is positioned coaxially within inner core member (<NUM>) of body member (<NUM>). As will be described in greater detail below, trocar (<NUM>) is operable to translate distally and proximally relative to body member (<NUM>) in response to rotation of knob (<NUM>) relative to casing (<NUM>) of handle assembly (<NUM>). Trocar (<NUM>) comprises a shaft (<NUM>) and a head (<NUM>). Head (<NUM>) includes a pointed tip (<NUM>) and a radially inwardly extending proximal surface (<NUM>). Head (<NUM>) and the distal portion of shaft (<NUM>) are configured for insertion into bore (<NUM>) of anvil (<NUM>). Proximal surface (<NUM>) and latch shelves (<NUM>) have complementary positions and configurations such that latch shelves (<NUM>) engage proximal surface (<NUM>) when shank (<NUM>) of anvil (<NUM>) is fully seated on trocar (<NUM>). Anvil (<NUM>) is thus secured to trocar (<NUM>) through a snap fit provided by latch members (<NUM>).

Staple driver member (<NUM>) is operable to actuate longitudinally within body member (<NUM>) in response to activation of motor (<NUM>) as will be described in greater detail below. As shown best in <FIG>, staple driver member (<NUM>) of the present example includes two distally presented concentric annular arrays of staple drivers (<NUM>). Staple drivers (<NUM>) are arranged to correspond with the arrangement of staple forming pockets (<NUM>) of anvil (<NUM>). Thus, each staple driver (<NUM>) is configured to drive a corresponding staple distally into a corresponding staple forming pocket (<NUM>) when stapling head assembly (<NUM>) is actuated (or "fired"). Staple driver member (<NUM>) also defines a bore (<NUM>) that is configured to coaxially and slidably receive core member (<NUM>) of body member (<NUM>). An annular array of studs (<NUM>) project distally from a distally presented surface surrounding bore (<NUM>).

A cylindraceous knife member (<NUM>) is coaxially positioned within a distally-opening central recess of staple driver member (<NUM>) that communicates with bore (<NUM>). Knife member (<NUM>) includes a distally presented, sharp circular cutting edge (<NUM>). Knife member (<NUM>) is sized such that knife member (<NUM>) defines an outer diameter that is just smaller than the diameter defined by the radially inner-most surfaces of the inner annular array of staple drivers (<NUM>). Knife member (<NUM>) also defines a central opening that is configured to coaxially receive core member (<NUM>) of body member (<NUM>). An annular array of openings (<NUM>) formed in knife member (<NUM>) is configured to mate with the annular array of studs (<NUM>) of staple driver member (<NUM>), such that knife member (<NUM>) is fixedly secured to staple driver member (<NUM>) via studs (<NUM>) and openings (<NUM>).

An annular deck member (<NUM>) is fixedly secured to a distal end of body member (<NUM>). Deck member (<NUM>) includes a distally presented stapling surface in the form of a deck surface (<NUM>) having two concentric annular arrays of staple openings (<NUM>). Staple openings (<NUM>) are arranged to align with the arrangement of staple drivers (<NUM>) of staple driver member (<NUM>) and staple forming pockets (<NUM>) of anvil (<NUM>) described above. Each staple opening (<NUM>) is configured to slidably receive and provide a pathway for a corresponding staple driver (<NUM>) to drive a corresponding staple distally through deck member (<NUM>) and into a corresponding staple forming pocket (<NUM>) when stapling head assembly (<NUM>) is actuated. As best seen in <FIG>, deck member (<NUM>) has a central opening that defines an inner diameter that is just slightly larger than the outer diameter defined by knife member (<NUM>). Deck member (<NUM>) is thus configured to permit knife member (<NUM>) to translate longitudinally through the central opening concurrently with longitudinal translation of staple driver member (<NUM>). In particular, knife member (<NUM>) is configured to actuate relative to deck member (<NUM>) between a proximal retracted position and a distal extended position, where cutting edge (<NUM>) is proximal to deck surface (<NUM>) in the proximal retracted position and distal to deck surface (<NUM>) in the distal extended position.

<FIG> shows various components of shaft assembly (<NUM>), which operatively couple components of stapling head assembly (<NUM>) with components of handle assembly (<NUM>). In particular, and as noted above, shaft assembly (<NUM>) includes an outer sheath (<NUM>) that extends between handle assembly (<NUM>) and body member (<NUM>) and includes a medial portion that extends along a curved path.

Shaft assembly (<NUM>) further includes a trocar actuation rod (<NUM>) having a proximal end operatively coupled with rotatable knob (<NUM>) and a distal end coupled with a flexible trocar actuation band assembly (<NUM>), the assembly of which is slidably housed within outer sheath (<NUM>). The distal end of trocar actuation band assembly (<NUM>) is fixedly secured to the proximal end of trocar shaft (<NUM>), such that trocar (<NUM>) will translate longitudinally relative to outer sheath (<NUM>) in response to translation of trocar actuation band assembly (<NUM>) and trocar actuation rod (<NUM>) relative to outer sheath (<NUM>), which occurs in response to rotation of rotatable knob (<NUM>). A clip (<NUM>) is fixedly secured to trocar actuation rod (<NUM>) and is configured to cooperate with complementary features within handle assembly (<NUM>) to prevent trocar actuation rod (<NUM>) from rotating within handle assembly (<NUM>) while still permitting trocar actuation rod (<NUM>) to translate longitudinally within handle assembly (<NUM>). Trocar actuation rod (<NUM>) further includes a section of coarse helical threading (<NUM>) and a section of fine helical threading (<NUM>) proximal to coarse helical threading (<NUM>), which are configured to control a rate of longitudinal advancement of trocar actuation rod (<NUM>), as described in greater detail below.

Shaft assembly (<NUM>) further includes a stapling head assembly driver (<NUM>) that is slidably housed within outer sheath (<NUM>) and about the combination of trocar actuation rod (<NUM>) and trocar actuation band assembly (<NUM>). Stapling head assembly driver (<NUM>) includes a distal end that is fixedly secured to the proximal end of staple driver member (<NUM>), a proximal end secured to a drive bracket (<NUM>) via a pin (<NUM>), and a flexible section disposed therebetween. It should therefore be understood that staple driver member (<NUM>) will translate longitudinally relative to outer sheath (<NUM>) in response to translation of stapling head assembly driver (<NUM>) and drive bracket (<NUM>) relative to outer sheath (<NUM>).

As shown in <FIG>, handle assembly (<NUM>) includes a casing (<NUM>) having a lower portion that defines an obliquely oriented pistol grip (<NUM>) and an upper portion that supports a user interface feature (<NUM>) and releasably receives a battery pack (<NUM>), as described in greater detail below. Handle assembly (<NUM>) further includes several features that are operable to actuate anvil (<NUM>) and stapling head assembly (<NUM>). In particular, handle assembly (<NUM>) includes a rotatable knob (<NUM>), a safety trigger (<NUM>), a firing trigger (<NUM>), a motor (<NUM>), and a motor activation module (<NUM>). Knob (<NUM>) is coupled with trocar actuation rod (<NUM>) via a nut (not shown), such that coarse helical threading (<NUM>) will selectively engage a thread engagement feature within the interior of the nut; and such that fine helical threading (<NUM>) will selectively engage a thread engagement feature within the interior of knob (<NUM>). These complementary structures are configured such that trocar actuation rod (<NUM>) will first translate proximally at a relatively slow rate, and then translate proximally at a relatively fast rate, in response to rotation of knob (<NUM>).

It should be understood that when anvil (<NUM>) is coupled with trocar (<NUM>), rotation of knob (<NUM>) will provide corresponding translation of anvil (<NUM>) relative to stapling head assembly (<NUM>). It should also be understood that knob (<NUM>) may be rotated in a first angular direction (e.g., clockwise) to retract anvil (<NUM>) proximally toward stapling head assembly (<NUM>); and in a second angular direction (e.g., counterclockwise) to extend anvil (<NUM>) distally away from stapling head assembly (<NUM>). Knob (<NUM>) may thus be used to adjust a gap distance (d) between opposing stapling surfaces (<NUM>, <NUM>) of anvil (<NUM>) and stapling head assembly (<NUM>) until a suitable gap distance (d) has been achieved, for example as shown in <FIG> described below.

Firing trigger (<NUM>) is operable to activate motor (<NUM>) to thereby actuate stapling head assembly (<NUM>) to staple and cut tissue clamped between anvil (<NUM>) and stapling head assembly (<NUM>). Safety trigger (<NUM>) is operable to selectively block actuation of firing trigger (<NUM>) based on the longitudinal position of anvil (<NUM>) in relation to stapling head assembly (<NUM>). Handle assembly (<NUM>) also includes components that are operable to selectively lock out both triggers (<NUM>, <NUM>) based on the position of anvil (<NUM>) relative to stapling head assembly (<NUM>). For instance, safety trigger (<NUM>) may be blocked from rotating from an engaged position to a disengaged position until the position of anvil (<NUM>) relative to stapling head assembly (<NUM>) is within a predefined range. Accordingly, until the anvil position is within the predefined range, actuation of firing trigger (<NUM>) is blocked by safety trigger (<NUM>), thereby inhibiting firing of stapling head assembly (<NUM>).

Firing trigger (<NUM>) is operable to actuate a switch of motor activation module (<NUM>) (<FIG>) when firing trigger (<NUM>) is pivoted proximally to a fired position. Motor activation module (<NUM>) is in communication with battery pack (<NUM>) and motor (<NUM>), such that motor activation module (<NUM>) is configured to provide activation of motor (<NUM>) with electrical power from battery pack (<NUM>) in response to firing trigger (<NUM>) actuating the switch of motor activation module (<NUM>). Thus, motor (<NUM>) will be activated when firing trigger (<NUM>) is pivoted. This activation of motor (<NUM>) will actuate stapling head assembly (<NUM>) via drive bracket (<NUM>), as described in greater detail below.

<FIG> show instrument (<NUM>) being used to form an anastomosis (<NUM>) between two tubular anatomical structures (<NUM>, <NUM>). By way of example only, the tubular anatomical structures (<NUM>, <NUM>) may comprise sections of a patient's esophagus, colon, or other portions of the patient's digestive tract, or any other tubular anatomical structures.

As shown in <FIG>, anvil (<NUM>) is positioned in one tubular anatomical structure (<NUM>) and stapling head assembly (<NUM>) is positioned in another tubular anatomical structure (<NUM>). As shown in <FIG>, anvil (<NUM>) is positioned in tubular anatomical structure (<NUM>) such that shank (<NUM>) protrudes from the open severed end (<NUM>) of tubular anatomical structure (<NUM>). In the present example, purse-string suture (<NUM>) is provided about a mid-region of shank (<NUM>) to generally secure the position of anvil (<NUM>) in tubular anatomical structure (<NUM>). Stapling head assembly (<NUM>) is positioned in tubular anatomical structure (<NUM>) such that trocar (<NUM>) protrudes from the open severed end (<NUM>) of tubular anatomical structure (<NUM>). A purse-string suture (<NUM>) is provided about a mid-region of shaft (<NUM>) to generally secure the position of stapling head assembly (<NUM>) in tubular anatomical structure (<NUM>). Stapling head assembly (<NUM>) is then urged distally to ensure that stapling head assembly (<NUM>) is fully seated at the distal end of tubular anatomical structure (<NUM>).

Next, anvil (<NUM>) is secured to trocar (<NUM>) by inserting trocar (<NUM>) into bore (<NUM>) as shown in <FIG>. Latch members (<NUM>) of anvil (<NUM>) engage head (<NUM>) of trocar (<NUM>), thereby providing a secure fit between anvil (<NUM>) and trocar (<NUM>). The operator then rotates knob (<NUM>) while holding casing (<NUM>) stationary via pistol grip (<NUM>). This rotation of knob (<NUM>) causes trocar (<NUM>) and anvil (<NUM>) to retract proximally. As shown in <FIG>, this proximal retraction of trocar (<NUM>) and anvil (<NUM>) compresses the tissue of tubular anatomical structures (<NUM>, <NUM>) between surfaces (<NUM>, <NUM>) of anvil (<NUM>) and stapling head assembly (<NUM>). As this occurs, the operator may observe the tactile resistance or feedback via knob (<NUM>) while turning knob (<NUM>), with such tactile resistance or feedback indicating that the tissue is being compressed. As the tissue is being compressed, the operator may visually observe the position of an indicator needle (not shown) within user interface feature (<NUM>) of handle assembly (<NUM>) to determine whether the gap distance (d) between opposing surfaces (<NUM>, <NUM>) of anvil (<NUM>) and stapling head assembly (<NUM>) is appropriate; and make any necessary adjustments via knob (<NUM>).

Once the operator has appropriately set the gap distance (d) via knob (<NUM>), the operator pivots safety trigger (<NUM>) toward pistol grip (<NUM>) to enable actuation of firing trigger (<NUM>). The operator then pivots firing trigger (<NUM>) toward pistol grip (<NUM>), thus causing firing trigger (<NUM>) to actuate the switch of motor activation module (<NUM>) and thereby activate motor (<NUM>) to rotate. This rotation of motor (<NUM>) causes actuation (or "firing") of stapling head assembly (<NUM>) by actuating drive bracket (<NUM>) distally to thereby drive knife member (<NUM>) and staple driver member (<NUM>) distally together, as shown in <FIG>.

As knife member (<NUM>) translates distally, cutting edge (<NUM>) of knife member (<NUM>) cuts excess tissue that is positioned within annular recess (<NUM>) of anvil (<NUM>) and the interior of knife member (<NUM>). Additionally, washer (<NUM>) positioned within annular recess (<NUM>) of anvil (<NUM>) is broken by knife member (<NUM>) when the knife member (<NUM>) completes a full distal range of motion from the position shown in <FIG> to the position shown in <FIG>. It should be understood that washer (<NUM>) may also serve as a cutting board for knife member (<NUM>) to assist in cutting of tissue.

As staple driver member (<NUM>) translates distally from the position shown in <FIG> to the position shown in <FIG>, staple driver member (<NUM>) drives staples (<NUM>) through the tissue of tubular anatomical structures (<NUM>, <NUM>) and into staple forming pockets (<NUM>) of anvil (<NUM>). Staple forming pockets (<NUM>) deform the driven staples (<NUM>) into a "B" shape or a three-dimensional shape, for example, such that the formed staples (<NUM>) secure the ends of tissue together, thereby coupling tubular anatomical structure (<NUM>) with tubular anatomical structure (<NUM>).

After the operator has actuated (or "fired") stapling head assembly (<NUM>) as shown in <FIG>, the operator rotates knob (<NUM>) to drive anvil (<NUM>) distally away from stapling head assembly (<NUM>), thereby increasing the gap distance (d) to facilitate release of the tissue between surfaces (<NUM>, <NUM>). The operator then removes instrument (<NUM>) from the patient, with anvil (<NUM>) still secured to trocar (<NUM>). With instrument (<NUM>) removed, the tubular anatomical structures (<NUM>, <NUM>) are left secured together by two annular arrays of staples (<NUM>) at an anastomosis (<NUM>) as shown in <FIG>. The inner diameter of the anastomosis (<NUM>) is defined by the severed edge (<NUM>) left by knife member (<NUM>).

As described above, stapling head assembly (<NUM>) is coupled to a distal end of shaft assembly (<NUM>). More particularly, body member (<NUM>) of stapling head assembly (<NUM>) is fixedly secured to outer sheath (<NUM>) of shaft assembly (<NUM>). It will be appreciated that body member (<NUM>) may be fixedly secured to outer sheath (<NUM>) via any suitable coupling technique to inhibit relative rotational and axial movement between body member (<NUM>) and outer sheath (<NUM>) and thereby inhibit inadvertent malfunctioning and/or detachment of stapling head assembly (<NUM>) from shaft assembly (<NUM>). For example, body member (<NUM>) may be fixedly secured to outer sheath (<NUM>) via magneforming (also referred to as "electromagnetic forming" or "EM forming"), such as by inducing a current in outer sheath (<NUM>) using pulsed electromagnetic fields to thereby reshape a distal end of outer sheath (<NUM>) into secure engagement with body member (<NUM>). In some instances, it may be desirable to fixedly secure body member (<NUM>) to outer sheath (<NUM>) via a different coupling technique other than magneforming, such as to reduce or eliminate the need for pulsed electromagnetic fields, for example. Each of the coupling features described below provides such functionality.

<FIG> show a portion of an exemplary circular surgical stapling instrument (<NUM>) that may be used to form anastomosis (<NUM>), and including a handle assembly (not shown), such as handle assembly (<NUM>), a shaft assembly (<NUM>) extending distally from the handle assembly, a stapling head assembly (<NUM>) at a distal end of shaft assembly (<NUM>), and an anvil (not shown), such as anvil (<NUM>), configured to releasably couple and cooperate with stapling head assembly (<NUM>) to clamp, staple, and cut tissue. Shaft assembly (<NUM>) and stapling head assembly (<NUM>) are similar to shaft assembly (<NUM>) and stapling head assembly (<NUM>) described above, respectively, except as otherwise described below. In this regard, stapling head assembly (<NUM>) of this example is coupled to a distal end of shaft assembly (<NUM>) and includes a tubular body member (<NUM>) and a staple driver member (not shown), such as staple driver member (<NUM>), slidably housed therein, and shaft assembly (<NUM>) of this example includes an outer sheath (<NUM>) that extends between the handle assembly and body member (<NUM>) along a longitudinal axis (L).

Body member (<NUM>) of stapling head assembly (<NUM>) includes a proximal expandable collar (<NUM>) defined by a plurality of circumferentially-arranged flexible tabs (<NUM>) having respective proximal free ends (<NUM>). As shown, flexible tabs (<NUM>) are spaced apart from each other by respective longitudinal slots (524a, 524b). Slots (524a, 524b) of the present version include a plurality of first slots (524a) having a uniform first width, and a single second slot (524b) having a second width greater than the first width, for reasons described below. In any event, each flexible tab (<NUM>) may be integrally formed with a distal remainder of body member (<NUM>) and cantilevered relative thereto, such that each flexible tab (<NUM>) is configured to flex radially outwardly from an unflexed state (<FIG>, <FIG>) to a flexed state (<FIG>), and is resiliently biased radially inwardly toward the unflexed state. In some versions, body member (<NUM>) and, more particularly, collar (<NUM>), may be constructed of a plastic material. It will be appreciated that a radially unexpanded state of collar (<NUM>) may be defined by each flexible tab (<NUM>) being in the respective unflexed state, and that a radially expanded state of collar (<NUM>) may be defined by each flexible tab (<NUM>) being in the respective flexed state. The integrally formed, cantilevered configurations of flexible tabs (<NUM>) relative to the distal remainder of body member (<NUM>) may assist in maintaining flexible tabs (<NUM>) in their unflexed states in the absence of external forces acting upon flexible tabs (<NUM>).

Collar (<NUM>) of the present version also includes a plurality of latching features in the form of an annular array of internal arcuate grooves (<NUM>) extending radially outwardly from radially inner surfaces of respective flexible tabs (<NUM>). Internal arcuate grooves (<NUM>) are aligned with each other in the circumferential direction to collectively define a generally annular internal recessed area. Collar (<NUM>) further includes a plurality of retention features in the form of an annular array of external arcuate grooves (<NUM>) extending radially inwardly from radially outer surfaces of respective flexible tabs (<NUM>). External arcuate grooves (<NUM>) are aligned with each other in the circumferential direction to collectively define a generally annular external recessed area. As shown, external arcuate grooves (<NUM>) are positioned on a proximal collar portion (<NUM>) that is disposed proximally relative to internal arcuate grooves (<NUM>). It will be appreciated that collar (<NUM>) and flexible tabs (<NUM>) may be configured and/or arranged in any other suitable manner(s), such as any of those describe below.

In the example shown, outer sheath (<NUM>) of shaft assembly (<NUM>) includes a relatively wide proximal sheath portion (<NUM>) and a relatively narrow distal sheath portion (<NUM>) such that an annular shoulder (<NUM>) is defined therebetween. In this regard, proximal sheath portion (<NUM>) may have a first external diameter substantially greater than an internal diameter of collar (<NUM>) to inhibit proximal sheath portion (<NUM>) from being received within collar (<NUM>), while distal sheath portion (<NUM>) may have a second external diameter substantially equal to or slightly less than the internal diameter of collar (<NUM>) to permit distal sheath portion (<NUM>) to be slidably received within collar (<NUM>). In the example shown, annular shoulder (<NUM>) is oriented substantially orthogonally relative to longitudinal axis (L).

Outer sheath (<NUM>) also includes a protrusion in the form of an annular ridge (<NUM>) extending radially outwardly from a radially outer surface of distal sheath portion (<NUM>) and spaced apart from shoulder (<NUM>) by an external annular channel (<NUM>). Annular ridge (<NUM>) extends circumferentially about distal sheath portion (<NUM>) and has a diameter greater than the internal diameter of collar (<NUM>) for urging flexible tabs (<NUM>) radially outwardly toward the respective flexed states. For example, the diameter of annular ridge (<NUM>) may be substantially equal to or slightly less than that of the generally annular internal recessed area defined by internal arcuate grooves (<NUM>) of collar (<NUM>) to permit annular ridge (<NUM>) to be received within internal arcuate grooves (<NUM>) with a snap-fit engagement. In the example shown, external annular channel (<NUM>) is also sized to receive proximal collar portion (<NUM>) with a snap-fit engagement. Annular ridge (<NUM>) of the present version includes a proximal abutment surface (<NUM>) oriented substantially orthogonally relative to longitudinal axis (L) and a distal cam surface (<NUM>) tapered radially outwardly in the proximal direction.

As shown, outer sheath (<NUM>) further includes a longitudinal key (<NUM>) extending radially outwardly from the radially outer surface of distal sheath portion (<NUM>) and intersecting annular ridge (<NUM>). Key (<NUM>) may have a width substantially equal to or slightly less than the second width of second slot (524b) and greater than the first width of first slots (524a), such that key (<NUM>) is configured to be slidably received within second slot (524b) but is not configured to be slidably received within first slots (524a). In this manner, second slot (524b) may define a keyway for receiving key (<NUM>) when shaft assembly (<NUM>) and stapling head assembly (<NUM>) are angularly oriented relative to each other about longitudinal axis (L) in a predetermined manner. Second slot (524b) and key (<NUM>) may thereby cooperate with each other to promote proper angular alignment between shaft assembly (<NUM>) and stapling head assembly (<NUM>) during coupling of stapling head assembly (<NUM>) to shaft assembly (<NUM>) and/or to assist in maintaining such proper angular alignment after stapling head assembly (<NUM>) has been coupled to shaft assembly (<NUM>).

Referring now to <FIG>, stapling head assembly (<NUM>) may be coupled to a distal end of shaft assembly (<NUM>) by angularly aligning stapling head assembly (<NUM>) with shaft assembly (<NUM>) and initially advancing collar (<NUM>) proximally over distal sheath portion (<NUM>) such that distal sheath portion (<NUM>) is slidably received within collar (<NUM>) with key (<NUM>) slidably received within second slot (524b), as shown in <FIG>. During such initial proximal advancement of collar (<NUM>), proximal free ends (<NUM>) of flexible tabs (<NUM>) may be distal of annular ridge (<NUM>) thereby permitting flexible tabs (<NUM>) to each remain in the respective unflexed state such that collar (<NUM>) may be in the radially unexpanded state.

Collar (<NUM>) may then continue to be advanced proximally over distal sheath portion (<NUM>), as indicated by arrow (A1) in <FIG>, to engage distal cam surface (<NUM>) of annular ridge (<NUM>) with proximal free ends (<NUM>) of flexible tabs (<NUM>). More particularly, distal cam surface (<NUM>) of annular ridge (<NUM>) may urge flexible tabs (<NUM>) radially outwardly toward the respective flexed states such that collar (<NUM>) may be transitioned toward the radially expanded state to permit proximal advancement of collar (<NUM>) over annular ridge (<NUM>), as indicated by arrows (A2, A3) in <FIG>.

As proximal advancement of collar (<NUM>) continues, as indicated by arrow (A4) in <FIG>, proximal free ends (<NUM>) of flexible tabs (<NUM>) may be disengaged from distal cam surface (<NUM>) of annular ridge (<NUM>), and internal arcuate grooves (<NUM>) and proximal collar portion (<NUM>) may become radially aligned with annular ridge (<NUM>) and external annular channel (<NUM>), respectively, thereby permitting flexible tabs (<NUM>) to resiliently return to their respective unflexed states such that collar (<NUM>) may return to the radially unexpanded state. In this regard, annular ridge (<NUM>) may be securely received within internal arcuate grooves (<NUM>) to provide a snap-fit engagement therebetween, and proximal collar portion (<NUM>) may be securely received within external annular channel (<NUM>) to provide a snap-fit engagement therebetween. For example, proximal collar portion (<NUM>) may be captured between shoulder (<NUM>) and abutment surface (<NUM>) with internal arcuate grooves (<NUM>) latched against abutment surface (<NUM>) to inhibit further relative movement between stapling head assembly (<NUM>) and shaft assembly (<NUM>) along longitudinal axis (L). In some versions, the radial alignment of proximal collar portion (<NUM>) with external annular channel (<NUM>) may coincide with a hard stop between proximal free ends (<NUM>) of flexible tabs (<NUM>) and shoulder (<NUM>). In any event, second slot (524b) and key (<NUM>) may cooperate with each other to inhibit relative rotation between stapling head assembly (<NUM>) and shaft assembly (<NUM>) about longitudinal axis (L).

In the example shown, a crimp ring (<NUM>) is positioned within external arcuate grooves (<NUM>) after annular ridge (<NUM>) and proximal collar portion (<NUM>) have been securely received within internal arcuate grooves (<NUM>) and external annular channel (<NUM>), respectively, in order to lock flexible tabs (<NUM>) in their respective unflexed states such that collar (<NUM>) may be securely maintained in the radially unexpanded state. In this manner, crimp ring (<NUM>) may assist with inhibiting further relative movement between stapling head assembly (<NUM>) and shaft assembly (<NUM>) along longitudinal axis (L) by preventing flexible tabs (<NUM>) from being urged radially outwardly, thereby preventing collar (<NUM>) from being distally retracted over annular ridge (<NUM>) or proximally advanced over shoulder (<NUM>). Crimp ring (<NUM>) of the present version is radially aligned with external annular channel (<NUM>) to clamp proximal free ends (<NUM>) of flexible tabs (<NUM>) within external annular channel (<NUM>). Crimp ring (<NUM>) may be tightly secured within external arcuate grooves (<NUM>) via crimping or any other suitable technique. In this regard, crimp ring (<NUM>) may be constructed of a ductile material, such as a metallic material.

Thus, stapling head assembly (<NUM>) and shaft assembly (<NUM>) may be securely and reliably coupled to each other in the manner set forth above, and may subsequently be used to perform an anastomosis procedure.

<FIG> show a portion of another exemplary circular surgical stapling instrument (<NUM>) that may be used to form anastomosis (<NUM>), and including a handle assembly (not shown), such as handle assembly (<NUM>), a shaft assembly (<NUM>) extending distally from the handle assembly, a stapling head assembly (<NUM>) at a distal end of shaft assembly (<NUM>), and an anvil (not shown), such as anvil (<NUM>), configured to releasably couple and cooperate with stapling head assembly (<NUM>) to clamp, staple, and cut tissue. Shaft assembly (<NUM>) and stapling head assembly (<NUM>) are similar to shaft assembly (<NUM>) and stapling head assembly (<NUM>) described above, respectively, except as otherwise described below. In this regard, stapling head assembly (<NUM>) of this example is coupled to a distal end of shaft assembly (<NUM>) and includes a tubular body member (<NUM>) and a staple driver member (not shown), such as staple driver member (<NUM>), slidably housed therein, and shaft assembly (<NUM>) of this example includes an outer sheath (<NUM>) that extends between the handle assembly and body member (<NUM>) along a longitudinal axis (not shown).

Body member (<NUM>) of stapling head assembly (<NUM>) includes a proximal expandable collar (<NUM>) defined by a plurality of circumferentially-arranged flexible tabs (<NUM>) having respective proximal free ends (<NUM>). As shown, flexible tabs (<NUM>) are spaced apart from each other by respective longitudinal slots (624a, 624b). Slots (624a, 624b) of the present version include a plurality of first slots (624a) having a uniform first width, and a single second slot (624b) having a second width greater than the first width, for reasons described below. In any event, each flexible tab (<NUM>) may be integrally formed with a distal remainder of body member (<NUM>) and cantilevered relative thereto, such that each flexible tab (<NUM>) is configured to flex radially outwardly from the illustrated unflexed state to a flexed state (not shown), and is resiliently biased radially inwardly toward the unflexed state. In some versions, body member (<NUM>) and, more particularly, collar (<NUM>), may be constructed of a plastic material. It will be appreciated that a radially unexpanded state of collar (<NUM>) may be defined by each flexible tab (<NUM>) being in the respective unflexed state, and that a radially expanded state of collar (<NUM>) may be defined by each flexible tab (<NUM>) being in the respective flexed state. The integrally formed, cantilevered configurations of flexible tabs (<NUM>) relative to the distal remainder of body member (<NUM>) may assist in maintaining flexible tabs (<NUM>) in their unflexed states in the absence of external forces acting upon flexible tabs (<NUM>).

Collar (<NUM>) of the present version also includes a plurality of latching features in the form of an annular array of apertures (<NUM>) extending radially through respective flexible tabs (<NUM>). Collar (<NUM>) further includes a plurality of retention features in the form of an annular array of external arcuate grooves (<NUM>) extending radially inwardly from radially outer surfaces of respective flexible tabs (<NUM>). External arcuate grooves (<NUM>) are aligned with each other in the circumferential direction to collectively define a generally annular external recessed area. As shown, external arcuate grooves (<NUM>) are positioned on a proximal collar portion (<NUM>) that is disposed proximally relative to apertures (<NUM>). It will be appreciated that collar (<NUM>) and flexible tabs (<NUM>) may be configured and/or arranged in any other suitable manner(s), such as any of those describe below.

In the example shown, outer sheath (<NUM>) of shaft assembly (<NUM>) includes a relatively wide proximal sheath portion (<NUM>) and a relatively narrow distal sheath portion (<NUM>) such that an annular shoulder (<NUM>) is defined therebetween. In this regard, proximal sheath portion (<NUM>) may have a first external diameter substantially greater than an internal diameter of collar (<NUM>) to inhibit proximal sheath portion (<NUM>) from being received within collar (<NUM>), while distal sheath portion (<NUM>) may have a second external diameter substantially equal to or slightly less than the internal diameter of collar (<NUM>) to permit distal sheath portion (<NUM>) to be slidably received within collar (<NUM>). In the example shown, annular shoulder (<NUM>) is oriented substantially orthogonally relative to the longitudinal axis.

Outer sheath (<NUM>) also includes a plurality of protrusions in the form of an annular array of detents (<NUM>) extending radially outwardly from a radially outer surface of distal sheath portion (<NUM>) for radial alignment with corresponding apertures (<NUM>) of collar (<NUM>), and spaced apart from shoulder (<NUM>) by an external, generally annular channel (<NUM>). Annular detents (<NUM>) are arranged circumferentially about distal sheath portion (<NUM>) and collectively have a diameter greater than the internal diameter of collar (<NUM>) for urging corresponding flexible tabs (<NUM>) radially outwardly toward the respective flexed states. Moreover, each detent (<NUM>) may have length and width dimensions substantially equal to or slightly less than those of apertures (<NUM>) of collar (<NUM>) to permit detents (<NUM>) to be received within corresponding apertures (<NUM>) with a snap-fit engagement. In the example shown, external annular channel (<NUM>) is also sized to receive proximal collar portion (<NUM>) with a snap-fit engagement. Each detent (<NUM>) of the present version includes a proximal abutment surface (<NUM>) oriented substantially orthogonally relative to the longitudinal axis and a distal cam surface (<NUM>) tapered radially outwardly in the proximal direction.

As shown, outer sheath (<NUM>) further includes a longitudinal key (<NUM>) extending radially outwardly from the radially outer surface of distal sheath portion (<NUM>). Key (<NUM>) may have a width substantially equal to or slightly less than the second width of second slot (624b) and greater than the first width of first slots (624a), such that key (<NUM>) is configured to be slidably received within second slot (624b) but is not configured to be slidably received within first slots (624a). In this manner, second slot (624b) may define a keyway for receiving key (<NUM>) when shaft assembly (<NUM>) and stapling head assembly (<NUM>) are angularly oriented relative to each other about the longitudinal axis in a predetermined manner. Second slot (624b) and key (<NUM>) may thereby cooperate with each other to promote proper angular alignment between shaft assembly (<NUM>) and stapling head assembly (<NUM>) during coupling of stapling head assembly (<NUM>) to shaft assembly (<NUM>) and/or to assist in maintaining such proper angular alignment after stapling head assembly (<NUM>) has been coupled to shaft assembly (<NUM>).

With continuing reference to <FIG>, stapling head assembly (<NUM>) may be coupled to a distal end of shaft assembly (<NUM>) by angularly aligning stapling head assembly (<NUM>) with shaft assembly (<NUM>) and initially advancing collar (<NUM>) proximally over distal sheath portion (<NUM>) such that distal sheath portion (<NUM>) is slidably received within collar (<NUM>) with key (<NUM>) slidably received within second slot (624b), as shown in <FIG>. During such initial proximal advancement of collar (<NUM>), proximal free ends (<NUM>) of flexible tabs (<NUM>) may be distal of detents (<NUM>) thereby permitting flexible tabs (<NUM>) to each remain in the respective unflexed state such that collar (<NUM>) may be in the radially unexpanded state.

Collar (<NUM>) may then continue to be advanced proximally over distal sheath portion (<NUM>) to engage distal cam surfaces (<NUM>) of detents (<NUM>) with proximal free ends (<NUM>) of corresponding flexible tabs (<NUM>), in a manner similar to that described above in connection with <FIG>. More particularly, distal cam surfaces (<NUM>) of detents (<NUM>) may urge the corresponding flexible tabs (<NUM>) radially outwardly toward the respective flexed states such that collar (<NUM>) may be transitioned toward the radially expanded state to permit proximal advancement of collar (<NUM>) over detents (<NUM>).

As proximal advancement of collar (<NUM>) continues, as indicated by arrow (A5) in <FIG>, proximal free ends (<NUM>) of flexible tabs (<NUM>) may be disengaged from distal cam surfaces (<NUM>) of detents (<NUM>), and apertures (<NUM>) and proximal collar portion (<NUM>) may become radially aligned with detents (<NUM>) and external annular channel (<NUM>), respectively, thereby permitting flexible tabs (<NUM>) to resiliently return to their respective unflexed states such that collar (<NUM>) may return to the radially unexpanded state, as shown in <FIG>. In this regard, detents (<NUM>) may be securely received within corresponding apertures (<NUM>) to provide a snap-fit engagement therebetween, and proximal collar portion (<NUM>) may be securely received within external annular channel (<NUM>) to provide a snap-fit engagement therebetween. For example, proximal collar portion (<NUM>) may be captured between shoulder (<NUM>) and abutment surfaces (<NUM>) with apertures (<NUM>) latched against abutment surfaces (<NUM>) to inhibit further relative movement between stapling head assembly (<NUM>) and shaft assembly (<NUM>) along the longitudinal axis. In some versions, the radial alignment of proximal collar portion (<NUM>) with external annular channel (<NUM>) may coincide with a hard stop between proximal free ends (<NUM>) of flexible tabs (<NUM>) and shoulder (<NUM>). In any event, second slot (624b) and key (<NUM>) may cooperate with each other to inhibit relative rotation between stapling head assembly (<NUM>) and shaft assembly (<NUM>) about the longitudinal axis.

In the example shown, a crimp ring (<NUM>) is positioned within external arcuate grooves (<NUM>) after detents (<NUM>) and proximal collar portion (<NUM>) have been securely received within apertures (<NUM>) and external annular channel (<NUM>), respectively, in order to lock flexible tabs (<NUM>) in their respective unflexed states such that collar (<NUM>) may be securely maintained in the radially unexpanded state. In this manner, crimp ring (<NUM>) may assist with inhibiting further relative movement between stapling head assembly (<NUM>) and shaft assembly (<NUM>) along the longitudinal axis by preventing flexible tabs (<NUM>) from being urged radially outwardly, thereby preventing collar (<NUM>) from being distally retracted over detents (<NUM>) or proximally advanced over shoulder (<NUM>). Crimp ring (<NUM>) of the present version is radially aligned with external annular channel (<NUM>) to clamp proximal free ends (<NUM>) of flexible tabs (<NUM>) within external annular channel (<NUM>). Crimp ring (<NUM>) may be tightly secured within external arcuate grooves (<NUM>) via crimping or any other suitable technique. In this regard, crimp ring (<NUM>) may be constructed of a ductile material, such as a metallic material.

Some versions of the devices described above may have application in conventional medical treatments and procedures conducted by a medical professional, as well as application in robotic-assisted medical treatments and procedures.

Some versions of the devices described above may be designed to be disposed of after a single use, or they can be designed to be used multiple times. They may, in either or both cases, be reconditioned for reuse after at least one use.

Claim 1:
A surgical stapling instrument (<NUM>, <NUM>), comprising:
(a) a body member (<NUM>, <NUM>) having a distal end, wherein the distal end is configured to be fixedly secured to an annular deck member (<NUM>) having a plurality of staple openings (<NUM>), wherein the body member (<NUM>, <NUM>) is configured to slidably house a staple driver member (<NUM>), wherein the body member (<NUM>, <NUM>) includes a collar (<NUM>, <NUM>) having at least one latching feature (<NUM>, <NUM>); and
(b) a shaft assembly (<NUM>, <NUM>), comprising:
(i) a proximal sheath portion (<NUM>, <NUM>),
(ii) a distal sheath portion (<NUM>, <NUM>), and
(iii) at least one protrusion (<NUM>, <NUM>) extending radially outwardly from the distal sheath portion (<NUM>, <NUM>), wherein the at least one protrusion (<NUM>, <NUM>) includes at least one abutment surface (<NUM>, <NUM>) configured to engage the at least one latching feature (<NUM>, <NUM>) of the collar (<NUM>, <NUM>);
characterized in that
the collar (<NUM>, <NUM>) is defined by a plurality of circumferentially-arranged flexible tabs (<NUM>, <NUM>) configured to flex radially outwardly and spaced apart from each other by a plurality of longitudinal slots (524a, 524b, 624a, 624b), and the latching feature (<NUM>, <NUM>) is defined on the flexible tabs (<NUM>, <NUM>) and configured to be engaged by the at least one protrusion (<NUM>, <NUM>) to mechanically couple the body member (<NUM>, <NUM>) to the shaft assembly (<NUM>, <NUM>).