Patent Description:
Circular stapling devices are known in the surgical arts and are commonly used to perform a variety of surgical procedures for joining tissue segments. These procedures include a variety of end-to-end and end-to-side anastomosis procedures that may be performed endoscopically. Typically, circular stapling devices include a tool assembly having an anvil assembly with an anvil head and an anvil center rod, and an approximation mechanism including an anvil retainer to which the anvil center rod is releasably coupled. During many surgical procedures in which a circular stapling device is used to join tissue segments, the tool assembly is positioned within a body cavity independently of the remaining portion of the stapling device and the anvil assembly is attached to the anvil retainer within the body cavity. During these surgical procedures, it is important that the clinician be able to confirm that the anvil assembly is properly attached to the anvil retainer without visualizing the stapling device before firing the stapling device to avoid potential injury to a patient.

<CIT> describes multiple examples of circular stapling devices, including in Figures <NUM>-<NUM> a reload including a housing, a staple cartridge fixed to the distal end portion of the housing, a staple driver assembly operably received within the housing, a knife assembly operably received within the housing, a blushing member received within the proximal end of the housing and a chip assembly mounted about the brushing member. The housing assembly includes an outer cylindrical portion and an inner cylindrical portion connected by a plurality of ribs coaxial and defining a recess. A trocar assembly, anvil assembly and strain gauge are also described.

A continuing need exists in the art for a circular stapling device having a mechanism for confirming to a clinician that an anvil assembly is properly attached to the anvil retainer of the stapling device without visualizing the stapling device. EP Patent Application <CIT> (prior art pursuant to Art. <NUM>(<NUM>) EPC) describes a surgical stapler and its movement relative to a shell assembly portion and means to obviate spline crash using anvil splines and shell splines.

The present invention is defined in independent claim <NUM>, and certain optional features thereof are defined in the dependent claims. The only protection sought is for the invention as claimed. One aspect of the present disclosure is directed to a stapling device including a shell assembly, an anvil retainer assembly, an anvil assembly, and a strain gauge. The shell assembly includes a housing and a staple cartridge. The housing has a distal portion supporting the staple cartridge, a proximal portion, an outer housing portion, and an inner housing portion. The outer housing portion and the inner housing portion define an annular cavity. The inner housing portion defines a through bore and supports at least one detection member. The anvil retainer assembly is movable between retracted and advanced positions within the through bore of the housing. The anvil assembly includes an anvil head and an anvil center rod having a boss. The anvil center rod has a proximal portion and a distal portion supporting the anvil head. The proximal portion of the anvil center rod is adapted to releasably couple with the anvil retainer assembly. The anvil assembly is movable in relation to the shell assembly between open and clamped positions. The at least one detection member is positioned to engage the boss of the anvil center rod to obstruct movement of the anvil assembly between the open and clamped positions, and the strain gauge is positioned to identify increased strain in the stapling device when the at least one detection member engages the boss.

Also here is described, and claimed as part of the stapling device, is a shell assembly including a housing and a staple cartridge. The housing includes a distal portion, a proximal portion, an outer housing portion, and an inner housing portion. The outer housing portion and the inner housing portion define an annular cavity and the inner housing portion defines a through bore. The inner housing portion of the housing supports at least one detection member. The at least one detection member has a radial portion that extends towards the through bore and is positioned to engage a center rod of an anvil assembly that is positioned within the through bore.

In embodiments, the at least one detection member includes a plurality of detection members that are spaced about the periphery of the inner housing portion of the housing of the shell assembly.

In some embodiments, each of the plurality of detection members includes a radial portion that extends inwardly from the inner housing portion.

In certain embodiments, the stapling device includes an adapter assembly that supports the shell assembly.

In embodiments, the strain gauge is supported on the adapter assembly.

In some embodiments, the stapling device includes a handle assembly and the adapter assembly is supported on the handle assembly.

In certain embodiments, the staple cartridge includes an annular body.

In embodiments, the shell assembly includes a pusher and an annular knife.

In some embodiments, the anvil retainer assembly includes a retainer member having a distal trocar portion configured to penetrate tissue.

In certain embodiments, the anvil retainer assembly includes a drive screw and the retainer member includes a proximal portion that defines a threaded bore, wherein the drive screw is positioned within the threaded bore.

In certain embodiments, the at least one detection member includes a plurality of detection legs.

Various embodiments of the presently disclosed stapling device are described herein below with reference to the drawings, wherein:.

The presently disclosed device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. However, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.

In this description, the term "proximal" is used generally to refer to that portion of the device that is closer to a clinician, while the term "distal" is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term "endoscopic" is used generally used to refer to endoscopic, laparoscopic, arthroscopic, and/or any other procedure conducted through small diameter incision or cannula. Further, the term "clinician" is used generally to refer to medical personnel including doctors, nurses, and support personnel.

<FIG> illustrate a surgical stapling device <NUM> including a handle assembly <NUM>, an adapter assembly <NUM> extending from the handle assembly <NUM>, a shell assembly <NUM> supported on a distal portion of the adapter assembly <NUM>, an anvil retainer assembly <NUM>, and anvil assembly <NUM> releasably supported on the anvil retainer assembly <NUM> (<FIG>). The handle assembly <NUM> is illustrated as a powered assembly and includes a stationary grip <NUM>, and actuation buttons <NUM> for controlling operation of functions of the stapling device <NUM> including approximation of the shell and anvil assemblies <NUM>, <NUM>, and firing of staples (not shown) from the shell assembly <NUM>. The elongate body <NUM> is coupled to the handle assembly <NUM> to translate power from the handle assembly <NUM> to the shell and anvil assemblies <NUM>, <NUM>. <CIT> ("the '<NUM> Patent") and <NUM>,<NUM>,<NUM> ("the '<NUM> Patent") disclose examples of surgical stapling devices including exemplary powered handle assemblies.

Although the present disclosure illustrates a powered assembly, it is envisioned that the advantages of the present disclosure as described in detail below are also applicable to surgical stapling devices having manually operated handle and body assemblies or robotically actuated surgical devices. <CIT> ("the '<NUM> Patent") discloses an example of a surgical stapling device including a manually actuated handle assembly. It is also envisioned that the presently disclosed stapling device can be supported on a robotic system and need not include a handle assembly.

Referring to <FIG>, the anvil assembly <NUM> includes an anvil head <NUM> and an anvil center rod <NUM>. The anvil head <NUM> includes a staple deforming surface <NUM> that includes staple deforming pockets <NUM>. In the illustrated embodiment, the anvil center rod <NUM> includes a proximal portion having a plurality of resilient fingers <NUM> (<FIG>) and a distal portion including an annular boss <NUM>. The plurality of resilient fingers <NUM> define a longitudinal bore <NUM> (<FIG>) that is dimensioned to receive and releasably engage a distal portion of the anvil retainer assembly <NUM> as described in further detail below. In embodiments, the anvil head <NUM> is pivotally coupled to the anvil center rod <NUM> and is movable between an operative position (<FIG>) for forming staples and a tilted, reduced profile position (not shown). For a more detailed description of an anvil assembly including an anvil center rod <NUM> having resilient fingers <NUM> and a pivotal anvil head <NUM>, see the '<NUM> Patent.

Referring also to <FIG>, the shell assembly <NUM> (<FIG>) is supported on the distal end of the elongate body <NUM> and includes a shell housing <NUM>, and an annular staple cartridge <NUM> that defines annular rows of staple receiving pockets <NUM> (<FIG>). Each of the staple receiving pockets <NUM> supports a staple <NUM> (<FIG>) that can be fired from the staple cartridge <NUM> via actuation of the handle assembly <NUM> (<FIG>) and deformed within the staple deforming pockets <NUM> (<FIG>) of the staple deforming surface <NUM> of the anvil head <NUM>. The shell housing <NUM> of the shell assembly <NUM> includes an outer housing portion <NUM> and an inner housing portion <NUM> that together define an annular cavity <NUM>. The annular cavity <NUM> supports, inter alia, a staple pusher <NUM> and an annular knife <NUM> such that the staple pusher <NUM> (<FIG>) and the annular knife <NUM> (<FIG>) are movable in relation to the staple cartridge <NUM> to eject the staples <NUM> from the staple cartridge <NUM> and to dissect or cut tissue positioned within an annulus <NUM> (<FIG>) defined by the staple cartridge <NUM>. The inner housing portion <NUM> is substantially cylindrical and defines a central through bore <NUM> (<FIG>) that receives the anvil retainer assembly <NUM>. The inner housing portion <NUM> of the shell housing <NUM> includes anvil detection members <NUM> which may be in the form of legs or fingers that extend distally from the inner housing portion <NUM>. Each of the anvil detection members or legs <NUM> includes a radial portion <NUM> that extends inwardly to a position above the through bore <NUM> as described in further detail below.

Referring also to <FIG>, the anvil retainer assembly <NUM> of the surgical stapling device <NUM> (<FIG>) includes a retainer member <NUM> that defines a threaded bore <NUM> (<FIG>), and a drive screw <NUM> that is received within the threaded bore <NUM> of the retainer member <NUM>. The drive screw <NUM> includes external threads <NUM> that mate with internal threads <NUM> formed along the threaded bore <NUM>. When the drive screw <NUM> is rotated in response to actuation of the handle assembly <NUM> (<FIG>) of the surgical stapling device <NUM>, engagement between the drive screw <NUM> and the retainer member <NUM> causes axial movement of the retainer member <NUM> through the through bore <NUM> of the inner housing portion <NUM> of the shell housing <NUM>.

Referring also to <FIG>, in embodiments, the retainer member <NUM> includes a trocar portion <NUM> and an annular retention recess <NUM> that defines a shoulder <NUM>. Each of the resilient fingers <NUM> of the anvil center rod <NUM> (<FIG>) defines an inwardly extending projection <NUM>. When the trocar portion <NUM> is received in the longitudinal bore <NUM> (<FIG>) of the anvil center rod <NUM>, the projections <NUM> (<FIG>) are received in the annular retention recess <NUM> of the retainer member <NUM> such that the projections <NUM> engage the shoulder <NUM> to releasably secure the anvil assembly to the retainer member <NUM> of the anvil retainer assembly <NUM>. As such, when the retainer member <NUM> is retracted into the through bore <NUM>, the anvil assembly <NUM> is moved from an open position (<FIG>) towards a clamped position (not shown) in which the staple deforming surface <NUM> (<FIG>) of the anvil assembly <NUM> is positioned in juxtaposed alignment with the staple cartridge <NUM>.

Referring to <FIG>, when the anvil assembly <NUM> is coupled to the anvil retainer assembly <NUM> and the retainer member <NUM> is retracted into the through bore <NUM> of the shell housing <NUM> by operating the handle assembly <NUM> (<FIG>), the center rod <NUM> of the anvil assembly <NUM> is also withdrawn into the through bore <NUM> as is known in the art. As the anvil center rod <NUM> is drawn into the through bore <NUM> in the direction indicated by arrow "A" in <FIG>, the annular boss <NUM> on the anvil center rod <NUM> moves towards the radial portions <NUM> (<FIG>) of the detection members or legs <NUM> of the inner housing portion <NUM> of the shell housing <NUM> (<FIG>).

Referring to <FIG>, when the anvil assembly <NUM> is retracted in the direction indicated by arrows "B" into the through bore <NUM> of the shell housing <NUM> to the extent at which the radial portions <NUM> of the detection legs <NUM> engage the boss <NUM> of the anvil center rod <NUM>, the detection legs <NUM> are deformed outwardly in the direction indicated by arrows "C" in <FIG>. The engagement between the detection legs <NUM> of the shell housing <NUM> and the boss <NUM> of the anvil center rod <NUM> obstructs movement of the anvil assembly <NUM> towards the clamped position. This obstruction increases the forces required to close or clamp the anvil assembly <NUM> and the staple cartridge <NUM>. The thickness and/or number of the detection legs <NUM> can be selected to control the degree or amount of obstruction on the anvil center rod <NUM> during clamping.

Referring to <FIG>, when the boss <NUM> on the anvil center rod <NUM> moves proximally past the radial portions <NUM> of the detection legs <NUM> in the direction indicated by arrows "D", the detection legs <NUM> return in the direction indicated by arrows "E" to their non-deformed condition to remove or reduce the obstruction forces on the anvil center rod <NUM>.

The surgical stapling device <NUM> includes a strain gauge <NUM> (shown schematically) that measures strain in the adapter assembly <NUM> (<FIG>) during the approximation and firing of the stapling device <NUM>. In embodiments, the strain gauge <NUM> can be supported in the adapter assembly <NUM>. In the present application, the strain gauge <NUM> can be used to measure the strain in the adapter assembly <NUM> during movement of the anvil assembly <NUM> in relation to the staple cartridge <NUM> to identify if an anvil assembly <NUM> is properly coupled to the anvil retainer assembly <NUM>. When an anvil assembly <NUM> is properly attached to the retainer member <NUM> of the anvil retainer assembly <NUM> and the anvil assembly <NUM> is moved from the open position towards the clamped position, engagement between the radial portions <NUM> of the detection legs <NUM> and the boss <NUM> on the anvil center rod <NUM> increases the strain in the adapter assembly <NUM> a preselected amount. This increase in strain in the adapter assembly <NUM> can be measured by the strain gauge <NUM> to provide an indication to the clinician that an anvil assembly <NUM> is coupled to the retainer member <NUM> of the anvil retainer assembly <NUM>. Conversely, if the strain in the adapter assembly <NUM> does not increase by the pre-selected amount, this provides an indication to the clinician that the boss <NUM> on the anvil center rod <NUM> has not engaged the detection legs <NUM> of the shell housing <NUM> and that an anvil assembly <NUM> is not coupled, or not properly coupled, to the anvil retainer assembly <NUM>. The strain gauge <NUM> can provide a signal to an audible or visual indicator (not shown) to alert the clinician to the presence or absence of an anvil assembly <NUM>.

For a more detailed discussion of the structure and function of a strain gauge see, e.g., (<NUM>-<NUM>) <CIT>.

Claim 1:
A stapling device (<NUM>) comprising:
a shell assembly (<NUM>) including a housing (<NUM>) and a staple cartridge (<NUM>), the housing (<NUM>) having a distal portion, a proximal portion, an outer housing portion (<NUM>) and an inner housing portion (<NUM>), the outer housing portion (<NUM>) and the inner housing portion (<NUM>) defining an annular cavity (<NUM>), the inner housing portion (<NUM>) defining a through bore (<NUM>), the staple cartridge (<NUM>) being supported on the distal portion of the housing (<NUM>);
an anvil retainer assembly (<NUM>) being movable between retracted and advanced positions within the through bore (<NUM>);
an anvil assembly (<NUM>) including an anvil head (<NUM>) and an anvil center rod (<NUM>), the anvil center rod (<NUM>) having a proximal portion, a distal portion, and an annular boss (<NUM>), the anvil head (<NUM>) being supported on the distal portion of the anvil center rod (<NUM>), the proximal portion of the anvil center rod (<NUM>) being adapted to releasably couple with the anvil retainer assembly (<NUM>), the anvil assembly (<NUM>) being movable in relation to the shell assembly (<NUM>) between an open position and a clamped position; and
a strain gauge (<NUM>);
characterised in that the inner housing portion (<NUM>) supports at least one detection member (<NUM>), and
wherein the at least one detection member (<NUM>) is positioned to engage the annular boss (<NUM>) of the anvil center rod (<NUM>) to obstruct movement of the anvil assembly (<NUM>) between the open position and the clamped position, the strain gauge (<NUM>) being positioned to identify increased strain in the stapling device (<NUM>) when the at least one detection member (<NUM>) engages the annular boss (<NUM>).