Patent Description:
One example of an instrument that may be used to provide an anastomosis is a circular surgical 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 surgical stapler may be configured to sever the tissue and seal the tissue substantially simultaneously. For instance, the circular surgical 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 surgical staplers may be used in open procedures or in endoscopic procedures. In some instances, a portion of the circular surgical stapler is inserted through a patient's naturally occurring orifice.

Examples of circular surgical staplers are described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>. Some circular surgical staplers may include a motorized actuation mechanism. Examples of circular surgical staplers with motorized actuation mechanisms are described in <CIT>, <CIT>, <CIT>, and <CIT>. <CIT> discloses a method for manufacturing an anvil of a surgical circular stapler. The anvil includes a head and a shank extending proximally from the head. The method includes: forming the head of a surgical circular stapler using a metal injection molding process, forming an annular array of staple forming pockets in the head; machining the shank of the surgical circular stapler; and coupling together the head and the shank of the surgical circular stapler that were separately manufactured. <CIT> discloses a circular stapling instrument that includes a body, an end effector, a trocar, and an anvil. The anvil head includes an annular surface defining a plurality of staple forming pockets. The plurality of staple forming pockets are configured to deform the plurality of staples when the anvil is in the staple forming position. The shank extends proximally from the annular stapling head. The shank and the anvil head cooperatively define a bore dimensioned to receive a portion of the trocar. The shank defines a lateral opening. The latch member is pivotally coupled with the shank via a living hinge. The latch member comprises a latch shelf configured to selectively couple the anvil with trocar when the trocar is inserted into the bore.

The present invention provides a method as recited in claim <NUM> and a surgical instrument as recited in claim <NUM>. Optional features are recited in the dependent claims.

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 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 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).

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>). Shaft assembly (<NUM>) extends distally from handle assembly (<NUM>) and includes a preformed bend, which may facilitate positioning of stapling head assembly (<NUM>) within a patient's colon.

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 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>). 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 an anvil coupling feature of stapling head assembly (<NUM>) in the form of a trocar (<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 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 shelves (<NUM>) are merely optional. Anvil (<NUM>) may be removably secured to a trocar (<NUM>) using any other suitable components, features, or techniques. In some versions, stapling head assembly (<NUM>) may include an actuatable first coupling feature that is similar in structure to shank (<NUM>), and anvil (<NUM>) may include a second coupling feature that is similar in structure to trocar (<NUM>) and is configured to releasably couple with the first coupling feature. 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>) 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>) in order 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>).

As shown 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>).

With continued reference to <FIG>, inner core member (<NUM>) of body member (<NUM>) defines a bore (<NUM>). A plurality of longitudinally extending splines (not shown) are spaced in an angular array within bore (<NUM>). The distal ends of splines (not shown) include lead-in edges 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>), and as anvil (<NUM>) is thereafter retracted proximally relative to stapling head assembly (<NUM>), lead-in edges (<NUM>) may cooperatively engage lead-in edges (not shown) to drive anvil (<NUM>) to rotate relative to trocar (<NUM>) to angularly align splines (<NUM>) of anvil (<NUM>) with the gaps between corresponding splines (not shown)) of body member (<NUM>). In this manner, when splines (<NUM>) of anvil (<NUM>) are positioned within the gaps between splines (not shown) 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>) are configured to ensure that staples ejected through staple openings (<NUM>) are accurately driven into corresponding staple forming pockets (<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>) may include a colored region (<NUM>). 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>). 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>).

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>). 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. 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. In instances in which head (<NUM>) and shank (<NUM>) are 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 of anvil (<NUM>) with instrument (<NUM>). Therefore, it may be desirable to manufacture exemplary anvils (500b, 700b, 900a, 1100b, 1300a) that provide such characteristics while also enabling anvils (500b, 700b, 900a, 1100b, 1300a) to function interchangeably with anvil (<NUM>) described above with reference to <FIG>. It is envisioned that one or more aspects of anvils (500b, 700b, 900a, 1100b, 1300a) may be combined with one or more aspects of <CIT>.

As will be described with reference to <FIG>, instrument (<NUM>) includes anvil (500b, 700b, 900a, 1100b, 1300a), which is intended to be used in place of anvil (<NUM>) described above with reference to <FIG>. As will be described in greater detail below, and similar to the functionality of anvil (<NUM>), each of anvils (500b, 700b, 900a, 1100b, 1300a) is configured to couple with trocar (<NUM>), or with an alternative actuatable coupling feature of stapling head assembly (<NUM>), and each is configured to deform staples driven by the staple driver. Furthermore, it will be appreciated that the exemplary manufacturing methods described below may be similarly employed for variations of anvils (500b, 700b, 900a, 1100b, 1300a) having a coupling feature other than a shank, such as a coupling feature similar in structure to trocar (<NUM>).

<FIG> show a first exemplary alternative anvil (<NUM>, 500a, 500b) during various manufacturing stages where completed anvil (500b) may be incorporated into instrument (<NUM>) of <FIG>, and <FIG> shows an exemplary method (<NUM>) of manufacturing anvil (500b). Anvil (500b) is configured to couple with anvil coupling feature (e.g., trocar (<NUM>)), so that anvil (<NUM>) is configured to deform staples driven by the staple driver. Anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>) that extends proximally from head (<NUM>).

Head (<NUM>) includes a proximal surface (<NUM>), which is shown in <FIG> without an annular array of staple forming pockets (<NUM>), which are formed later as discussed below. Staple forming pockets (<NUM>) are shown schematically in <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>). Distal outer surface (<NUM>) of head (<NUM>) includes one or more apertures (<NUM>), with two being shown, that may be used to couple with a cap (not shown), but which may be similar to cap (<NUM>). Head (<NUM>) also includes a tapered portion (<NUM>) extending proximally from distal outer surface (<NUM>).

Shank (<NUM>) extends along a longitudinal axis (LA) and defines a bore (<NUM>). Bore (<NUM>) is shown as a conical bore that extends through only a portion of shank (<NUM>), which is subsequently refined through one or more machining processes. Similar to shank (<NUM>), shank (<NUM>) includes a set of longitudinally extending splines (<NUM>) that are spaced about shank (<NUM>) in an angular array, where the proximal ends of splines (<NUM>) include a lead-in edge (<NUM>). Lateral openings (<NUM>) provide clearance for a latch member (not shown), but which may be similar to latch member (<NUM>), to deflect radially outwardly from longitudinal axis (LA) defined by shank (<NUM>).

Method (<NUM>) includes forming head (<NUM>) and shank (<NUM>) using at least one metal injection molding process to produce anvil (<NUM>) as shown and described above with reference to <FIG>. In this version, head (<NUM>) may be simultaneously formed with shank (<NUM>) using the same metal injection molding process. Head (<NUM>) and shank (<NUM>) are shown as being integrally formed together as a unitary piece. 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). The shape and dimensions of anvil (<NUM>) may be optimized for the metal injection molding process. For example, shank (<NUM>) of <FIG> has a generally solid shape (<NUM>) except for bore (<NUM>) and apertures (<NUM>). This generally solid shape (<NUM>) may improve the structural integrity of anvil (<NUM>) during the metal injection molding process.

As shown in <FIG>, after forming head (<NUM>) and shank (<NUM>) using metal injection molding, at step (<NUM>), method (<NUM>) includes machining select portions of head (510a) and/or shank (520a). Selective machining may reduce the time and cost associated with machining an entirety of anvil (<NUM>). As shown by comparing the cross-sections of <FIG> and <FIG>, a groove (<NUM>) may be machined into inner edge (516a) also referred to as an inner side wall of head (510a). Additionally, select portions of proximal, central, and distal portions (542a, 544a, 546a) of shank (520a) may be machined to improve select dimensional tolerances which without machining anvil (500a) in its entirety. A through bore (<NUM>) is machined into shank (<NUM>) so as to extend completely through longitudinal axis (LA) of shank (<NUM>). In other words, through bore (<NUM>) extends from a tapered proximal end (<NUM>) of shank (<NUM>) to a distal end (550a) of head (<NUM>). Additionally, distal end (548a) may be machined to include a taper.

Splines (526a) and lateral openings (524a) may be refined through one or more machining processes. For example, lead-in edges (<NUM>) of splines (526a) may be machined into shank (<NUM>). Splines (526a) are configured to align with features of instrument (<NUM>). Splines (526a) are configured to engage corresponding splines (not shown) of 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 (526a) are precisely and consistently positioned in relation to staple forming pockets (<NUM>).

In this version, staple forming pockets (<NUM>) are formed into head (510b) of anvil (500b) after metal injection molding head (<NUM>). At step (<NUM>), method (<NUM>) may include coining or electrochemically machining staple forming pockets (<NUM>) into proximal surface (512a) of head (510a). While not shown, in some versions, staple forming pockets (<NUM>) may be initially formed using one or more machining processes during step (<NUM>) whereby coining and/or electrochemically improves select dimensional tolerances of select portions of staple forming pockets (<NUM>). As shown in <FIG>, staple forming pockets (<NUM>) are arranged in two concentric annular arrays. Alternatively, staple forming pockets (<NUM>) may be arranged in three or more concentric annular arrays. 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. Alternatively, staple forming pockets (<NUM>) may be formed using coining or electrochemically machining.

Coining is a form of precision stamping where a workpiece is subjected to a sufficiently high stress so as to induce plastic flow on the surface of the material. The plastic flow reduces surface grain size and work hardens proximal surface (512a), 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.

Method (<NUM>) may optionally include electropolishing at least a portion of the annular array of staple forming pockets (<NUM>). Electropolishing is an electrochemical finishing process that removes a thin layer of material from a metal part. Electropolishing results in a shiny and smooth surface finish. Method (<NUM>) may optionally include magnetically deburring or bead blasting anvil (<NUM>, 500a, 500b) (e.g., head (510a, 510b)). Magnetic deburring removes light burrs from non-ferrous parts. In magnetic deburring, rotating magnets move small stainless-steel pins around a bowl of the magnetic deburring machine, rubbing the small stainless-steel pins against the portion of anvil (<NUM>, 500a, 500b) being deburred.

While not shown, shank (520a) may include a pair of pivoting latch members 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 may be inserted into bore (<NUM>) at any time after step (<NUM>) of metal injection molding. For example, latch members may be inserted into bore (<NUM>) after step (<NUM>) of machining anvil (<NUM>) or after step (<NUM>) of coining or electrochemically machining staple forming pockets (<NUM>). The latch members may be 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 (520a). The latch members allow anvil (500b) to be removably secured to a trocar (<NUM>) of stapling head assembly (<NUM>). When shank (520a) is secured to trocar (<NUM>) and trocar (<NUM>) is retracted proximally, the inner diameter of bore (<NUM>) in inner core member (<NUM>) of inner 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 (500b) from being released from trocar (<NUM>) during firing of stapling head assembly (<NUM>). In some versions, the latch members may be omitted, such that anvil (500b) may be removably secured to a trocar (<NUM>) using any other suitable components, features, or techniques.

<FIG> show a second exemplary alternative anvil (<NUM>, 700a, 700b) in various manufacturing stages, where anvil (700b) may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (<NUM>, 500b) described above, and <FIG> shows an exemplary method of manufacturing anvil (700b). 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>), an inner edge (<NUM>), an annular recess (<NUM>), a distal outer surface (<NUM>), a tapered portion (<NUM>). Similar to shank (<NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a set of longitudinally extending splines (<NUM>), a proximal portion (<NUM>), a central portion (<NUM>), and a distal portion (<NUM>).

At step (<NUM>), method (<NUM>) includes forming head (<NUM>) and shank (<NUM>) using at least one metal injection molding process to produce anvil (<NUM>) shown and described above with reference to <FIG>. Similar to anvil (<NUM>), head (<NUM>) may be simultaneously formed with shank (<NUM>) using the same metal injection molding process. Unlike anvil (<NUM>) shown and described with reference to <FIG>, anvil (<NUM>) includes annular array of staple forming pockets (<NUM>) formed in head (<NUM>) of anvil (<NUM>) during the metal injection molding process. For example, staple forming pockets (<NUM>) may be formed simultaneously with head (<NUM>) during the metal injection molding process. Staple forming pockets (<NUM>) are shown schematically in <FIG> and <FIG>. In this version, a locking feature (<NUM>) may be used to retain a washer (not shown but similar to washer (<NUM>)). The shape and dimensions of anvil (<NUM>) may be optimized for the metal injection molding process. Similar to shank (<NUM>), shank (<NUM>) has a generally solid shape (<NUM>) except for bore (<NUM>) and recesses (<NUM>).

After forming head (<NUM>) and shank (<NUM>) using metal injection molding, at step (<NUM>), method (<NUM>) may include machining select portions of head (710a) and/or shank (720a) of anvil (800a). As shown by comparing the cross-sections of <FIG> and <FIG>, a groove (<NUM>) similar to groove (<NUM>) may be machined into inner edge (716a), also referred to as an inner side wall of head (710a). Proximal, central, and distal portions (742a, 744a, 746a) of shank (720a) may benefit from subsequent machining to improve select dimensional tolerances. As shown in the cross-sectional view of <FIG>, a through bore (<NUM>) is machined into shank (720a) that extends completely through longitudinal axis (LA) of shank (720a). In other words, through bore (<NUM>) extends from a tapered proximal end (<NUM>) of shank (720a) to a distal end (<NUM>) of head (710a). Through bore (<NUM>) includes a portion of bore (<NUM>) formed through the metal injection molding process. Portions of splines (726a), such as lead in edges (<NUM>), and lateral openings (724a) may be machined into shank (720a) to improve dimensional tolerances.

At step (<NUM>), method (<NUM>) may include coining or electrochemically machining at least a portion of staple forming pockets (714a) into head (710b) of anvil (700b). Since staple forming pockets (<NUM>) are formed into head (<NUM>) of anvil (<NUM>) during the metal injection molding process, coining or electrochemically machining may produce a smoother surface and a denser surface than another portion (e.g., an outer portion) that was not coined or electrochemically machined. Selective coining or electrochemically machining of staple forming pockets is additionally shown and described in <CIT>. Similar to method (<NUM>), method (<NUM>) may optionally include electropolishing at least a portion of staple forming pockets (<NUM>, 714a). Similar to method (<NUM>), method (<NUM>) may optionally include magnetically deburring or bead blasting at least head (<NUM>, 710a, 710b) as described above.

<FIG> show a third exemplary alternative anvil (<NUM>, 900a) in various manufacturing stages where anvil (900a) may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (<NUM>, 500b, 700b) described above, and <FIG> shows an exemplary method (<NUM>) of manufacturing anvil (900a). Similar to anvils (<NUM>, <NUM>, <NUM>), anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>). Unlike anvils (<NUM>, <NUM>, <NUM>), head (<NUM>) is not integrally formed together with shank (<NUM>). Similar to head (<NUM>, <NUM>), head (<NUM>) includes a proximal surface (<NUM>), an inner edge (<NUM>), an annular recess (<NUM>), a distal outer surface (<NUM>), and a tapered portion (<NUM>). Similar to shank (<NUM>, <NUM>, <NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a set of longitudinally extending splines (<NUM>), a proximal portion (<NUM>), a central portion (<NUM>), and a distal portion (<NUM>).

Unlike heads (<NUM>, <NUM>, <NUM>), head (<NUM>) includes a recessed portion (<NUM>) that extends proximally from a distal outer surface (<NUM>) as shown in <FIG>. 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 shank (<NUM>). Recessed portion (<NUM>) of head (<NUM>) extends proximally from distal outer surface (<NUM>). Recessed surface (<NUM>) is surrounded by wall (<NUM>), with aperture (<NUM>) extending through recessed surface (<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.

Unlike shanks (<NUM>, <NUM>, <NUM>), as shown in <FIG>, shank (<NUM>) includes a flange (<NUM>) extending radially outward from distal portion (<NUM>) of shank (<NUM>). Flange (<NUM>) includes opposing proximal and distal surfaces (<NUM>, <NUM>). Aperture (<NUM>) is configured to receive shank (<NUM>) therethrough. Recessed portion (<NUM>) is sized and configured to receive flange (<NUM>) of shank (<NUM>).

At step (<NUM>), method (<NUM>) includes forming head (<NUM>) and shank (<NUM>) using at least one metal injection molding process to produce head (<NUM>) shown in <FIG> and shank (<NUM>) shown in <FIG>. Head (<NUM>) and shank (<NUM>) may be separately formed using separate metal injection molding processes. For example, head (<NUM>) may be formed separately from shank (<NUM>) using a first metal injection molding process, and shank (<NUM>) may be separately formed from head (<NUM>) using a second metal injection molding process. The shape and dimensions of anvil (<NUM>) may be optimized for the metal injection molding process. Unlike shanks (<NUM>, <NUM>), as shown in <FIG>, bore (<NUM>) includes a narrow portion (<NUM>) extending along longitudinal axis (LA). In other words, bore (<NUM>) has a non-uniform width, with distal portion (<NUM>) of shank (<NUM>) having a different width than central portion (<NUM>).

After forming head (<NUM>) and shank (<NUM>) using the metal injection molding process, at step (<NUM>), method (<NUM>) may include machining select portions of head (910a) and/or shank (920a). As shown by comparing the perspective views of <FIG> and <FIG>, a groove (<NUM>) (similar to groove (<NUM>)) may be machined into inner edge (916a), also referred to as an inner side wall of head (910a). Proximal, central, and distal portions (942a, 944a, 946a) of shank (920a) may benefit from subsequent machining to improve select dimensional tolerances. A through bore (<NUM>) may be machined (e.g., using a drilling process) into shank (920a) so that through bore (<NUM>) extends completely through shank (920a). Portions of splines (926a), such as lead in edges (<NUM>), and lateral openings (924a) may be machined into shank (920a) to improve dimensional tolerances. Staple forming pockets (<NUM>) may be formed at step (<NUM>) through machining or at step (<NUM>) through coining and/or electrochemically machining.

At step (<NUM>), method (<NUM>) includes coupling head (910a) and shank (920a) together that were separately formed. In some versions, step (<NUM>) may be performed before or during step (<NUM>). Tapered proximal end (<NUM>) of shank (920a) is inserted though aperture (<NUM>) of head (<NUM>). Recessed portion (<NUM>) is sized and configured to receive flange (<NUM>) of shank (920a). As shown in <FIG>, recessed surface (<NUM>) of recessed portion (<NUM>) is in direct contact with proximal surface (<NUM>) of flange (<NUM>) once head (910a) is coupled with shank (920a). Recessed portion (<NUM>) of head (<NUM>) may be in direct contact with proximal surface (<NUM>) of flange (<NUM>) once head (910a) is coupled with shank (920a). The depth of recessed portion (<NUM>) may be 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.

As shown in <FIG>, an outer perimeter (<NUM>) of flange (<NUM>) of shank (920a) may be welded together with head (910b) using a continuous weld (<NUM>) to secure head (910b) and shank (920a) together. One such suitable welding process is laser welding that is used to join together metals or thermoplastics using a laser beam to form a weld. Laser welding may reduce, or altogether eliminate, subsequent manufacturing processes (e.g., grinding) to refine continuous weld (<NUM>). In some versions, continuous weld (<NUM>) may be optionally ground down so distal outer surface (<NUM>) of head (910b) is generally flush with distal surface of flange (<NUM>) after head (910b) is coupled with shank (920a). The device used to join head (910b) and shank (920a) together may have appropriate indexing capabilities in order to reliably and consistently achieve the proper angular positioning of head (910b) and shank (920a) to thereby provide precise and consistent positioning of splines (926a) in relation to staple forming pockets (<NUM>).

Similar to methods (<NUM>, <NUM>), at step (<NUM>), method (<NUM>) may include coining and/or electrochemically machining staple forming pockets (<NUM>). Coining or electrochemically machining staple forming pocket (<NUM>) results in a smoother surface and a denser surface than another portion that was not coined or electrochemically machined. As shown in <FIG>, proximal surface (912a) of head (910b) defines an annular array of staple forming pockets (<NUM>). In some versions, staple forming pockets (<NUM>) may be formed simultaneously with head (910b) during the metal injection molding process. Similar to methods (<NUM>, <NUM>), method (<NUM>) may optionally include electropolishing at least a portion of the annular array of staple forming pockets (<NUM>). Similar to methods (<NUM>, <NUM>), method (<NUM>) may optionally include magnetically deburring or bead blasting at least head (910b) of anvil (900a).

<FIG> show a fourth exemplary alternative anvil (<NUM>, 1100a, 1100b) in various manufacturing stages where anvil (1100b) may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (<NUM>, 500b, 700b, 900a) described above, and <FIG> shows an exemplary method of manufacturing anvil (1100b). Similar to anvils (<NUM>, <NUM>, <NUM>), anvil (<NUM>) includes a head (<NUM>) and a shank (<NUM>) which are machined as head (1110a) and shank (1120a). Similar to head (<NUM>), head (<NUM>) includes a proximal surface (<NUM>), staple forming pockets (<NUM>), an inner edge (<NUM>), an annular recess (<NUM>), a distal outer surface (<NUM>), a tapered portion (<NUM>), a recessed portion (<NUM>), a recessed surface (<NUM>), an annular wall (<NUM>), and an aperture (<NUM>). Similar to shank (<NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a set of longitudinally extending splines (<NUM>), a proximal portion (<NUM>), a central portion (<NUM>), and a distal portion (<NUM>), a proximal end (<NUM>), a flange (<NUM>), and opposing proximal and distal surfaces (<NUM>, <NUM>).

At step (<NUM>), method (<NUM>) includes using at least one metal injection molding process to form head (<NUM>) shown in <FIG> and shank (<NUM>) shown in <FIG>. Head (<NUM>) and shank (<NUM>) may be separately formed using metal injection molding processes. For example, head (<NUM>) may be formed separately from shank (<NUM>) using a first metal injection molding process, and shank (<NUM>) may be separately formed from head (<NUM>) using a second metal injection molding process. Unlike head (<NUM>), staple forming pockets (<NUM>) are formed into head (<NUM>) during the metal injection molding process. The shape and dimensions of anvil (<NUM>) may be optimized for the metal injection molding process. Shank (<NUM>) has a generally solid shape (<NUM>) except for bore (<NUM>) and recesses (<NUM>).

After forming head (<NUM>) and shank (<NUM>) using the metal injection molding process, at step (<NUM>), method (<NUM>) may include machining select portions of head (1110a) and/or shank (1120a). As shown in <FIG>, a groove (<NUM>) similar to groove (<NUM>) may be machined into inner edge (1116a), also referred to as an inner side wall of head (1110a). Proximal, central, and distal portions (1142a, 1144a, 1146a) of shank (1120a) may benefit from subsequent machining to improve select dimensional tolerances. Regarding shank (1120a), a through bore (<NUM>) is machined into shank (1120a) that extends completely through longitudinal axis (LA) of shank (1120a). Portions of splines (1126a), such as lead-in edges (<NUM>) may be machined into shank (1120a) and lateral openings (1124a) may be refined to improve dimensional tolerances. Tapered proximal end (1148a) may also be machined.

At step (<NUM>), method (<NUM>) includes coupling head (1110a) and shank (1120a) together that were separately formed and machined. In some versions, step (<NUM>) may be performed before step (<NUM>), so that head (1110a) and shank (1120a) may be coupled then machined. In some versions, an outer perimeter (<NUM>) of flange (<NUM>) may be welded together with head (1110a) using a continuous weld (<NUM>) to secure head (1110a) and shank (1120a) together. As shown in <FIG>, recessed surface (<NUM>) of recessed portion (<NUM>) is in direct contact with proximal surface (<NUM>) of flange (<NUM>) once head (1110a) is coupled with shank (1120a). Distal outer surface (<NUM>) of head (1110a) is generally flush with distal surface of flange (<NUM>) after head (1110a) is coupled with shank (1120a).

Similar to step (<NUM>), at step (<NUM>), method (<NUM>) may include coining or electrochemically machining at least a portion of staple forming pockets (1114a) of head (1110a) (see <FIG>). Since staple forming pockets (<NUM>) are formed into head (<NUM>) during the metal injection molding process, at least a portion of staple forming pocket (1114a) may be coined or electrochemical machined. The portion of staple forming pocket (1114a) subsequently coined or electrochemically machined produces a smoother surface and a denser surface than another portion (e.g., an outer portion) that was not coined or electrochemically machined. In some versions, step (<NUM>) may be performed before step (<NUM>), so that head (1110a) and shank (1120a) may be coupled before being coined or electrochemically machined. Similar to method (<NUM>), method (<NUM>) may optionally include electropolishing at least a portion of the annular array of staple forming pockets (<NUM>). Similar to method (<NUM>), method (<NUM>) may optionally include magnetically deburring or bead blasting at least head (1110a, 1110b) of anvil (1100a, 1100b).

<FIG> show a fifth exemplary alternative anvil (<NUM>, 1300a) in various manufacturing stages where anvil (1300a) may be incorporated into instrument (<NUM>) of <FIG> in place of anvil (500b, 700b, 900a, 1100b) described above, and <FIG> shows an exemplary method of manufacturing anvil (1300a). Similar to anvil (<NUM>, <NUM>, <NUM>, <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>), an inner edge (<NUM>), an annular recess (<NUM>), a distal outer surface (<NUM>), a tapered portion (<NUM>), a recessed portion (<NUM>), a recessed surface (<NUM>), an annular wall (<NUM>), and an aperture (<NUM>). Similar to shank (<NUM>), shank (<NUM>) includes a bore (<NUM>), lateral openings (<NUM>), a proximal portion (<NUM>), a central portion (<NUM>), a distal portion (<NUM>), a proximal end (<NUM>), a flange (<NUM>), and opposing proximal and distal surfaces (<NUM>, <NUM>).

At step (<NUM>), method (<NUM>) includes using at least one metal injection molding process to form head (<NUM>) and shank (<NUM>). Metal injection molded head (<NUM>) may be similar to head (<NUM>) that omits staple forming pockets (<NUM>) or head (<NUM>) that includes staple forming pockets <NUM>) formed using metal injection molding. Head (<NUM>) and shank (<NUM>) may be separately formed using metal injection molding processes. For example, head (<NUM>) may be formed separately from shank (<NUM>) using a first metal injection molding process, and shank (<NUM>) may be separately formed from head (<NUM>) using a second metal injection molding process. The shape and dimensions of anvil (<NUM>) may be optimized for the metal injection molding process. As shown in <FIG>, shank (<NUM>) has a generally solid shape (<NUM>) except for bore (<NUM>) and one or more recessed portions, shown as proximal and distal recessed portions (<NUM>, <NUM>). Proximal and distal recessed portions (<NUM>, <NUM>) are configured to subsequently receive an insert (<NUM>) as described below.

After forming head (<NUM>) and shank (<NUM>) using the metal injection molding process, at step (<NUM>), method (<NUM>) includes machining select portions of shank (1320a) and optionally head (<NUM>). Head (<NUM>) includes a groove (<NUM>) similar to groove (<NUM>), machined into inner edge (<NUM>). Proximal, central, and distal portions (1342a, 1344a, 1346a) of shank (1320a) may benefit from subsequent machining to improve select dimensional tolerances. Regarding shank (1320a), a through bore (<NUM>) is machined into shank (1320a) that extends completely through longitudinal axis (LA) of shank (<NUM>). Lateral openings (1324a) and distal end (1342a) may also be machined to improve dimensional tolerances.

At step (<NUM>), method (<NUM>) includes injection molding an insert (<NUM>) onto shank (1320a). Unlike anvils (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>), anvil (<NUM>) includes insert (<NUM>) coupled with central portion (1344a) of shank (1320a). Insert (<NUM>) is formed of a polymeric material onto shank (1320a), such that step (<NUM>) includes plastic injection molding onto shank (1320a). Unlike the previously described shanks, insert (<NUM>) includes a plurality of splines (<NUM>). Splines (<NUM>) are configured to align with features (gaps between splines) of instrument (<NUM>). Insert (<NUM>) circumferentially surrounds at least a portion of central portion (1344a) of shank (1320a). Splines (1326a) include lead-in edges (<NUM>). Shank (1320a) includes proximal and distal retaining portions (<NUM>, <NUM>) configured to retain insert (<NUM>) and prevent insert (<NUM>) from moving proximally or distally relative to shank (1320a). Using insert (<NUM>) may reduce, or altogether eliminate, machining of shank (<NUM>) into shank (1320a). Insert (<NUM>) includes proximal and distal inwardly facing portions (<NUM>, <NUM>). As shown, proximal inwardly facing portion (<NUM>) is coupled with proximal recessed portion (<NUM>) and distal inwardly facing portion (<NUM>) is coupled with distal recessed portion (<NUM>). Distal end (<NUM>) may be machined to include a tapered distal; end (1348a).

At step (<NUM>), method (<NUM>) includes coupling head (<NUM>) and shank (1320a) together that were separately formed. As shown in <FIG>, recessed surface (<NUM>) of recessed portion (<NUM>) is in direct contact with proximal surface (<NUM>) of flange (<NUM>) once head (<NUM>) is coupled with shank (1320a). 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 some versions, step (<NUM>) may be performed before step (<NUM>). In some versions, an outer perimeter (<NUM>) of flange (<NUM>) may be welded together with head (<NUM>) using a continuous weld (<NUM>) to secure head (<NUM>) and shank (1320a) together. One such suitable welding process is laser welding that is used to join together metals or thermoplastics using a laser beam to form a weld. Laser welding may reduce or eliminate the need for subsequent manufacturing processes (e.g., grinding).

Similar to step (<NUM>), at step (<NUM>), method (<NUM>) may include coining or electrochemically machining staple forming pockets (<NUM>) (shown schematically in <FIG>). In some versions, since staple forming pockets (<NUM>) are formed into head (<NUM>) of anvil (<NUM>) during the metal injection molding process, a select portion of staple forming pockets (<NUM>) may be coined or electrochemical machined. The portion of staple forming pocket (<NUM>) subsequently coined or electrochemically machined results in a smoother surface and a denser surface than another portion (e.g., an outer portion) that was not coined or electrochemically machined. Similar to method (<NUM>), method (<NUM>) may optionally include electropolishing at least a portion of the annular array of staple forming pockets (<NUM>). Similar to method (<NUM>), method (<NUM>) may optionally include magnetically deburring or bead blasting at least head (<NUM>).

Those of ordinary skill in the art will understand that staples formed by anvil (500b, 700b, 900a, 1100b, 1300a) 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 (500b, 700b, 900a, 1100b, 1300a) may have an appearance similar to at least some of the staples shown and described in <CIT>. By way of further example only, the staples formed using anvil (500b, 700b, 900a, 1100b, 1300a) 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>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

In addition to or in lieu of the foregoing, anvil (<NUM>, <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.

Versions described above may be designed to be disposed of after a single use, or they can be designed to be used multiple times. Reconditioning may include any combination of the steps of disassembly of the systems, instruments, and/or portions thereof, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, some versions of the systems, instruments, and/or portions thereof may be disassembled, and any number of the particular pieces or parts of the systems, instruments, and/or portions thereof may be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, some versions of the systems, instruments, and/or portions thereof may be reassembled for subsequent use either at a reconditioning facility, or by an operator immediately prior to a procedure. Those skilled in the art will appreciate that reconditioning of systems, instruments, and/or portions thereof may utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned systems, instruments, and/or portions thereof, are all within the scope of the present application.

In one sterilization technique, the systems, instruments, and/or portions thereof is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and system, instrument, and/or portion thereof may then be placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation may kill bacteria on the system, instrument, and/or portion thereof and in the container. The sterilized systems, instruments, and/or portions thereof may then be stored in the sterile container for later use. Systems, instruments, and/or portions thereof may also be sterilized using any other technique known in the art, including but not limited to beta or gamma radiation, ethylene oxide, or steam.

Claim 1:
A method (<NUM>) of manufacturing an anvil (<NUM>, 1300a) of a circular surgical stapler (<NUM>), wherein the anvil (<NUM>, 1300a) includes a head (<NUM>) and a coupling feature that includes a shank (<NUM>) that extends proximally from the head (<NUM>), the method comprising:
(a) forming each of the head (<NUM>) and the coupling feature (<NUM>) using at least one metal injection molding process (<NUM>); and characterized by:
(b) after forming the coupling feature, machining (<NUM>) a through bore (<NUM>) into the shank (<NUM>) so that the through bore (<NUM>) extends completely through the shank (<NUM>) of the coupling feature along a longitudinal axis of the coupling feature; and
(c) plastic injection molding (<NUM>) an insert (<NUM>) formed of a polymeric material onto the shank (<NUM>).