Knife for circular surgical stapler

Abstract

The device includes a body, a shaft, and a stapling head assembly. The shaft extends distally from the body. The stapling head assembly is positioned at a distal end of the shaft. The stapling head assembly includes a staple driver member and a knife member. The staple driver member is configured to drive a plurality of staples into tissue. The knife member is configured to cut the tissue. The knife member includes a proximal end, a distal end, and a barrel extending between the proximal and distal ends. The barrel includes at least one coupling feature that operably couples the knife member to the staple driver member.

Description

[Background technology]

[0001] In some surgical procedures (e.g., colorectal surgery, bariatric surgery, thoracic surgery, etc.), a portion of a patient's digestive tract (e.g., gastrointestinal tract and / or esophagus, etc.) may be resected to remove unwanted tissue or for other reasons. After the tissue is removed, the remaining portions of the digestive tract may be joined together by end-to-end, end-to-side, or side-to-side anastomosis. The anastomosis may provide a substantially unobstructed flow path from one portion of the digestive tract to another portion of the digestive tract without leakage of any kind from the anastomosis site.

[0002] One example of an instrument that may be used to provide an anastomosis is a circular stapler. Some such staplers are operable to clamp a layer of tissue, cut the clamped layer of tissue, and drive staples through the clamped layer of tissue to substantially seal the tissue to one another adjacent the cut ends of the tissue layers to join the two cut ends of the anatomical lumen. The circular stapler may be configured to cut the tissue and substantially simultaneously seal the tissue. For example, the circular stapler may cut excess tissue that is internal to the annular array of staples at the anastomosis to provide a substantially smooth transition between the anatomical lumens that are joined at the anastomosis. Circular staplers may be used in open or endoscopic surgery. In some cases, a portion of the circular stapler is inserted through a natural opening in the patient's body.

[0003] Examples of circular staplers are U.S. Patent No. 5,205,459, issued April 27, 1993, entitled "Surgical Anastomosis Stapling Instrument"; U.S. Patent No. 5,271,544, issued December 21, 1993, entitled "Surgical Anastomosis Stapling Instrument"; U.S. Patent No. 5,275,322, issued January 4, 1994, entitled "Surgical Anastomosis Stapling Instrument"; U.S. Patent No. 5,285,945, issued February 15, 1994, entitled "Surgical Anastomosis Stapling Instrument"; U.S. Patent No. 5,292,053, issued March 8, 1994, entitled "Surgical Anastomosis Stapling Instrument"; No. 5,333,773, issued Aug. 2, 1994, entitled "Surgical Anastomosis Stapling Instrument;" U.S. Patent No. 5,350,104, issued Sep. 27, 1994, entitled "Surgical Anastomosis Stapling Instrument;" U.S. Patent No. 5,533,661, issued July 9, 1996, entitled "Surgical Anastomosis Stapling Instrument;" and U.S. Patent No. 8,910,847, issued Dec. 16, 2014, entitled "Low Cost Anvil Assembly for a Circular Stapler." The disclosures of each of the above-cited U.S. patents are incorporated herein by reference.

[0004] Some circular staplers may include a motorized actuation mechanism. Examples of circular staplers with motorized actuation mechanisms are described in U.S. Patent Application Publication No. 2015 / 0083772, published March 26, 2015, now abandoned, entitled "Surgical Stapler with Rotary Cam Drive and Return"; U.S. Patent No. 9,936,949, issued April 10, 2018, entitled "Surgical Stapling Instrument with Drive Assembly Having Toggle Features"; U.S. Patent No. 9,907,552, issued March 6, 2018, entitled "Control Features for Motorized Surgical Stapling Instrument"; and U.S. Patent No. 9,713,469, issued July 25, 2017, entitled "Surgical Stapler with Rotary Cam Drive". The disclosures of each of the above-cited U.S. Patent Application Publications are incorporated herein by reference.

[0005] While many different types of surgical stapling instruments and related components have been made and used, it is believed that no one prior to the present inventors has made or used the invention as set forth in the appended claims. [Brief description of the drawings]

[0006] While this specification concludes with claims particularly pointing out and distinctly claiming the present technology, the technology will be better understood from the following description of certain embodiments taken in conjunction with the accompanying drawings, in which like reference numerals identify the same elements and in which: [Figure 1] FIG. 1 is a perspective view of an exemplary circular stapler. [Diagram 2] 2 is a perspective view of the circular stapler of FIG. 1 with the battery pack removed from the handle assembly and the anvil removed from the stapling head assembly; [Diagram 3]2 is an exploded perspective view of the circular stapler of FIG. 1, with portions of the shaft assembly shown separated from one another; [Figure 4] FIG. 2 is a perspective view of the anvil of the circular stapler of FIG. [Diagram 5] FIG. 5 is another perspective view of the anvil of FIG. [Figure 6] FIG. 5 is an exploded side elevational view of the anvil of FIG. [Figure 7] FIG. 2 is a perspective view of a stapling head assembly of the circular stapler of FIG. [Figure 8] FIG. 8 is a perspective cross-sectional view of an inner body member of the stapling head assembly of FIG. 7; [Figure 9] FIG. 8 is an exploded perspective view of the stapling head assembly of FIG. 7; [Figure 10] FIG. 8 is an exploded perspective view of a first exemplary alternative knife member and a first exemplary alternative staple driver member that may be incorporated into the stapling head assembly of FIG. 7; [Figure 11] FIG. 11 is a top view of the knife member and staple driver member of FIG. [Figure 12A] 8 is a side elevational view showing the anvil of FIG. 4 in a first longitudinal position relative to the stapling head assembly of FIG. 7; [Figure 12B] 8 is a side elevational view showing the anvil of FIG. 4 in a second longitudinal position relative to the stapling head assembly of FIG. 7; [Figure 13A] FIG. 8 is a cross-sectional side view of the anvil of FIG. 4 positioned in a first section of the digestive tract and the stapling head assembly of FIG. 7 positioned in a second section of the digestive tract, with the anvil separated from the stapling head assembly. [Figure 13B] FIG. 8 is a cross-sectional side view of the anvil of FIG. 4 positioned in a first section of the digestive tract and the stapling head assembly of FIG. 7 positioned in a second section of the digestive tract, with the anvil secured to the stapling head assembly; [Figure 13C]FIG. 8 is a cross-sectional side view of the anvil of FIG. 4 positioned in a first segment of the digestive tract and the stapling head assembly of FIG. 7 positioned in a second segment of the digestive tract with the anvil retracted toward the stapling head assembly, thereby clamping tissue between the anvil and the stapling head assembly. [Figure 13D] FIG. 8 is a cross-sectional side view illustrating the anvil of FIG. 4 positioned in a first section of the digestive tract and the stapling head assembly of FIG. 7 positioned in a second section of the digestive tract with the stapling head assembly actuated to cut and staple clamped tissue. [Figure 13E] FIG. 13B is a cross-sectional side view showing the first and second segments of the digestive tract of FIG. 13A joined together by an end-to-end anastomosis. [Figure 14] 8 is a perspective view of a second exemplary alternative knife member, an exemplary mid-coupler, and a second exemplary alternative staple driver member that may be incorporated into the stapling head assembly of FIG. 7; [Figure 15] FIG. 15 is an exploded perspective view of the knife member, mid-coupler, and staple driver member of FIG. [Figure 16] FIG. 16 is a perspective view of the knife member of FIG. 15. [Figure 17] FIG. 16 is a plan view of the knife member of FIG. 15. [Figure 18] FIG. 16 is a perspective view of the intermediate coupler of FIG. 15. [Figure 19] FIG. 16 is a plan view of the intermediate coupler of FIG. 15. [Figure 20] FIG. 16 is a perspective view of the staple driver member of FIG. 15; [Figure 21] FIG. 16 is a top view of the staple driver member of FIG. 15 . [Figure 22] FIG. 15 is a cross-sectional side view of the knife member, mid-coupler, and staple driver member of FIG. 14 prior to coupling. [Diagram 23] FIG. 15 is a cross-sectional side view of the knife member, mid-coupler, and staple driver member of FIG. 14 after being coupled; [Figure 24]8 is a cross-sectional side view of a third exemplary alternative knife member and a third exemplary alternative staple driver member that may be incorporated into the stapling head assembly of FIG. 7 prior to the knife member and staple driver member being coupled to one another; [Diagram 25] FIG. 25 is a cross-sectional side view of the knife member and staple driver member of FIG. 24 after the knife member and staple driver member have been coupled together;

[0007] The drawings are not intended to be limiting in any manner, and it is contemplated that various embodiments of the technology may be embodied in other various ways, including those not necessarily depicted in the drawings. The accompanying drawings, which are incorporated in and form a part of this specification, illustrate several aspects of the technology and, together with the description, serve to explain the principles of the technology, with the understanding that the technology is not limited to the precise arrangements shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The following description of a specific embodiment of the present technology should not be used to limit its scope. Other embodiments, features, aspects, embodiments, and advantages of the present technology will become apparent to those skilled in the art from the following description, which is illustrative and is one of the best modes contemplated for carrying out the present technology. As will be understood, the technology described herein is capable of other different and obvious embodiments, all without departing from the technology. Thus, the drawings and description should be regarded as illustrative in nature, and not restrictive.

[0009] This application is a continuation of U.S. Patent Application Publication No. 2015 / 0083772, published on March 26, 2015, and entitled "Surgical Stapler with Rotary Cam Drive and Return," now abandoned; U.S. Patent No. 9,907,552, issued on March 6, 2018, and entitled "Control Features for Motorized Surgical Instrument;" U.S. Patent No. 10,478,189, issued on November 19, 2019, and entitled "Method of Applying an Annular Array of Staples to Tissue;" U.S. Patent Application Publication No. 2018 / 0132853, published on May 17, 2018, and entitled "Circular Stapler with Recessed Deck;" and U.S. Patent Application Publication No. 2018 / 0132849, published on May 17, 2018, and entitled "Staple Forming Pocket Configurations for Circular Surgical Instruments." "Stapler Anvil"; the disclosure of U.S. Patent Application Publication No. 2018 / 0310938, published November 1, 2018, entitled "Hysteresis Removal Feature in Surgical Stapling Instrument," is incorporated by reference.

[0010] I. Overview of an Exemplary Surgical Circular Stapling Surgical Instrument 1-2 illustrate an exemplary surgical circular stapling instrument (10) that may be used to provide an end-to-end, side-to-side, or end-to-side anastomosis between two cross-sections of an anatomical lumen, such as a portion of a patient's digestive tract. The instrument (10) of this example includes a handle assembly (100), a shaft assembly (200), a stapling head assembly (300), and an anvil (400). The handle assembly (100) includes a casing (110) that defines an obliquely oriented pistol grip (112). In some variations, the pistol grip (112) is oriented vertically. In some other variations, the pistol grip (112) is omitted. The handle assembly (100) further includes a user feedback feature (114). In some variations, a series of hash marks, colored areas, and / or other fixed indicators are positioned adjacent to the user feedback feature (114). Various suitable alternative features and configurations for handle assembly (100) will be apparent to those of ordinary skill in the art in view of the teachings herein.

[0011] The instrument (10) of the present embodiment further includes a battery pack (120). The battery pack (120) is operable to power a motor (not shown) within the pistol grip (112), as will be described in more detail below. The battery pack (120) is removable from the handle assembly (100). In particular, as shown in FIGS. 1-2, the battery pack (120) may be inserted into a socket (116) defined by the casing (110). After the battery pack (120) is fully inserted into the socket (116), a latch (122) of the battery pack (120) may resiliently engage and snap into an interior feature of the casing (110). To remove the battery pack (120), an operator may push the latches (122) inward to disengage them from the interior features of the casing (110) and then pull the battery pack (120) proximally out of the socket (116). It should be understood that the battery pack (120) and the handle assembly (100) may have complementary electrical contacts, pins and sockets, and / or other features that provide a path for electrical communication from the battery pack (120) to the electrically powered components in the handle assembly (100) when the battery pack (120) is inserted into the socket (116). It should also be understood that in some variations, the battery pack (120) is integrally integrated into the handle assembly (100) such that the battery pack (120) is not removable from the handle assembly (100).

[0012] The shaft assembly (200) extends distally from the handle assembly (100) and includes a preformed bend. In some variations, the preformed bend is configured to facilitate positioning the stapling head assembly (300) within the colon of a patient. A variety of suitable bend angles or radii of curvature that may be used will be apparent to one of ordinary skill in the art in view of the teachings herein. In some other variations, the shaft assembly (200) is straight and there is no preformed bend in the shaft assembly (200). Various exemplary components may be incorporated into the shaft assembly (200), as will be described in more detail below.

[0013] The stapling head assembly (300) is disposed at the distal end of the shaft assembly (200). As shown in FIGS. 1-2 and described in more detail below, the anvil (400) is configured to removably couple to the shaft assembly (200) adjacent the stapling head assembly (300). As also described in more detail below, the anvil (400) and stapling head assembly (300) are configured to cooperate to manipulate tissue in three ways, including clamping tissue, cutting tissue, and stapling tissue. A knob (130) at the proximal end of the handle assembly (100) is rotatable relative to the casing (110) to allow precise clamping of tissue between the anvil (400) and the stapling head assembly (300). When safety trigger (140) of handle assembly (100) is pivoted away from firing trigger (150) of handle assembly (100), firing trigger (150) can be actuated such that tissue is cut and stapled.

[0014] II. Exemplary Drive Assembly 3 illustrates various components of the shaft assembly (200), which connects components of the stapling head assembly (300) to components of the handle assembly (100). In particular, and as described above, the shaft assembly (200) includes an outer sheath (210) that extends between the handle assembly (100) and the body member (310). In this embodiment, the outer sheath (210) is rigid and includes a pre-formed curved section, as noted above.

[0015] The shaft assembly (200) further includes a trocar actuation rod (220) and a trocar actuation band assembly (230). A distal end of the trocar actuation band assembly (230) is fixedly attached to a proximal end of the shaft (332) of the trocar (330). A proximal end of the trocar actuation band assembly (230) is fixedly attached to a distal end of the trocar actuation rod (220). It should thus be understood that the trocar (330) translates longitudinally relative to the outer sheath (210) in response to the trocar actuation band assembly (230) and trocar actuation rod (220) translating relative to the outer sheath (210). The trocar actuation band assembly (230) is configured with a bend such that the trocar actuation band assembly (230) can move along a preformed curve in the shaft assembly (200) as the trocar actuation band assembly (230) is translated longitudinally relative to the outer sheath (210). However, the trocar actuation band assembly (230) has sufficient column strength and tensile strength to transfer distal and proximal forces from the trocar actuation rod (220) to the shaft (332) of the trocar (330). The trocar actuation rod (220) is rigid. The clip (222) is fixedly attached to the trocar actuation rod (220), and the clip (222) is configured to cooperate with complementary features in the handle assembly (100) to prevent the trocar actuation rod (220) from rotating within the handle assembly (100) while allowing the trocar actuation rod (220) to translate longitudinally within the handle assembly (100). The trocar actuation rod (220) further includes a coarse helical thread (224) and a fine helical thread (226).

[0016] The shaft assembly (200) further includes a stapling head assembly driver (240) that is slidably received within the outer sheath (210). A distal end of the stapling head assembly driver (240) is fixedly attached to a proximal end of a staple driver member (350). A proximal end of the stapling head assembly driver (240) is fixed to a drive bracket (250) via a pin (242). Thus, it should be understood that in response to the stapling head assembly driver (240) and drive bracket (250) translating relative to the outer sheath (210), the staple driver member (350) translates longitudinally relative to the outer sheath (210). The stapling head assembly driver (240) is configured with a bend such that the stapling head assembly driver (240) can move along a preformed curve in the shaft assembly (200) as the stapling head assembly driver (240) translates longitudinally relative to the outer sheath (210). However, the stapling head assembly driver (240) has sufficient column strength to transfer distal forces from the drive bracket (250) to the staple driver member (350). The drive bracket (250) includes a notch (252).

[0017] Although not shown in FIG. 3, it should be understood that the shaft assembly (200) may further include one or more spacer elements within the outer sheath (210). Such spacer elements may be configured to support the trocar actuation band assembly (230) and / or the stapling head assembly driver (240) while the trocar actuation band assembly (230) and / or the stapling head assembly driver (240) translate through the outer sheath (210). For example, such spacer elements may prevent the trocar actuation band assembly (230) and / or the stapling head assembly driver (240) from distorting while the trocar actuation band assembly (230) and / or the stapling head assembly driver (240) translate through the outer sheath (210). Various suitable forms that such spacer elements may take will be apparent to those of skill in the art in view of the teachings herein.

[0018] As shown in FIG. 3, the handle assembly (100) includes several components operable to actuate the anvil (400) and the stapling head assembly (300). The handle assembly (100) also includes components operable to selectively lock out the triggers (140, 150) based on the position of the anvil (400) relative to the stapling head assembly (300). When the triggers (140, 150) are locked out, the firing trigger (150) is prevented from initiating actuation of the stapling head assembly (300). Thus, the firing trigger (150) is operable to initiate actuation of the stapling head assembly (300) only when the position of the anvil (400) relative to the stapling head assembly (300) is within a predetermined range. The components of the handle assembly (100) that provide the above operability are described in more detail below.

[0019] III. Exemplary Anvils In the following discussion of the anvil (400), the terms "distal" and "proximal" (and variations thereof) are used to refer to the orientation of the anvil (400) when the anvil (400) is coupled to the shaft assembly (200) of the instrument (10). Thus, the proximal features of the anvil (400) are closer to the operator of the instrument (10), while the distal features of the anvil (400) are further from the operator of the instrument (10).

[0020] As best seen in FIGS. 4-6, the anvil (400) of this embodiment includes a head (410) and a shank (420). The head (410) includes a proximal surface (412) that defines a plurality of staple forming pockets (414). The staple forming pockets (414) are arranged in a concentric annular array of two rows in this embodiment. In some other variations, the staple forming pockets (414) are arranged in a concentric annular array of three or more rows. The staple forming pockets (414) are configured to deform the staples as the staples are driven into the staple forming pockets (414). For example, each staple forming pocket (414) may deform a generally U-shaped staple into a B-shape, as is known in the art. As best seen in FIG. 4, the proximal surface (412) terminates at an inner edge (416) that defines the outer boundary of an annular recess (418) that surrounds the shank (420).

[0021] The stem (420) defines a bore (422) and includes a pair of pivoting latch members (430) positioned within the bore (422). As best seen in FIG. 4, each latch member (430) includes a T-shaped distal end (432), a rounded proximal end (434), and a latch shelf (436) located distally relative to the proximal end (434). The T-shaped distal end (432) secures the latch member (430) within the bore (422). The latch members (430) are positioned within the bore (422) such that the proximal end (434) is positioned at the proximal end of a lateral opening (424) molded through a sidewall of the stem (420). The lateral opening (424) thus provides clearance for the proximal end (434) and latch shelf (436) to deflect radially outward from the longitudinal axis defined by the shank (420). However, the latch member (430) is configured to resiliently bias the proximal end (434) and latch shelf (436) to pivot radially inward toward the longitudinal axis defined by the shank (420). In this manner, the latch member (430) acts as a retaining clip, which allows the anvil (400) to be removably secured to the trocar (330) of the stapling head assembly (300), as will be described in more detail below. However, it should be understood that the latch shelf (436) is merely optional. The anvil (400) may be removably secured to the trocar (330) using any other suitable components, mechanisms, or techniques.

[0022] As best shown in Figures 4-5, the shank (420) of this embodiment includes a set of longitudinally extending splines (426) spaced about the shank (420) in an angular array. The proximal end of each spline (426) includes a respective leading edge (428). The plurality of longitudinally extending splines (316) (see Figure 8) are equidistantly spaced in the angular array within the bore (314). As will be explained in more detail below, the splines (426) are configured to engage corresponding splines (316) of the body member (310) of the stapling head assembly (300) to consistently provide a predetermined angular alignment between the anvil (400) and the stapling head assembly (300). As also described below, this angular alignment can ensure that the staple forming pockets (414) of the anvil (400) are in proper and consistent angular alignment with the staple openings (324) of the stapling head assembly (300).

[0023] In some cases, it may be desirable to change the configuration and arrangement of the staple forming pockets (414) within the anvil (400). It should be understood that reconfiguring and repositioning the staple forming pockets (414) may result in a reconfiguration and repositioning of the staples (90) formed by the staple forming pockets (414). For example, the configuration and arrangement of the staple forming pockets (414) may affect the structural integrity of the anastomosis (70) secured by the staples (90). In addition, the configuration and arrangement of the staple forming pockets (414) may affect the hemostasis achieved in the anastomosis (70) secured by the staples (90). The following description relates to several exemplary variations of the anvil (400) that provide different configurations and arrangements of the staple forming pockets than the staple forming pockets (414). Various suitable ways in which the alternative configurations for the anvil (400) described below may be incorporated into the instrument (10) will be apparent to those skilled in the art in view of the teachings herein.

[0024] For example, staples formed using the exemplary alternative anvils may have an appearance similar to at least a portion of the staples shown and described in U.S. Patent No. 10,092,292, issued October 9, 2018, entitled "Staple Forming Features for Surgical Stapling Instrument," the disclosure of which is incorporated herein by reference. By way of further example only, the formed staples may have an appearance similar to at least a portion of the staples shown and described in U.S. Patent Application Publication No. 2018 / 0132849, published May 17, 2018, entitled "Staple Forming Pocket Configurations for Circular Surgical Stapler Anvil," the disclosure of which is incorporated herein by reference.

[0025] Additionally or alternatively, the anvil (400) may be further constructed and operable in accordance with at least some of the teachings of the following patent documents, the disclosures of which are incorporated herein by reference: U.S. Patent Nos. 5,205,459; 5,271,544; 5,275,322; 5,285,945; 5,292,053; 5,333,773; 5,350,104; 5,533,661; and / or 8,910,847. Still other suitable configurations will be apparent to those of skill in the art in view of the teachings herein.

[0026] IV. Exemplary Stapling Head Assembly A. Overview As best seen in Figures 7-9, the stapling head assembly (300) of this embodiment is coupled to the distal end of the shaft assembly (200) and comprises a body member (310) and a slidable staple driver member (350). The body member (310) includes a distally extending cylindrical inner core member (312). The body member (310) is fixedly attached to the outer sheath (210) of the shaft assembly (200). Thus, the body member (310) and the outer sheath (210) together serve as a mechanical base for the stapling head assembly (300).

[0027] As shown in FIG. 8, the inner core member (312) of the body member (310) defines a bore (314). When the shank (420) is secured to the trocar (330) and the trocar (330) is retracted proximally, the inner diameter of the bore (314) in the inner core member (312) of the body member (310) laterally restrains the latch member (430) to maintain engagement between the latch shelf (436) and the proximal surface (338) of the head (334) of the trocar (330). This engagement prevents the anvil (400) from being released from the trocar (330) during firing of the stapling head assembly (300). The distal end of the splines (316) includes a leading edge (318) configured to complement a leading edge (428) of the splines (426) on the shank (420) of the anvil (400). In particular, after shank (420) is secured to trocar (330), as will be described in more detail below, and when anvil (400) is thereafter retracted proximally relative to stapling head assembly (300), as will be described in more detail below, leading edges (318, 428) may cooperatively engage one another to drive the anvil (400) in rotation relative to trocar (330) and bring splines (426) of the anvil (400) into angular alignment with the gaps between splines (316) of body member (310). Thus, splines (316, 426) are configured to cooperate with one another such that staples expelled through staple openings (324) are consistently and accurately driven into corresponding staple forming pockets (414) regardless of the angular orientation of anvil (400) relative to stapling head assembly (300) when the anvil (400) is initially secured to trocar (330).

[0028] The trocar (330) is coaxially positioned within the inner core member (312) of the body member (310). As will be described in more detail below, the trocar (330) is operable to translate distally and proximally relative to the body member (310) in response to rotation of the knob (130) relative to the casing (110) of the handle assembly (100). The trocar (330) comprises a shaft (332) and a head (334). The head (334) includes a pointed tip (336) and an inwardly extending proximal surface (338). Thus, the shaft (332) is reduced in outer diameter just proximal to the head (334), with the proximal surface (338) providing a transition between the reduced outer diameter of the shaft (332) and the outer diameter of the head (334). In this embodiment, the tip (336) is pointed, but is not sharp. Thus, the tip (336) does not easily cause trauma to tissue due to accidental contact with the tissue. The head (334) and the distal portion of the shaft (332) are configured to be inserted into the hole (422) of the anvil (400). The proximal surface (338) and the latch shelf (436) have a complementary position and configuration such that the latch shelf (436) engages the proximal surface (338) when the shank (420) of the anvil (400) is fully seated on the trocar (330). Thus, the anvil (400) is secured to the trocar (330) via a snap fit by the latch member (430).

[0029] The staple driver member (350) is operable to actuate longitudinally within the body member (310) in response to activation of a motor, as will be described in more detail below. The staple driver member (350) includes two concentric annular arrays of staple drivers (352) presented distally. The staple drivers (352) are arranged to correspond to the arrangement of the staple forming pockets (414) described above. Thus, each staple driver (352) is configured to drive a corresponding staple into a corresponding staple forming pocket (414) upon actuation of the stapling head assembly (300). As described above, it should be understood that the arrangement of the staple drivers (352) can be modified just as the staple forming pockets (414) can be modified. The staple driver member (350) also defines a bore (354) configured to coaxially receive the inner core member (312) of the body member (310). An annular array of studs (356) projects distally from the distally presented surface surrounding the holes (354).

[0030] The knife member (340) is coaxially positioned within the staple driver member (350). The knife member (340) includes a distally presented sharpened circular cutting edge (342). The knife member (340) is sized such that the knife member (340) defines an outer diameter that is smaller than the diameter defined by the inner annular array of staple drivers (352). The knife member (340) has a cylindrical wall (360) integrally formed with a proximal flange (362). The proximal flange (362) extends radially inward relative to the cylindrical wall (360). The inner diameter of the proximal flange (362) of the knife member (340) defines an opening (344) configured to coaxially receive an inner core member (e.g., the inner core member (312) of the body member (310)). The proximal flange (362) includes an annular array of apertures (346). The annular array of apertures (346) formed in the knife member (340) is configured to complement the annular array of studs (356) of the staple driver member (350), such that the knife member (340) is fixedly attached to the staple driver member (350) via the studs (356) and the apertures (346). By way of example only, the studs (356) may be heat staked to the knife member (340) using techniques known in the art. Other suitable structural relationships between the knife member (340) and the staple driver member (350) will be apparent to those of ordinary skill in the art in view of the teachings herein.

[0031] A deck member (320) is fixedly attached to the body member (310). The deck member (320) includes a distally directed deck surface (322) that defines two concentric annular arrays of staple openings (324). The staple openings (324) are arranged to correspond to the arrangement of the staple drivers (352) and staple forming pockets (414) described above. Thus, each staple opening (324) is configured to provide a path for a corresponding staple driver (352) to drive a corresponding staple through the deck member (320) and into the corresponding staple forming pocket (414) when the stapling head assembly (300) is actuated. It should also be understood that in some cases, the configuration and arrangement of the staple openings (324) in the deck member (320) may be modified just as may the arrangement of the staple forming pockets (414). It should also be appreciated that a variety of structures and techniques may be used to accommodate the staples within the stapling head assembly (300) before the stapling head assembly (300) is actuated. Such structures and techniques used to accommodate the staples within the stapling head assembly (300) may prevent the staples from inadvertently dropping out of the staple openings (324) before the stapling head assembly (300) 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 shown in FIG. 7, the deck member (320) defines an inner diameter that is only slightly larger than the outer diameter defined by the knife member (340). Thus, the deck member (320) is configured to permit the knife member (340) to translate distally to a point where the cutting edge (342) is distal to the deck surface (322).

[0032] B. Exemplary Alternative Knife and Staple Driver Members Figures 10-11 illustrate a first exemplary alternative knife member (540) and a first exemplary alternative staple driver member (550) that may be used with a modified version of instrument (10). In particular, Figure 10 illustrates an exploded perspective view of the knife member (540) and staple driver member (550), and Figure 11 illustrates a top view of the knife member (540) and staple driver member (550) of Figure 10. The knife member (540) and staple driver member (550) of this embodiment are constructed and operative like the knife member (340) and staple driver member (350) detailed above, except for the differences described below.

[0033] Similar to staple driver member (350), staple driver member (550) is operable to actuate longitudinally within a body member (e.g., body member (310)) in response to actuation of a motor. Staple driver member (550) includes two concentric annular arrays of distally presented staple drivers (552). The staple drivers (552) are arranged to correspond to the arrangement of the staple forming pockets (similar to staple forming pockets (414)) described above. Staple driver member (550) defines a bore (554) configured to coaxially receive an inner core member (e.g., inner core member (312) of body member (310)). An annular array of studs (556) protrude distally from a distally presented surface surrounding the bore (554).

[0034] Similar to knife member (340), knife member (540) may be coaxially positioned within staple driver member (550). Knife member (540) includes a distally presented, sharpened, circular cutting edge (542). Knife member (540) includes a body (558). Body (558) has a cylindrical wall (560) integrally formed with a proximal flange (562). The proximal flange (562) extends radially inward relative to the cylindrical wall (560). An inner diameter of the proximal flange (562) of knife member (540) defines an opening (544) configured to coaxially receive an inner core member (e.g., inner core member (312) of body member (310)). Proximal flange (562) includes an annular array of openings (546).

[0035] The annular array of apertures (546) formed in the knife member (540) is configured to complement the annular array of studs (556) of the staple driver member (550), with the knife member (540) being fixedly attached to the staple driver member (550) via the studs (556) and apertures (546). In particular, FIG. 11 illustrates six individual studs (556) of the staple driver member (550) disposed in six respective apertures (546) of the knife member (540). By way of example only, the studs (556) may be heat staked to the knife member (540) using techniques known in the art. The knife member (540) and staple driver member (550) may be driven distally as also shown in FIG. 13D with respect to the stapling head assembly (300). As knife member (540) translates distally, cutting edge (542) of knife member (540) cuts excess tissue positioned within the annular recess (e.g., annular recess (418) of anvil (400)) and within the interior of knife member (540).

[0036] C. Exemplary Anvil Ligation Detection In some variations of the instrument (10), it may be desirable to provide the instrument (10) with features configured to indicate proper and / or improper coupling of the anvil (400) to the trocar (330) of the stapling head assembly (300). In the example shown in Figures 12A-12B, the trocar (330) includes a colored region (333) that is longitudinally positioned in a position such that the colored region (333) is exposed before the shank (420) is fully seated on the trocar (330) (Figure 12A) and is covered when the shank (420) is fully seated on the trocar (330) (Figure 12B).

[0037] Additionally or alternatively, the stapling head assembly (300) may be further constructed and operative in accordance with at least some of the teachings of the following patent documents, the disclosures of which are incorporated herein by reference: U.S. Patent Nos. 5,205,459, 5,271,544, 5,275,322, 5,285,945, 5,292,053, 5,333,773, 5,350,104, 5,533,661, and / or 8,910,847. Still other suitable configurations will be apparent to those skilled in the art in view of the teachings herein.

[0038] D. Exemplary Tissue Gripping Features It may be desirable to provide variations of the stapling head assembly (300) that include features that enhance gripping of tissue during actuation of the stapling head assembly (300) to facilitate effective tissue cutting and deployment of staples without increasing the risk of damaging the patient's tissue as the stapling head assembly (300) slides along the tissue during positioning of the stapling head assembly (300). By way of further example, one such deck member is shown and described in U.S. patent application Ser. No. 16 / 583,690, entitled "Circular Surgical Stapler," filed Sep. 26, 2019, the disclosure of which is incorporated herein by reference.

[0039] V. Exemplary Clamping and Firing Procedures 13A-13E illustrate an instrument (10) used to create an anastomosis (70) between two tubular anatomical structures (20, 40). By way of example only, the tubular anatomical structures (20, 40) may include a section of the patient's esophagus, a section of the patient's colon, other sections of the patient's digestive tract, or any other tubular anatomical structures. As shown in FIG. 13A, an anvil (400) is positioned within one tubular anatomical structure (20) and a stapling head assembly (300) is positioned within the other tubular anatomical structure (40). In a variation in which the tubular anatomical structures (20, 40) include sections of the patient's colon, the stapling head assembly (300) may be inserted through the patient's rectum. It should also be understood that while the procedure illustrated in FIGS. 13A-13E is an open surgical procedure, the procedure may also be performed as a laparoscopic procedure. A variety of suitable methods in which instrument (10) may be used to laparoscopically create an anastomosis (70) will be apparent to those skilled in the art in view of the teachings herein.

[0040] As shown in FIG. 13A, the anvil (400) is positioned within the tubular anatomical structure (20) such that the shank (420) protrudes from the open cutting end (22) of the tubular anatomical structure (20). In this embodiment, a purse string suture (30) is provided around a central region of the shank (420) to roughly secure the position of the anvil (400) within the tubular anatomical structure (20). In some other variations, the purse string suture (30) is fastened around the proximal end of the shank (420). In some such variations, the proximal end of the shank (420) may include a notch or other feature to securely capture the purse string suture (30). Continuing with this embodiment, the stapling head assembly (300) is positioned within the tubular anatomical structure (40) such that the trocar (330) protrudes from the open cutting end (42) of the tubular anatomical structure (20). A purse string suture (50) is provided around the central region of the shaft (332) to roughly secure the position of the stapling head assembly (300) within the tubular anatomical structure (40). The stapling head assembly (300) is then urged distally to ensure that the stapling head assembly (300) is fully seated in the distal end of the tubular anatomical structure (40).

[0041] Next, as shown in FIG. 13B, the anvil (400) is secured to the trocar (330) by inserting the trocar (330) through the hole (422). The latch member (430) engages the head (334) of the trocar (330), thereby providing a secure fit between the anvil (400) and the trocar (330). The operator then rotates the knob (130) via the pistol grip (112) while holding the casing (110) stationary. This rotation of the knob (130) retracts the trocar (330) and anvil (400) proximally. As shown in FIG. 13C, this proximal retraction of the trocar (330) and anvil (400) causes the tissue of the tubular anatomical structure (20, 40) to be compressed between the surfaces (412, 322) of the anvil (400) and the stapling head assembly (300). As this occurs, the operator can observe tactile resistance or feedback through the knob (130) as the knob (130) is rotated, which indicates that the tissue is being compressed. As the tissue is compressed, the operator can use the user feedback feature (114) to determine whether the gap distance (d) between the opposing surfaces (412, 322) of the anvil (400) and the stapling head assembly (300) is adequate, and make adjustments via the knob (130) if necessary.

[0042] After the operator properly sets the gap distance (d) via knob (130), the operator actuates safety trigger (140) to enable actuation of firing trigger (150). The operator then actuates firing trigger (150), which actuates stapling head assembly (300) by driving knife member (340) and staple driver member (350) distally, as shown in FIG. 13D. As knife member (340) translates distally, cutting edge (342) of knife member (340) severs excess tissue positioned within annular recess (418) of anvil (400) and within the interior of knife member (340).

[0043] As shown in FIG. 5, the anvil (400) of this embodiment includes a breakaway washer (417) within an annular recess (418). This washer (417) is broken by the knife member (340) when the knife member (340) moves through its full distal range of motion from the position illustrated in FIG. 13C to the position illustrated in FIG. 13D. The gradually increasing radius of curvature of the second surface region provides an increasing mechanical advantage as the knife member (340) reaches the end of its distal motion, which may provide a greater force required to break the washer (417). Of course, in some variations, the breakaway washer (417) may be omitted entirely. It should be appreciated that in variations in which a washer (417) is included, the washer (417) may also serve as a cutting board for the knife member (340) to aid in the cutting of tissue.

[0044] As the staple driver member (350) translates distally from the position shown in Figure 13C to the position shown in Figure 13D, the staple driver member (350) drives the staples (90) through the tissue of the tubular anatomical structure (20, 40) and into the staple forming pockets (414) of the anvil (400). The staple forming pockets (414) cause the driven staples (90) to deform into a B-shape or into a three-dimensional shape, as is known in the art. In either case, the formed staples (90) securely close the ends of the tissue together.

[0045] As shown in FIG. 13D, after the operator actuates the stapling head assembly (300), the operator rotates the knob (130) to drive the anvil (400) distally away from the stapling head assembly (300) to increase the gap distance (d) and facilitate the release of tissue between the surfaces (412, 322). The operator then removes the instrument (10) from the patient with the anvil (400) still secured to the trocar (330). Referring again to the example in which the tubular anatomical structures (20, 40) comprise a section of the patient's colon, the instrument (10) may be removed through the patient's rectum. Once the instrument (10) is removed, the tubular anatomical structures (20, 40) are left securely closed by the double annular array of staples (90) at the anastomosis (70), as shown in FIG. 13E. The inner diameter of the anastomosis (70) is defined by the cut edge (60) left by the knife member (340).

[0046] VI. EXEMPLARY ALTERNATIVE KNIFE MEMBER CONNECTIONS In some cases, the knife member (340, 540) may be manufactured using a material that may be a fully annealed steel material. This material may be deep drawn to form the proximal flange (362, 562) of the knife member (340, 540). This deep drawing process may limit the material selection for the knife member (340, 540) and / or may limit the range of manufacturing processes suitable for the knife member (340, 540). The material selection and / or manufacturing process may affect the mechanical properties (e.g., hardness) of the knife member (340, 540). For example, a softer material that is desired for a deep drawing process may be cold worked to obtain the desired hardness. The deep drawing process may have slight variations in the wall thickness of the cylindrical wall (360, 560). In addition, the heat staking process used to couple the knife member (340, 540) with the staple driver member (350, 550) may be process dependent.

[0047] For at least these reasons, it may be desirable to couple the knife members (340, 540) to the staple driver members (350, 550) in a manner that expands the range of materials suitable for the knife members (340, 540) to provide additional manufacturing flexibility and / or to provide a more uniform wall thickness of the cylindrical wall (360, 560) of the knife members (340, 540).

[0048] A. Indirect connection of knife components 14-23 show a second exemplary alternative knife member (610), a second exemplary alternative staple driver member (612), and an exemplary connector (614). In particular, FIG. 14 shows a perspective view of the knife member (610), the staple driver member (612), and the connector (614), and FIG. 15 shows an exploded perspective view of the knife member (610), the staple driver member (612), and the connector (614). The knife member (610) and the staple driver member (612) of this embodiment are configured and operable like the knife members (340, 540) and the staple driver members (350, 550), with differences that are described below. The connector (614) may couple with both the knife member (610) and the staple driver member (612) and provide an indirect connection between the knife member (610) and the staple driver member (612).

[0049] Knife member (610), staple driver member (612), and connector (614) may be incorporated into modified variations of instrument (10), which may include a body (shown as handle assembly (100)), a shaft (shown as shaft assembly (200)), and anvil (shown as anvil (400)). For example, knife member (610), staple driver member (612), and connector (614) may be insertable into stapling head assembly (300) in place of knife member (340) and staple driver member (350). The stapling head assembly (300) may be operable to drive an annular array of at least one staple (90) through tissue and may include a knife member (610), a staple driver member (612), a connector (614), as well as an inner body member (310), a deck member (320), a trocar (330), and an annular array of at least one staple (90). The stapling head assembly (300) defines a longitudinal axis (LA). The stapling head assembly (300) includes an anvil coupling feature (e.g., a trocar (330)). The anvil (400) is configured to couple with the trocar (330) and deform the annular array of at least one staple (90) driven by the staple driver member (612).

[0050] 1. Second Exemplary Alternative Knife Member 16-17 illustrate a knife member (610). In particular, FIG. 16 illustrates a perspective view of the knife member (610) of FIG. 15, and FIG. 17 illustrates a plan view of the knife member (610) of FIG. 16. The knife member (610) includes a proximal end (616), a distal end (618), and a barrel (620) extending between the proximal end (616) and the distal end (618). The distal end (618) of the knife member (610) includes a circular cutting edge (622) configured to cut tissue. The barrel (620) defines an inner surface (624) and an outer surface (626) of the knife member (610). The barrel (620) extends along a longitudinal axis (LA) of the stapling head assembly (300). The barrel (620) includes at least one coupling feature (shown as an opening (628)) that operably couples the knife member (610) with the staple driver member (612). The coupling feature is shown as an opening (628), however, various suitable coupling features are envisioned. Additionally, while four individual radially spaced coupling features are shown, more or fewer coupler features are envisioned, which may have the same or different spacing along the knife member (610). The opening (628) is shown as a rectangular opening that extends completely through the barrel (620), however, the openings (628) may have various suitable shapes and sizes, and may be the same or different from one another. As shown in FIG. 16, the opening (628) has a width (W).

[0051] As shown in FIG. 17, the cylindrical body (620) of the knife member (610) defines a central cavity (630) configured to coaxially receive an inner core member (e.g., the inner core member (312) of the body member (310). Similar to the knife members (340, 540), the knife member (610) may be coaxially positioned within the staple driver member (612). As shown, the cylindrical body (620) has a generally uniform thickness (t) disposed between an inner surface (624) and an outer surface (626). The inner surface (624) defines an inner diameter (ID) of the knife member (610), and the outer surface (626) defines an outer diameter (OD) of the knife member (610). Unlike knife members (340, 540), the proximal end (616) of knife member (610) does not include a radially inwardly extending proximal flange (similar to proximal flanges (362, 562)). Thus, knife member (610) is not shown as including an annular array of openings (346, 546) disposed in proximal flange (362, 562). Knife member (610) may be formed from a metallic material. Knife member (610) is sized such that an outer diameter (OD) of knife member (610) is smaller than a diameter defined by an inner annular array of staple drivers (660) of staple driver member (610) described below. Central cavity (630) of knife member (610) is configured to coaxially receive an inner core member (e.g., inner core member (312) of body member (310)).

[0052] 2. Exemplary Connectors 18-19 show the connector (614). In particular, FIG. 18 shows a perspective view of the connector (614) of FIG. 15, and FIG. 19 shows a plan view of the connector (614) of FIG. 18. As discussed in more detail below with reference to FIGS. 22-23, the connector (614) is configured to couple the knife member (610) with the staple driver member (612). For example, the connector (614) may be directly coupled to both the knife member (610) and the staple driver member (612). As shown in FIG. 18, the connector (614) includes a proximal end (632), a distal end (634), and a body (636) disposed between the proximal end (632) and the distal end (634). The proximal end (632) of the connector (614) includes a planar proximal surface (638) (see FIG. 22).

[0053] The body (636) of the connector (614) includes a base (640) and a number of arms (642) extending distally from the base (640). The body (636) includes an inner surface (644) and an outer surface (646). The base (640) of the connector (614) may include an inwardly extending flange (652). The inwardly extending flange (652) may increase the surface area contacting the staple driver member (612), which may provide a more robust or stronger connection. The connector (614) may be formed from a polymeric material. The arms (642) may be flexible such that one or more of the arms (642) may be deflected radially inward to couple with the knife member (610). The arms (642) may be separated by a number of slots (648).

[0054] The connector (614) includes at least one interlocking feature (shown as protrusion (650)) that is lockingly engaged with at least one interlocking feature of the barrel (620) of the knife member (610). The interlocking feature of the connector (614) is shown as protrusion (650), although a variety of suitable interlocking features are envisioned. Additionally, while four individual radially spaced interlocking features are shown in FIG. 19, more or fewer interlocking features having the same or different spacing are envisioned. The protrusion (650) is shown as having a width (W) that corresponds to the width (W) of the opening (628) of the knife member (610). The protrusion (650) may extend radially outward from the arm (642). The protrusion (650) extends from an outer surface (646) of the body (636). Protrusions (650) are configured to lockingly engage openings (628) in barrel (620) of knife member (610). Although protrusions (650) are shown as outwardly rounded protrusions, protrusions (650) may have a variety of suitable shapes and sizes and may be the same or different from one another. Protrusions (650) may be integrally formed as a single piece with arms (642).

[0055] 3. Second Exemplary Alternative Staple Driver Member 20-21 illustrate a staple driver member (612). In particular, FIG. 20 illustrates a perspective view of the staple driver member (612) of FIG. 15, and FIG. 21 illustrates a plan view of the staple driver member (612) of FIG. 20. Similar to the staple driver members (350, 550), the staple driver member (612) is operable to actuate longitudinally within a body member (e.g., body member (310)) in response to actuation of a motor. The staple driver member (612) includes a proximal end (654), a distal end (656), and a body (658) disposed between the proximal end (654) and the distal end (656). The body (658) includes two concentric annular arrays presented distally of the staple driver (660). The staple drivers (660) are positioned to correspond to the positioning of the staple forming pockets (similar to staple forming pockets (414)) described above, such that each staple driver (660) is configured to drive a corresponding staple into a corresponding staple forming pocket (414) of the anvil (400) upon actuation of the stapling head assembly (300).

[0056] As discussed above, it should be understood that the arrangement of the staple driver (660) may be modified just as the arrangement of the staple forming pockets (414). The staple driver member (612) includes an inner surface (662) defining a bore (664) configured to coaxially receive an inner core member (e.g., the inner core member (312) of the body member (310). As shown in FIG. 21, the inner surface (662) may be generally circular. Unlike the staple driver members (350, 550), the staple driver member (612) is not shown as including an annular array of studs (e.g., an annular array of studs (356, 556)) projecting distally from a distally presented surface (shown as a planar surface (666) in FIGS. 23-24) surrounding the bore (664).

[0057] The knife member (610), staple driver member (612), and connector (614) may be driven distally, as also shown in FIG. 13D for the stapling head assembly (300). As the knife member (610) translates distally, the cutting edge (622) of the knife member (610) severs excess tissue located within the annular recess (e.g., the annular recess (418) of the anvil (400)) and within the interior of the knife member (610). The inner diameter of the anastomosis is defined by the cut edges left by the knife member (610). Other suitable structural relationships between the knife member (610) and the staple driver member (612) will be apparent to those of skill in the art in view of the teachings herein.

[0058] 4. Exemplary Knife Attachment Methods A method of manufacture will also be described with reference to Figures 22-23. Figure 22 shows a cross-sectional side view of the knife member (610), staple driver member (612) and connector (614) of Figure 14 prior to the components being coupled together. Figure 23 shows a cross-sectional side view of the knife member (610), staple driver member (612) and connector (614) of Figure 14 after the components have been coupled together.

[0059] According to an exemplary embodiment, to form the knife member (610), a blank may be created by cutting a long hollow tube to a desired length. Once formed, the blank may be centerless ground so that the blank has a uniform wall thickness. Thus, the knife member (610) may have a greater concentricity between the inside diameter (ID) and the outside diameter (OD) relative to the knife members (340, 540). The outside diameter (OD) of the knife member (610) may be the same or similar to the knife members (340, 540). Additionally, the knife member (610) may have a higher hardness and / or may be more suitable for one or more grinding processes and is less likely to develop burrs compared to the exemplary materials (e.g., SS305) used to form the knife members (340, 540). SS305 is an austenitic chromium-nickel stainless steel that is corrosion resistant and is suitable for rigorous cold forging operations. SS305 may be more suitable for deep drawing, which may be used to produce the knife members (340, 540) as opposed to grinding operations, which may be used to form the knife members (610). As mentioned above, the knife members (610, 710) may be formed from metallic materials. For example, the knife members (610, 710) may be formed from a variety of steel alloys, including, but not limited to, SS303 and SS304. SS303 is an austenitic stainless steel that may allow for a wide range of machining operations, and the addition of sulfur may help break down turnings while reducing cutting tool resistance. SS304 is an austenitic stainless steel that may contain a nickel content of about 8-10.5 weight percent and a chromium content of about 18-20 weight percent. The high amount of chromium and nickel may provide SS304 with corrosion resistance.

[0060] It is envisioned that the knife member (610) may be coupled together with the connector (614) before or after the connector (614) is coupled with the staple driver member (612). For example, the method may include welding the connector (614) to the staple driver member (612) before or after the knife member (610) is mechanically coupled with the connector (614). In particular, the connector (614) may be welded to the staple driver member (612), and then the knife member (610) may be inserted between an inner surface (662) of the staple driver member (612) and an outer surface (646) of the connector (614) and subsequently fixably coupled with the connector (614) as described below. Alternatively, knife member (610) may be mechanically coupled with connector (614) by coupling protrusion (650) with opening (28), and connector (614) may then be inserted into staple driver member (612) and fixably coupled together. As shown, planar proximal surface (638) of connector (614) may be fixably coupled together with planar surface (666) of staple driver member (612) using at least one welding process. For example, the welding process may include harmonic welding (i.e., sonic welding). However, it is also envisioned that connector (614) may be fixably coupled together with staple driver member (612) using a variety of other suitable methods (e.g., overmolding).

[0061] According to an exemplary embodiment, with regard to coupling between knife member (610) and connector (614), respective coupling features of knife member (610) and connector (614) may directly fixably attach knife member (610) to connector (614). For example, at least one coupling feature (e.g., opening (628)) of barrel (620) of knife member (610) may couple with at least one corresponding coupling feature (e.g., protrusion (650)) of connector (614) to operably couple knife member (610) to staple driver member (612). Connector (614) may be coaxially disposed within central cavity (630) of barrel (620) of knife member (610).

[0062] With respect to the coupling of the knife member (610) and the connector (614), the arms (642) of the connector (614) may be flexible such that one or more of the arms (642) of the connector (614) may deflect radially inward. As shown, as the knife member (610) translates relative to the connector (614), the protrusions (650) of the connector (614) deflect radially inward. To fixably attach the connector (614) and the staple driver member (612) together, the protrusions (650) of the connector (614) deflect radially outward into corresponding openings (628) of the knife member (610). This causes the protrusions (650) of the connector (614) to snap into corresponding openings (628) of the knife member (610). As shown in Figure 23, the knife member (610) is indirectly coupled (i.e., not directly coupled) to the staple driver member (612). However, it is contemplated that the knife member (610) may be directly coupled to the staple driver member (612), as described below with reference to Figures 24-25.

[0063] Various advantages may be obtained with this method of attachment, including one or more of an increased sharpness of the cutting edge (622) of the knife member (610), a generally uniform tip radius of the cutting edge (622) of the knife member (610), an increased hardness of the knife member (610), and / or reduced variation in height of the knife member (610). The reduced variation in height of the knife member (610) may allow for a more uniform cutting force against the breakaway washer (417) and / or a simpler manufacturing process.

[0064] B. Direct connection of knife components Figures 24-25 show a third exemplary alternative knife member (710) and a third exemplary alternative staple driver member (712). Figure 24 shows a cross-sectional side view of the knife member (710) and staple driver member (712) prior to coupling the components together. Figure 25 shows a cross-sectional side view of the knife member (710) and staple driver member (712) after they have been coupled together. According to this exemplary embodiment, the knife member (710) couples directly to the staple driver member (712).

[0065] The knife member (710) and staple driver member (712) of this embodiment are configured and operable like knife member (610) and staple driver member (612), with the differences described below. Like knife member (610) and staple driver member (612), knife member (710) and staple driver member (712) may be incorporated into modified variations of instrument (10), which may include a body (shown as handle assembly (100)), a shaft (shown as shaft assembly (200)), and anvil (shown as anvil (400)). For example, knife member (710) and staple driver member (712) may be insertable into stapling head assembly (300) in place of knife member (340) and staple driver member (350).

[0066] 1. Third Exemplary Alternative Knife Member The knife member (710) is similar to the knife member (610) shown and described with reference to Figures 16-17 and 22-23. The knife member (710) includes a proximal end (716), a distal end (718), and a barrel (720) extending between the proximal end (716) and the distal end (718). The distal end (718) of the knife member (710) includes a circular cutting edge (722) configured to cut tissue. The barrel (720) defines an inner surface (724) and an outer surface (726) of the knife member (710). The barrel (720) extends along a longitudinal axis (LA) of the stapling head assembly (300). Body (720) includes at least one interlocking feature (shown as aperture (728)), which may be similar to aperture (628) that fixably interlocks knife member (710) with staple driver member (712). Although the interlocking feature is shown as aperture (728), a variety of suitable interlocking features are envisioned. As with apertures (628), the number and spacing of apertures (728) may vary. Although apertures (728) are shown as rectangular apertures extending completely through body (720), apertures (728) may have a variety of suitable shapes and sizes, and may be the same or different from one another.

[0067] As shown, the cylindrical body (720) of the knife member (710) defines a central cavity (730) configured to coaxially receive an inner core member (e.g., the inner core member (312) of the body member (310). The knife member (710) may be coaxially positioned within the staple driver member (712). Unlike the knife members (340, 540), the proximal end (716) of the knife member (710) does not include a radially inwardly extending proximal flange (similar to the proximal flanges (362, 562)). Thus, the knife member (710) is not shown as including an annular array of openings (346, 546) disposed in the proximal flanges (362, 562). The knife member (710) may be formed from a metallic material. Knife member (710) is sized such that the outer diameter of knife member (710) is smaller than the diameter defined by the inner annular array of staple drivers (760) of staple driver member (710) described below. Central cavity (730) of knife member (710) is configured to coaxially receive an inner core member (e.g., inner core member (312) of body member (310)).

[0068] 2. Third Exemplary Alternative Staple Driver Member Staple driver member (712) is similar to staple driver member (612) shown and described with reference to Figures 20-23. Similar to staple driver members (350, 550, 612), staple driver member (712) is operable to actuate longitudinally within a body member (e.g., body member (310)) in response to actuation of a motor. Staple driver member (712) includes a proximal end (754), a distal end (756), and a body (758) disposed between the proximal end (754) and the distal end (756). Body (758) includes two concentric annular arrays of staple drivers (760) presented distally. Staple drivers (760) are arranged to correspond to the arrangement of staple forming pockets (similar to staple forming pockets (414)) described above. Staple driver member (712) includes an inner surface (762) that defines a bore (764) configured to coaxially receive an inner core member (e.g., inner core member (312) of body member (310)). Unlike staple driver members (350, 550), but similar to staple driver member (612), staple driver member (712) is not shown as including an annular array of studs (e.g., annular array of studs (356, 556)) projecting distally from a distally presented surface (shown as planar surface (766) in FIGS. 24-25) that surrounds bore (764).

[0069] Unlike staple driver member (612), staple driver member (712) includes at least one interlocking feature (shown as protrusion (750)) that is lockingly engaged with at least one interlocking feature of barrel (720) of knife member (710). Although the interlocking feature of staple driver member (712) is shown as protrusion (750), various suitable interlocking features are envisioned. As with protrusion (650), the number and spacing of protrusions (750) can vary. Protrusions (750) are configured to lockingly engage with openings (728) of barrel (720) of knife member (710). Although protrusions (750) are shown as inwardly rounded protrusions, protrusions (750) may have various suitable shapes and sizes, and may be the same or different from one another. Staple driver member (712) may be formed from a polymeric material. The protrusion (750) may be integrally formed as a single piece with the inner surface (762).

[0070] Knife member (710) and staple driver member (712) may be driven distally, as also shown in FIG. 13D for stapling head assembly (300). As knife member (710) translates distally, cutting edge (722) of knife member (710) severs excess tissue located within the annular recess (e.g., annular recess (418) of anvil (400)) and within the interior of knife member (710). Other suitable structural relationships between knife member (710) and staple driver member (712) will be apparent to those of skill in the art in view of the teachings herein.

[0071] 3. Exemplary Knife Attachment Methods A method of manufacture will also be described with reference to Figures 24-25. According to an exemplary embodiment, respective interlocking features of the knife member (710) and the staple driver member (712) may directly and securably attach the knife member (710) to the staple driver member (712). For example, at least one interlocking feature (e.g., opening (728)) of the barrel (720) of the knife member (710) may interlock with at least one corresponding interlocking feature (e.g., protrusion (750)) of the staple driver member (712) to interlock the knife member (710) with the staple driver member (712).

[0072] The inner surface (762) of the staple driver member (712) can be flexible such that the protrusions (750) of the staple driver member (712) deflect radially outward as the knife member (710) translates relative to the staple driver member (712). To fixably attach the knife member (710) and the staple driver member (712) together, the protrusions (750) of the staple driver member (712) deflect radially inward into corresponding openings (728) of the knife member (710). Unlike the protrusions (650), which face outward, the protrusions (750) are shown as facing inward. This causes the protrusions (750) of the staple driver member (712) to snap into corresponding openings (728) of the knife member (710). As shown, there is no connection between the proximal end (716) of the knife member (710) and the planar surface (766) of the staple driver member (712). However, it is envisioned that the planar surface (766) may be connected to the proximal end (716) in addition to the connection provided by the projection (750) of the staple driver member (712) and the opening (728) of the knife member (710).

[0073] VII. Exemplary Combinations The following examples relate to various non-exhaustive methods in which the teachings herein may be combined or applied. The following examples are not intended to limit the scope of any claims that may be presented in this application or at any time in a subsequent filing of this application. No disclaimer is intended. The following examples are provided for illustrative purposes only. It is contemplated that the various teachings herein may be configured and applied in many other ways. It is also contemplated that certain features referred to in the following examples may be omitted in some variations. Thus, none of the aspects or features referred to below should be considered critical unless later expressly so indicated by the inventors or their successors. If a claim presented in this application or a subsequent application related to this application includes additional features other than those referred to below, those additional features should not be considered added for any reason regarding patentability. EXAMPLES

[0074] 1. An apparatus comprising: (a) a body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly including: (i) a staple driver member configured to drive a plurality of staples into tissue; and (ii) a knife member configured to cut tissue, the knife member including: (A) a proximal end, (B) a distal end, and (C) a barrel extending between the proximal and distal ends, the barrel including at least one coupling feature operably coupling the knife member to the staple driver member. EXAMPLES

[0075] The apparatus of example 1, wherein the connecting feature of the cylinder is provided on a cylindrical surface of the cylinder. EXAMPLES

[0076] The device of any one or more of Examples 1-2, wherein the stapling head assembly further comprises a connector that couples the knife member with the staple driver member. EXAMPLES

[0077] 4. The apparatus of example 3, wherein the connector is coaxially disposed within a central cavity of the cylindrical body of the knife member. EXAMPLES

[0078] The device of any one or more of Examples 3-4, wherein the connector includes at least one coupling feature that is lockingly engaged with at least one coupling feature of the barrel of the knife member. EXAMPLES

[0079] An apparatus as described in any one or more of Examples 3-5, wherein at least one connection feature of the barrel of the knife member includes a plurality of openings, and at least one connection feature of the connector includes a plurality of outward protrusions that are lockingly engaged with the plurality of openings of the barrel of the knife member. EXAMPLES

[0080] The device of any one or more of Examples 3-6, wherein the connector includes a proximal end, a distal end, and a body disposed between the proximal end and the distal end, the proximal end of the connector includes a flat surface, the staple driver member includes a flat surface, and the flat surfaces of the connector and the staple driver member are fixably coupled together. EXAMPLES

[0081] The device of any one or more of Examples 3-7, wherein the connector is formed from a polymeric material. EXAMPLES

[0082] The device of any one or more of Examples 1-2, wherein the staple driver member includes an inner wall, the inner wall of the staple driver member including at least one interlocking feature that is lockingly engaged with at least one interlocking feature of the barrel of the knife member. EXAMPLES

[0083] The device of Example 9, wherein at least one connecting feature of the barrel of the knife member includes a plurality of openings, and at least one connecting feature of the inner wall of the staple driver member includes a plurality of inward protrusions that are lockingly engaged with the multiple openings of the barrel of the knife member. EXAMPLES

[0084] A device described in any one or more of Examples 9-10, wherein at least one connecting feature of the barrel of the knife member is directly connected to at least one connecting feature of the inner wall of the staple driver member. EXAMPLES

[0085] The device of any one or more of Examples 1-11, wherein the distal end of the knife member comprises a circular cutting edge configured to cut tissue. EXAMPLES

[0086] The apparatus of any one or more of Examples 1-12, wherein the stapling head assembly defines a longitudinal axis and the barrel of the knife member extends along the longitudinal axis. EXAMPLES

[0087] The device of any one or more of Examples 1-13, wherein the stapling head assembly includes at least one annular array of staples and the staple driver member is operable to drive the at least one annular array of staples through tissue. EXAMPLES

[0088] The device of Example 14, wherein the stapling head assembly includes an anvil connection feature, and the device further includes an anvil, the anvil configured to connect with the anvil connection feature, and the anvil further configured to deform the annular array of at least one staple driven by the staple driver member. EXAMPLES

[0089] 1. A device comprising: (a) a body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising: (i) a staple driver member; and (ii) a knife member including: (A) a proximal end; (B) a distal end including a circular cutting edge configured to cut tissue; and (C) a body extending between the proximal and distal ends, the body including at least one coupling feature; and (iii) a connector coupled to both the staple driver member and the knife member, the connector including at least one coupling feature lockingly engaged with the at least one coupling feature of the body of the knife member to couple the knife member with the connector. EXAMPLES

[0090] The device of Example 16, wherein at least one connection feature of the body of the knife member includes a plurality of openings, and at least one connection feature of the connector includes a plurality of outward protrusions that are lockingly engaged with a plurality of openings in the barrel of the knife member. EXAMPLES

[0091] The device of any one or more of Examples 16-17, wherein the stapling head assembly includes at least one annular array of staples and the staple driver member is operable to drive the at least one annular array of staples through tissue. EXAMPLES

[0092] 1. A method of manufacturing a surgical stapler, the surgical stapler including a body, a shaft extending distally from the body, and a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly including a staple driver member and a knife member, the knife member including a proximal end, a distal end, and a barrel extending between the proximal and distal ends, the method including: (a) coupling at least one coupling feature of the barrel of the knife member with at least one corresponding coupling feature of one of the staple driver members or connectors, thereby operably coupling the knife member to the staple driver member. EXAMPLES

[0093] 20. The method of example 19, further comprising harmonic welding the connector to the staple driver member.

[0094] VIII.Other It should also be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein can be combined with any one or more of the other teachings, expressions, embodiments, examples, etc. described herein. Thus, the above teachings, expressions, embodiments, examples, etc. should not be considered in isolation with respect to each other. Various suitable ways in which the teachings herein can be combined will be readily apparent to those skilled in the art in view of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

[0095] At least some of the teachings herein may also be found in U.S. Patent Application Publication No. 2017 / 0258471, published on September 14, 2017, entitled "Methods and Systems for Performing Circular Stapling," the disclosure of which is incorporated herein by reference; U.S. Patent Application Publication No. 2015 / 0083772, published on March 26, 2015, now abandoned, entitled "Surgical Stapler with Rotary Cam Drive and Return," the disclosure of which is incorporated herein by reference; U.S. Patent No. 9,936,949, issued on April 10, 2018, entitled "Surgical Stapling Instrument with Drive Assembly Having Toggle Features," the disclosure of which is incorporated herein by reference; and U.S. Patent No. 9,907,552, issued on March 6, 2018, entitled "Control Features for Motorized Surgical Stapling," the disclosure of which is incorporated herein by reference. No. 9,713,469, issued on July 25, 2017, entitled "Surgical Stapler with Rotary Cam Drive," the disclosure of which is incorporated herein by reference; U.S. Pat. No. 10,226,253, issued on March 12, 2019, entitled "Firing Assembly for Circular Stapler," the disclosure of which is incorporated herein by reference; and U.S. Pat. No. 10,478,189, issued on November 19, 2019, entitled "Method of Applying an Annular Array of Staples to Tissue," the disclosure of which is incorporated herein by reference. Various suitable ways in which the teachings of this specification can be combined with the teachings of the above-referenced patents, publications, and patent applications will be apparent to those skilled in the art.

[0096] Although the examples herein are described in the context of a circular stapling instrument, it should be understood that the various teachings herein may be readily applied to a variety of other types of surgical instruments. By way of example only, the various teachings herein may be readily applied to linear stapling devices (e.g., endocutters). As another merely illustrative example, the various teachings herein may be readily applied to motorized electrosurgical devices. For example, the various teachings herein may be readily combined with the various teachings of U.S. Patent No. 9,161,803, issued October 20, 2015, entitled "Motor Driven Electrosurgical Device with Mechanical and Electrical Feedback," the disclosure of which is incorporated herein by reference, as would be apparent to one of ordinary skill in the art. Other suitable types of instruments to which the teachings herein may be applied, and various methods in which the teachings herein may be applied to such instruments, will be apparent to one of ordinary skill in the art.

[0097] It is understood that all or part of any patent, publication, or other disclosure referred to herein as being incorporated by reference is incorporated herein only to the extent that the incorporated content does not conflict with existing definitions, opinions, or other disclosures set forth in this disclosure. As such, and to the extent necessary, the disclosures explicitly set forth herein shall take precedence over any conflicting statements incorporated herein by reference. Any content, or portions thereof, that is referred to herein as being incorporated by reference but that conflicts with current definitions, opinions, or other disclosures set forth herein shall be incorporated only to the extent that no conflict occurs between the incorporated content and the current disclosures.

[0098] Variations of the above described devices may be applied to robotic-assisted medical procedures and surgeries as well as traditional medical procedures and surgeries performed by medical professionals. By way of example only, the various teachings herein may be readily incorporated into robotic surgical systems such as the DAVINCI™ system by Intuitive Surgical, Inc. (Sunnyvale, California).

[0099] The above variations may be designed to be disposed of after a single use, or they may be designed to be used multiple times. The variations, in either or both cases, can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular parts, and subsequent reassembly. In particular, some variations of the device can be disassembled, and any number of the particular parts or pieces of the device can be selectively replaced or removed in any combination. Upon cleaning and / or replacement of particular parts, some variations of the device can be reassembled for subsequent use at a reconditioning facility, or by a user immediately prior to a procedure. Those skilled in the art will appreciate that reconditioning of a device can utilize a variety of techniques for disassembly, cleaning / replacement, and reassembly. The use of such techniques, and the resulting reconditioned device, are all within the scope of the present application.

[0100] By way of example only, the variations described herein may be sterilized before and / or after treatment. In one sterilization technique, the device is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and device may then be placed in a radiation field that can penetrate the container, such as gamma radiation, x-rays, or high-energy electron beams. The radiation may kill bacteria on the device and in the container. The sterilized device may then be stored in the sterile container for later use. The device 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.

[0101] Although various embodiments of the present invention have been shown and described, further adaptations of the methods and systems described herein may be achieved by those skilled in the art through appropriate modifications without departing from the scope of the present invention. Although some of such possible modifications have been mentioned, other modifications will be apparent to those skilled in the art. For example, the above examples, embodiments, geometries, materials, dimensions, proportions, steps, etc. are illustrative and not required. Thus, it is understood that the scope of the present invention should be considered in relation to the following claims and is not limited to the details of construction and operation shown and described in the specification and drawings.

[0102] [Embodiment] (1) An apparatus comprising: (a) a main body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising: (i) a staple driver member configured to drive a plurality of staples into tissue; (ii) a knife member configured to cut the tissue, the knife member comprising: (A) a proximal end; (B) a distal end; (C) a cylindrical body extending between the proximal end and the distal end, the cylindrical body including at least one coupling feature operably coupling the knife member with the staple driver member. (2) The device of embodiment 1, wherein the connecting feature of the cylinder is provided on a cylindrical surface of the cylinder. (3) The device of claim 1, wherein the stapling head assembly further comprises a connector connecting the knife member with the staple driver member. (4) The device of embodiment 3, wherein the connector is coaxially disposed within a central cavity of the cylinder of the knife member. (5) The device of claim 3, wherein the connector includes at least one coupling feature that is lockingly engaged with the at least one coupling feature of the barrel of the knife member.

[0103] (6) The device of embodiment 3, wherein the at least one connection feature of the barrel of the knife member includes a plurality of openings, and the at least one connection feature of the connector includes a plurality of outward protrusions that are lockingly engaged with the plurality of openings of the barrel of the knife member. (7) The device of embodiment 3, wherein the connector includes a proximal end, a distal end, and a body disposed between the proximal end and the distal end, the proximal end of the connector includes a flat surface, the staple driver member includes a flat surface, and the flat surfaces of the connector and the staple driver member are fixably coupled together. (8) The device of embodiment 3, wherein the connector is formed from a polymeric material. (9) The device of claim 1, wherein the staple driver member includes an inner wall, the inner wall of the staple driver member including at least one interlocking feature that is lockingly engaged with the at least one interlocking feature of the barrel of the knife member. (10) The device of embodiment 9, wherein the at least one interlocking feature of the barrel of the knife member includes a plurality of openings, and the at least one interlocking feature of the inner wall of the staple driver member includes a plurality of inward protrusions that are lockingly engaged with the plurality of openings in the barrel of the knife member.

[0104] (11) The device of claim 9, wherein the at least one connecting feature of the barrel of the knife member is directly connected to the at least one connecting feature of the inner wall of the staple driver member. (12) The device of embodiment 1, wherein the distal end of the knife member includes a circular cutting edge configured to cut tissue. (13) The apparatus of claim 1, wherein the stapling head assembly defines a longitudinal axis and the barrel of the knife member extends along the longitudinal axis. (14) The apparatus of embodiment 1, wherein the stapling head assembly includes at least one annular array of staples, and the staple driver member is operable to drive the at least one annular array of staples through tissue. (15) The apparatus of claim 14, wherein the stapling head assembly includes an anvil interface feature, the apparatus further comprising an anvil, the anvil configured to interface with the anvil interface feature, the anvil further configured to deform the annular array of at least one staple driven by the staple driver member.

[0105] (16) An apparatus comprising: (a) a main body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising: (i) a staple driver member; (ii) a knife member, the knife member comprising: (A) a proximal end; (B) a distal end including a circular cutting edge configured to cut tissue; (C) a knife member comprising: a body extending between the proximal end and the distal end, the body including at least one coupling feature; (iii) a connector coupled to both the staple driver member and the knife member, the connector including at least one coupling feature lockingly engaged with the at least one coupling feature of the body of the knife member to couple the knife member with the connector. (17) The apparatus of claim 16, wherein the at least one coupling feature of the body of the knife member includes a plurality of openings, and the at least one coupling feature of the connector includes a plurality of outward protrusions that are lockingly engaged with the plurality of openings in the barrel of the knife member. (18) The apparatus of embodiment 16, wherein the stapling head assembly includes at least one annular array of staples, and the staple driver member is operable to drive the at least one annular array of staples through the tissue. (19) A method of manufacturing a surgical stapler comprising: a body, a shaft extending distally from the body, and a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising a staple driver member and a knife member, the knife member comprising a proximal end, a distal end, and a barrel extending between the proximal end and the distal end, the method comprising: (a) coupling at least one coupling feature of the barrel of the knife member with at least one corresponding coupling feature of one of the staple driver members or connectors, thereby operably coupling the knife member with the staple driver member. (20) The method of claim 19, further comprising harmonic welding the connector to the staple driver member.

Claims

1. An apparatus comprising: (a) a main body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising: (i) a staple driver member configured to drive a plurality of staples into tissue; (ii) a knife member configured to cut the tissue, the knife member comprising: (A) a proximal end; (B) a distal end; (C) a barrel extending between the proximal end and the distal end, the barrel including at least one coupling feature operably coupling the knife member with the staple driver member; the stapling head assembly further includes a connector connecting the knife member with the staple driver member; The device, wherein the connector includes a proximal end, a distal end, and a body disposed between the proximal end and the distal end, the proximal end of the connector includes a flat surface, the staple driver member includes a flat surface, and the flat surfaces of the connector and the staple driver member are fixably coupled together.

2. The apparatus of claim 1 , wherein the interlocking feature of the cylinder is provided on a cylindrical surface of the cylinder.

3. The apparatus of claim 1 , wherein the connector is coaxially disposed within a central cavity of the cylindrical body of the knife member.

4. The apparatus of claim 1 , wherein the connector includes at least one interlocking feature lockingly engaged with the at least one interlocking feature of the barrel of the knife member.

5. 5. The apparatus of claim 4, wherein the at least one interlocking feature of the barrel of the knife member includes a plurality of openings, and the at least one interlocking feature of the connector includes a plurality of outward protrusions that are lockingly engaged with the plurality of openings of the barrel of the knife member.

6. The device of claim 1 , wherein the connector is formed from a polymeric material.

7. 10. The apparatus of claim 1, wherein the staple driver member includes an interior wall, the interior wall of the staple driver member including at least one interlocking feature that is lockingly engaged with the at least one interlocking feature of the barrel of the knife member.

8. 8. The device of claim 7, wherein the at least one interlocking feature of the barrel of the knife member includes a plurality of openings, and the at least one interlocking feature of the inner wall of the staple driver member includes a plurality of inward protrusions that are lockingly engaged with the plurality of openings in the barrel of the knife member.

9. The apparatus of claim 7 , wherein the at least one interlocking feature of the barrel of the knife member is directly connected to the at least one interlocking feature of the inner wall of the staple driver member.

10. The apparatus of claim 1 , wherein the distal end of the knife member includes a circular cutting edge configured to cut the tissue.

11. The apparatus of claim 1 , wherein the stapling head assembly defines a longitudinal axis, and the barrel of the knife member extends along the longitudinal axis.

12. The apparatus of claim 1 , wherein the stapling head assembly includes at least one annular array of staples, and the staple driver member is operable to drive the at least one annular array of staples through the tissue.

13. 13. The apparatus of claim 12, wherein the stapling head assembly includes an anvil interlocking feature, the apparatus further comprising an anvil, the anvil configured to interlock with the anvil interlocking feature, the anvil further configured to deform the annular array of the at least one staple driven by the staple driver member.

14. An apparatus comprising: (a) a main body; (b) a shaft extending distally from the body; and (c) a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising: (i) a staple driver member; (ii) a knife member, said knife member comprising: (A) a proximal end; (B) a distal end including a circular cutting edge configured to cut tissue; (C) a knife member comprising: a barrel extending between the proximal end and the distal end, the barrel including at least one interlocking feature; and (iii) a connector coupled to both said staple driver member and said knife member, said connector including at least one coupling feature lockingly engaged with said at least one coupling feature of the barrel of the knife member to couple said knife member with said connector; The device, wherein the connector includes a proximal end, a distal end, and a body disposed between the proximal end and the distal end, the proximal end of the connector includes a flat surface, the staple driver member includes a flat surface, and the flat surfaces of the connector and the staple driver member are fixably coupled together.

15. 15. The apparatus of claim 14, wherein the at least one interlocking feature of the barrel of the knife member includes a plurality of openings, and the at least one interlocking feature of the connector includes a plurality of outward protrusions that are lockingly engaged with the plurality of openings of the barrel of the knife member.

16. The apparatus of claim 14, wherein the stapling head assembly includes at least one annular array of staples, and the staple driver member is operable to drive the at least one annular array of staples through the tissue.

17. 11. A method of manufacturing a surgical stapler comprising: a body, a shaft extending distally from the body, and a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising a staple driver member and a knife member, the knife member comprising a proximal end, a distal end, and a barrel extending between the proximal end and the distal end, the stapling head assembly further comprising a connector coupling the knife member with the staple driver member, the connector comprising a proximal end, a distal end, and a body disposed between the proximal end and the distal end, the proximal end of the connector comprising a flat surface, the staple driver member comprising a flat surface, the connector and the flat surfaces of the staple driver member being fixably coupled together, the method comprising: (a) coupling at least one coupling feature of the barrel of the knife member with at least one corresponding coupling feature of one of the connectors, thereby operably coupling the knife member with the staple driver member.

18. A method of manufacturing a surgical stapler comprising: a body, a shaft extending distally from the body, and a stapling head assembly positioned at a distal end of the shaft, the stapling head assembly comprising a staple driver member and a knife member, the knife member comprising a proximal end, a distal end, and a cylindrical body extending between the proximal end and the distal end, the method comprising: (a) coupling at least one coupling feature of the barrel of the knife member with at least one corresponding coupling feature of one of the staple driver members or connectors, thereby operatively coupling the knife member with the staple driver member; The method further includes harmonic welding the connector with the staple driver member.

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