Patent Description:
Circular stapling devices are utilized by clinicians to apply one or more surgical fasteners, e.g., staples or two-part fasteners, to body tissue for the purpose of joining segments of body tissue together and/or for the creation of an anastomosis. Circular stapling devices generally include a cartridge or shell assembly supporting a plurality of annular rows of staples, an anvil assembly operatively associated with the cartridge assembly and having annular arrays of staple receiving pockets for providing a surface against which the plurality of annular rows of staples can be formed, and an annular blade for cutting tissue.

During a typical tissue fastening procedure, the anvil assembly of the stapling device is positioned within one segment of body tissue and the shell assembly and a body portion of the stapling device supporting the shell assembly are positioned in an adjacent segment of body tissue. The anvil assembly is then attached to the body portion of the stapling device and the stapling device is actuated to approximate the anvil assembly with a staple cartridge of the shell assembly and clamp the body tissue segments together.

Typically, the anvil assembly includes an anvil shaft that includes splines that mate with splines formed within a shell housing of the shell assembly to align the staple forming pockets of the anvil assembly with staple receiving pockets of the staple cartridge of the shell assembly. The splines on the anvil shaft and on the shell housing of the shell assembly include left and right tapered ends that define an apex. When the right tapered ends of the splines of the anvil assembly engage the left tapered ends of the shell assembly (or vice versa), the anvil assembly will be rotated to allow the splines of the anvil assembly to pass between the splines of shell assembly to align the anvil assembly with the shell assembly. However, if the right tapered end of one spline of the anvil assembly engages the right tapered end of one spline of the shell assembly and a left tapered end of another spline of the anvil assembly engages the left tapered end of another spline of the shell assembly, or if the apexes of the splines of the anvil assembly and the shell assembly simultaneously hit head on, i.e., crash, the splines of the anvil assembly and the shell assembly may be damaged and/or the anvil assembly and the shell assembly may bind such that approximation of the anvil and shell assemblies is prevented or malformation of the staples may occur during firing of the stapling device.

A continuing need exist for circular stapling devices that mitigate or prevent spline crash to more reliably align the staple forming pockets of the anvil assembly with the staple receiving pockets of the staple cartridge of the shell assembly.

<CIT> discloses adapter assemblies for use with and to electrically and mechanically interconnect electromechanical surgical devices and surgical reloads, and surgical systems including handheld electromechanical surgical devices and adapter assemblies for connecting surgical reloads to the handheld electromechanical surgical devices.

This disclosure relates generally to oscillating an anvil assembly of a surgical stapler relative to a shell assembly of the surgical stapler when spline crash is detected to rotate the anvil assembly relative to the shell assembly to obviate the spline crash.

In one aspect of the present disclosure, a surgical stapler includes an anvil assembly having an anvil spline, a shell assembly having a shell spline, and a handle assembly having an anvil retainer. The shell assembly is secured to a distal portion of the handle assembly and the anvil assembly is secured to the anvil retainer. The handle assembly includes a motor that is configured to extend and retract the anvil retainer through the shell assembly such that the anvil assembly is moved away and towards the shell assembly. The surgical stapler further includes a processing unit configured to send control signals to the motor to oscillate the anvil retainer between extension and retraction in a first oscillation pattern to obviate a spline crash between the anvil spline and the shell spline. The motor is configured to oscillate the anvil retainer between extension and retraction in a second oscillation pattern that is different form the first oscillation pattern to resume retraction of the anvil assembly relative to the shell assembly after the first oscillation pattern.

In aspects, oscillating the anvil retainer in the first oscillation pattern includes cycling the motor between extending the anvil retainer a first distance and then retracting the anvil retainer the first distance. Oscillating the anvil retainer in the first oscillation pattern may include cycling the motor in a range of about <NUM> to about <NUM> cycles before oscillating the anvil retainer in the second oscillation pattern. Oscillating the anvil retainer in the second oscillation pattern may include cycling the motor between extending the anvil retainer a second distance and then retracting the anvil retainer a third distance that is greater than the second distance. Oscillating the anvil retainer in the second oscillation pattern may include cycling the motor in a range of about <NUM> to about <NUM> cycles before retracting the anvil retainer until the anvil is in the clamped position. Oscillating the anvil retainer in the second oscillation pattern may include cycling the motor half of the number of cycles as the number of cycles the motor is cycled during oscillating the anvil retainer in the first oscillation pattern.

In some aspects, the third distance is equal to the first distance. The second distance may be half of the third distance. Oscillating the motor in the first oscillation pattern may include cycling the motor at a frequency in a range of about. <NUM>-<NUM>.

In certain aspects, oscillating the anvil retainer in the first oscillation pattern includes cycling the motor to extend the anvil retainer for a first time period and then to retract the anvil retainer for a second time period equal to the first time period. Oscillating the anvil retainer in the second oscillation pattern may include cycling the motor to retract the anvil retainer for a fourth time period that is greater than the third time period. The third time period may be half of the fourth time period. The fourth time period may be equal to the first time period.

In particular aspects, oscillating the motor in the first oscillation pattern and oscillating the motor in the second oscillation pattern may include cycling the motor at the same frequency.

Further, to the extent consistent, any of the aspects described herein may be used in conjunction with any or all of the other aspects described herein.

Various aspects of the present disclosure are described hereinbelow with reference to the drawings, which are incorporated in and constitute a part of this specification, wherein:.

Embodiments of the present disclosure are now described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein, the term "clinician" refers to a doctor, a nurse, or any other care provider and may include support personnel. Throughout this description, the term "proximal" refers to the portion of the device or component thereof that is closer to the clinician and the term "distal" refers to the portion of the device or component thereof that is farther from the clinician. In addition, the term "endoscopic" is used generally to refer to endoscopic, laparoscopic, arthroscopic, and/or any other procedure conducted through small diameter incision or cannula.

Referring to <FIG> and <FIG>, the presently disclosed surgical stapling device shown generally as <NUM> includes a handle assembly <NUM>, an elongated body portion <NUM> that extends distally from the handle assembly <NUM>, and a tool assembly <NUM> that is supported on a distal portion of the elongated body portion <NUM>. The tool assembly <NUM> includes a cartridge or shell assembly <NUM> that supports a staple cartridge 18a and an anvil assembly <NUM> that supports an anvil <NUM>. The handle assembly <NUM> includes a processing unit or controller <NUM> in communication with an approximation control 21a to activate a motor <NUM> to move the anvil assembly <NUM> between unclamped or spaced-apart and clamped positions in relation to the cartridge assembly <NUM>, a firing control 21b to activate a firing mechanism (not shown) to fire staples (not shown) from the staple cartridge 18a into tissue, and a battery <NUM> that provides power to the handle assembly <NUM> including the motor <NUM> and the processing unit <NUM>. For a detailed description of an exemplary circular stapling device reference can be made to <CIT> ("the '<NUM> Patent").

The staple cartridge 18a of the shell assembly <NUM> and the anvil <NUM> of the anvil assembly <NUM>, have an annular configuration. The anvil assembly <NUM> is movable in relation to the shell assembly <NUM> from a spaced position to a clamped position to move the anvil <NUM> into juxtaposed alignment with the staple cartridge 18a. The staple cartridge 18a defines staple receiving slots 18b that are aligned with staple deforming recesses (not shown) of the anvil <NUM> when the staple cartridge 18a and the anvil <NUM> are properly aligned such that staples ejected from the staple receiving slots 18b are deformed within the staple receiving recesses when the stapling device <NUM> is fired.

The anvil assembly <NUM> is supported on an anvil retainer <NUM> (<FIG>) which forms part of an approximation mechanism (not shown) of the stapling device <NUM>. The anvil retainer <NUM> is configured to releasably engage the anvil assembly <NUM>. The anvil retainer <NUM> includes a distal portion and a proximal portion. The distal portion of the anvil retainer <NUM> extends from a distal end of the elongate body portion <NUM> of the stapling device <NUM> and through the shell assembly <NUM> to a position to engage the anvil assembly <NUM>. The proximal portion of the anvil retainer <NUM> is operatively connected to the motor <NUM> such that activation of the approximation control 21a causes the anvil retainer <NUM> to move within the shell assembly <NUM> to move the anvil assembly <NUM> in relation to the staple cartridge 18a between the spaced position and the clamped position. The shell assembly <NUM> includes an annular knife (not shown) that is movable from a retracted position to an advanced position within the shell assembly <NUM> during firing of the stapling device <NUM> to transect tissue clamped between the staple cartridge 18a and the anvil <NUM>.

Referring to <FIG>, the shell assembly <NUM> is releasably coupled to a distal portion of the elongated body <NUM> of the stapling device <NUM> to facilitate replacement of the shell assembly <NUM> after each firing of the stapling device <NUM>. Examples of mechanisms for releasably coupling the shell assembly <NUM> to the elongate body portion <NUM> of the stapling device <NUM> are described in <CIT>, <CIT>, and <CIT>.

Referring to <FIG>, the anvil assembly <NUM> includes an anvil head <NUM> and an anvil shaft <NUM> and the shell assembly <NUM> includes a shell housing <NUM> having an inner housing portion <NUM> that defines a through bore 28a. The anvil head <NUM> supports an anvil 22a that defines annular arrays of staple deforming recesses 22b and the staple cartridge 18a defines annular arrays of staple receiving slots 18b. An anvil retainer <NUM> (shown in phantom) includes a distal end that is configured to releasably engage the anvil shaft <NUM> of the anvil assembly <NUM>. The anvil retainer <NUM> is received within the through bore 28a and is movable between retracted and advanced positions. When the anvil shaft <NUM> is coupled to the anvil retainer <NUM> and the anvil retainer <NUM> is retracted (via the motor <NUM>, <FIG>), the anvil shaft <NUM> is drawn into the through bore 28a of the inner housing portion <NUM> of the shell housing <NUM>.

In order to align the arrays of staple deforming recesses 22b of the anvil head <NUM> of the anvil assembly <NUM> with the staple receiving slots 18b of the staple cartridge 18a of the shell assembly <NUM>, the anvil shaft <NUM> includes a plurality of anvil splines <NUM> including adjacent anvil splines 34a, 34b (<FIG>) that are received within guide channels <NUM> defined between adjacent shell splines <NUM> formed along an inner wall of the inner housing portion <NUM> of the shell housing <NUM>. Each of the anvil splines <NUM> of the anvil assembly <NUM> defines a central axis "Z" and left and right tapered cam surfaces 38a, 38b positioned on opposite sides of the central axis "Z" as viewed in <FIG>. The tapered surfaces 38a, 38b meet at their proximal ends at an apex <NUM>. Similarly, each of the shell splines <NUM> of the shell assembly <NUM> defines a central axis "X" and left and right tapered cam surfaces 42a, 42b positioned on opposite sides of the central axis "X". The tapered surfaces 42a, 142b meet at their distal ends at an apex <NUM>.

When the anvil assembly <NUM> is attached to the anvil retainer <NUM> and the anvil retainer <NUM> and anvil assembly <NUM> are retracted into the through bore 128a (<FIG>) of the inner housing portion <NUM> of the shell housing <NUM>, the anvil splines <NUM> of the anvil assembly <NUM> move towards the shell splines <NUM> of the shell assembly <NUM>. If the anvil splines <NUM> are misaligned with channels <NUM> defined between the shell splines <NUM> of the shell assembly <NUM>, the apexes <NUM> of the anvil splines 34a, 34b will engage one of the cam surfaces 42a, 42b of the shell splines <NUM> to rotate or "clock" the anvil assembly <NUM> relative to the shell assembly <NUM>. When all of the apexes <NUM> of all of the anvil splines 34a, 34b (only two are shown) engage the left tapered cam surface 42a of the shell splines <NUM>, the engagement urges or cams the anvil assembly <NUM> to rotate in the direction indicated by arrow "S" to realign the anvil splines 34a, 34b so that they enter into the channels <NUM> defined between the shell splines <NUM> of the shell assembly <NUM>. Similarly, when all of the apexes <NUM> of all of the anvil splines 34a, 34b engage the right tapered cam surface 42b of the shell splines <NUM>, the engagement urges or cams the anvil assembly <NUM> to rotate in the direction indicated by arrow "T" to clock the anvil shaft <NUM> to realign the anvil splines 34a, 34b so that they enter into the channels <NUM> defined between the shell splines <NUM> of the shell assembly <NUM>. However, if the apexes <NUM> of any two of the anvil splines 34a, 34b simultaneously engage the left and right tapered cam surfaces 42a, 42b of the two shell splines <NUM> of the shell assembly <NUM>, the engagement simultaneously urges or cams the anvil assembly <NUM> in opposite directions. When this happens, the anvil splines 34a, 34b and the shell splines <NUM> may bind until one or both of the anvil splines <NUM> and/or the shell splines <NUM> fractures. In addition, if the apexes <NUM> of the anvil splines 34a, 34b are aligned with the apexes <NUM> of the shell splines <NUM>, the apexes may crash into each other causing damage to the anvil splines 34a, 34b and/or shell splines <NUM>. When the anvil splines <NUM> and <NUM> crash into or bind with each other and proper alignment between staple receiving recesses <NUM> of the anvil assembly <NUM> and staple receiving slots <NUM> of the shell assembly <NUM> is not achieved, improper staple formation or locking of the stapling device <NUM> may result.

It is contemplated that the shell assembly <NUM> and/or the anvil assembly <NUM> may be designed and/or include features to reduce the possibility of spline crash and/or reduce the impact of spline crash. Examples of exemplary designs and features are disclosed in <CIT> entitled "TOOL ASSEMBLY INCLUDING AXIALLY SPACED SPLINES," <NUM>/<NUM>,<NUM> entitled "INSERTS, SPLINES, AND METHODS FOR REDUCING AND/OR ELIMINATING SPLINE CRASH IN SURGICAL INSTRUMENTS," <CIT> entitled "ANVIL ASSEMBLY OF CIRCULAR STAPLING DEVICE INCLUDING ALIGNMENT SPLINES," <NUM>/<NUM>,<NUM> entitled "TOOL ASSEMBLY INCLUDING AXIALLY SPACED SPLINES," and <CIT> entitled "CIRCULAR STAPLING DEVICE WITH A-FRAME SPLINES," and International Patent Application No. <CIT> entitled "CIRCULAR STAPLING DEVICE WITH ALIGNMENT SPLINES.

With reference to <FIG>, the motor <NUM> is operably coupled to a retainer driver <NUM> that is coupled to the anvil retainer <NUM>. The retainer driver <NUM> extends and retracts the anvil retainer <NUM> through the shell assembly <NUM>. In embodiments, the retainer driver <NUM> is a power screw that is operably coupled to the motor <NUM>. When the anvil retainer <NUM> is coupled to the anvil shaft <NUM>, the anvil shaft <NUM>, and thus the anvil head <NUM>, cooperates with the extension and the retraction of the anvil retainer <NUM> to move the anvil assembly <NUM> between the spaced-apart and approximated positions.

The stapling device <NUM> includes one or more sensors <NUM> in communication with the processing unit <NUM> to determine a clamping force of the anvil retainer <NUM>. For example, a sensor <NUM> may be disposed in the handle assembly <NUM> between the motor <NUM> and the battery <NUM> (<FIG>) to determine an amount of power supplied to the motor <NUM>. Another sensor <NUM> may be operably coupled to the motor <NUM> to measure a torque of the motor <NUM>. Further, another sensor <NUM> may be a strain gauge disposed on the anvil retainer <NUM> to determine strain of the anvil retainer <NUM>.

In use, when the approximation control 21a is actuated, the motor <NUM> is activated to rotate in a first direction, e.g., clockwise, to retract the anvil retainer <NUM>. While the motor <NUM> is activated, the sensors <NUM> determine the clamping force exerted by the anvil retainer <NUM>. In embodiments, the motor <NUM> is a linear actuator that is operably coupled to the anvil retainer <NUM>. When the anvil shaft <NUM> is coupled to the anvil retainer <NUM>, the anvil retainer <NUM> draws the anvil shaft <NUM> into the bore 28a (<FIG>) of the shell assembly <NUM>. The clamping force may vary as a result of resistance of the anvil shaft <NUM> and/or the anvil head <NUM>. For example, as the anvil head <NUM> moves through and/or compresses tissue between the anvil head and the shell assembly <NUM>, the clamping force may increase and decrease. In addition, when the anvil splines <NUM> engage the shell splines <NUM>, the clamping force may increase. Further, in the case of spline crash, as detailed above including straddling, the clamping force will increase significantly.

The processing unit <NUM> monitors the clamping force to detect spline crash. Specifically, when the clamping force exceeds a predetermined threshold, the processing unit <NUM> determines that spline crash is occurring. When the clamping force exceeds the predetermined threshold, the processing unit <NUM> begins a spline crash correction algorithm (Crash Algorithm) to prevent a spline crash and to reduce or eliminate damage from a spline crash. The predetermined threshold may be set by the manufacturer or may be selectable by the clinician. The predetermined threshold is set above a clamping force to overcome normal frictional forces between the shell assembly <NUM> and the anvil assembly <NUM> and the compressing of tissue between the anvil head <NUM> and the shell assembly <NUM>.

With additional reference to <FIG> and <FIG>, the Crash Algorithm <NUM> is detailed in accordance with the present disclosure with respect to a position of the anvil retainer <NUM> within the bore 28a (<FIG>) of the shell assembly <NUM>. Initially, when the clamping force exceeds the predetermined threshold (Step <NUM>). The intersection of the Time and the Position axes is the time at which the clamping force exceeds the predetermined threshold and the position of the anvil retainer <NUM> at which the clamping force exceeds the predetermined threshold such that the Crash Algorithm is run. As soon as the clamping force exceeds the predetermined threshold, the processing unit <NUM> stops the motor <NUM> to stop retraction of the anvil retainer <NUM> (Step <NUM>). By immediately stopping retraction of the anvil retainer <NUM>, damage from an actual or potential spline crash may be prevented.

Once retraction of the anvil retainer <NUM> is stopped, the processing unit <NUM> sends control signals to the motor <NUM> for a first oscillation (Step <NUM>) to oscillate between a first or retraction direction, e.g., clockwise, and a second or extension direction, e.g., counter-clockwise, beginning with the second direction. During the first oscillation, the amount of oscillation in the first and second directions are approximately equal to one another. For example, the motor <NUM> may rotate in the second direction by <NUM> degree and then rotate in the first direction by <NUM> degree and repeating this oscillation and a predetermined frequency. Without wishing to be bound to a specific frequency, it has been observed that <NUM> oscillation per second (<NUM> hertz) for <NUM> seconds produces the amount of movement or controlled vibration necessary to allow for movement of the interfering splines resulting in self-alignment of the splines. The frequency of the first oscillation may slightly rotate the anvil shaft <NUM> relative to the shell assembly <NUM> to misalign the apexes <NUM> (<FIG>) of the anvil shaft <NUM> from the apexes <NUM> (<FIG>) of the shell splines <NUM> such that spline crash is prevented. The first oscillation period can be maintained and define a first time-period.

It will be appreciated that by first extending the anvil retainer <NUM> and then quickly retracting the anvil retainer <NUM>, a small rotation of the anvil shaft <NUM> may be induced such that the anvil shaft <NUM> rotates such that the apexes <NUM> of the anvil splines <NUM> are rotated to be offset from the apexes <NUM> of the shell splines <NUM> such that spline crash is obviated.

After the first oscillation, the processing unit <NUM> sends control signals to the motor <NUM> for a second oscillation (Step <NUM>) to oscillate the anvil retainer <NUM> while beginning to gradually resume retracting the anvil retainer <NUM>. During the second oscillation, the amount of each oscillation in the first direction is greater than the amount of each oscillation in the second direction. For example, the motor <NUM> may rotate in the second direction by <NUM> degree and then rotate in the first direction by <NUM> degrees such that each oscillation of the second oscillation results in <NUM> degrees of rotation of the motor <NUM> towards retraction. The second oscillation is occurs at about the same frequency of the first oscillation or may occur at a slightly slower frequency to account for the additional movement in the first direction. It is contemplated that the amount of oscillation in the first direction may be equal during each oscillation of the second oscillation or may increase for each subsequent oscillation. This increase in amount of oscillation may be linear or exponential. The second oscillation gradually begins to retract the anvil retainer <NUM> to assist in avoiding spline crash and to reduce initial engagement between the anvil splines <NUM> and the shell splines <NUM>.

During the first and second oscillations, the clamping force is monitored to ensure that the clamping force does not exceed the predetermined threshold. If the clamping force exceeds the predetermined threshold during the first oscillation, the motor <NUM> may be rotated in the second direction an extra amount, e.g., about <NUM> degrees, for about <NUM>-<NUM> oscillations. After these oscillations the first oscillation may be restarted or the second oscillation may be started. If the clamping force exceeds the predetermined threshold during the second oscillation, the motor <NUM> is rotated in the second direction to the initial position and then the first oscillation is restarted. In the event that the predetermined threshold is met multiple times during the first and second oscillations, e.g., about <NUM> times, the processing unit <NUM> may fully extend the anvil retainer <NUM> and provide feedback to a clinician of an error.

Once the second oscillation is completed, the processing unit <NUM> sends control signals to the motor <NUM> to resume retraction of the anvil retainer <NUM> until the anvil assembly <NUM> is in the clamped position (Step <NUM>). During this retraction, the anvil splines <NUM> engage the shell splines <NUM> to clock the anvil assembly <NUM> with the shell assembly <NUM> as detailed above.

The Crash Algorithm may reduce the impact of a perceived or actual spline crash allow for clamping of tissue between an anvil assembly <NUM> and a shell assembly <NUM> without requiring a signification extension of the anvil assembly <NUM> away from the shell assembly <NUM>. Additionally, the Crash Algorithm may increase confidence of a clinician during a surgical procedure that tissue is properly clamped between the anvil assembly <NUM> and the shell assembly <NUM> before firing of the staples.

Claim 1:
A surgical stapler (<NUM>) comprising:
an anvil assembly (<NUM>) including an anvil spline (34a, 34b);
a shell assembly (<NUM>) including a shell spline (<NUM>); and
a handle assembly (<NUM>) including an anvil retainer, the shell assembly secured to a distal portion of the handle assembly and the anvil assembly secured to the anvil retainer, the handle assembly including a motor (<NUM>) configured to extend and retract the anvil retainer through the shell assembly such that the anvil assembly is moved away and towards the shell assembly, and a processing unit (<NUM>)
configured to send control signals to the motor to oscillate the anvil retainer between extension and retraction in a first oscillation pattern to obviate a spline crash between the anvil spline and the shell spline,
characterised in that
the processing unit is further configured to send control signals to the motor to oscillate the anvil retainer between extension and retraction in a second oscillation pattern different from the first oscillation pattern to resume retraction of the anvil assembly relative to the shell assembly after oscillating the anvil retainer in the first oscillation pattern.