Spline crash correction with motor oscillation

A method for obviating spline crash in a surgical stapler that utilizes a motor of the surgical stapler includes oscillating an anvil retainer of the surgical stapler in a first oscillation pattern, oscillating the anvil retainer in a second oscillation pattern that is different from the first oscillation pattern after the first oscillation pattern, and retracting the anvil retainer until an anvil of the surgical stapler is in a clamped position relative to a shell assembly after the second oscillation pattern. Oscillating the anvil retainer in the first oscillation pattern includes oscillating the anvil retainer in a longitudinal direction between extension and retraction with the motor such that the anvil moves towards and away from the shell assembly. Oscillating the anvil retainer in the second oscillation pattern includes moving the anvil towards and away from the shell assembly.

BACKGROUND

1. Technical Field

The present disclosure is directed to circular stapling devices, and more particularly, to powered circular stapling devices with motors that include a spline crash correction algorithm.

2. Discussion of Related Art

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.

SUMMARY

This disclosure relates generally methods of 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 an aspect of the present disclosure, a method for obviating spline crash in a surgical stapler that utilizes a motor of the surgical stapler includes oscillating an anvil retainer of the surgical stapler in a first oscillation pattern, oscillating the anvil retainer in a second oscillation pattern that is different from the first oscillation pattern after the first oscillation pattern, and retracting the anvil retainer until an anvil of the surgical stapler is in a clamped position relative to a shell assembly after the second oscillation pattern. Oscillating the anvil retainer in the first oscillation pattern includes the motor oscillating the anvil retainer in a longitudinal direction between extension and retraction such that the anvil moves towards and away from the shell assembly. Oscillating the anvil retainer in the second oscillation pattern includes the motor moving the anvil towards and away from the shell assembly.

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 5 to about 20 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 5 to about 10 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 0.25-5 Hz.

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.

In aspects, the method includes detecting potential spline crash of an anvil spline of an anvil assembly of the surgical stapler with a shell spline of the shell assembly of the surgical stapler before oscillating the anvil retainer in the first oscillation pattern. The method may include detecting potential spline crash of the anvil spline with the shell spline after oscillating the anvil retainer in the first oscillation pattern and repeating oscillating the anvil retainer in the first oscillation pattern.

In another aspect of the present disclosure, the method for obviating spline crash in a surgical stapler utilizing a motor of the surgical stapler includes oscillating an anvil retainer in a first oscillation pattern and retracting the anvil retainer until the anvil is in a clamped position relative to a shell assembly after the first oscillation pattern. Oscillating the anvil retainer in the first oscillation pattern includes utilizing a motor to extend and retract an anvil retainer such that the anvil of the surgical stapler moves towards and away from the shell assembly of the surgical stapler in the first oscillation pattern.

In some aspects, oscillating the anvil retainer in the first oscillation pattern includes cycling the motor between extension and retraction for about 10 to about 20 cycles.

In another 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 motor is configured 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.

In aspects, the motor is configured to oscillation 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.

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.

DETAILED DESCRIPTION

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 toFIGS. 1 and 2, the presently disclosed surgical stapling device shown generally as10includes a handle assembly12, an elongated body portion14that extends distally from the handle assembly12, and a tool assembly16that is supported on a distal portion of the elongated body portion14. The tool assembly16includes a cartridge or shell assembly18that supports a staple cartridge18aand an anvil assembly20that supports an anvil22. The handle assembly12includes a processing unit or controller54in communication with an approximation control21ato activate a motor11to move the anvil assembly20between unclamped or spaced-apart and clamped positions in relation to the cartridge assembly18, a firing control21bto activate a firing mechanism (not shown) to fire staples (not shown) from the staple cartridge18ainto tissue, and a battery13that provides power to the handle assembly12including the motor11and the processing unit54. For a detailed description of an exemplary circular stapling device reference can be made to U.S. Pat. No. 9,833,235 (“the'235 Patent”), the entire contents of which are hereby incorporated by reference.

The staple cartridge18aof the shell assembly18and the anvil22of the anvil assembly20, have an annular configuration. The anvil assembly20is movable in relation to the shell assembly18from a spaced position to a clamped position to move the anvil22into juxtaposed alignment with the staple cartridge18a. The staple cartridge18adefines staple receiving slots18bthat are aligned with staple deforming recesses (not shown) of the anvil22when the staple cartridge18aand the anvil22are properly aligned such that staples ejected from the staple receiving slots18bare deformed within the staple receiving recesses when the stapling device10is fired.

The anvil assembly20is supported on an anvil retainer30(FIG. 2) which forms part of an approximation mechanism (not shown) of the stapling device10. The anvil retainer30is configured to releasably engage the anvil assembly20. The anvil retainer30includes a distal portion and a proximal portion. The distal portion of the anvil retainer30extends from a distal end of the elongate body portion14of the stapling device10and through the shell assembly18to a position to engage the anvil assembly20. The proximal portion of the anvil retainer30is operatively connected to the motor11such that activation of the approximation control21acauses the anvil retainer30to move within the shell assembly18to move the anvil assembly20in relation to the staple cartridge18abetween the spaced position and the clamped position. The shell assembly18includes an annular knife (not shown) that is movable from a retracted position to an advanced position within the shell assembly18during firing of the stapling device10to transect tissue clamped between the staple cartridge18aand the anvil22.

Referring toFIG. 2, the shell assembly18is releasably coupled to a distal portion of the elongated body14of the stapling device10to facilitate replacement of the shell assembly18after each firing of the stapling device10. Examples of mechanisms for releasably coupling the shell assembly18to the elongate body portion14of the stapling device10are described in U.S. Patent Publication Nos. 2016/0310141, 2016/0192938, and 2016/0192934. The entire disclosure of each of these publications is hereby incorporated by reference.

Referring toFIG. 3, the anvil assembly20includes an anvil head22and an anvil shaft24and the shell assembly18includes a shell housing26having an inner housing portion28that defines a through bore28a. The anvil head22supports an anvil22athat defines annular arrays of staple deforming recesses22band the staple cartridge18adefines annular arrays of staple receiving slots18b. An anvil retainer130(shown in phantom) includes a distal end that is configured to releasably engage the anvil shaft24of the anvil assembly20. The anvil retainer30is received within the through bore28aand is movable between retracted and advanced positions. When the anvil shaft24is coupled to the anvil retainer30and the anvil retainer30is retracted (via the motor11,FIG. 1), the anvil shaft24is drawn into the through bore28aof the inner housing portion28of the shell housing26.

In order to align the arrays of staple deforming recesses22bof the anvil head22of the anvil assembly20with the staple receiving slots18bof the staple cartridge18aof the shell assembly18, the anvil shaft24includes a plurality of anvil splines34including adjacent anvil splines34a,34b(FIG. 4) that are received within guide channels48defined between adjacent shell splines36formed along an inner wall of the inner housing portion28of the shell housing26. Each of the anvil splines34of the anvil assembly20defines a central axis “Z” and left and right tapered cam surfaces38a,38bpositioned on opposite sides of the central axis “Z” as viewed inFIG. 4. The tapered surfaces38a,38bmeet at their proximal ends at an apex40. Similarly, each of the shell splines36of the shell assembly18defines a central axis “X” and left and right tapered cam surfaces42a,42bpositioned on opposite sides of the central axis “X”. The tapered surfaces42a,142bmeet at their distal ends at an apex44.

When the anvil assembly20is attached to the anvil retainer30and the anvil retainer30and anvil assembly20are retracted into the through bore128a(FIG. 3) of the inner housing portion28of the shell housing26, the anvil splines34of the anvil assembly20move towards the shell splines36of the shell assembly18. If the anvil splines34are misaligned with channels48defined between the shell splines36of the shell assembly18, the apexes40of the anvil splines34a,34bwill engage one of the cam surfaces42a,42bof the shell splines36to rotate or “clock” the anvil assembly20relative to the shell assembly18. When all of the apexes40of all of the anvil splines34a,34b(only two are shown) engage the left tapered cam surface42aof the shell splines36, the engagement urges or cams the anvil assembly20to rotate in the direction indicated by arrow “S” to realign the anvil splines34a,34bso that they enter into the channels48defined between the shell splines36of the shell assembly18. Similarly, when all of the apexes40of all of the anvil splines34a,34bengage the right tapered cam surface42bof the shell splines36, the engagement urges or cams the anvil assembly20to rotate in the direction indicated by arrow “T” to clock the anvil shaft24to realign the anvil splines34a,34bso that they enter into the channels48defined between the shell splines36of the shell assembly18. However, if the apexes40of any two of the anvil splines34a,34bsimultaneously engage the left and right tapered cam surfaces42a,42bof the two shell splines36of the shell assembly18, the engagement simultaneously urges or cams the anvil assembly20in opposite directions. When this happens, the anvil splines34a,34band the shell splines36may bind until one or both of the anvil splines34and/or the shell splines36fractures. In addition, if the apexes40of the anvil splines34a,34bare aligned with the apexes44of the shell splines36, the apexes may crash into each other causing damage to the anvil splines34a,34band/or shell splines36. When the anvil splines34and36crash into or bind with each other and proper alignment between staple receiving recesses27of the anvil assembly20and staple receiving slots28of the shell assembly18is not achieved, improper staple formation or locking of the stapling device10may result.

It is contemplated that the shell assembly18and/or the anvil assembly20may 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 U.S. Provisional Patent Application Ser. No. 62/549,266 entitled “CIRCULAR STAPLING DEVICE WITH OFFSET SPLINE TIP,” (now U.S. Patent Publication No. 2019/0059901), and 62/779,718 entitled “INSERTS, SPLINES, AND METHODS FOR REDUCING AND/OR ELIMINATING SPLINE CRASH IN SURGICAL INSTRUMENTS,” U.S. patent application Ser. No. 15/441,296 entitled “ANVIL ASSEMBLY OF CIRCULAR STAPLING DEVICE INCLUDING ALIGNMENT SPLINES,” 15/441,994 entitled “TOOL ASSEMBLY INCLUDING AXIALLY SPACED SPLINES,” and 15/935,260 entitled “CIRCULAR STAPLING DEVICE WITH A-FRAME SPLINES,” and International Patent Application No. PCT/CN2017/077862 entitled “CIRCULAR STAPLING DEVICE WITH ALIGNMENT SPLINES.” The entire disclosure of each of these applications is hereby incorporated by reference.

With reference toFIG. 5, the motor11is operably coupled to a retainer driver31that is coupled to the anvil retainer30. The retainer driver31extends and retracts the anvil retainer30through the shell assembly18. In embodiments, the retainer driver31is a power screw that is operably coupled to the motor11. When the anvil retainer30is coupled to the anvil shaft24, the anvil shaft24, and thus the anvil head22, cooperates with the extension and the retraction of the anvil retainer30to move the anvil assembly20between the spaced-apart and approximated positions.

The stapling device10includes one or more sensors51in communication with the processing unit54to determine a clamping force of the anvil retainer30. For example, a sensor51may be disposed in the handle assembly12between the motor11and the battery13(FIG. 1) to determine an amount of power supplied to the motor11. Another sensor51may be operably coupled to the motor11to measure a torque of the motor11. Further, another sensor51may be a strain gauge disposed on the anvil retainer30to determine strain of the anvil retainer30.

In use, when the approximation control21ais actuated, the motor11is activated to rotate in a first direction, e.g., clockwise, to retract the anvil retainer30. While the motor11is activated, the sensors51determine the clamping force exerted by the anvil retainer30. In embodiments, the motor11is a linear actuator that is operably coupled to the anvil retainer30. When the anvil shaft24is coupled to the anvil retainer30, the anvil retainer30draws the anvil shaft24into the bore28a(FIG. 3) of the shell assembly18. The clamping force may vary as a result of resistance of the anvil shaft24and/or the anvil head22. For example, as the anvil head22moves through and/or compresses tissue between the anvil head and the shell assembly18, the clamping force may increase and decrease. In addition, when the anvil splines34engage the shell splines36, 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 unit54monitors the clamping force to detect spline crash. Specifically, when the clamping force exceeds a predetermined threshold, the processing unit54determines that spline crash is occurring. When the clamping force exceeds the predetermined threshold, the processing unit54begins 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 assembly18and the anvil assembly20and the compressing of tissue between the anvil head22and the shell assembly18.

With additional reference toFIGS. 6 and 7, the Crash Algorithm300is detailed in accordance with the present disclosure with respect to a position of the anvil retainer30within the bore28a(FIG. 3) of the shell assembly18. Initially, when the clamping force exceeds the predetermined threshold (Step310). 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 retainer30at 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 unit54stops the motor11to stop retraction of the anvil retainer30(Step320). By immediately stopping retraction of the anvil retainer30, damage from an actual or potential spline crash may be prevented.

Once retraction of the anvil retainer30is stopped, the processing unit54sends control signals to the motor11for a first oscillation (Step330) 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 motor11may rotate in the second direction by 1 degree and then rotate in the first direction by 1 degree and repeating this oscillation and a predetermined frequency. Without wishing to be bound to a specific frequency, it has been observed that 5 oscillation per second (5 hertz) for 5 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 shaft24relative to the shell assembly18to misalign the apexes40(FIG. 4) of the anvil shaft24from the apexes44(FIG. 4) of the shell splines36such 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 retainer30and then quickly retracting the anvil retainer30, a small rotation of the anvil shaft24may be induced such that the anvil shaft24rotates such that the apexes40of the anvil splines34are rotated to be offset from the apexes44of the shell splines36such that spline crash is obviated.

After the first oscillation, the processing unit54sends control signals to the motor11for a second oscillation (Step340) to oscillate the anvil retainer30while beginning to gradually resume retracting the anvil retainer30. 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 motor11may rotate in the second direction by 1 degree and then rotate in the first direction by 1.5 degrees such that each oscillation of the second oscillation results in 0.5 degrees of rotation of the motor11towards 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 retainer30to assist in avoiding spline crash and to reduce initial engagement between the anvil splines34and the shell splines36.

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 motor11may be rotated in the second direction an extra amount, e.g., about 0.5 degrees, for about 2-5 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 motor11is 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 4 times, the processing unit54may fully extend the anvil retainer30and provide feedback to a clinician of an error.

Once the second oscillation is completed, the processing unit54sends control signals to the motor11to resume retraction of the anvil retainer30until the anvil assembly20is in the clamped position (Step350). During this retraction, the anvil splines34engage the shell splines36to clock the anvil assembly20with the shell assembly18as detailed above.

The Crash Algorithm may reduce the impact of a perceived or actual spline crash allow for clamping of tissue between an anvil assembly20and a shell assembly18without requiring a signification extension of the anvil assembly20away from the shell assembly18. Additionally, the Crash Algorithm may increase confidence of a clinician during a surgical procedure that tissue is properly clamped between the anvil assembly20and the shell assembly18before firing of the staples.