Staple forming features for surgical stapling instrument

Abstract

An end effector for a surgical instrument comprises a first jaw and a second jaw. The first jaw is configured to receive a staple cartridge. The second jaw is movable relative to the first jaw and is configured to provide an anvil for forming staples. The anvil has staple forming pockets. Each staple forming pocket comprises first and second staple forming surface regions configured to receive respective first and second staple legs. The first and second staple forming surface regions each have a respective length that is greater than half of the length of the staple forming pocket. The staple forming surface regions may include convex surfaces that drive staple legs laterally. The pocket minimizes re-entry of staple leg tips into tissue.

Description

BACKGROUND

In some settings, endoscopic surgical instruments may be preferred over traditional open surgical devices since a smaller incision may reduce the post-operative recovery time and complications. Consequently, some endoscopic surgical instruments may be suitable for placement of a distal end effector at a desired surgical site through the cannula of a trocar. These distal end effectors may engage tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, stapler, clip applier, access device, drug/gene therapy delivery device, and energy delivery device using ultrasound, RF, laser, etc.). Endoscopic surgical instruments may include a shaft between the end effector and a handle portion, which is manipulated by the clinician. Such a shaft may enable insertion to a desired depth and rotation about the longitudinal axis of the shaft, thereby facilitating positioning of the end effector within the patient. Positioning of an end effector may be further facilitated through inclusion of one or more articulation joints or features, enabling the end effector to be selectively articulated or otherwise deflected relative to the longitudinal axis of the shaft.

Examples of endoscopic surgical instruments include surgical staplers. Some such staplers are operable to clamp down on layers of tissue, cut through the clamped layers of tissue, and drive staples through the layers of tissue to substantially seal the severed layers of tissue together near the severed ends of the tissue layers. Merely exemplary surgical staplers are disclosed in U.S. Pat. No. 4,805,823, entitled “Pocket Configuration for Internal Organ Staplers,” issued Feb. 21, 1989; U.S. Pat. No. 5,415,334, entitled “Surgical Stapler and Staple Cartridge,” issued May 16, 1995; U.S. Pat. No. 5,465,895, entitled “Surgical Stapler Instrument,” issued Nov. 14, 1995; U.S. Pat. No. 5,597,107, entitled “Surgical Stapler Instrument,” issued Jan. 28, 1997; U.S. Pat. No. 5,632,432, entitled “Surgical Instrument,” issued May 27, 1997; U.S. Pat. No. 5,673,840, entitled “Surgical Instrument,” issued Oct. 7, 1997; U.S. Pat. No. 5,704,534, entitled “Articulation Assembly for Surgical Instruments,” issued Jan. 6, 1998; U.S. Pat. No. 5,814,055, entitled “Surgical Clamping Mechanism,” issued Sep. 29, 1998; U.S. Pat. No. 6,978,921, entitled “Surgical Stapling Instrument Incorporating an E-Beam Firing Mechanism,” issued Dec. 27, 2005; U.S. Pat. No. 7,000,818, entitled “Surgical Stapling Instrument Having Separate Distinct Closing and Firing Systems,” issued Feb. 21, 2006; U.S. Pat. No. 7,143,923, entitled “Surgical Stapling Instrument Having a Firing Lockout for an Unclosed Anvil,” issued Dec. 5, 2006; U.S. Pat. No. 7,303,108, entitled “Surgical Stapling Instrument Incorporating a Multi-Stroke Firing Mechanism with a Flexible Rack,” issued Dec. 4, 2007; U.S. Pat. No. 7,367,485, entitled “Surgical Stapling Instrument Incorporating a Multistroke Firing Mechanism Having a Rotary Transmission,” issued May 6, 2008; U.S. Pat. No. 7,380,695, entitled “Surgical Stapling Instrument Having a Single Lockout Mechanism for Prevention of Firing,” issued Jun. 3, 2008; U.S. Pat. No. 7,380,696, entitled “Articulating Surgical Stapling Instrument Incorporating a Two-Piece E-Beam Firing Mechanism,” issued Jun. 3, 2008; U.S. Pat. No. 7,404,508, entitled “Surgical Stapling and Cutting Device,” issued Jul. 29, 2008; U.S. Pat. No. 7,434,715, entitled “Surgical Stapling Instrument Having Multistroke Firing with Opening Lockout,” issued Oct. 14, 2008; U.S. Pat. No. 7,721,930, entitled “Disposable Cartridge with Adhesive for Use with a Stapling Device,” issued May 25, 2010; U.S. Pub. No. 2010/0264193, entitled “Surgical Stapling Instrument with An Articulatable End Effector,” published Oct. 21, 2010, issued Apr. 2, 2013 as U.S. Pat. No. 8,408,439; and U.S. Pub. No. 2012/0239012, entitled “Motor-Driven Surgical Cutting Instrument with Electric Actuator Directional Control Assembly,” published Sep. 20, 2012, issued Jun. 4, 2013 as U.S. Pat. No. 8,453,914. The disclosure of each of the above-cited U.S. Patents and U.S. Patent Publications is incorporated by reference herein.

While the surgical staplers referred to above are described as being used in endoscopic procedures, it should be understood that such surgical staplers may also be used in open procedures and/or other non-endoscopic procedures. By way of example only, a surgical stapler may be inserted through a thoracotomy and thereby between a patient's ribs to reach one or more organs in a thoracic surgical procedure that does not use a trocar as a conduit for the stapler. Such procedures may include the use of the stapler to sever and close a vessel leading to a lung. For instance, the vessels leading to an organ may be severed and closed by a stapler before removal of the organ from the thoracic cavity. Of course, surgical staplers may be used in various other settings and procedures.

While various kinds of surgical stapling instruments and associated components have been made and used, it is believed that no one prior to the inventor(s) has made or used the invention described in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and, together with the general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the present invention.

FIG. 1 depicts a perspective view of an exemplary articulating surgical stapling instrument;

FIG. 2 depicts a side elevational view of the instrument of FIG. 1;

FIG. 3 depicts a perspective view of an opened end effector of the instrument of FIG. 1;

FIG. 4A depicts a side cross-sectional view of the end effector of FIG. 3, taken along line 4-4 of FIG. 3, with the firing beam in a proximal position;

FIG. 4B depicts a side cross-sectional view of the end effector of FIG. 3, taken along line 4-4 of FIG. 3, with the firing beam in a distal position;

FIG. 5 depicts an end cross-sectional view of the end effector of FIG. 3, taken along line 5-5 of FIG. 3;

FIG. 6 depicts an exploded perspective view of the end effector of FIG. 3;

FIG. 7 depicts a perspective view of the end effector of FIG. 3, positioned at tissue and having been actuated once in the tissue;

FIG. 8 depicts a schematic view of an exemplary control circuit for use in the instrument of FIG. 1;

FIG. 9 depicts a perspective view of the handle assembly of the instrument of FIG. 1, with a housing half removed;

FIG. 10 depicts a perspective view of drive assembly components from the handle assembly of FIG. 9;

FIG. 11 depicts a perspective view of an elongate member from the drive assembly of FIG. 10;

FIG. 12 depicts a perspective view of an exemplary alternative anvil that may be incorporated into the instrument of FIG. 1;

FIG. 13 depicts a bottom plan view of the anvil of FIG. 12;

FIG. 14 depicts an enlarged plan view of a staple forming pocket of the anvil of FIG. 12;

FIG. 15 depicts a cross-sectional view of the staple forming pocket of FIG. 14, taken along line 15-15 of FIG. 14;

FIG. 16 depicts a cross-sectional view of the staple forming pocket of FIG. 14, taken along line 16-16 of FIG. 15;

FIG. 17 depicts a side elevational view of an exemplary staple formed by the staple forming pocket of FIG. 14, disposed in tissue;

FIG. 18A depicts a side elevational view of the staple of FIG. 17 in an unformed state, initially contacting the staple forming pocket of FIG. 14 in a first stage of staple formation;

FIG. 18B depicts a side elevational view of the staple of FIG. 17 being driven into the staple forming pocket of FIG. 14 in a second stage of staple formation;

FIG. 18C depicts a side elevational view of the staple of FIG. 17 being driven further into the staple forming pocket of FIG. 14 in a third stage of staple formation;

FIG. 18D depicts a side elevational view of the staple of FIG. 17 being driven further into the staple forming pocket of FIG. 14 in a fourth stage of staple formation;

FIG. 18E depicts a side elevational view of the staple of FIG. 17 being fully driven into the staple forming pocket of FIG. 14 at a final stage of staple formation;

FIG. 19 depicts a perspective view of another exemplary alternative anvil that may be incorporated into the instrument of FIG. 1;

FIG. 20 depicts a bottom plan view of the anvil of FIG. 19;

FIG. 21 depicts an enlarged perspective view of staple forming pockets of the anvil of FIG. 19;

FIG. 22 depicts an enlarged plan view of a staple forming pocket of the anvil of FIG. 19;

FIG. 23 depicts a perspective cross-sectional view of the staple forming pocket of FIG. 22, taken along line 23-23 of FIG. 22;

FIG. 24 depicts a side elevational view of an exemplary staple formed by the staple forming pocket of FIG. 19, disposed in tissue;

FIG. 25A depicts a side elevational view of the staple of FIG. 24 in an unformed state, initially contacting the staple forming pocket of FIG. 19 in a first stage of staple formation;

FIG. 25B depicts a side elevational view of the staple of FIG. 24 being driven into the staple forming pocket of FIG. 19 in a second stage of staple formation;

FIG. 25C depicts a side elevational view of the staple of FIG. 24 being driven into the staple forming pocket of FIG. 19 in a third stage of staple formation;

FIG. 25D depicts a side elevational view of the staple of FIG. 24 being fully driven into the staple forming pocket of FIG. 19 at a final stage of staple formation;

FIG. 26 depicts a perspective view of another exemplary alternative staple forming pocket that may be incorporated in to the anvil of the instrument of FIG. 1;

FIG. 27 depicts an enlarged plan view of the staple forming pocket of FIG. 26;

FIG. 28 depicts a cross-sectional view of the staple forming pocket of FIG. 26, taken along line 28-28 of FIG. 27;

FIG. 29 depicts a cross-sectional view of the staple forming pocket of FIG. 26, taken along line 29-29 of FIG. 28;

FIG. 30 depicts a perspective view of another exemplary alternative staple forming pocket that may be incorporated in to the anvil of the instrument of FIG. 1;

FIG. 31 depicts an enlarged plan view of the staple forming pocket of FIG. 30;

FIG. 32 depicts a cross-sectional view of the staple forming pocket of FIG. 30, taken along line 32-32 of FIG. 31;

FIG. 33A depicts a perspective view of a staple being driven into the staple forming pocket of FIG. 30 in a first stage of staple formation;

FIG. 33B depicts a perspective view of the staple of FIG. 33A being further driven into the staple forming pocket of FIG. 30 in a second stage of staple formation;

FIG. 33C depicts a side cross-sectional view of the staple of FIG. 33A being fully driven into the staple forming pocket of FIG. 30 at a final stage of staple formation;

FIG. 34 depicts a top plan view of the staple of FIG. 33A having been fully driven into the staple forming pocket of FIG. 30;

FIG. 35 depicts a perspective view of another exemplary alternative staple forming pocket that may be incorporated in to the anvil of the instrument of FIG. 1;

FIG. 36 depicts an enlarged plan view of the staple forming pocket of FIG. 35;

FIG. 37 depicts a cross-sectional view of the staple forming pocket of FIG. 35, taken along line 37-37 of FIG. 36;

FIG. 38 depicts a perspective view of another exemplary alternative staple forming pocket that may be incorporated in to the anvil of the instrument of FIG. 1;

FIG. 39 depicts an enlarged plan view of the staple forming pocket of FIG. 38;

FIG. 40 depicts a cross-sectional view of the staple forming pocket of FIG. 38, taken along line 40-40 of FIG. 39;

FIG. 41 depicts a bottom elevational view of staple forming pockets on another exemplary alternative anvil that may be incorporated into the instrument of FIG. 1;

FIG. 42 depicts a top plan view of staples formed by the staple forming pockets of FIG. 41; and

FIG. 43 depicts layers of tissue secured by the staples of FIG. 42.

The drawings are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings. The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.

DETAILED DESCRIPTION

The following description of certain examples of the invention should not be used to limit the scope of the present invention. Other examples, features, aspects, embodiments, and advantages of the invention will become apparent to those skilled in the art from the following description, which is by way of illustration, one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different and obvious aspects, all without departing from the invention. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive.

I. Exemplary Surgical Stapler

FIGS. 1-7 depict an exemplary surgical stapling and severing instrument (10) that is sized for insertion, in a nonarticulated state as depicted in FIG. 1, through a trocar cannula to a surgical site in a patient for performing a surgical procedure. By way of example only, such a trocar may be inserted in a patient's abdomen, between two of the patient's ribs, or elsewhere. In some settings, instrument (10) is used without a trocar. For instance, instrument (10) may be inserted directly through a thoracotomy or other type of incision. Instrument (10) of the present example includes a handle portion (20) connected to a shaft (22). Shaft (22) distally terminates in an articulation joint (11), which is further coupled with an end effector (12). It should be understood that terms such as “proximal” and “distal” are used herein with reference to a clinician gripping handle portion (20) of instrument (10). Thus, end effector (12) is distal with respect to the more proximal handle portion (20). It will be further appreciated that for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute.

In some versions, shaft (22) is constructed in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,402, entitled “Surgical Instrument with Multi-Diameter Shaft,” filed on even date herewith, now U.S. Pat. No. 9,795,379, issued Oct. 24, 2017, the disclosure of which is incorporated by reference herein. Other suitable configurations for shaft (22) will be apparent to those of ordinary skill in the art in view of the teachings herein.

Once articulation joint (11) and end effector (12) are inserted through the cannula passageway of a trocar, articulation joint (11) may be remotely articulated, as depicted in phantom in FIG. 1, by an articulation control (13), such that end effector (12) may be deflected from the longitudinal axis (LA) of shaft (22) at a desired angle (α). End effector (12) may thereby reach behind an organ or approach tissue from a desired angle or for other reasons. In some versions, articulation joint (11) enables deflection of end effector (12) along a single plane. In some other versions, articulation joint (11) enables deflection of end effector along more than one plane. Articulation joint (11) and articulation control (13) may be configured in accordance with the teachings of any of the numerous references that are cited herein. Alternatively, articulation joint (11) and/or articulation control (13) may have any other suitable configuration. By way of example only, articulation control (13) may instead be configured as a knob that rotates about an axis that is perpendicular to the longitudinal axis (LA) of shaft (22).

In some versions, articulation joint (11) and/or articulation control (13) are/is constructed and operable in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,067, entitled “Surgical Instrument End Effector Articulation Drive with Pinion and Opposing Racks,” filed on even date herewith, now U.S. Pat. No. 9,186,142, issued Nov. 17, 2015, the disclosure of which is incorporated by reference herein. Articulation joint (11) may also be constructed and operable in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,402, now U.S. Pat. No. 9,795,379, issued Oct. 24, 2017, the disclosure of which is incorporated by reference herein. Other suitable forms that articulation joint (11) and articulation control (13) may take will be apparent to those of ordinary skill in the art in view of the teachings herein.

End effector (12) of the present example includes a lower jaw (16) and a pivotable anvil (18). In some versions, lower jaw (16) is constructed in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,417, entitled “Installation Features for Surgical Instrument End Effector Cartridge,” filed on even date herewith, now U.S. Pat. No. 9,808,248, issued Nov. 7, 2017, the disclosure of which is incorporated by reference herein. Anvil (18) may be constructed in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,106, now U.S. Pat. No. 9,517,065, issued Dec. 13, 2016, entitled “Integrated Tissue Positioning and Jaw Alignment Features for Surgical Stapler,” filed on even date herewith, the disclosure of which is incorporated by reference herein; at least some of the teachings of U.S. patent application Ser. No. 13/780,120, entitled “Jaw Closure Feature for End Effector of Surgical Instrument,” filed on even date herewith, now U.S. Pat. No. 9,839,421, issued Dec. 12, 2017, the disclosure of which is incorporated by reference herein; and/or at least some of the teachings below. Other suitable forms that lower jaw (16) and anvil (18) may take will be apparent to those of ordinary skill in the art in view of the teachings herein.

Handle portion (20) includes a pistol grip (24) and a closure trigger (26). Closure trigger (26) is pivotable toward pistol grip (24) to cause clamping, or closing, of the anvil (18) toward lower jaw (16) of end effector (12). Such closing of anvil (18) is provided through a closure tube (32) and a closure ring (33), which both longitudinally translate relative to handle portion (20) in response to pivoting of closure trigger (26) relative to pistol grip (24). Closure tube (32) extends along the length of shaft (22); and closure ring (33) is positioned distal to articulation joint (11). Articulation joint (11) is operable to communicate/transmit longitudinal movement from closure tube (32) to closure ring (33).

Handle portion (20) also includes a firing trigger (28). An elongate member (136) (shown in FIG. 11) longitudinally extends through shaft (22) and communicates a longitudinal firing motion from handle portion (20) to a firing beam (14) in response to actuation of firing trigger (28). This distal translation of firing beam (14) causes the stapling and severing of clamped tissue in end effector (12), as will be described in greater detail below. Thereafter, triggers (26, 28) may be released to release the tissue from end effector (12).

FIGS. 3-6 depict end effector (12) employing an E-beam form of firing beam (14) to perform a number of functions. It should be understood that an E-beam form is just a merely illustrative example. Firing beam (14) may take any other suitable form, including but not limited to non-E-beam forms. As best seen in FIGS. 4A-4B, firing beam (14) includes a transversely oriented upper pin (38), a firing beam cap (44), a transversely oriented middle pin (46), and a distally presented cutting edge (48). Upper pin (38) is positioned and translatable within a longitudinal anvil slot (42) of anvil (18). Firing beam cap (44) slidably engages a lower surface of lower jaw (16) by having firing beam (14) extend through lower jaw slot (45) (shown in FIG. 4B) that is formed through lower jaw (16). Middle pin (46) slidingly engages a top surface of lower jaw (16), cooperating with firing beam cap (44). Thereby, firing beam (14) affirmatively spaces end effector (12) during firing.

Some non-E-beam forms of firing beam (14) may lack upper pin (38), middle pin (46) and/or firing beam cap (44). Some such versions of instrument (10) may simply rely on closure ring (33) or some other feature to pivot anvil (18) to a closed position and hold anvil (18) in the closed position while firing beam (14) advances to the distal position. By way of example only, firing beam (14) and/or associated lockout features may be constructed and operable in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,082, entitled “Lockout Feature for Movable Cutting Member of Surgical Instrument,” filed on even date herewith, now U.S. Pat. No. 9,717,497, issued Aug. 1, 2017, the disclosure of which is incorporated by reference herein. Other suitable forms that firing beam (14) may take will be apparent to those of ordinary skill in the art in view of the teachings herein.

FIG. 3 shows firing beam (14) of the present example proximally positioned and anvil (18) pivoted to an open position, allowing an unspent staple cartridge (37) to be removably installed into a channel of lower jaw (16). As best seen in FIGS. 5-6, staple cartridge (37) of this example includes a cartridge body (70), which presents an upper deck (72) and is coupled with a lower cartridge tray (74). As best seen in FIG. 3, a vertical slot (49) is formed through part of staple cartridge (37). As also best seen in FIG. 3, three rows of staple apertures (51) are formed through upper deck (72) on one side of vertical slot (49), with another set of three rows of staple apertures (51) being formed through upper deck (72) on the other side of vertical slot (49). Of course, any other suitable number of staple rows (e.g., two rows, four rows, any other number) may be provided. Referring back to FIGS. 4A-6, a wedge sled (41) and a plurality of staple drivers (43) are captured between cartridge body (70) and tray (74), with wedge sled (41) being located proximal to staple drivers (43). Wedge sled (41) is movable longitudinally within staple cartridge (37); while staple drivers (43) are movable vertically within staple cartridge (37). Staples (47) are also positioned within cartridge body (70), above corresponding staple drivers (43). In particular, each staple (47) is driven vertically within cartridge body (70) by a staple driver (43) to drive staple (47) out through an associated staple aperture (51). As best seen in FIGS. 4A-4B and 6, wedge sled (41) presents inclined cam surfaces that urge staple drivers (43) upwardly as wedge sled (41) is driven distally through staple cartridge (37).

In some versions, staple cartridge (37) is constructed and operable in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,106, now U.S. Pat. No. 9,517,065, issued Dec. 13, 2016, the disclosure of which is incorporated by reference herein. In addition or in the alternative, staple cartridge (37) may be constructed and operable in accordance with at least some of the teachings of U.S. patent application Ser. No. 13/780,417, now U.S. Pat. No. 9,808,248, issued Nov. 7, 2017, the disclosure of which is incorporated by reference herein. Other suitable forms that staple cartridge (37) may take will be apparent to those of ordinary skill in the art in view of the teachings herein.

With end effector (12) closed as depicted in FIGS. 4A-4B by distally advancing closure tube (32) and closure ring (33), firing beam (14) is then advanced in engagement with anvil (18) by having upper pin (38) enter longitudinal anvil slot (42). A pusher block (80) (shown in FIG. 5) is located at the distal end of firing beam (14), and is configured to engage wedge sled (41) such that wedge sled (41) is pushed distally by pusher block (80) as firing beam (14) is advanced distally through staple cartridge (37) when firing trigger (28) is actuated. During such firing, cutting edge (48) of firing beam (14) enters vertical slot (49) of staple cartridge (37), severing tissue clamped between staple cartridge (37) and anvil (18). As shown in FIGS. 4A-4B, middle pin (46) and pusher block (80) together actuate staple cartridge (37) by entering into vertical slot (49) within staple cartridge (37), driving wedge sled (41) into upward camming contact with staple drivers (43) that in turn drive staples (47) out through staple apertures (51) and into forming contact with staple forming pockets (53) (shown in FIG. 3) on the inner surface of anvil (18). FIG. 4B depicts firing beam (14) fully distally translated after completing severing and stapling of tissue. It should be understood that staple forming pockets (53) are intentionally omitted from the view in FIGS. 4A-4B; but staple forming pockets (53) are shown in FIG. 3. It should also be understood that anvil (18) is intentionally omitted from the view in FIG. 5.

FIG. 7 shows end effector (12) having been actuated through a single stroke through tissue (90). As shown, cutting edge (48) (obscured in FIG. 7) has cut through tissue (90), while staple drivers (43) have driven three alternating rows of staples (47) through the tissue (90) on each side of the cut line produced by cutting edge (48). Staples (47) are all oriented substantially parallel to the cut line in this example, though it should be understood that staples (47) may be positioned at any suitable orientations. In the present example, end effector (12) is withdrawn from the trocar after the first stroke is complete, spent staple cartridge (37) is replaced with a new staple cartridge, and end effector (12) is then again inserted through the trocar to reach the stapling site for further cutting and stapling. This process may be repeated until the desired amount of cuts and staples (47) have been provided. Anvil (18) may need to be closed to facilitate insertion and withdrawal through the trocar; and anvil (18) may need to be opened to facilitate replacement of staple cartridge (37).

It should be understood that cutting edge (48) may sever tissue substantially contemporaneously with staples (47) being driven through tissue during each actuation stroke. In the present example, cutting edge (48) just slightly lags behind driving of staples (47), such that a staple (47) is driven through the tissue just before cutting edge (48) passes through the same region of tissue, though it should be understood that this order may be reversed or that cutting edge (48) may be directly synchronized with adjacent staples. While FIG. 7 shows end effector (12) being actuated in two layers (92, 94) of tissue (90), it should be understood that end effector (12) may be actuated through a single layer of tissue (90) or more than two layers (92, 94) of tissue. It should also be understood that the formation and positioning of staples (47) adjacent to the cut line produced by cutting edge (48) may substantially seal the tissue at the cut line, thereby reducing or preventing bleeding and/or leaking of other bodily fluids at the cut line. Furthermore, while FIG. 7 shows end effector (12) being actuated in two substantially flat, apposed planar layers (92, 94) of tissue, it should be understood that end effector (12) may also be actuated across a tubular structure such as a blood vessel, a section of the gastrointestinal tract, etc. FIG. 7 should therefore not be viewed as demonstrating any limitation on the contemplated uses for end effector (12). Various suitable settings and procedures in which instrument (10) may be used will be apparent to those of ordinary skill in the art in view of the teachings herein.

It should be understood that instrument (10) may be configured and operable in accordance with any of the teachings of U.S. Pat. No. 4,805,823; U.S. Pat. No. 5,415,334; U.S. Pat. No. 5,465,895; U.S. Pat. No. 5,597,107; U.S. Pat. No. 5,632,432; U.S. Pat. No. 5,673,840; U.S. Pat. No. 5,704,534; U.S. Pat. No. 5,814,055; U.S. Pat. No. 6,978,921; U.S. Pat. No. 7,000,818; U.S. Pat. No. 7,143,923; U.S. Pat. No. 7,303,108; U.S. Pat. No. 7,367,485; U.S. Pat. No. 7,380,695; U.S. Pat. No. 7,380,696; U.S. Pat. No. 7,404,508; U.S. Pat. No. 7,434,715; U.S. Pat. No. 7,721,930; U.S. Pub. No. 2010/0264193, issued as U.S. Pat. No. 8,408,439; and/or 2012/0239012, issued as U.S. Pat. No. 8,453,914. As noted above, the disclosures of each of those patents and publications are incorporated by reference herein. Additional exemplary modifications that may be provided for instrument (10) will be described in greater detail below. Various suitable ways in which the below teachings may be incorporated into instrument (10) will be apparent to those of ordinary skill in the art. Similarly, various suitable ways in which the below teachings may be combined with various teachings of the patents/publications cited herein will be apparent to those of ordinary skill in the art. It should also be understood that the below teachings are not limited to instrument (10) or devices taught in the patents cited herein. The below teachings may be readily applied to various other kinds of instruments, including instruments that would not be classified as surgical staplers. Various other suitable devices and settings in which the below teachings may be applied will be apparent to those of ordinary skill in the art in view of the teachings herein.

II. Exemplary Motorized Drive Features

In the present example, instrument (10) provides motorized control of firing beam (14). FIGS. 8-11 show exemplary components that may be used to provide motorized control of firing beam (14). In particular, FIG. 8 shows an exemplary control circuit (100) that may be used to power an electric motor (102) with electric power from a battery pack (104) (also shown in FIGS. 1-2). Electric motor (102) is operable to translate firing beam (14) longitudinally as will be described in greater detail below. It should be understood that the entire control circuit (100), including motor (102) and battery pack (104), may be housed within handle portion (20). FIG. 8 shows firing trigger (28) as an open switch, though it should be understood that this switch is closed when firing trigger (28) is actuated. Circuit (100) of this example also includes a safety switch (106) that must be closed in order to complete circuit (100), though it should be understood that safety switch (106) is merely optional. Safety switch (106) may be closed by actuating a separate button, slider, or other feature on handle portion (20).

Circuit (100) of the present example also includes a lockout switch (108), which is configured to be closed by default but is automatically opened in response to a lockout condition. By way of example only, a lockout condition may include one or more of the following: the absence of a cartridge (37) in lower jaw (16), the presence of a spent (e.g., previously fired) cartridge (37) in lower jaw (16), an insufficiently closed anvil (18), a determination that instrument (10) has been fired too many times, and/or any other suitable conditions. Various sensors, algorithms, and other features that may be used to detect lockout conditions will be apparent to those of ordinary skill in the art in view of the teachings herein. Similarly, other suitable kinds of lockout conditions will be apparent to those of ordinary skill in the art in view of the teachings herein. It should be understood that circuit (100) is opened and thus motor (102) is inoperable when lockout switch (108) is opened. A lockout indicator (110) (e.g., an LED, etc.) is operable to provide a visual indication of the status of lockout switch (108). By way of example only, lockout switch (108), lockout indicator (110), and associated components/functionality may be configured in accordance with at least some of the teachings of U.S. Pat. No. 7,644,848, entitled “Electronic Lockouts and Surgical Instrument Including Same,” issued Jan. 12, 2010, the disclosure of which is incorporated by reference herein.

Once firing beam (14) reaches a distal-most position (e.g., at the end of a cutting stroke), an end-of-stroke switch (112) is automatically switched to a closed position, reversing the polarity of the voltage applied to motor (102). This reverses the direction of rotation of motor (102), it being understood that the operator will have released firing trigger (28) at this stage of operation. In this operational state, current flows through a reverse direction indicator (114) (e.g., an LED, etc.) to provide a visual indication to the operator that motor (102) rotation has been reversed. Various suitable ways in which end-of-stroke switch (112) may be automatically switched to a closed position when firing beam (14) reaches a distal-most position will be apparent to those of ordinary skill in the art in view of the teachings herein. Similarly, various suitable forms that reverse direction indicator (114) may take will be apparent to those of ordinary skill in the art in view of the teachings herein.

Handle portion (20) of the present example also includes a manual return switch (116), which is also shown in circuit (100). Manual return switch (116) is configured to act as a “bailout” feature, enabling the operator to quickly begin retracting firing beam (14) proximally during a firing stroke. In other words, manual return switch (116) may be manually actuated when firing beam (14) has only been partially advanced distally. Manual return switch (116) may provide functionality similar to end-of-stroke switch (112), reversing the polarity of the voltage applied to motor (102) to thereby reverse the direction of rotation of motor (102). Again, this reversal may be visually indicated through reverse direction indicator (114).

In some versions, one or more of switches (28, 106, 108, 112, 116) are in the form of microswitches. Other suitable forms will be apparent to those of ordinary skill in the art in view of the teachings herein. In addition to or in lieu of the foregoing, at least part of circuit (100) may be configured in accordance with at least some of the teachings of U.S. Pat. No. 8,210,411, entitled “Motor-Driven Surgical Instrument,” issued Jul. 3, 2012, the disclosure of which is incorporated by reference herein.

FIGS. 9-11 show various mechanical components that may be used to provide motorized translation of firing beam (14). In particular, FIG. 9 shows motor (102) housed in pistol grip (24) of handle portion (20). It should be understood that battery pack (104) (shown in FIGS. 1-2) may also be located in pistol grip (24) (e.g., below motor (102)) and/or elsewhere within handle portion (20). Motor (102) has a drive shaft (120) that is coupled with a gear assembly (122). Gear assembly (122) has an external casing (not shown) and is operable to drive an upper gear (126), which is shown in FIG. 10. Upper gear (126) meshes with a pinion (128), which is rotatably supported by a pin (129) secured in handle portion (20). It should therefore be understood that activation of motor (102) will ultimately rotate pinion (128) within handle portion (20).

As also shown in FIGS. 9-10, a translating rack (130) includes teeth (132) that mesh with pinion (128), such that rack (130) translates longitudinally when pinion (128) rotates. As shown in FIG. 11, rack (130) is coupled with an elongate member (136), which extends through shaft (22) and includes a distal end (138) that couples with the proximal end of firing beam (14). Elongate member (136) translates within shaft (22), such that elongate member (136) communicates longitudinal motion of rack (130) to firing beam (14). It should therefore be understood that activation of motor (102) will ultimately translate firing beam (14) within end effector (12). In particular, motor (102) may drive firing beam (14) distally to sever tissue (90) and drive staples (47) into tissue (90). A switch actuation arm (134) extends laterally from rack (130), and is positioned to engage end-of-stroke switch (112) when firing beam (14) reaches a distal-most position (e.g., after tissue (90) has been severed and staples (47) have been driven into tissue (90)). As noted above, this engagement of end-of-stroke switch (112) automatically reverses motor (102) to return firing beam (14) from the distal-most position to the proximal position, enabling anvil (18) to be pivoted away from lower jaw (16) to release tissue (90).

Use of the term “pivot” (and similar terms with “pivot” as a base) should not be read as necessarily requiring pivotal movement about a fixed axis. In some versions, anvil (18) pivots about an axis that is defined by a pin (or similar feature) that slides along an elongate slot or channel as anvil (18) moves toward lower jaw (16). In such versions, the pivot axis translates along the path defined by the slot or channel while anvil (18) simultaneously pivots about that axis. In addition or in the alternative, the pivot axis may slide along the slot/channel first, with anvil (18) then pivoting about the pivot axis after the pivot axis has slid a certain distance along the slot/channel. It should be understood that such sliding/translating pivotal movement is encompassed within terms such as “pivot,” “pivots,” “pivotal,” “pivotable,” “pivoting,” and the like. Of course, some versions may provide pivotal movement of anvil (18) about an axis that remains fixed and does not translate within a slot or channel, etc.

In addition to or in lieu of the foregoing, the features operable to drive firing beam (14) may be configured in accordance with at least some of the teachings of U.S. Pub. No. 2012/0239012, issued as U.S. Pat. No. 8,453,914, the disclosure of which is incorporated by reference herein. Other suitable components, features, and configurations for providing motorization of firing beam (14) will be apparent to those of ordinary skill in the art in view of the teachings herein. It should also be understood that some other versions may provide manual driving of firing beam (14), such that a motor may be omitted. By way of example only, firing beam (14) may be actuated in accordance with at least some of the teachings of any other patent/publication reference cited herein.

III. Exemplary Anvil Configurations

As noted above, wedge sled (41) provides a camming action to drive staple drivers (43) upwardly within staple cartridge (37) when wedge sled (41) is driven distally. This upward movement of staple drivers (43) pushes staples (47) upwardly and out through staple apertures (51). This forces each staple (47) into an associated staple forming pocket (53) of anvil (18), ultimately resulting in bent/formed staples (47). The legs of the staples (47) penetrate layers (90, 92) of tissue as they are driven toward anvil (18), such that the formed staples (47) secure the layers (90, 92) of tissue (as shown in FIG. 7).

It should be understood that the configuration of staple forming pockets (53) may have a significant impact on the configuration of formed staples (47), such that varying the configuration of a staple forming pocket (53) may significantly vary the configuration of a staple (47) formed by staple forming pocket (53). Furthermore, it will be understood that varying the configuration of a staple (47) formed by staple forming pocket (53) may have a significant impact on how that formed staple (47) interacts with layers (90, 92) of tissue. For instance, some formed staple (47) configurations may provide greater hemostasis in layers (90, 92) of tissue than other formed staple (47) configurations. As another merely illustrative example, some formed staple (47) configurations may secure apposition of layers (90, 92) of tissue better than other formed staple (47) configurations. As yet another merely illustrative example, some formed staple (47) configurations may impose more trauma on layers (90, 92) of tissue (e.g., by tearing the tissue more) than other formed staple (47) configurations, which may affect the ability of the formed staples (47) to provide hemostasis and/or secure apposition of layers (90, 92), etc. Several exemplary configurations for staple forming pockets (53) will be described in greater detail below; while others will be apparent to those of ordinary skill in the art in view of the teachings herein.

A. Exemplary Staple Forming Pockets with Aligned Channels

FIGS. 12-13 show an exemplary anvil (200) that may be used in place of anvil (18) described above. Anvil (200) of this example defines a longitudinally extending slot (204), which is similar to anvil slot (42) described above. An upper portion of firing beam (14) translates through anvil slot (42) during a cutting/stapling stroke of instrument (10). Anvil (200) also includes a tissue contacting surface (202) that presses against tissue when the tissue is clamped between anvil (200) and upper deck (72) of staple cartridge (37). A series of staple forming pockets (210) are recessed relative to tissue contacting surface (202). In the present example, anvil (200) has two rows (206, 208) of staple forming pockets (210) on each side of slot (204). However, it should be understood that any other suitable number of rows of staple forming pockets (210) may be provided on each side of slot (204). By way of example only, some other versions may include three rows of staple forming pockets (210) on each side of slot (204). It should also be noted that, on each side of slot (204), inner row (206) is longitudinally offset relative to an outer row (208). The results of such an offset would be similar to what is shown in FIG. 7, where formed staples (47) are longitudinally offset among adjacent rows. Of course, staple forming pockets (210) may have any other suitable arrangements relationships with each other.

FIGS. 14-16 show a single staple forming pocket (210) in greater detail. It should be understood that all staple forming pockets (210) of anvil (200) may be similarly configured. Staple forming pocket (210) of this example provides a first channel (220) and a second channel (240). Second channel (240) is aligned with first channel (220). A dividing wall surface (260) separates channels (220, 240). Channels (220, 240) are symmetric about a vertical plane that passes through wall along and that extends transversely relative to staple forming pocket (210).

Channel (220) is longitudinally defined by a downwardly sloping concave surface (222), which smoothly transitions into an upwardly sloping concave surface (224), which terminates at dividing wall surface (260). Channel (220) is laterally defined by a pair of sidewalls (226, 228), which are vertically angled such that the lower regions of sidewalls (226, 228) are closer to each other than the upper regions of sidewalls (226, 228). Sidewalls (226, 228) are also laterally angled such that the ends of sidewalls (226, 228) adjacent to dividing wall surface (260) are closer to each other than the ends of sidewalls (226, 228) further away from dividing wall surface (260).

Channel (240) is longitudinally defined by a downwardly sloping concave surface (242), which smoothly transitions into an upwardly sloping concave surface (244), which terminates at dividing wall surface (260). Channel (240) is laterally defined by a pair of sidewalls (246, 248), which are vertically angled such that the lower regions of sidewalls (246, 248) are closer to each other than the upper regions of sidewalls (246, 248). Sidewalls (246, 248) are also laterally angled such that the ends of sidewalls (246, 248) adjacent to dividing wall surface (260) are closer to each other than the ends of sidewalls (246, 248) further away from dividing wall surface (260).

Staple forming pocket (210) also includes lead-in surfaces (280, 282) that extend along the length of staple forming pocket (210). Lead-in surface (280) is adjacent to sidewalls (226, 246) and dividing wall surface (260). Lead-in surface (282) is adjacent to sidewalls (228, 248) and dividing wall surface (260). Lead-in surfaces (280, 282) are vertically angled to assist in guiding the tips of staple legs into channels (220, 240) as the staple is being driven toward staple forming pocket (210). However, the angle defined between each lead-in surface (280, 282) and the horizontal plane (along which tissue contacting surface (202) lies) is less than the angle defined between each sidewall (226, 246, 228, 248) and the same horizontal plane. It should be understood that lead-in surfaces (280, 282) may also alleviate very localized tissue compression at staple forming pocket (210) during the final stages of staple formation.

FIG. 17 shows an exemplary staple (250) that has been formed by staple forming pocket (210), securing two layers (92, 94) of tissue in apposition. Staple (250) includes a crown (252), a first leg (270) having a tissue piercing tip (272), and a second leg (290) having a tissue piercing tip (292). As shown, legs (270, 290) are bent toward each other, with tips (272, 292) passing through a plane along which crown (252) lies. The formation of staple (250) is illustrated in FIGS. 18A-18E. When tips (272, 292) initially contact surfaces (222, 242), legs (270, 290) are substantially straight and perpendicular to crown (252). As staple (250) is driven further toward staple forming pocket (210), to the point where each tip (272, 292) reaches the apex (A₁) of each respective channel (220, 240), surfaces (222, 242) cammingly drive tips (272, 292) toward each other, which results in legs (270, 290) bending toward each other as shown in FIG. 18B. As staple (250) is driven further toward staple forming pocket (210), surfaces (224, 244) cammingly drive tips (272, 292) toward crown (252) as shown in FIG. 18C. As staple (250) is driven further toward staple forming pocket (210), surfaces (222, 224, 242, 244) continue to deform legs (270, 290) such that tips (272, 292) clear dividing wall surface (260) as shown in FIG. 18D. Once staple (250) is fully driven into staple forming pocket (210), tips (272, 292) pass crown (252), as shown in FIG. 18E and in FIG. 17. Thus, tips (272, 292) are driven through both layers (92, 94) of tissue twice, with tips (272, 292) being positioned past the same side of layer (92) as crown (252). It should be noted that formed staple (250) has a “B” shape in this example. It should also be noted that tips (272, 292) are positioned on the same lateral side of crown (252) after staple (250) is formed in this example. In some instances, tips (272, 292) do not pass crown (252), but nevertheless pass through at least layer (94) and perhaps layer (92) twice.

Referring back to FIG. 18A, it should be noted that staple forming pocket (210) provides a distance (d₁) between a longitudinal axis of each leg (270, 290) and a parallel axis passing through the apex (A₁) of each corresponding channel (220, 240). In addition, staple forming pocket (210) provides a distance (d₂) between a vertical axis passing through the center of crown (252) and a parallel axis passing through the apex (A₁) of each channel (220, 240). As will be described in greater detail below, it may be desirable in some instances to shift apexes (A₁) closer toward the vertical axis passing through the center of crown (252), thereby increasing distance (d₁) and reducing distance (d₂). In either case, it should be understand that it may be desirable in some instances to have the distance (d₁) on one side of pocket (210) be greater than the corresponding distance (d₁) on the other side of pocket (210). Similarly, it may be desirable in some instances to have the distance (d₂) be greater on one side of pocket than the corresponding distance (d₂) on the other side of pocket (210). It is thus contemplated that a pocket may be asymmetric about a vertical plane that passes through dividing wall surface (260).

B. Exemplary Staple Forming Pockets with Channels Separated by Full Oblique Wall

FIGS. 19-21 show an exemplary anvil (300) that may be used in place of anvil (18) described above. Anvil (300) of this example defines a longitudinally extending slot (304), which is similar to anvil slot (42) described above. An upper portion of firing beam (14) translates through anvil slot (42) during a cutting/stapling stroke of instrument (10). Anvil (300) also includes a tissue contacting surface (302) that presses against tissue when the tissue is clamped between anvil (300) and upper deck (72) of staple cartridge (37). A series of staple forming pockets (310) are recessed relative to tissue contacting surface (302). In the present example, anvil (300) has three rows of staple forming pockets (310) on each side of slot (304). However, it should be understood that any other suitable number of rows of staple forming pockets (310) may be provided on each side of slot (304). By way of example only, some other versions may include two rows or more than three rows of staple forming pockets (310) on each side of slot (304). It should also be noted that, on each side of slot (304), each row of staple forming pockets (310) is longitudinally offset relative to the adjacent row of staple forming pockets (310). The results of such an offset would be similar to what is shown in FIG. 7, where formed staples (47) are longitudinally offset among adjacent rows. Of course, staple forming pockets (310) may have any other suitable arrangements relationships with each other.

FIGS. 22-23 show staple forming pocket (310) in greater detail. It should be understood that all staple forming pockets (310) of anvil (300) may be similarly configured. Staple forming pocket (310) of this example provides a first channel (320) and a second channel (340). While channels (320, 340) are generally parallel with each other, channels (320, 340) are not aligned with each other in this example. A dividing wall (360) separates channels (320, 340). Wall (360) is obliquely oriented relative to slot (304) of anvil (300). Channels (320, 340) are asymmetric in this example, though there are substantial similarities between the configuration of channel (340) and the configuration of channel (320).

Channel (320) is longitudinally defined by a downwardly sloping concave surface (322), which smoothly transitions into an upwardly sloping concave surface (324), which terminates at tissue contacting surface (302) at a terminal end (321) of channel (320). In some instances, surface (322) is defined by a single radius. In some other instances, surface (322) is defined by more than one radius. In addition or in the alternative, surface (322) may include a combination of one or more surfaces defined by one or more radii and one or more flat surfaces that are vertical, horizontal, or otherwise angled.

Channel (320) is laterally defined on one side by a first sidewall (323), a second sidewall, (325), and a third sidewall (326). Channel (320) is laterally defined on the other side by a fourth sidewall (328). It should be understood that any other suitable number of sidewalls may be used to define channel (320). First sidewall (323) is generally parallel with fourth sidewall (328) in the present example, though it should be understood that other suitable relationships may be provided. Second sidewall (325) defines a first oblique angle relative to fourth sidewall (328). Third sidewall (326) defines a second oblique angle relative to fourth sidewall (328). The first oblique angle is greater than the second oblique angle. Thus, when viewing the width across the length of channel (320), channel (320) is widest at the staple leg entry end (319) and along the short length defined between first sidewall (323) and fourth sidewall (328). The width of channel (320) then drastically narrows along the part of the length defined between second sidewall (325) and fourth sidewall (328). The width of channel (320) continues to narrow (but less drastically) along the part of the length defined between third sidewall (326) and fourth sidewall (328). Channel (320) is at its narrowest width at terminal end (321).

In the present example, the transition between first sidewall (323) and second sidewall (325) is smooth, with a generally concave curvature. The transition between second sidewall (325) and third sidewall (326) is also smooth, with a generally convex curvature. In addition, the transitions between the upper boundaries of sidewalls (323, 325, 326, 328) and tissue contacting surface (302) are smooth, with a generally convex curvature. In some other versions, the edges between the upper boundaries of sidewalls (323, 325, 326, 328) and tissue contacting surface (302) are chamfered, providing a flat but angled lead-in from tissue contacting surface (302) to sidewalls (323, 325, 326, 328). Alternatively any other suitable types of transitions may be used. It should also be understood that all of sidewalls (323, 325, 326, 328) extend up to tissue contacting surface (302) in this example, excepting a relatively short and uniform rounded/chamfered transition about the upper perimeter defined by sidewalls (323, 325, 326, 328).

Channel (340) is longitudinally defined by a downwardly sloping concave surface (342), which smoothly transitions into an upwardly sloping concave surface (344), which terminates at tissue contacting surface (302) at a terminal end (341) of channel (340). In some instances, surface (342) is defined by a single radius. In some other instances, surface (342) is defined by more than one radius. In addition or in the alternative, surface (342) may include a combination of one or more surfaces defined by one or more radii and one or more flat surfaces that are vertical, horizontal, or otherwise angled.

Channel (340) is laterally defined on one side by a first sidewall (343), a second sidewall, (345), and a third sidewall (346). Channel (340) is laterally defined on the other side by a fourth sidewall (348). It should be understood that any other suitable number of sidewalls may be used to define channel (340). First sidewall (343) is generally parallel with fourth sidewall (348) in the present example, though it should be understood that other suitable relationships may be provided. Second sidewall (345) defines a first oblique angle relative to fourth sidewall (348). Third sidewall (346) defines a second oblique angle relative to fourth sidewall. The first oblique angle is greater than the second oblique angle. Thus, when viewing the width across the length of channel (340), channel (340) is widest at the staple leg entry end (339) and along the short length defined between first sidewall (343) and fourth sidewall (348). The width of channel (340) then drastically narrows along the part of the length defined between second sidewall (345) and fourth sidewall (348). The width of channel (340) continues to narrow (but less drastically) along the part of the length defined between third sidewall (346) and fourth sidewall (348). Channel (340) is at its narrowest width at terminal end (341).

In the present example, the transition between first sidewall (343) and second sidewall (345) is smooth, with a generally concave curvature. The transition between second sidewall (345) and third sidewall (346) is also smooth, with a generally convex curvature. In addition, the transitions between the upper boundaries of sidewalls (343, 345, 346, 348) and tissue contacting surface (302) are smooth, with a generally convex curvature. In some other versions, the edges between the upper boundaries of sidewalls (343, 345, 346, 348) and tissue contacting surface (302) are chamfered, providing a flat but angled lead-in from tissue contacting surface (302) to sidewalls (343, 345, 346, 348). Alternatively any other suitable types of transitions may be used. It should also be understood that all of sidewalls (343, 345, 346, 348) extend up to tissue contacting surface (302) in this example, excepting a relatively short and uniform rounded/chamfered transition about the upper perimeter defined by sidewalls (343, 345, 346, 348).

As can be seen in FIG. 22, sidewalls (326, 346) together define dividing wall (360). Dividing wall (360) extends to a height where the top of dividing wall (360) is substantially flush with tissue contacting surface (302). As can also be seen in FIG. 22, the transition from second sidewall (325) of channel (320) to third sidewall (326) of channel (320) is located within the same longitudinal region of staple forming pocket (310) as terminal end (341) of channel (340). In other words, the transition from second sidewall (325) of channel (320) to third sidewall (326) of channel (320) is located directly lateral to terminal end (341) of channel (340). Likewise, the transition from second sidewall (345) of channel (340) to third sidewall (346) of channel (340) is located within the same longitudinal region of staple forming pocket (310) as terminal end (321) of channel (320). In other words, the transition from second sidewall (345) of channel (340) to third sidewall (346) of channel (340) is located directly lateral to terminal end (321) of channel (320). It should be understood that staple forming pocket (310) generally defines a longitudinal axis extending from the left side of FIG. 22 to the right side of FIG. 22 (with FIG. 22 being viewed in a landscape orientation). The full length of staple forming pocket (310) extends along this longitudinal axis; while the full width of staple forming pocket (310) spans laterally relative to this longitudinal axis. A portion of staple forming pocket (310) that is associated with a particular point or range along the longitudinal axis may be regarded as a “longitudinal region” of staple forming pocket (310). A “longitudinal region” may thus include the full width of staple forming pocket (310) at a particular point or particular range of length along the longitudinal axis.

FIG. 24 shows an exemplary staple (350) that has been formed by staple forming pocket (310), securing two layers (92, 94) of tissue in apposition. Staple (350) includes a crown (352), a first leg (370) having a tissue piercing tip (372), and a second leg (390) having a tissue piercing tip (392). As shown, legs (370, 390) are bent toward each other, but legs (370, 390) do not pass through a plane along which crown (352) lies. The formation of staple (350) is illustrated in FIGS. 25A-25D. When tips (372, 392) initially contact surfaces (322, 342), legs (370, 390) are substantially straight and perpendicular to crown (352). In addition, legs (370, 390) and crown (352) all lie along a common vertical plane. As staple (350) is driven further toward staple forming pocket (310), to the point where each tip (372, 392) reaches the apex (A₂) of each respective channel (320, 340), surfaces (322, 342) cammingly drive tips (372, 392) toward each other, which results in legs (370, 390) bending toward each other as shown in FIG. 25B. As staple (350) is driven further toward staple forming pocket (310), sidewalls (324, 344) cammingly drive tips (372, 392) toward crown (352) as shown in FIG. 25C. In addition, sidewalls (325, 326) drive tip (372) laterally away from the vertical plane referred to above; while surfaces (345, 346) drive tip (392) laterally away from the vertical plane referred to above. Legs (370, 390) and crown (352) thus no longer lie along a common vertical plane at this stage. In particular, legs (370, 390) and tips (372, 392) have been driven laterally in opposite directions relative to crown (352).

As staple (350) is driven further toward staple forming pocket (310), surfaces (322, 324, 342, 344) and sidewalls (324, 324, 325, 326) continue to deform legs (370, 390) such that tips (372, 392) are eventually positioned at the respective terminal ends (321, 341) of staple forming pockets (320, 340) as shown in FIG. 25D. Thus, tips (372, 392) only pass through layer (92) of tissue once in this example. In some instances, however, tips (372, 392) are driven to the point where they pass back into layer (94) of tissue as shown in FIG. 24. In some other instances, tips (372, 392) do not pass back into layer (94), such that tips (372, 392) only pass through layer (94) of tissue once. Regardless of whether tips (372, 392) pass back through layer (94) of tissue a second time, it should be understood that tips (372, 392) may be laterally offset relative to a vertical plane passing along the length of crown (352). In particular, tip (372) may be positioned on one lateral side of such a plane while tip (392) is positioned on the other lateral side of such a plane. The resulting lateral offset form may have an appearance similar to that shown in FIG. 34, which will be described in greater detail below.

Referring back to FIG. 25A, it should be noted that staple forming pocket (310) provides a distance (d₃) between a longitudinal axis of each leg (370, 390) and a parallel axis passing through the apex (A₂) of each corresponding channel (320, 340). In addition, staple forming pocket (310) provides a distance (d₄) between a vertical axis passing through the center of crown (352) and a parallel axis passing through the apex (A₂) of each channel (320, 340). As can be seen by comparing FIG. 25A with FIG. 18A, the distance (d₃) is greater than the distance (d₁), with the distance (d₄) being less than the distance (d₂). Thus, the apexes (A₂) in staple forming pocket (310) are closer to the vertical axis passing through the center of crown (352) than the apexes (A₁) of staple forming pocket (210) are to the vertical axis passing through the center of crown (252). Such a difference in configuration may promote inward bending of legs (370, 390) better, may minimize the elongation of the entry hole ultimately created by each leg (370, 390) in tissue, and/or may provide other results. In addition, it should be noted that channels (320, 340) have a greater length than channels (220, 240), which may reduce the likelihood of legs (370, 390) undesirably exiting channels (320, 340) before staple formation is complete. In some versions, channels (320, 340) are also deeper than channels (220, 240), which may assist in preventing tips (372, 392) from passing through at least layer (92) if not both layers (92, 94) a second time during staple formation.

In some settings, a staple (350) formed by staple forming pocket (310) may provide greater hemostasis of apposed tissue layers (92, 94), may provide greater structural integrity with respect to the apposition of tissue layers (92, 94), may have a reduced likelihood to undesirably pull through tissue layers (92, 94), may provide a reduced likelihood of tissue later tearing at the staple line, and/or may otherwise minimize trauma to tissue layers (92, 94), particularly when compared to staple (250) formed by staple forming pocket (210). When sealing certain tissue structures (e.g., a fragile artery, etc.), it may be desirable to minimize the amount of tissue puncturing by a staple. Formed staple (350) may minimize such puncturing (e.g., as compared to formed staple (250)) by not passing back trough layer (92) a second time; and in some instances not passing back through layer (94) a second time. By minimizing the fold-back motion of staple legs (370, 390) formed by staple forming pocket (310), the resulting formed staple (350) may bear more resemblance and functional similarity to a secure tissue clip than a conventional staple. Such a clip-like configuration may result in more tissue being captured between legs (370, 390) and crown (352) than might otherwise be captured between legs (270, 290) and crown (252); which may in turn result in better tissue integrity and a reduced tendency for the tissue to tear near staple (350). Minimizing the fold-back motion of staple legs (370, 390) during the process of staple formation may also reduce the total force required to form staple (350); as compared to the forces required to form a staple using a conventional staple forming pocket. This may reduce the force required to advance firing beam (14) distally during a firing stroke.

C. Exemplary Staple Forming Pockets with Channels Separated by Partial Wall

FIGS. 26-29 show another merely exemplary staple forming pocket (410) that may be readily incorporated into any of the anvils (18, 200, 300) referred to herein, among others. Staple forming pocket (410) of this example provides a first channel (420) and a second channel (440). While channels (420, 440) are generally parallel with each other, channels (420, 440) are not aligned with each other in this example. A dividing wall (460) separates channels (420, 440). Wall (460) is parallel with the slot (42, 204, 304) of anvil (18, 200, 300). Channels (420, 440) are asymmetric in this example, though there are substantial similarities between the configuration of channel (440) and the configuration of channel (420).

Channel (420) is longitudinally defined by a downwardly sloping concave surface (422), which smoothly transitions into an upwardly sloping concave surface (424), which terminates at recessed surface (403) at a terminal end (421) of channel (420). In some instances, surface (422) is defined by a single radius. In some other instances, surface (422) is defined by more than one radius. In addition or in the alternative, surface (422) may include a combination of one or more surfaces defined by one or more radii and one or more flat surfaces that are vertical, horizontal, or otherwise angled. Recessed surface (403) is recessed below tissue contacting surface (402) in the present example. In some instances, this may reduce localized pressure on tissue during a stapling sequence.

Channel (420) is laterally defined on one side by a first sidewall (423), a second sidewall, (425), and a third sidewall (426). Channel (420) is laterally defined on the other side by a fourth sidewall (428). It should be understood that any other suitable number of sidewalls may be used to define channel (420). First sidewall (423) is generally parallel with fourth sidewall (428) in the present example, though it should be understood that other suitable relationships may be provided. Second sidewall (425) defines an oblique angle relative to fourth sidewall (428). Third sidewall (426) is generally parallel with fourth sidewall (428). Thus, when viewing the width across the length of channel (420), channel (420) is widest at the staple leg entry end (419) and along the short length defined between first sidewall (423) and fourth sidewall (428). The width of channel (420) then drastically narrows along the part of the length defined between second sidewall (425) and fourth sidewall (428). The width of channel (420) remains substantially consistently narrow along the remaining length of channel (420), defined between third sidewall (426) and fourth sidewall (428) until channel (420) reaches its terminal end (421).

In the present example, the transition between first sidewall (423) and second sidewall (425) is smooth, with a generally concave curvature. The transition between second sidewall (425) and third sidewall (426) is also smooth, as is the transition between second sidewall (425) and recessed surface (403), with a generally convex curvature. In addition, the transitions between the upper boundaries of sidewalls (423, 426, 428) and tissue contacting surface (402) are smooth, with a generally convex curvature. In some other versions, the edges between the upper boundaries of sidewalls (423, 426, 428) and tissue contacting surface (402) are chamfered, providing a flat but angled lead-in from tissue contacting surface (402) to sidewalls (423, 426, 428). Alternatively any other suitable types of transitions may be used. It should also be understood that all of sidewalls (423, 426, 428) extend up to tissue contacting surface (402) in this example, excepting a relatively short and uniform rounded/chamfered transition about the upper perimeter defined by sidewalls (423, 426, 428).

Channel (440) is longitudinally defined by a downwardly sloping concave surface (442), which smoothly transitions into an upwardly sloping concave surface (444), which terminates at tissue contacting surface (402) at a terminal end (441) of channel (440). Channel (440) is laterally defined on one side by a first sidewall (443), a second sidewall, (445), and a third sidewall (446). In some instances, surface (442) is defined by a single radius. In some other instances, surface (442) is defined by more than one radius. In addition or in the alternative, surface (442) may include a combination of one or more surfaces defined by one or more radii and one or more flat surfaces that are vertical, horizontal, or otherwise angled.

Channel (440) is laterally defined on the other side by a fourth sidewall (448). First sidewall (443) is generally parallel with fourth sidewall (448). Second sidewall (445) defines an oblique angle relative to fourth sidewall (448). It should be understood that any other suitable number of sidewalls may be used to define channel (440). Third sidewall (446) is generally parallel with fourth sidewall (448), though it should be understood that other suitable relationships may be provided. Thus, when viewing the width across the length of channel (440), channel (440) is widest at the staple leg entry end (439) and along the short length defined between first sidewall (443) and fourth sidewall (448). The width of channel (440) then drastically narrows along the part of the length defined between second sidewall (445) and fourth sidewall (448). The width of channel (440) remains substantially consistently narrow along the remaining length of channel (440), defined between third sidewall (446) and fourth sidewall (448) until channel (440) reaches its terminal end (441).

In the present example, the transition between first sidewall (443) and second sidewall (445) is smooth, with a generally concave curvature. The transition between second sidewall (445) and third sidewall (446) is also smooth, as is the transition between second sidewall (445) and recessed surface (403), with a generally convex curvature. In addition, the transitions between the upper boundaries of sidewalls (443, 446, 448) and tissue contacting surface (402) are smooth, with a generally convex curvature. In some other versions, the edges between the upper boundaries of sidewalls (443, 446, 448) and tissue contacting surface (402) are chamfered, providing a flat but angled lead-in from tissue contacting surface (402) to sidewalls (443, 446, 448). Alternatively any other suitable types of transitions may be used. It should also be understood that all of sidewalls (443, 446, 448) extend up to tissue contacting surface (402) in this example, excepting a relatively short and uniform rounded/chamfered transition about the upper perimeter defined by sidewalls (443, 446, 448).

As can be seen in FIGS. 27 and 29, sidewalls (426, 446) together define dividing wall (460). Unlike dividing wall (360) described above, dividing wall (460) of this example is not flush with tissue contacting surface (402); and is instead recessed relative to tissue contacting surface (402) as best seen in FIG. 28. A pair of edges (462, 464) provide a transition from tissue contacting surface (402) to dividing wall (460). Edges (462, 464) are obliquely oriented relative to slot (42, 204, 304) of anvil (18, 200, 300) and further provide a vertically angled transition down to dividing wall (460).

As best seen in FIG. 27, edge (462) is located within the same longitudinal region of staple forming pocket (410) as the transition from second sidewall (425) of channel (420) to third sidewall (426) of channel (420); and terminal end (441) of channel (440). In other words, edge (462) is located generally lateral to the transition from second sidewall (425) of channel (420) to third sidewall (426) of channel (420); and generally lateral to terminal end (441) of channel (440). Likewise, edge (464) is located within the same longitudinal region of staple forming pocket (410) as the transition from second sidewall (445) of channel (440) to third sidewall (446) of channel (440); and terminal end (421) of channel (420). In other words, edge (464) is located generally lateral to the transition from second sidewall (445) of channel (440) to third sidewall (446) of channel (440); and generally lateral to terminal end (421) of channel (420).

A staple formed by staple forming pocket (410) may look similar to staple (350) shown in FIG. 24. In particular, surfaces (422, 442) may drive tips (372, 374) toward each other as legs (370, 390) are initially driven into respective channels (420, 440). As staple (350) is further driven into staple forming pocket (410), surfaces (424, 444) may drive tips toward crown (352). In addition, sidewall (425) may drive tip (372) in one direction laterally away from a vertical plane passing through dividing wall (460) and crown (352); while sidewall (445) drives tip (392) in the opposite direction laterally away from the same vertical plane passing through dividing wall (460) and crown (352). Surfaces (422, 424, 442, 444) and sidewalls (425, 426, 428, 445, 446, 448) may ultimately deform legs (370, 390) to the point where they are configured similar to what is shown in FIGS. 24 and 34. For instance, staple forming pocket (410) may form a staple (350) where tips (372, 392) only pass back into layer (94) (if at all), without also passing back into layer (92) a second time; and where tips (372, 392) are laterally offset relative to a vertical plane passing along the length of crown (352).

It should be understood that each channel (420, 440) may have a respective apex, and that the spacing of these apexes may be similar to the spacing of apexes (A₂) of channels (320, 340) described above. In other words, the apexes in staple forming pocket (410) may be closer to a vertical axis passing through the center of an associated staple crown than the apexes (A₁) of staple forming pocket (210) are to the vertical axis passing through the center of crown (252). Such a difference in configuration may promote inward bending of the legs better, may minimize the elongation of the entry hole ultimately created by each staple leg in tissue, and/or may provide other results. In addition, it should be noted that channels (420, 440) have a greater length than channels (220, 240), which may reduce the likelihood of associated staple legs undesirably exiting channels (420, 440) before staple formation is complete. In some versions, channels (420, 440) are also deeper than channels (220, 240), which may assist in preventing associated staple leg tips from passing through at least layer (92) if not both layers (92, 94) a second time during staple formation.

In some settings, a staple formed by staple forming pocket (410) may provide greater hemostasis of apposed tissue layers (92, 94), may provide greater structural integrity with respect to the apposition of tissue layers (92, 94), may have a reduced likelihood to undesirably pull through tissue layers (92, 94), may provide a reduced likelihood of tissue later tearing at the staple line, and/or may otherwise minimize trauma to tissue layers (92, 94), particularly when compared to staple (250) formed by staple forming pocket (210). When sealing certain tissue structures (e.g., a fragile artery, etc.), it may be desirable to minimize the amount of tissue puncturing by a staple. A staple formed by pocket (410) may minimize such puncturing (e.g., as compared to formed staple (250)) by not passing back trough layer (92) a second time; and in some instances not passing back through layer (94) a second time. By minimizing the fold-back motion of the staple legs formed by staple forming pocket (410), the resulting formed staple may bear more resemblance and functional similarity to a secure tissue clip than a conventional staple. Such a clip-like configuration may result in more tissue being captured between the legs and the crown of the formed staple than might otherwise be captured between legs (270, 290) and crown (252); which may in turn result in better tissue integrity and a reduced tendency for the tissue to tear near the staple. Minimizing the fold-back motion of the staple legs during the process of staple formation may also reduce the total force required to form the staple using staple forming pocket (410); as compared to the forces required to form a staple using a conventional staple forming pocket. This may reduce the force required to advance firing beam (14) distally during a firing stroke.

D. Exemplary Staple Forming Pockets with Single Channel and Oblique Deflection Walls

FIGS. 30-34 show another merely exemplary staple forming pocket (510) that may be readily incorporated into any of the anvils (18, 200, 300) referred to herein, among others. Staple forming pocket (510) of this example provides a single continuous channel (512) having a first cam feature (520) projecting laterally into channel (512) and a second cam feature (540) projecting laterally into channel (512). Channel (512) includes a first terminal end (514) for receiving a first staple leg and a second terminal end (516) for receiving a second staple leg. Channel (512) includes a concave entry surface (515) at end (514), a concave entry surface (517) at end (516), and a flat floor surface (518) that joins surfaces (515, 517) and provides a lowest point in the longitudinal mid region of channel (512). It should be understood that terms such as “downwardly” and “lowest” are used here in reference to pocket (510) being oriented as shown in FIG. 32, with tissue contacting surface (502) being presented upwardly. In actual use, tissue contacting surface (502) may in fact be presented downwardly, such that the orientation of pocket (510) would be flipped from the orientation shown in FIG. 32. Thus, terms such as “downwardly,” “upwardly,” “lowest,” “top,” “bottom,” and the like should not be read as limiting how the inventors contemplate any of the devices herein being necessarily oriented during actual use of the devices.

A first outer sidewall (542) extends from first terminal end (514) to second cam feature (540). A second outer sidewall (522) extends from second terminal end (516) to first cam feature (520). Outer sidewalls (522, 542) are angled relative to a vertical plane passing longitudinally along the center of staple forming pocket (510), such that sidewalls (522, 542) provide a lead-in to surfaces (515, 514) and floor (518). In other words, the lateral spacing between sidewalls (522, 542) is greater at the top of sidewalls (522, 542) (i.e., at tissue contact surface (502)) than the lateral spacing between sidewalls (522, 542) at the bottom of sidewalls (522, 542).

First cam feature (520) includes a laterally concave sidewall (524), a convex transition region (526), and a longitudinal sidewall (528). It should be understood that the distance between laterally concave sidewall (524) and outer sidewall (542) is greater than the distance between longitudinal sidewall (528) and outer sidewall (542). A terminal convex sidewall (527) is located at the opposite end of longitudinal sidewall (528). First cam feature (520) also includes a ramp (529). As best seen in FIG. 32, ramp (529) is concave and is defined by a radius of curvature that is less than the radius of curvature defining surface (517). Ramp (529) thus presents a curve that is steeper than the curve presented by surface (517). Second cam feature (540) includes a laterally concave sidewall (544), a convex transition region (546), and a longitudinal sidewall (548). It should be understood that the distance between laterally concave sidewall (544) and outer sidewall (522) is greater than the distance between longitudinal sidewall (548) and outer sidewall (522). A terminal convex sidewall (547) is located at the opposite end of longitudinal sidewall (548). First cam feature (540) also includes a ramp (549). Ramp (549) is concave and is defined by a radius of curvature that is less than the radius of curvature defining surface (515). Ramp (549) thus presents a curve that is steeper than the curve presented by surface (515).

FIGS. 33A-34 show an example of how a staple (550) may be formed by staple forming pocket (510). In particular, FIG. 33A shows how surfaces (515, 517) drive legs (570, 590) of staple (550) toward each other as staple (550) is initially driven into staple forming pocket (510). As staple (550) is driven further into staple forming pocket (510), floor surface (518) guides legs (570, 590) and sidewalls (524, 526, 528) cooperate to drive leg (570) in one direction laterally away from a vertical plane passing through crown (552); while sidewalls (544, 546, 548) cooperate to drive leg (590) in the opposite direction laterally away from the same vertical plane passing through crown (552). This lateral deflection of legs (570, 590) is shown in FIG. 33B. This lateral deflection of legs (570, 590) prevents legs (570, 590) from colliding with each other during formation of staple (550). It should be understood that this lateral deflection of legs (570, 590) also steers tip (572) into ramp (549) while also steering tip (592) into ramp (529). Ramps (529, 549) thus drive the corresponding tips (592, 572) upwardly toward a horizontal plane passing through crown (552), as shown in FIG. 33C. The lateral deflection of legs (570, 590) after staple (550) has been formed by staple forming pocket (510) can be best seen in FIG. 34. It should be understood that formed staple (550) may engage layers (92, 94) of tissue similar to the manner shown in FIG. 24. For instance, staple forming pocket (510) may form a staple (550) where tips (572, 592) only pass back into layer (94) (if at all), without also passing back into layer (92) a second time.

While staple forming pocket (510) of the present example defines just one single continuous channel (512), it should be understood that the combination of surface (517), floor (518), and ramp (529) may effectively define one sub-channel while the combination of surface (515), floor (518), and ramp (549) effectively define another sub-channel. It should further be understood that each sub-channel of staple forming pocket (510) may have an associated effective apex, and that the spacing of these effective apexes may be similar to the spacing of apexes (A₂) of channels (320, 340) described above. In other words, the effective apexes in staple forming pocket (510) may be closer to a vertical axis passing through the center of staple crown (552) than the apexes (A₁) of staple forming pocket (210) are to the vertical axis passing through the center of crown (252). Such a difference in configuration may promote inward bending of legs (570, 590) better, may minimize the elongation of the entry hole ultimately created by each staple leg (570, 590) in tissue, and/or may provide other results. In addition, it should be noted that the effective sub-channels of staple forming pocket (510) have a greater length than channels (220, 240), which may reduce the likelihood of associated staple legs undesirably exiting channels (420, 440) before staple formation is complete. In some versions, the effective sub-channels of staple forming pocket (510) are also deeper than channels (220, 240), which may assist in preventing associated staple leg tips from passing through at least layer (92) if not both layers (92, 94) a second time during staple formation.

In some settings, a staple (550) formed by staple forming pocket (510) may provide greater hemostasis of apposed tissue layers (92, 94), may provide greater structural integrity with respect to the apposition of tissue layers (92, 94), may have a reduced likelihood to undesirably pull through tissue layers (92, 94), may provide a reduced likelihood of tissue later tearing at the staple line, and/or may otherwise minimize trauma to tissue layers (92, 94), particularly when compared to staple (250) formed by staple forming pocket (210). When sealing certain tissue structures (e.g., a fragile artery, etc.), it may be desirable to minimize the amount of tissue puncturing by a staple. Formed staple (550) may minimize such puncturing (e.g., as compared to formed staple (250)) by not passing back trough layer (92) a second time; and in some instances not passing back through layer (94) a second time. By minimizing the fold-back motion of staple legs (570, 590) formed by staple forming pocket (510), the resulting formed staple (550) may bear more resemblance and functional similarity to a secure tissue clip than a conventional staple. Such a clip-like configuration may result in more tissue being captured between legs (570, 590) and crown (552) than might otherwise be captured between legs (270, 290) and crown (252); which may in turn result in better tissue integrity and a reduced tendency for the tissue to tear near staple (550). Minimizing the fold-back motion of staple legs (570, 590) during the process of staple formation may also reduce the total force required to form staple (550); as compared to the forces required to form a staple using a conventional staple forming pocket. This may reduce the force required to advance firing beam (14) distally during a firing stroke.

E. Exemplary Staple Forming Pockets with Single Channel and Full Deflection Protrusions

FIGS. 35-37 show another merely exemplary staple forming pocket (610) that may be readily incorporated into any of the anvils (18, 200, 300) referred to herein, among others. Staple forming pocket (610) of this example provides a single continuous channel (612) having a first deflection protrusion (620) projecting laterally into channel (612) and a second deflection protrusion (640) projecting laterally into channel (612). Channel (612) includes a first terminal end (614) for receiving a first staple leg and a second terminal end (616) for receiving a second staple leg. Channel (612) includes a concave entry surface (615) at end (614), a concave entry surface (617) at end (616), and a flat floor surface (618) that joins surfaces (615, 617) and provides a lowest point in the longitudinal mid region of channel (612).

A first outer sidewall (642) extends from first terminal end (614) to second deflection protrusion (640). A second outer sidewall (622) extends from second terminal end (616) to first deflection protrusion (620). Outer sidewalls (622, 642) are angled relative to a vertical plane passing longitudinally along the center of staple forming pocket (610), such that sidewalls (622, 642) provide a lead-in to surfaces (615, 617) and floor (618). In other words, the lateral spacing between sidewalls (622, 642) is greater at the top of sidewalls (622, 642) (i.e., at tissue contact surface (602)) than the lateral spacing between sidewalls (622, 642) at the bottom of sidewalls (622, 642).

First deflection protrusion (620) includes a laterally concave sidewall (624) leading to a convex sidewall (626), which terminates in second outer sidewall (622). Like sidewall (622), sidewalls (624, 626) are sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (610), such that sidewalls (624, 626) provide a lead-in to surfaces (615, 617) and floor (618). It should also be understood that sidewalls (624, 626) vertically extend all the way to the top of channel (612), such that the tops of sidewalls (624, 626) terminate at tissue contact surface (602).

Second deflection protrusion (640) includes a laterally concave sidewall (644) leading to a convex sidewall (646), which terminates in first outer sidewall (642). Like sidewall (642), sidewalls (644, 646) are sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (610), such that sidewalls (644, 646) provide a lead-in to surfaces (615, 617) and floor (618). It should also be understood that sidewalls (644, 646) vertically extend all the way to the top of channel (612), such that the tops of sidewalls (644, 646) terminate at tissue contact surface (602).

When a staple is driven into staple forming pocket (610), the result may be similar to the result shown in FIGS. 24 and 34. In particular, surfaces (615, 617) may drive the legs of the staple toward each other as the staple is initially driven into staple forming pocket (610). Protrusions (620, 640) may eventually deflect the legs of the staple laterally in opposite directions, such that the legs do not collide with each other during formation of the staple and such that the legs are ultimately positioned on opposite sides of a vertical plane passing through the crown of the staple (e.g., as shown in FIG. 34). The tips of the staple legs may ultimately pass through layers (92, 94) of tissue just once, without even passing back through layer (94). In some versions, the tips of the staple legs may at least pass back through layer (94) a second time (e.g., as shown in FIG. 24).

It should be understood that a staple formed by staple forming pocket (610) may provide greater hemostasis of apposed tissue layers (92, 94), may provide greater structural integrity with respect to the apposition of tissue layers (92, 94), may have a reduced likelihood to undesirably pull through tissue layers (92, 94), may provide a reduced likelihood of tissue later tearing at the staple line, and/or may otherwise minimize trauma to tissue layers (92, 94), particularly when compared to staple (250) formed by staple forming pocket (210). When sealing certain tissue structures (e.g., a fragile artery, etc.), it may be desirable to minimize the amount of tissue puncturing by a staple. A staple formed by pocket (610) may minimize such puncturing (e.g., as compared to formed staple (250)) by not passing back trough layer (92) a second time; and in some instances not passing back through layer (94) a second time. By minimizing the fold-back motion of the staple legs formed by staple forming pocket (610), the resulting formed staple may bear more resemblance and functional similarity to a secure tissue clip than a conventional staple. Such a clip-like configuration may result in more tissue being captured between the legs and the crown of the formed staple than might otherwise be captured between legs (270, 290) and crown (252); which may in turn result in better tissue integrity and a reduced tendency for the tissue to tear near the staple. Minimizing the fold-back motion of the staple legs during the process of staple formation may also reduce the total force required to form the staple using staple forming pocket (610); as compared to the forces required to form a staple using a conventional staple forming pocket. This may reduce the force required to advance firing beam (14) distally during a firing stroke.

F. Exemplary Staple Forming Pockets with Single Channel and Partial Deflection Protrusions

FIGS. 38-40 show another merely exemplary staple forming pocket (710) that may be readily incorporated into any of the anvils (18, 200, 300) referred to herein, among others. Staple forming pocket (710) of this example provides a single continuous channel (712) having a first deflection protrusion (720) projecting laterally into channel (712) and a second deflection protrusion (740) projecting laterally into channel (712). Channel (712) includes a first terminal end (714) for receiving a first staple leg and a second terminal end (716) for receiving a second staple leg. Channel (712) includes a concave entry surface (715) at end (714), a concave entry surface (717) at end (716), and a flat floor surface (618) that joins surfaces (715, 717) and provides a lowest point in the longitudinal mid region of channel (712).

Channel (712) is further defined by a first outer sidewall (722) and a second outer sidewall (742). Sidewalls (722, 742) are angled relative to a vertical plane passing longitudinally along the center of staple forming pocket (710), such that sidewalls (722, 742) provide a lead-in to surfaces (715, 717) and floor (718). In other words, the lateral spacing between sidewalls (722, 742) is greater at the top of sidewalls (722, 742) (i.e., at tissue contact surface (702)) than the lateral spacing between sidewalls (722, 742) at the bottom of sidewalls (722, 742).

First deflection protrusion (720) includes an angled upper wall (721), and a laterally angled sidewall (724) leading to a convex sidewall (726), which terminates in first outer sidewall (722) Like sidewall (722), sidewalls (724, 726) are sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (710), such that sidewalls (724, 726) provide a lead-in to surfaces (715, 717) and floor (718). Upper wall (721) is also sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (710), though with an angle that is less steep than the angle provided by sidewalls (724, 726). As best seen in FIG. 40, upper wall (721) is positioned below tissue contact surface (702), such that protrusion (720) is entirely recessed in channel (712) in this example.

Second deflection protrusion (740) includes an angled upper wall (741), and a laterally angled sidewall (744) leading to a convex sidewall (746), which terminates in second outer sidewall (742). Like sidewall (742), sidewalls (744, 746) are sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (710), such that sidewalls (744, 746) provide a lead-in to surfaces (715, 717) and floor (718). Upper wall (741) is also sloped relative to a vertical plane passing longitudinally along the center of staple forming pocket (710), though with an angle that is less steep than the angle provided by sidewalls (744, 746). As best seen in FIG. 40, upper wall (741) is positioned below tissue contact surface (702), such that protrusion (740) is entirely recessed in channel (712) in this example.

When a staple is driven into staple forming pocket (710), the result may be similar to the result shown in FIGS. 24 and 34. In particular, surfaces (715, 717) may drive the legs of the staple toward each other as the staple is initially driven into staple forming pocket (710). Protrusions (720, 740) may eventually deflect the legs of the staple laterally in opposite directions, such that the legs do not collide with each other during formation of the staple and such that the legs are ultimately positioned on opposite sides of a vertical plane passing through the crown of the staple (e.g., as shown in FIG. 34). The tips of the staple legs may ultimately pass through layers (92, 94) of tissue just once, without even passing back through layer (94). In some versions, the tips of the staple legs may at least pass back through layer (94) a second time (e.g., as shown in FIG. 24).

It should be understood that a staple formed by staple forming pocket (710) may provide greater hemostasis of apposed tissue layers (92, 94), may provide greater structural integrity with respect to the apposition of tissue layers (92, 94), may have a reduced likelihood to undesirably pull through tissue layers (92, 94), may provide a reduced likelihood of tissue later tearing at the staple line, and/or may otherwise minimize trauma to tissue layers (92, 94), particularly when compared to staple (250) formed by staple forming pocket (210). When sealing certain tissue structures (e.g., a fragile artery, etc.), it may be desirable to minimize the amount of tissue puncturing by a staple. A staple formed by pocket (710) may minimize such puncturing (e.g., as compared to formed staple (250)) by not passing back trough layer (92) a second time; and in some instances not passing back through layer (94) a second time. By minimizing the fold-back motion of the staple legs formed by staple forming pocket (710), the resulting formed staple may bear more resemblance and functional similarity to a secure tissue clip than a conventional staple. Such a clip-like configuration may result in more tissue being captured between the legs and the crown of the formed staple than might otherwise be captured between legs (270, 290) and crown (252); which may in turn result in better tissue integrity and a reduced tendency for the tissue to tear near the staple. Minimizing the fold-back motion of the staple legs during the process of staple formation may also reduce the total force required to form the staple using staple forming pocket (710); as compared to the forces required to form a staple using a conventional staple forming pocket. This may reduce the force required to advance firing beam (14) distally during a firing stroke.

G. Exemplary Varied Array of Staple Forming Pockets

In some exemplary anvils, all of the staple forming pockets have the same configuration. In some other exemplary anvils, at least some of the staple forming pockets are different from each other. An example of this is shown in FIG. 41, which shows a portion of an anvil (800) having two rows of a first kind of staple forming pockets (210) and a row of a second kind of staple forming pockets (310). Anvil (800) includes a tissue contact surface (802), an anvil slot (804) (which is similar to anvil slot (42) described above), and an outer side (806). It should be understood that FIG. 41 just shows pockets (210, 310) on one side of slot (804), and that a mirror image arrangement of pockets (210, 310) would be on the other side of slot (804) such that anvil (800) is symmetric about a plane extending perpendicularly out of the drawing sheet along the length of slot (804).

Pockets (210) are the same as pockets (210) shown in FIGS. 12-16 and described above. Pockets (310) are the same as pockets (310) shown in FIGS. 19-23 and described above. Of course, any other suitable pocket configurations may be used. It should also be understood that any suitable arrangement may be used. For instance, a first row (810) may include a first type of staple forming pocket, with a second row (820) including a second type of staple forming pocket, with a third row (830) including a third type of staple forming pocket. As another merely illustrative example, the staple forming pockets of at least one row (810, 820, 830) may be oriented in one direction; while the staple forming pockets of at least one other row (810, 820, 830) may be oriented in another direction. In some versions, the staple forming pockets of one row (810, 820, 830) are oriented obliquely relative to the staple forming pockets of the other rows (810, 820, 830). In addition or the alternative, the staple forming pockets of one row (810, 820, 830) may be oriented perpendicularly relative to the staple forming pockets of the other rows (810, 820, 830). Even the staple forming pockets of a particular row (810, 820, 830) may be oriented differently from other staple forming pockets in the same row (810, 820, 830) (e.g., alternating perpendicular or oblique orientations, etc.). Various suitable arrangements and combinations of pocket configurations will be apparent to those of ordinary skill in the art in view of the teachings here.

FIGS. 42-43 show a series of staples (250, 350) formed by anvil (800). Staples (250) are the same as staple (250) shown in FIGS. 17-18E and described above. Staple (350) is the same as staple (350) shown in FIGS. 24-25D and described above. As best seen in FIG. 42, in each formed staple (250), legs (270, 290) remain positioned along a vertical plane passing through crown (252), such that legs (270, 290) are obscured in the top plan view of FIG. 42. However, legs (370, 390) of staple (350) are deflected laterally and obliquely relative to the vertical plane passing through crown (352) of staple (350), due to the configuration of pocket (310) as described above. FIG. 43 depicts these formed staples (250, 350) as applied to layers (92, 94). Since pockets (210) are positioned closest to slot (804), staples (250) are positioned closest to the cut line (96) created by cutting edge (48) of firing beam (14).

IV. Miscellaneous

It should be understood that any one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, embodiments, examples, etc. that are described herein. The above-described teachings, expressions, embodiments, examples, etc. should therefore not be viewed in isolation relative to each other. Various suitable ways in which the teachings herein may be combined will be readily apparent to those of ordinary skill in the art in view of the teachings herein. Such modifications and variations are intended to be included within the scope of the claims.

It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

Versions of the devices described above may have application in conventional medical treatments and procedures conducted by a medical professional, as well as application in robotic-assisted medical treatments and procedures. By way of example only, various teachings herein may be readily incorporated into a robotic surgical system such as the DAVINCI™ system by Intuitive Surgical, Inc., of Sunnyvale, Calif. Similarly, those of ordinary skill in the art will recognize that various teachings herein may be readily combined with various teachings of any of the following: U.S. Pat. No. 5,792,135, entitled “Articulated Surgical Instrument For Performing Minimally Invasive Surgery With Enhanced Dexterity and Sensitivity,” issued Aug. 11, 1998, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 5,817,084, entitled “Remote Center Positioning Device with Flexible Drive,” issued Oct. 6, 1998, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 5,878,193, entitled “Automated Endoscope System for Optimal Positioning,” issued Mar. 2, 1999, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,231,565, entitled “Robotic Arm DLUS for Performing Surgical Tasks,” issued May 15, 2001, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,783,524, entitled “Robotic Surgical Tool with Ultrasound Cauterizing and Cutting Instrument,” issued Aug. 31, 2004, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,364,888, entitled “Alignment of Master and Slave in a Minimally Invasive Surgical Apparatus,” issued Apr. 2, 2002, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 7,524,320, entitled “Mechanical Actuator Interface System for Robotic Surgical Tools,” issued Apr. 28, 2009, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 7,691,098, entitled “Platform Link Wrist Mechanism,” issued Apr. 6, 2010, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 7,806,891, entitled “Repositioning and Reorientation of Master/Slave Relationship in Minimally Invasive Telesurgery,” issued Oct. 5, 2010, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2013/0012957, entitled “Automated End Effector Component Reloading System for Use with a Robotic System, published Jan. 10, 2013, now U.S. Pat. No. 8,844,789, issued Sep. 30, 2014, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0199630, entitled “Robotically-Controlled Surgical Instrument with Force-Feedback Capabilities,” published Aug. 9, 2012, now U.S. Pat. No. 8,820,605, issued Sep. 2, 2014, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0132450, entitled “Shiftable Drive Interface for Robotically-Controlled Surgical Tool,” published May 31, 2012, issued Dec. 31, 2013 as U.S. Pat. No. 8,616,431, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0199633, entitled “Surgical Stapling Instruments with Cam-Driven Staple Deployment Arrangements,” published Aug. 9, 2012, issued Nov. 5, 2013 as U.S. Pat. No. 8,573,461, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0199631, entitled “Robotically-Controlled Motorized Surgical End Effector System with Rotary Actuated Closure Systems Having Variable Actuation Speeds,” published Aug. 9, 2012, issued Dec. 10, 2013 as U.S. Pat. No. 8,602,288, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0199632, entitled “Robotically-Controlled Surgical Instrument with Selectively Articulatable End Effector,” published Aug. 9, 2012, now U.S. Pat. No. 9,301,759, issued Apr. 5, 2016, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0203247, entitled “Robotically-Controlled Surgical End Effector System,” published Aug. 9, 2012, now U.S. Pat. No. 8,783,541, issued Jul. 22, 2014, the disclosure of which is incorporated by reference herein; U.S. Pub. No. 2012/0211546, entitled “Drive Interface for Operably Coupling a Manipulatable Surgical Tool to a Robot,” published Aug. 23, 2012, issued Jul. 9, 2013 as U.S. Pat. No. 8,479,969; U.S. Pub. No. 2012/0138660, entitled “Robotically-Controlled Cable-Based Surgical End Effectors,” published Jun. 7, 2012, now U.S. Pat. No. 8,800,838, issued Aug. 12, 2017, the disclosure of which is incorporated by reference herein; and/or U.S. Pub. No. 2012/0205421, entitled “Robotically-Controlled Surgical End Effector System with Rotary Actuated Closure Systems,” published Aug. 16, 2012, issued Nov. 5, 2013 as U.S. Pat. No. 8,573,465, the disclosure of which is incorporated by reference herein.

Versions of the devices described above may be designed to be disposed of after a single use, or they can be designed to be used multiple times. Versions may, in either or both cases, be reconditioned for reuse after at least one use. Reconditioning may include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, some versions of the device may be disassembled, and any number of the particular pieces or parts of the device may be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, some versions of the device may be reassembled for subsequent use either 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 may utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application.

By way of example only, versions described herein may be sterilized before and/or after a procedure. 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 field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation may kill bacteria on the device and in the container. The sterilized device may then be stored in the sterile container for later use. A 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.

Having shown and described various embodiments of the present invention, further adaptations of the methods and systems described herein may be accomplished by appropriate modifications by one of ordinary skill in the art without departing from the scope of the present invention. Several of such potential modifications have been mentioned, and others will be apparent to those skilled in the art. For instance, the examples, embodiments, geometrics, materials, dimensions, ratios, steps, and the like discussed above are illustrative and are not required. Accordingly, the scope of the present invention should be considered in terms of the following claims and is understood not to be limited to the details of structure and operation shown and described in the specification and drawings.

Claims

1. An end effector of a surgical instrument, the end effector comprising: (a) a first jaw, wherein the first jaw is configured to receive a staple cartridge; and(b) a second jaw, wherein the second jaw is movable relative to the first jaw, wherein the second jaw is configured to provide an anvil for forming staples driven from a staple cartridge received in the first jaw, wherein the anvil comprises: (i) a tissue contacting surface, and(ii) a staple forming pocket adjacent to the tissue contacting surface, wherein the staple forming pocket defines a length along a longitudinal axis, wherein the staple forming pocket comprises: (A) a first staple forming surface region configured to receive a first staple leg, wherein the first staple forming surface region defines a first sidewall, a second sidewall, a third sidewall, and a fourth sidewall, wherein the first staple forming surface region is laterally defined on a first side by the first, second and third sidewall portions and on a second side by the fourth sidewall portion,wherein the first sidewall of the first staple forming surface region has a shorter length than the second sidewall,wherein the first side of the first staple forming surface region is positioned opposite of the second side of the first staple forming surface region, and(B) a second staple forming surface region configured to receive a second staple leg, wherein the second staple forming surface region defines a first sidewall, a second sidewall, a third sidewall, and a fourth sidewall, wherein the second staple forming surface region is laterally defined on a first side by the first, second and third sidewall portions and on a second side by the fourth sidewall portion,wherein the first sidewall of the second staple forming surface region has a shorter length than the second sidewall,wherein the first side of the second staple forming surface region is positioned opposite of the second side of the second staple forming surface region, and(C) a dividing structure located between the first staple forming surface region and the second staple forming surface region,wherein the third sidewall of the first staple forming surface region and third sidewall of the second staple forming surface region abut one another to thereby define the dividing structure; andwherein the first sidewall portion of each of the first and second staple forming surface region has a first length, wherein the second sidewall portion of each of the first and second staple forming surface region has a second length, wherein the third sidewall portion of each of the first and second staple forming surface region has a third length, wherein the fourth sidewall portion of each of the first and second staple forming surface region has a fourth length, wherein the first length is less than the second length, wherein the third length is less than the fourth length.

2. The end effector of claim 1, wherein the first staple forming surface region is defined within a first channel, wherein the second staple forming surface region is defined within a second channel.

3. The end effector of claim 2, wherein the dividing structure separates the first channel from the second channel.

4. The end effector of claim 1, wherein the dividing structure is obliquely oriented relative to the longitudinal axis of the staple forming pocket.

5. The end effector of claim 4, wherein the first sidewall portion of each of the first and second staple forming surface region defines a first angle relative to the longitudinal axis of the staple forming pocket, wherein the second sidewall portion of each of the first and second staple forming surface region defines a second angle relative to the longitudinal axis of the staple forming pocket, wherein the first angle is greater than the second angle.

6. The end effector of claim 5, wherein the third sidewall portion of each of the first and second staple forming surface region defines a third angle relative to the longitudinal axis of the staple forming pocket, wherein the fourth sidewall portion of each of the first and second staple forming surface region defines a fourth angle relative to the longitudinal axis of the staple forming pocket, wherein the third angle is greater than the fourth angle.

7. The end effector of claim 6, wherein the first angle is equal to the third angle.

8. The end effector of claim 7, wherein the second angle is equal to the fourth angle.

9. The end effector of claim 1, wherein the first channel terminates at a region along the length of the staple forming pocket that is common with the region along the length of the staple forming pocket where the third sidewall portion of each of the first and second staple forming surface region transitions to the fourth sidewall portion of each of the first and second staple forming surface region, wherein the second channel terminates at a region along the length of the staple forming pocket that is common with the region along the length of the staple forming pocket where the first sidewall portion of each of the first and second staple forming surface region transitions to the second sidewall portion of each of the first and second staple forming surface region.

10. An end effector of a surgical instrument, the end effector comprising: (a) a first jaw, wherein the first jaw is configured to receive a staple cartridge; and(b) a second jaw, wherein the second jaw is pivotable relative to the first jaw, wherein the second jaw is configured to provide an anvil for forming staples driven from a staple cartridge received in the first jaw, wherein the second jaw comprises: (i) a tissue contacting surface, and(ii) a staple forming pocket adjacent to the tissue contacting surface, wherein the staple forming pocket defines a length along a longitudinal axis, wherein the staple forming pocket comprises: (A) a first staple forming surface region configured to receive a first staple leg, wherein the first staple forming surface region includes a first convex surface configured to drive a staple leg laterally relative to the longitudinal axis, wherein the first staple forming surface region defines a first sidewall, a second sidewall, a third sidewall, and a fourth sidewall, and(B) a second staple forming surface region configured to receive a second staple leg, wherein the second staple forming surface region includes a second convex surface configured to drive a staple leg laterally relative to the longitudinal axis, wherein the second staple forming surface region defines a first sidewall, a second sidewall, a third sidewall, and a fourth sidewall;wherein the first sidewalls of each of the first and second staple forming surface regions are separated by the second sidewalls of each of the first and second staple forming surface regions by a first transition portion and extend parallel to one another and parallel to the longitudinal axis;wherein the third sidewalls of each of the first and second staple forming surface regions are separated by the second sidewalls of each of the first and second staple forming surface regions by a second transition portion and extend parallel to one another and obliquely relative to the longitudinal axis;wherein the fourth sidewalls of each of the first and second staple forming surface regions extend along a side facing the first, second and third sidewall portions of each of the first and second staple forming surface regions and extend obliquely relative to the longitudinal axis but at a different angle than the third sidewalls.

11. An end effector of a surgical instrument, the end effector comprising: (a) a first jaw, wherein the first jaw is configured to receive a staple cartridge; and(b) a second jaw, wherein the second jaw is pivotable relative to the first jaw, wherein the second jaw is configured to provide an anvil for forming staples driven from a staple cartridge received in the first jaw, wherein the second jaw comprises: (i) a tissue contacting surface, and(ii) a staple forming pocket adjacent to the tissue contacting surface, wherein the staple forming pocket defines a length along a longitudinal axis, wherein the longitudinal axis extends along the length of the staple forming pocket through a laterally central region of the staple forming pocket, wherein the staple forming pocket comprises: (A) a first region configured to receive a first staple leg, wherein the first region includes a first surface region configured to drive a staple leg laterally relative to the longitudinal axis,(B) a second region configured to receive a second staple leg, wherein the second region includes a second surface region configured to drive a staple leg laterally relative to the longitudinal axis, wherein parts of the first and second regions extend along a common range of the length of the staple forming pocket such that portions of the first and second regions are positioned lateral to each other, and(C) a dividing wall located between the first staple forming surface region and the second staple forming surface region,wherein the dividing wall is defined by a first sidewall portion, and a second sidewall portion,wherein the first sidewall portion further defines an inner side of the first staple forming surface region,wherein the second sidewall portion defines an inner side of the second staple forming surface region, andwherein the first and second sidewall portions are parallel with each other and are oblique with the longitudinal axis of the staple forming pocket;wherein the first sidewall portion includes a third sidewall portion extending obliquely therefrom to further define the inner side of the first staple forming surface region;wherein the second sidewall portion includes a fourth sidewall portion extending obliquely therefrom to further define the inner side of the second staple forming surface region;wherein the fourth sidewalls of each of the first and second staple forming regions are laterally opposite of the first sidewall, second sidewall, and third sidewall of the respective staple forming regions to define the staple forming pocket;wherein the first, second, third and fourth sidewalls are defined by substantially straight surfaces; andwherein a first transition member connects the first sidewall to the second sidewall and a second transition member connects the second sidewall to the third sidewall.