Patent Description:
One example of an instrument that may be used to provide an anastomosis is a circular stapler. Some such staplers are operable to clamp down on layers of tissue, cut through the clamped layers of tissue, and drive staples through the clamped layers of tissue to substantially seal the layers of tissue together near the severed ends of the tissue layers, thereby joining the two severed ends of the anatomical lumen together. The circular stapler may be configured to sever the tissue and seal the tissue substantially simultaneously. For instance, the circular stapler may sever excess tissue that is interior to an annular array of staples at an anastomosis, to provide a substantially smooth transition between the anatomical lumen sections that are joined at the anastomosis. Circular staplers may be used in open procedures or in endoscopic procedures. In some instances, a portion of the circular stapler is inserted through a patient's naturally occurring orifice.

Examples of circular staplers are described in <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>; and <CIT>.

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

<CIT> discloses a method of manufacturing an anvil assembly that includes injection molding an anvil base, the anvil base having a tissue contact surface having a plurality of annular rows of staple deforming pockets.

For clarity of disclosure, the terms "proximal" and "distal" are defined herein relative to a human or robotic operator of the surgical instrument. The term "proximal" refers the position of an element closer to the human or robotic operator of the surgical instrument and further away from the surgical end effector of the surgical instrument. The term "distal" refers to the position of an element closer to the surgical end effector of the surgical instrument and further away from the human or robotic operator of the surgical instrument. In addition, the terms "first" and "second" are used herein to distinguish one or more portions of the surgical instrument. For example, a first assembly and a second assembly may be alternatively and respectively described as a second assembly and a first assembly. The terms "first" and "second" and other numerical designations are merely exemplary of such terminology and are not intended to unnecessarily limit the invention described herein.

<FIG> depict an exemplary surgical circular 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 comprises a handle assembly (<NUM>), a shaft assembly (<NUM>), a stapling head assembly (<NUM>), and an anvil (<NUM>). Handle assembly (<NUM>) comprises a casing (<NUM>) defining an obliquely oriented pistol grip (<NUM>). In some versions, pistol grip (<NUM>) is perpendicularly oriented. In some other versions, pistol grip (<NUM>) is omitted. Handle assembly (<NUM>) further includes a user feedback feature (<NUM>) that permits viewing of a movable indicator needle (not shown) as will be described in greater detail below. In some versions, a series of hash marks, colored regions, and/or other fixed indicators are positioned adjacent to user feedback feature (<NUM>) in order to provide a visual context for indicator needle.

Instrument (<NUM>) includes a battery pack (<NUM>). Battery pack (<NUM>) is operable to provide electrical power to a motor (<NUM>) in pistol grip (<NUM>). In particular, as shown in <FIG>, battery pack (<NUM>) may be inserted into a socket (<NUM>) defined by casing (<NUM>). Once battery pack (<NUM>) is fully inserted in socket (<NUM>), latches (<NUM>) of battery pack (<NUM>) may resiliently engage interior features of casing (<NUM>) to provide a snap fit. It should be understood that battery pack (<NUM>) and handle assembly (<NUM>) may have complementary electrical contacts, pins and sockets, and/or other features that provide paths for electrical communication from battery pack (<NUM>) to electrically powered components in handle assembly (<NUM>) when battery pack (<NUM>) is inserted in socket (<NUM>). Shaft assembly (<NUM>) extends distally from handle assembly (<NUM>) and includes a preformed bend. In some versions, the preformed bend is configured to facilitate positioning of stapling head assembly (<NUM>) within a patient's colon. Various suitable bend angles or radii that may be used will be apparent to those of ordinary skill in the art in view of the teachings herein.

Stapling head assembly (<NUM>) is located at the distal end of shaft assembly (<NUM>). As shown in <FIG>, anvil (<NUM>) is configured to removably couple with shaft assembly (<NUM>), adjacent to stapling head assembly (<NUM>). 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 knob (<NUM>) at the proximal end of handle assembly (<NUM>) is rotatable relative to casing (<NUM>) 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 tissue.

As shown in <FIG>, anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>). Head (<NUM>) includes a proximal surface (<NUM>) that defines an annular array of staple forming pockets (<NUM>). Staple forming pockets (<NUM>) are arranged in two concentric annular arrays in the present example. In some other versions, staple forming pockets (<NUM>) are arranged in three or more concentric annular arrays. Staple forming pockets (<NUM>) are configured to deform staples as the staples are driven into staple forming pockets (<NUM>). For instance, each staple forming pocket (<NUM>) may deform a generally "U" shaped staple into a "B" shape as is known in the art. As best seen in <FIG>, proximal surface (<NUM>) terminates at an inner edge (<NUM>), which defines an outer boundary of an annular recess (<NUM>) surrounding shank (<NUM>).

Shank (<NUM>) defines a bore (<NUM>) and includes a pair of pivoting latch members (<NUM>) positioned in bore (<NUM>). As best seen in <FIG>, each latch member (<NUM>) includes a "T" shaped distal end (<NUM>), a rounded proximal end (<NUM>), and a latch shelf (<NUM>) located distal to proximal end (<NUM>). "T" shaped distal ends (<NUM>) secure latch members (<NUM>) within bore (<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>). Lateral openings (<NUM>) thus provide clearance for distal ends (<NUM>) and latch shelves (<NUM>) to deflect radially outwardly from the longitudinal axis defined by shank (<NUM>). However, latch members (<NUM>) are configured to resiliently bias distal ends (<NUM>) and latch shelves (<NUM>) to pivot radially inwardly toward the longitudinal axis defined by shank (<NUM>). Latch members (<NUM>) thus act as retaining clips. This allows anvil (<NUM>) to be removably secured to a trocar (<NUM>) of stapling head assembly (<NUM>) as will be described in greater detail below. When shank (<NUM>) is secured to trocar (<NUM>) and trocar (<NUM>) is retracted proximally, the inner diameter of bore (<NUM>) in inner core member (<NUM>) of body member (<NUM>) laterally constrains latch members (<NUM>) to maintain engagement between latch shelves (<NUM>) and proximal surface (<NUM>) of head (<NUM>) of trocar (<NUM>). This engagement prevents anvil (<NUM>) from being released from trocar (<NUM>) during firing of stapling head assembly (<NUM>). It should be understood, however, that latch members (<NUM>) are merely optional. Anvil (<NUM>) may be removably secured to a trocar (<NUM>) using any other suitable components, features, or techniques. As shown in <FIG>, anvil (<NUM>) of the present example includes a breakable washer (<NUM>) within annular recess (<NUM>). This washer (<NUM>) is broken by knife member (<NUM>) when the knife member (<NUM>) completes a full distal range of motion.

As shown in <FIG>, shank (<NUM>) of the present example includes a set of longitudinally extending splines (<NUM>) that are spaced about shank (<NUM>) in an angular array. The proximal end of each spline (<NUM>) includes a respective lead-in edge (<NUM>). As described in greater detail below, splines (<NUM>) are configured to engage corresponding splines (<NUM>) of an inner body member (<NUM>) of stapling head assembly (<NUM>) in order to consistently provide a predetermined angular alignment between anvil (<NUM>) and stapling head assembly (<NUM>). As also described below, this angular alignment may ensure that staple forming pockets (<NUM>) of anvil (<NUM>) are consistently angularly aligned appropriately with staple openings (<NUM>) of stapling head assembly (<NUM>). Thus, in the present example, splines (<NUM>) are precisely and consistently positioned in relation to staple forming pockets (<NUM>). In versions where head (<NUM>) and shank (<NUM>) are initially formed as separate pieces and then later joined together, the machine or other device that is used to join head (<NUM>) and shank (<NUM>) together may have appropriate indexing capabilities in order to reliably and consistently achieve the proper angular positioning of head (<NUM>) and shank (<NUM>) to thereby provide precise and consistent positioning of splines (<NUM>) in relation to staple forming pockets (<NUM>). Various suitable ways in which such results may be achieved will be apparent to those of ordinary skill in the art in view of the teachings herein. In some other versions, head (<NUM>) and shank (<NUM>) are formed together simultaneously, as a single unitary construction.

As best seen in <FIG>, stapling head assembly (<NUM>) of the present example is coupled to a distal end of shaft assembly (<NUM>) and comprises a body member (<NUM>) and a slidable staple driver member (not shown). Body member (<NUM>) includes a distally extending cylindraceous inner core member (<NUM>). Body member (<NUM>) is fixedly secured to an outer sheath (<NUM>) of shaft assembly (<NUM>). Body member (<NUM>) and outer sheath (<NUM>) thus serve together as a mechanical ground for stapling head assembly (<NUM>).

As shown in <FIG>, inner core member (<NUM>) of body member (<NUM>) defines a bore (<NUM>). A plurality of longitudinally extending splines (<NUM>) are equidistantly spaced in an angular array within bore (<NUM>). The distal ends of splines (<NUM>) include lead-in edges (<NUM>) that are configured to complement lead-in edges (<NUM>) of splines (<NUM>) on shank (<NUM>) of anvil (<NUM>). In particular, after shank (<NUM>) is secured to trocar (<NUM>) as described in greater detail below, and as anvil (<NUM>) is thereafter retracted proximally relative to stapling head assembly (<NUM>) as also described in greater detail below, lead-in edges (<NUM>, <NUM>) may cooperatively engage each other to drive anvil (<NUM>) to rotate relative to trocar (<NUM>) to angularly align splines (<NUM>) of anvil (<NUM>) with the gaps between splines (<NUM>) of body member (<NUM>). The gaps between splines (<NUM>) may be configured to have a width that is substantially equal to the width of splines (<NUM>). In this manner, when splines (<NUM>) of anvil (<NUM>) are positioned within the gaps between splines (<NUM>) of body member (<NUM>), anvil (<NUM>) may achieve a predetermined angular alignment relative to stapling head assembly (<NUM>). This predetermined angular alignment may ensure that staple openings (<NUM>) of deck member (<NUM>) are precisely aligned with corresponding staple forming pockets (<NUM>) of anvil (<NUM>). Thus, splines (<NUM>, <NUM>) are configured to cooperate with each other to ensure that staples ejected through staple openings (<NUM>) are accurately driven into corresponding staple forming pockets (<NUM>, <NUM>, <NUM>) on a consistent basis, regardless of the angular orientation of anvil (<NUM>) relative to stapling head assembly (<NUM>) at the time anvil (<NUM>) is initially secured to trocar (<NUM>).

Trocar (<NUM>) is positioned coaxially within inner core member (<NUM>) of body member (<NUM>). Trocar (<NUM>) includes a colored region (<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 an inwardly extending proximal surface (<NUM>). Shaft (<NUM>) thus provides a reduced outer diameter just proximal to head (<NUM>), with surface (<NUM>) providing a transition between that reduced outer diameter of shaft (<NUM>) and the outer diameter of head (<NUM>). While tip (<NUM>) is pointed in the present example, tip (<NUM>) is not sharp. Tip (<NUM>) will thus not easily cause trauma to tissue due to inadvertent contact with tissue. Head (<NUM>) and the distal portion of shaft (<NUM>) are configured for insertion in 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 due to latch members (<NUM>). Knife member (<NUM>) includes a distally presented, sharp circular cutting edge (<NUM>). Knife member (<NUM>) also defines an opening that is configured to coaxially receive core member (<NUM>) of body member (<NUM>).

A deck member (<NUM>) is fixedly secured to body member (<NUM>). Deck member (<NUM>) includes a distally presented deck surface (<NUM>) defining two concentric annular arrays of staple openings (<NUM>). Staple openings (<NUM>) are arranged to correspond with the arrangement of staple drivers and staple forming pockets (<NUM>) described above. Thus, each staple opening (<NUM>) is configured to provide a path for a corresponding staple driver to drive a corresponding staple through deck member (<NUM>) and into a corresponding staple forming pocket (<NUM>) when stapling head assembly (<NUM>) is actuated. It should be understood that the arrangement of staple openings (<NUM>) may be modified just like the arrangement of staple forming pockets (<NUM>) as described above. It should also be understood that various structures and techniques may be used to contain staples within stapling head assembly (<NUM>) before stapling head assembly (<NUM>) is actuated. Such structures and techniques that are used to contain staples within stapling head assembly (<NUM>) may prevent the staples from inadvertently falling out through staple openings (<NUM>) before stapling head assembly (<NUM>) is actuated. Various suitable forms that such structures and techniques may take will be apparent to those of ordinary skill in the art in view of the teachings herein. As best seen in <FIG>, deck member (<NUM>) 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 allow knife member (<NUM>) to translate distally to a point where cutting edge (<NUM>) is distal to deck surface (<NUM>).

As described above, anvil (<NUM>) of instrument (<NUM>) may be machined as a single unitary component or anvil (<NUM>) may be manufactured by initially forming head (<NUM>) and shank (<NUM>) as separate pieces and then later joining head (<NUM>) and shank (<NUM>) together. Because head (<NUM>) and shank (<NUM>) may be initially formed as separate pieces, it may be desirable to strengthen the coupling between head (<NUM>) and shank (<NUM>). Additionally, it may be desirable to make head (<NUM>) and shank (<NUM>) using different manufacturing processes and in a low-cost manner. Moreover, it may be desirable to refine certain portions and surfaces of head (<NUM>) and/or shank (<NUM>) to improve the operability anvil (<NUM>) with instrument (<NUM>). Therefore, it may therefore be desirable to manufacture exemplary anvils (<NUM>, <NUM>, <NUM>) that address these and other shortcomings, while also enabling anvils (<NUM>, <NUM>, <NUM>) to function interchangeably with anvil (<NUM>) described above with reference to <FIG>.

As will be described with reference to <FIG>, surgical instrument (<NUM>) includes anvil (<NUM>, <NUM>, <NUM>), that is intended to be used in place of anvil (<NUM>) described above with reference to <FIG>. As previously described, surgical instrument (<NUM>) includes a body (shown as handle assembly (<NUM>)), shaft assembly (<NUM>) extending distally from handle assembly (<NUM>), stapling head assembly (<NUM>), and anvil (<NUM>). Stapling head assembly (<NUM>) is positioned at a distal end of shaft assembly (<NUM>). Stapling head assembly (<NUM>) includes an anvil coupling feature (shown as trocar (<NUM>)), at least one annular array of staples, and the staple driver. As will be described in greater detail below and similar to the functionality of anvil (<NUM>), anvils (<NUM>, <NUM>, <NUM>) are each configured to couple with trocar (<NUM>) and each are configured to deform staples driven by the staple driver.

<FIG> show various perspective views of a first exemplary anvil (<NUM>) that may be incorporated into instrument (<NUM>) of <FIG>. Anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>). Shank (<NUM>) extends proximally from head (<NUM>) and is configured to be coupled with head (<NUM>) once formed. Head (<NUM>) includes a proximal surface (<NUM>) that defines an annular array of staple forming pockets (<NUM>) shown in <FIG>. As shown, staple forming pockets (<NUM>) are arranged in two concentric annular arrays, similar to those shown in <FIG>. Alternatively, staple forming pockets (514b) may be arranged in three or more concentric annular arrays, similar to those shown in <FIG>.

Staple forming pockets (<NUM>) are configured to deform the staples as the staples are driven into staple forming pockets (<NUM>). For instance, each staple forming pocket (<NUM>) may deform a generally "U" shaped staple into a "B" shape as is known in the art. As shown in <FIG> and <FIG>, proximal surface (<NUM>) of head (<NUM>) terminates at an inner edge (<NUM>), which defines an outer boundary of an annular recess (<NUM>) surrounding shank (<NUM>). As will be described in greater detail with reference to <FIG>, head (<NUM>), including staple forming pockets (<NUM>), may be formed using an injection molding process, such as a metal injection molding process. Metal injection molding (MIM) refers to any metalworking process where finely-powdered metal is mixed with a binder material to create a feedstock that is subsequently shaped and solidified using molding process (such as injection molding). Metal injection molding allows for high volume, complex parts to be shaped. Alternatively, head (<NUM>) may be formed from a polymeric material using an injection molding process. As will be described in greater detail with reference to <FIG>, at least a portion of at least one staple forming pocket (<NUM>) may be coined or electrochemically machined to improve one or more properties of staple forming pockets (<NUM>).

Shank (<NUM>) includes a longitudinally extending body (<NUM>) that defines a bore (<NUM>) and may include a pair of pivoting latch members (not shown) positioned in bore (<NUM>), that may be similar in structure and function to latch members (<NUM>) described above with reference to shank (<NUM>) of anvil (<NUM>). The latch members are positioned within bore (<NUM>) such that the distal ends are positioned at the proximal ends of lateral openings (<NUM>), which are formed through the sidewall of shank (<NUM>). Lateral openings (<NUM>) provide clearance for the latch member to deflect radially outwardly from the longitudinal axis defined by shank (<NUM>). The latch members allow anvil (<NUM>) to be removably secured to a trocar (<NUM>) of stapling head assembly (<NUM>). When shank (<NUM>) is secured to trocar (<NUM>) and trocar (<NUM>) is retracted proximally, the inner diameter of bore (<NUM>) in inner core member (<NUM>) of body member (<NUM>) laterally constrains the latch members to maintain engagement with proximal surface (<NUM>) of head (<NUM>) of trocar (<NUM>). This engagement prevents anvil (<NUM>) from being released from trocar (<NUM>) during firing of stapling head assembly (<NUM>). The latch members may be omitted, such that anvil (<NUM>) may be removably secured to a trocar (<NUM>) using any other suitable components, features, or techniques.

As shown in <FIG>, shank (<NUM>) includes a set of longitudinally extending splines (<NUM>) that are spaced about shank (<NUM>) in an angular array. The proximal end of each spline (<NUM>) includes a respective lead-in edge (<NUM>). Splines (<NUM>) are configured to engage corresponding splines (<NUM>) of an inner body member (<NUM>) of stapling head assembly (<NUM>) to consistently provide a predetermined angular alignment between anvil (<NUM>) and stapling head assembly (<NUM>). This angular alignment may ensure that staple forming pockets (<NUM>) of anvil (<NUM>) are consistently angularly aligned appropriately with staple openings (<NUM>) of stapling head assembly (<NUM>). Thus, splines (<NUM>) are precisely and consistently positioned in relation to staple forming pockets (<NUM>). As shown in <FIG>, shank (<NUM>) further includes a flange (<NUM>) extending radially outward from a distal end (<NUM>) of shank (<NUM>). As a result, flange (<NUM>) has a larger area than longitudinally extending body (<NUM>) of shank (<NUM>). Flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>). As described in greater detail with reference to <FIG>, shank (<NUM>) may be machined using one or more machining processes.

As shown in <FIG> and <FIG>, head (<NUM>) includes a recessed portion (<NUM>) that extends proximally from a distal outer surface (<NUM>). Recessed portion (<NUM>) includes a recessed surface (<NUM>) surrounded by an annular wall (<NUM>), with an aperture (<NUM>) extending through recessed surface (<NUM>) that is configured to receive longitudinally extending body (<NUM>) of shank (<NUM>). As shown, aperture (<NUM>) is concentric to both distal outer surface (<NUM>) and recessed surface (<NUM>); however, other positionings of aperture (<NUM>) relative to distal outer surface (<NUM>) and recessed surface (<NUM>) are also envisioned. As shown in <FIG>, recessed portion (<NUM>) is sized and configured to receive flange (<NUM>) of shank (<NUM>). While recessed portion (<NUM>) and flange (<NUM>) are shown as circular, it is also envisioned that recessed portion (<NUM>) and flange (<NUM>) may have a variety of other shapes (e.g. rectangular) that may prevent relative rotation of head (<NUM>) and shank (<NUM>), if desired.

Distal outer surface (<NUM>) also includes one or more recesses (<NUM>), with two being shown, which may be used to secure a distal feature (such as a cap). Head (<NUM>) may also include a tapered portion (<NUM>) extending proximally from distal outer surface (<NUM>). Tapered portion (<NUM>) is shown as a chamfer. Recessed surface (<NUM>) of recessed portion (<NUM>) may be in direct contact with proximal surface (<NUM>) of flange (<NUM>) once head (<NUM>) is coupled with shank (<NUM>). As shown in <FIG>, distal outer surface (<NUM>) of head (<NUM>) is generally flush with distal surface of flange (<NUM>) after head (<NUM>) is coupled with shank (<NUM>). In other words, the depth of recessed portion (<NUM>) is about the same as the thickness of flange (<NUM>). However, the depth of recessed portion (<NUM>) and/or the thickness of flange (<NUM>) may vary. Additionally, distal outer surface (<NUM>) may be arcuate, if desired.

As shown in <FIG>, head (<NUM>) may be coupled to shank (<NUM>) using a cap (<NUM>), shown as a thin anvil plate. Cap (<NUM>) is configured to sandwich flange (<NUM>) of shank (<NUM>) between cap (<NUM>) and head (<NUM>). Cap (<NUM>) includes proximal and distal surfaces (<NUM>, <NUM>). According to an embodiment, the cap (<NUM>) may be of polymeric material. According to the invention, a cap (<NUM>) is overmolded onto head (<NUM>) using one or more overmolding processes. More specifically, cap (<NUM>) may be overmolded onto distal surface (<NUM>) of flange (<NUM>) and/or distal outer surface (<NUM>) of head (<NUM>). As a result, cap (<NUM>) may not be a separate component. Alternatively, cap (<NUM>) may be selectively coupleable to head (<NUM>) using one or more securement features that are configured to couple with recess (<NUM>). As shown, cap (<NUM>) is formed from a polymeric material; however, cap (<NUM>) may be formed from any suitable material.

Staple forming pockets (<NUM>) may be formed simultaneously with or after head (<NUM>) is formed. For example, <FIG> show perspective views of head (<NUM>), but with staple forming pockets (<NUM>) not yet formed. As described in greater detail with reference to <FIG>, at least a portion of head (<NUM>) may be machined after forming head (<NUM>) if desired.

As shown in <FIG>, at least a portion of staple forming pocket (<NUM>) may be coined or electrochemical machined after forming staple forming pocket (<NUM>) using an injection molding process (e.g. a metal injection molding process). More specifically, <FIG> shows a staple forming pocket (514a) prior to being coined or electrochemically machined, while <FIG> shows the staple forming pocket (<NUM>) of <FIG>, after being coined or electrochemically machined. As shown in <FIG>, staple forming pocket (514a) includes a central portion (570a) disposed between outer portions (572a, 574a). As shown in <FIG>, central portion (<NUM>) of staple forming pocket (<NUM>) is subsequently coined or electrochemically machined, which results in a smoother surface and a denser surface than another portion (e.g. outer portions (<NUM>, <NUM>)) that was not coined or electrochemical machined. As a result, outer portions (<NUM>, <NUM>) have surface that is rougher and less dense than central portion (<NUM>) of staple forming pocket (<NUM>). Alternatively, the entire staple forming pocket (<NUM>), including outer portions (<NUM>, <NUM>), may be coined or electrochemically machined, if desired.

Coining is a form of precision stamping where a workpiece is subjected to a sufficiently high stress to induce plastic flow on the surface of the material. The plastic flow reduces surface grain size and work hardens the surface of the workpiece, while the material deeper within the workpiece retains its toughness and ductility. Coining also improves the dimensional tolerances of staple forming pocket (<NUM>). Electrochemical machining (ECM) is a method of removing metal using one or more electrochemical processes. Electrochemical machining may be used for mass production due to cost effectiveness and is utilized for working extremely hard materials or materials that are difficult to machine using conventional methods. Electrochemical machining may cut small or uniquely-shaped angles, intricate contours, or cavities in hard metals workpieces.

<FIG> shows central portion (570a) of staple forming pocket (514a) taken along line 14A-14A of <FIG>, while <FIG> shows central portion (<NUM>) of staple forming pocket (<NUM>), taken along line 14B-14B of <FIG>. As shown when comparing <FIG> with <FIG>, central portion (570a) having been coined or electrochemically machined is both smoother and denser than another portion (e.g. outer portions (<NUM>, <NUM>)) of the same staple forming pocket (<NUM>) that was not coined or electrochemically machined.

<FIG> shows a portion of staple forming pocket (514a) of <FIG>, taken along line 15A-15A, while <FIG> shows a portion of staple forming pocket (<NUM>) of <FIG>, taken along line 15B-15B. As shown when comparing <FIG> with <FIG>, a channel (<NUM>) results after the coining or electrochemical machining process. <FIG> shows an annular array of staple forming pockets (<NUM>) of <FIG>, after being coined or electrochemically machined. More specifically, central portions (<NUM>) are coined or electrochemically machined.

<FIG> shows another an annular array of staple forming pockets (514b) after being coined or electrochemically machined. Similar to staple forming pockets (<NUM>), staple forming pockets (514b) also include a central portion (570b) and outer portions (572b, 574b). As shown, a central portion (570b) is coined or electrochemically machined, and as a result, is both smoother and denser than another portion (e.g. outer portions (572b, 574b)) of same staple forming pocket (514b) that is not coined or electrochemically machined.

<FIG> shows a perspective view of a second exemplary anvil (<NUM>) that may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (<NUM>, <NUM>) described above. Similar to anvil (<NUM>), anvil (<NUM>) includes a head (<NUM>), a shank (<NUM>), and a cap (<NUM>). As discussed in greater detail below, unlike cap (<NUM>), cap (<NUM>) includes one or more engagement features. Similar to head (<NUM>), head (<NUM>) includes a proximal surface (<NUM>), staple forming pockets (<NUM>), a recessed portion (<NUM>), a distal outer surface (<NUM>), a recessed surface (<NUM>), an annular wall (<NUM>), an aperture (<NUM>), recesses (<NUM>), and a tapered portion (<NUM>). Similar to shank (<NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a set of longitudinally extending splines (<NUM>), lead-in edges (<NUM>), a flange (<NUM>), and a distal end (<NUM>). Similar to flange (<NUM>), flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>). Similar to cap (<NUM>), cap (<NUM>) includes opposing proximal distal surfaces (<NUM>, <NUM>).

Proximal surface (<NUM>) of head (<NUM>) defines an annular array of staple forming pockets (<NUM>), which are similar to those shown in <FIG>. As described in greater detail with reference to <FIG>, head (<NUM>), including staple forming pockets (<NUM>), may be formed using a metal injection molding process and subsequently machined using one or more machining processes. As previously described with reference to staple forming pocket (<NUM>) in <FIG>, at least a portion of at least one staple forming pocket (<NUM>) may be coined or electrochemically machined to improve one or more properties of staple forming pockets (<NUM>). Recessed portion (<NUM>) of head (<NUM>) extends proximally from distal outer surface (<NUM>). Recessed surface (<NUM>) is surrounded by annular wall (<NUM>), with aperture (<NUM>) extending through recessed surface (<NUM>). Aperture (<NUM>) is configured to receive longitudinally extending body (<NUM>) of shank (<NUM>) therethrough. Recessed portion (<NUM>) is sized and configured to receive flange (<NUM>) of shank (<NUM>). Recessed portion (<NUM>) of head (<NUM>) may be in direct contact with proximal surface (<NUM>) of flange (<NUM>), once head (<NUM>) is coupled with shank (<NUM>). Distal outer surface (<NUM>) of head (<NUM>) also includes one or more recesses (<NUM>), with two being shown, which may be used to secure a distal feature, such as cap (<NUM>). Tapered portion (<NUM>) extends proximally from distal outer surface (<NUM>).

As shown in <FIG>, shank (<NUM>) extends proximally from head (<NUM>) and is configured to be coupled with head (<NUM>) once formed. While not shown in <FIG>, shank (<NUM>) includes an outwardly extending portion (<NUM>). As shown in <FIG>, flange (<NUM>) extending radially outward from distal end (<NUM>) of shank (<NUM>). Flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>). As described in greater detail with reference to <FIG>, shank (<NUM>) may be formed using a metal injection molding process and subsequently machined using one or more machining processes. As a result, both head (<NUM>) and shank (<NUM>) may be separately formed using metal injection molding processes. Additionally, both head (<NUM>) and shank (<NUM>) may be separately machined after being formed from the respective metal injection molding processes.

Head (<NUM>) may be coupled to shank (<NUM>) using cap (<NUM>), shown in this exemplary embodiment as an arcuate cap. Cap (<NUM>) is configured to sandwich flange (<NUM>) of shank (<NUM>) between cap (<NUM>) and head (<NUM>). Unlike cap (<NUM>), cap (<NUM>) is selectively couplable to head (<NUM>) using one or more securement features. For example, cap (<NUM>) may include at least one proximally facing projection (<NUM>), that is configured to couple with at least one corresponding recess (<NUM>). As such, coupling cap (<NUM>) with head (<NUM>) includes inserting proximally facing projections (<NUM>) into recesses (<NUM>). While each recess (<NUM>) is shown as extending completely through distal outer surface (<NUM>), it is envisioned that recesses (<NUM>) may extend only partly through distal outer surface (<NUM>). While cap (<NUM>) is shown as being formed from a polymeric material; it is envisioned that cap (<NUM>) may be formed from any suitable material. As shown, distal surface (<NUM>) of cap (<NUM>) is rounded, forming a hemispherical shape.

<FIG> shows a perspective view of a third exemplary anvil (<NUM>) that may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (<NUM>, <NUM>) described above. Similar to anvil (<NUM>), anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>). Similar to head (<NUM>), head (<NUM>) includes a proximal surface (<NUM>), staple forming pockets (<NUM>), a recessed portion (<NUM>), a distal outer surface (<NUM>), a recessed surface (<NUM>), an annular wall (<NUM>), an aperture (<NUM>), and a tapered portion (<NUM>). Similar to shank (<NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a set of longitudinally extending splines (<NUM>), lead-in edges (<NUM>), and a flange (<NUM>) and a distal end (<NUM>). Similar to flange (<NUM>), flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>).

Proximal surface (<NUM>) of head (<NUM>) defines an annular array of staple forming pockets (<NUM>), which are similar to those shown in <FIG>. As described in greater detail with reference to <FIG>, head (<NUM>), including staple forming pockets (<NUM>), may be formed using a metal injection molding process and subsequently machined using one or more machining processes. As previously described with reference to staple forming pocket (<NUM>) in <FIG>, at least a portion of at least one staple forming pocket (<NUM>) may be coined or electrochemically machined to improve one or more properties of staple forming pockets (<NUM>). Recessed portion (<NUM>) of head (<NUM>) extends proximally from distal outer surface (<NUM>). Recessed surface (<NUM>) is surrounded by annular wall (<NUM>), with aperture (<NUM>) extending through recessed surface (<NUM>). Aperture (<NUM>) is configured to receive longitudinally extending body (<NUM>) of shank (<NUM>) therethrough. Recessed portion (<NUM>) is sized and configured to receive flange (<NUM>) of shank (<NUM>). Recessed surface (<NUM>) of recessed portion (<NUM>) may be in direct contact with proximal surface (<NUM>) of flange (<NUM>), once head (<NUM>) is coupled with shank (<NUM>). Tapered portion (<NUM>) extends proximally from distal outer surface (<NUM>).

As shown in <FIG>, shank (<NUM>) extends proximally from head (<NUM>) and is configured to be coupled with head (<NUM>) once formed. While not shown in <FIG>, shank (<NUM>) includes an outwardly extending portion (<NUM>). As shown in <FIG>, flange (<NUM>) extend radially outward from distal end (<NUM>) of shank (<NUM>). Flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>). Distal surface (<NUM>) of flange (<NUM>) includes an inner shallow portion (<NUM>) and a rounded outer edge portion (<NUM>). As shown, rounded outer edge portion (<NUM>) includes a distal most portion (<NUM>) that is the distal most point of shank (<NUM>). A proximal surface (<NUM>) of flange (<NUM>) is coupled with distal outer surface (<NUM>) of head (<NUM>). Shank (<NUM>) may be formed using a metal injection molding process and subsequently machined using one or more machining processes.

<FIG> shows an exemplary method (<NUM>) of manufacturing anvils (<NUM>, <NUM>, <NUM>) that may be incorporated into instrument (<NUM>) of <FIG>. As previously described, anvil (<NUM>, <NUM>, <NUM>) includes head (<NUM>, <NUM>, <NUM>) and shank (<NUM>, <NUM>, <NUM>) that extends proximally from head (<NUM>, <NUM>, <NUM>). At step (<NUM>), method (<NUM>) includes forming head (<NUM>, <NUM>, <NUM>), including staple forming pockets (<NUM>, <NUM>, <NUM>), using an injection molding machine (<NUM>). Staple forming pockets (<NUM>, <NUM>, <NUM>) may be formed simultaneously with or after head (<NUM>, <NUM>, <NUM>) is formed using a metal injection molding. For example, head (<NUM>, <NUM>, <NUM>) may be formed using a metal injection molding process using a metal injection molding machine. At step (<NUM>), method (<NUM>) includes machining at least a portion of head (<NUM>, <NUM>, <NUM>). Machining may include coining or electrochemical machining at least a portion of at least one staple forming pocket (<NUM>, <NUM>, <NUM>) using a stamping or ECM machine (<NUM>). As previously described, the portion of staple forming pocket (<NUM>, <NUM>, <NUM>) coined or electrochemically machined is both smoother and denser than another portion that was not coined or electrochemical machined. Other benefits may also be achieved.

At step (<NUM>), method (<NUM>) includes forming shank (<NUM>, <NUM>, <NUM>) using an injection molding machine (<NUM>). Injection molding machine (<NUM>) may be the same or different than injection molding machine (<NUM>). Shank (<NUM>, <NUM>, <NUM>) may be formed using a metal injection molding process using a metal injection molding machine. At step (<NUM>), method (<NUM>) includes machining shank (<NUM>, <NUM>, <NUM>) using a lathe (<NUM>). If desired, shank (<NUM>, <NUM>, <NUM>) may be machined from a single piece of material without be previously formed using an injection molding process.

At step (<NUM>), method (<NUM>) includes coupling head (<NUM>, <NUM>, <NUM>) with shank (<NUM>, <NUM>, <NUM>) that were separately manufactured. Coupling head (<NUM>, <NUM>) with shank (<NUM>, <NUM>) may include coupling cap (<NUM>, <NUM>) with head (<NUM>, <NUM>) to sandwich flange (<NUM>, <NUM>) of shank (<NUM>, <NUM>) between cap (<NUM>, <NUM>) and head (<NUM>, <NUM>). More specifically, where cap (<NUM>) includes proximally facing projections (<NUM>), coupling cap (<NUM>) with head (<NUM>) includes inserting proximally facing projections (<NUM>) into recesses (<NUM>) of head (<NUM>). It is envisioned that coupling head (<NUM>, <NUM>, <NUM>) with shank (<NUM>, <NUM>, <NUM>) may include, for example, one or more overmolding, welds, adhesive, and/or mechanical securement features (e.g. projections (<NUM>)).

Those of ordinary skill in the art will understand that staples formed by anvil (<NUM>, <NUM>, <NUM>, <NUM>) will have a three-dimensional profile, where the legs are angularly offset from a plane passing through a crown of the staple; in addition to being bent generally toward each other. By way of example only, the staples formed using anvil (<NUM>, <NUM>, <NUM>, <NUM>) may have an appearance similar to at least some of the staples shown and described in <CIT>, now <CIT>. By way of further example only, the staples formed using anvil (<NUM>, <NUM>, <NUM>, <NUM>) may have an appearance similar to at least some of the staples shown and described in <CIT>. Additional features of anvils are disclosed in <CIT>; <CIT>, now abandoned; <CIT>, now <CIT>; <CIT>; <CIT>; <CIT>, <CIT>, now <CIT>, and <CIT>, now <CIT>.

In addition to or in lieu of the foregoing, anvil (<NUM>, <NUM>, <NUM>, <NUM>) may be further constructed and operable in accordance with at least some of the teachings of <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and/or <CIT>. Still other suitable configurations will be apparent to one of ordinary skill in the art in view of the teachings herein.

It should also be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, embodiments, examples, etc. that are described herein.

At least some of the teachings herein may also be readily combined with one or more teachings of <CIT>. Other suitable kinds of instruments in which the teachings herein may be applied, and various ways in which the teachings herein may be applied to such instruments, will be apparent to those of ordinary skill in the art.

Versions described above may be designed to be disposed of after a single use, or they can be designed to be used multiple times.

Claim 1:
A method of manufacturing an anvil of a surgical circular stapler, wherein the anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>) extending proximally from the head, wherein the shank includes a flange (<NUM>) extending radially outward from a distal end of the shank, the method comprising:
(a) forming the head (<NUM>) of a surgical circular stapler using a metal injection molding process;
(b) forming an annular array of staple forming pockets (<NUM>) in the head (<NUM>);
(c) machining the shank (<NUM>) of the surgical circular stapler; and
(d) coupling together the head (<NUM>) and the shank (<NUM>) of the surgical circular stapler that were separately manufactured, by overmolding a cap onto the head of the anvil to sandwich the flange of the shank between the cap and the head.