WO2025088481A1

WO2025088481A1 - Powered surgical stapler and method for determining staple and cut force based on clamping distance

Info

Publication number: WO2025088481A1
Application number: PCT/IB2024/060358
Authority: WO
Inventors: Haley E. Strassner; Alexander J. Hart; Emily R. SHEA; Phani K. Bidarahalli; Samantha A. SHIRK; Amy L. Kung; Alexander W. CAULK; Jeremy G. FIDOCK
Original assignee: Covidien LP
Current assignee: Covidien LP
Priority date: 2023-10-25
Filing date: 2024-10-22
Publication date: 2025-05-01
Anticipated expiration: 2026-04-25

Abstract

A powered circular stapler includes an anvil, a reload, and a processor for controlling operation of clamping, stapling, and cutting operation. The processor is used for determining a final clamp position during approximation of the anvil relative to the reload; calculating a target staple force as a function of the final clamp position; comparing the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil; and determining whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

Description

POWERED SURGICAL STAPLER AND METHOD FOR DETERMINING STAPLE AND CUT FORCE BASED ON CLAMPING DISTANCE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63/592,999, filed October 25, 2023, the entire content of each of which is incorporated herein by reference.

BACKGROUND

1. Technical Field

[0002] The present disclosure relates to surgical devices. More specifically, the present disclosure relates to handheld electromechanical surgical systems for performing surgical clamping, stapling, and cutting procedures.

2. Background of Related Art

[0003] Circular staplers are used in a surgical procedure to reattach rectum portions that were previously transected, or similar procedures. Circular clamping, cutting and stapling instruments may be manually actuated and may include a pistol or linear grip-styled structure having an elongated shaft extending therefrom and a staple cartridge supported on the distal end of the elongated shaft. A physician may insert an anvil assembly of the circular stapling instrument through an incision and toward the transected rectum portions. The physician may also insert the remainder of the circular stapling instrument (including the cartridge assembly) into a rectum of a patient and maneuver the instrument up the colonic tract of the patient toward the transected rectum portions. The anvil and cartridge assemblies are approximated toward one another, and staples are ejected from the cartridge assembly toward the anvil assembly to form the staples in tissue to affect an end-to-end anastomosis, and an annular knife is advanced to core a portion of the clamped tissue portions. After the end-to-end anastomosis has been affected, the circular stapling apparatus is removed from the surgical site. Powered surgical staplers have also been developed and utilize one or more motors to clamp, cut, and staple tissue.

[0004] Device manufacturers have historically controlled the compression and staple as functions of the device being used (i.e., diameter of a staple reload), which are selected by the user to accommodate the tissue properties for the clinical application. When staple height and compression distance are pre-selected before properly assessing tissue properties, there exists a risk that the incorrect staple height and compression distance are selected for that tissue. This may lead to issues such as ischemia, bleeding, and lack of mechanical apposition, which may then lead to serious complications including postoperative anastomotic leak.

SUMMARY

[0005] The present disclosure provides a powered circular stapler that is configured to operate in a plurality of independently-controlled sequences, namely, clamping, stapling, cutting, and unclamping to form an anastomosis by connecting two portions of a structure (e.g., intestine, colon, etc.). The powered circular stapler includes a handle assembly having a power source and one or more motors coupled to the power source. The stapler also includes an adapter assembly having multiple transmission assemblies, e.g., drive shafts, which transmit actuation from the powered handle. The powered handle assembly and the adapter assembly may be reusable.

[0006] Clamping is accomplished by moving the anvil in a proximal direction to compress tissue between the anvil and a reload assembly, which includes a plurality of staples. The anvil and the reload assembly may be disposable. During stapling, the staples are ejected from the reload assembly into the clamped tissue and are deformed against the anvil. Cutting includes moving an annular knife through the compressed and stapled tissue until the knife contacts the anvil. During unclamping, the anvil assembly is moved distally away from the cut tissue and the reload assembly. [0007] The powered circular stapler according to the present disclosure is controlled by a processor with integrated sensors and may compress and staple tissue to achieve desired pressures and forces rather than pre- determined distances. In these cases, the stapler determines the appropriate pressures and forces for the application to customize for those tissue properties in an attempt to minimize undue trauma, ischemia, and bleeding and to ensure proper mechanical apposition.

[0008] Determination of the proper stapling and cutting forces for the tissue being fired on may be done during the clamping and compression sequence of the process, which offers the stapler an opportunity to collect data about the properties of the tissue. The present disclosure provides algorithm embodied as software instructions stored in memory and executable by a processor. The algorithm determines the staple and cutting forces based on this compression distance. In particular, the algorithm uses the compression distance, which is a function of the force seen during compression, which itself is a function of the tissue properties. This feature prevents excessive staple forces in thinner tissue and allows a higher staple force in challenging tissue cases as well as for customizing cut parameters to be based on information obtained by the stapler during clamping, which itself is based on measured tissue properties (i.e., measured force). [0009] According to one embodiment of the present disclosure, a powered surgical device disclosed. The surgical device includes a power source, a first motor, and a second motor coupled to the power source. The device also includes a reload having a plurality of staples and a staple driver movable by the second motor for pushing the plurality of staples from the reload. The device further includes an anvil approximated relative to the reload by the first motor and a sensor for measuring a clamp force imparted by the anvil and a staple force imparted by the staple driver. The device additionally includes a controller for determining a final clamp position during approximation of the anvil relative to the reload, calculating a target staple force as a function of the final clamp position, comparing the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil, and determining whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

[0010] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the controller may also determine the final clamp position based on the measured clamp force. The measured clamp force may be monitored during the anvil moving from a maximum clamp position to a minimum clamp position. The controller may also determine the final clamp position by comparing the measured clamp force to a minimum force threshold and the final clamp position corresponds to a position at which the measured clamp force reaches a minimum force threshold. The final clamp position corresponds to the maximum clamp position when the measured clamp force does not reach a minimum force threshold. The controller may further receive a minimum staple force value and a maximum staple force value. The controller may additionally calculate the target staple force by increasing the minimum staple force value by an adjustment factor. The controller may also calculate the adjustment factor as a function of the final clamp position. The controller may further receive a minimum staple position and a maximum staple position. The controller may further compare the measured staple force to the target staple force during advancement of the staple driver from the minimum staple position to the maximum staple position. In response to the measured staple force reaching the target staple force prior to the staple driver reaching the minimum staple position the controller may increase the target staple force to a maximum staple force value.

[0011] According to another embodiment of the present disclosure, a method for controlling a powered stapler is disclosed. The method includes activating a first motor for approximating an anvil relative to a reload may include a plurality of staples and a staple driver movable, measuring, at a sensor, a clamp force imparted by the anvil, and determining a final clamp position during approximation of the anvil relative to the reload. The method also include calculating, at a controller, a target staple force as a function of the final clamp position, activating a second motor for advancing a staple driver relative to the reload to push the plurality of staples from the reload, and measuring, at the sensor, a staple force imparted by the staple driver. The method additionally includes comparing, at the controller, the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil and determining, at the controller, whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

[0012] Implementations of the above embodiment may include one or more of the following features. According to one aspect of the above embodiment, the method may also include determining, at the controller, the final clamp position based on the measured clamp force, where the measured clamp force is monitored during the anvil moving from a maximum clamp position to a minimum clamp position. The method may further include determining, at the controller, the final clamp position by comparing the measured clamp force to a minimum force threshold and the final clamp position corresponds to a position at which the measured clamp force reaches a minimum force threshold. The final clamp position may correspond to the maximum clamp position when the measured clamp force does not reach a minimum force threshold. The method may additionally include receiving, at the controller, a minimum staple force value and a maximum staple force value. The method may also include calculating, at the controller, the target staple force by increasing the minimum staple force value by an adjustment factor. The method may further include calculating, at the controller, the adjustment factor as a function of the final clamp position. The method may additionally include receiving, at the controller, a minimum staple position and a maximum staple position and increasing the target staple force to a maximum staple force value in response to the measured staple force reaching the target staple force prior to the staple driver reaching the minimum staple position the controller. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the present disclosure are described herein with reference to the accompanying drawings, wherein:

[0014] FIG. 1 is a perspective view of a handheld surgical instrument including a handle assembly, an adapter assembly, and an end effector, according to an embodiment of the present disclosure;

[0015] FIG. 2 is a schematic diagram of the handle assembly, the adapter assembly, and the end effector of FIG. 1 ;

[0016] FIG. 3 is a side perspective view of the adapter assembly and the end effector, an annular reload and an anvil assembly, attached to the adapter assembly of FIG. 1 according to an embodiment of the present disclosure;

[0017] FIG. 4 is a perspective view of a clamping transmission assembly disposed within the adapter assembly of FIG. 1, shown partially in phantom;

[0018] FIG. 5 is a perspective view of a stapling transmission assembly disposed within the adapter assembly of FIG. 1, shown partially in phantom;

[0019] FIG. 6 is a cross-sectional view of a reload of the end effector of FIG. 1 ;

[0020] FIG. 7 is a perspective view of the adapter assembly, shown partially disassembled, with a strain gauge assembly;

[0021] FIGS. 8 A and 8B are a flowchart of a method for controlling the surgical instrument of FIG. 1 during the stapling sequence according to an embodiment of the present disclosure;

[0022] FIG. 9 is a schematic diagram illustrating travel distance and speed of the anvil assembly and a corresponding motor during a clamping sequence performed by the handheld surgical device of FIG. 1 according to an embodiment of the present disclosure; and

[0023] FIG. 10 is a schematic diagram illustrating travel distance and force of a staple driver during a stapling sequence performed by the handheld surgical device of FIG. 1 according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0024] Embodiments of the presently disclosed surgical devices, and adapter assemblies for surgical devices and/or handle assemblies are 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 “distal” refers to that portion of the surgical instrument, or component thereof, farther from the user, while the term “proximal” refers to that portion of the surgical instrument, or component thereof, closer to the user.

[0025] The present disclosure provides a powered circular stapler 1 having a handle assembly, an adapter assembly coupled to the handle assembly, and an end effector coupled to the adapter assembly. The stapler allows for full, independent control of three functions: clamping, stapling, and cutting. This allows certain portions of the stapler to adapt if the tissue presents a non-ideal situation.

[0026] FIG. 1 illustrates a surgical device, such as, for example, a powered circular stapler 1 for forming end-to-end anastomosis (“EEA”), including a handle assembly 100, which is configured for selective connection with an adapter assembly 200. The adapter assembly 200 is configured for selective connection with an end effector 300, which includes a reload 400 and an anvil assembly 500. The end effector 300 is configured to produce a surgical effect on tissue of a patient, namely, forming an anastomosis by connecting two portions of a structure (e.g., intestine, colon, etc.) by clamping, stapling, and cutting tissue grasped within the end effector 300.

[0027] The handle assembly 100 includes a power handle 101 and an outer shell housing 10 configured to selectively receive and encase power handle 101. The shell housing 10 includes a distal half-section 10a and a proximal half-section 10b pivotably connected to distal half-section 10a. When joined, distal and proximal half-sections 10a, 10b define a shell cavity therein in which power handle 101 is disposed.

[0028] Distal and proximal half-sections 10a, 10b of shell housing 10 are divided along a plane that traverses a longitudinal axis “X” of adapter assembly 200. Distal half-section 10a of shell housing 10 defines a connecting portion 20 configured to accept a corresponding drive coupling assembly 210 (FIG. 3) of adapter assembly 200. Distal half-section 10a of shell housing 10 supports a toggle control button 30. Toggle control button 30 is capable of being actuated in four directions (e.g., a left, right, up and down).

[0029] With reference to FIGS. 1 and 2, the power handle 101 includes a main controller circuit board 142, a rechargeable battery 144 configured to supply power to any of the electrical components of handle assembly 100, and a plurality of motors 152 coupled to the battery 144. The power handle 101 also includes a screen 146. In embodiments, the motors 152 may be coupled to any suitable power source configured to provide electrical energy to the motor 152, such as an AC/DC transformer. Each of the motors 152 is coupled a motor controller 143 which controls the operation of the corresponding motor 152 including the flow of electrical energy from the battery 144 to the motor 152. A main controller 147 is provided that controls the power handle 101. The main controller 147 is configured to execute software instructions embodying algorithms disclosed herein, such as clamping, stapling, and cutting algorithms which control operation of the power handle 101.

[0030] The motor controller 143 includes a plurality of sensors 408a ... 408n configured to measure operational states of the motor 152 and the battery 144. The sensors 408a-n include a strain gauge 408b and may also include voltage sensors, current sensors, temperature sensors, telemetry sensors, optical sensors, and combinations thereof. The sensors 408a-408n may measure voltage, current, and other electrical properties of the electrical energy supplied by the battery 144. The sensors 408a-408n may also measure angular velocity (e.g., rotational speed) as revolutions per minute (RPM), torque, temperature, current draw, and other operational properties of the motor 152. The sensor 408a also includes an encoder configured to count revolutions or other indicators of the motor 152, which is then use by the main controller 147 to calculate linear movement of components movable by the motor 152. Angular velocity may be determined by measuring the rotation of the motor 152 or a drive shaft (not shown) coupled thereto and rotatable by the motor 152. The position of various axially movable drive shafts may also be determined by using various linear sensors disposed in or in proximity to the shafts or extrapolated from the RPM measurements. In embodiments, torque may be calculated based on the regulated current draw of the motor 152 at a constant RPM. In further embodiments, the motor controller 143 and/or the main controller 147 may measure time and process the above-described values as a function of time, including integration and/or differentiation, e.g., to determine the rate of change in the measured values. The main controller 147 is also configured to determine distance traveled of various components of the adapter assembly 200 and/or the end effector 300 by counting revolutions of the motor 152.

[0031] The motor controller 143 is coupled to the main controller 147, which includes a plurality of inputs and outputs for interfacing with the motor controller 143. In particular, the main controller 147 receives measured sensor signals from the motor controller 143 regarding operational status of the motor 152 and the battery 144 and, in turn, outputs control signals to the motor controller 143 to control the operation of the motor 152 based on the sensor readings and specific algorithm instructions. The main controller 147 is also configured to accept a plurality of user inputs from a user interface (e.g., switches, buttons, touch screen, etc. coupled to the main controller 147).

[0032] The main controller 147 is also coupled to a memory 141. The memory 141 may include volatile (e.g., RAM) and non-volatile storage configured to store data, including software instructions for operating the power handle 101. The main controller 147 is also coupled to the strain gauge 408b of the adapter assembly 200 using a wired or a wireless connection and is configured to receive strain measurements from the strain gauge 408b which are used during operation of the power handle 101.

[0033] The power handle 101 includes a plurality of motors 152 each including a respective motor shaft (not explicitly shown) extending therefrom and configured to drive a respective transmission assembly. Rotation of the motor shafts by the respective motors function to drive shafts and/or gear components of adapter assembly 200 in order to perform the various operations of handle assembly 100. In particular, motors 152 of power handle 101 are configured to drive shafts and/or gear components of adapter assembly 200 in order to selectively extend/retract a trocar member 274 (FIG. 4) of a trocar assembly 270 of adapter assembly 200. Extension/retraction of the trocar member 274 opens/closes end effector 300 (when anvil assembly 500 is connected to trocar member 274 of trocar assembly 270), fire an annular array of staples 423 of reload 400, and move an annular knife 444 of reload 400.

[0034] The reload 400 includes a storage device 402 configured to store operating parameters of the reload 400 including starting clamping force, maximum clamping force, a force factor, and the like. Each type of reload 400 may have a corresponding starting clamping force, which the main controller 147 may obtain automatically by reading the starting clamping force value from the storage device 402 and/or set manually by the user by selecting either the type of the reload 400 or the clamping force directly. Starting clamping force may be any suitable threshold from about 100 pounds to about 200 pounds, in embodiments, the target clamping force may be approximately 150 pounds. In embodiments, a 33 mm sized reload 400 may have a clamping force of about 150 lbs.

[0035] Turning now to FIGS. 3 and 4, adapter assembly 200 includes an outer knob housing 202 and an outer tube 206 extending from a distal end of knob housing 202. Knob housing 202 and outer tube 206 are configured and dimensioned to house the components of adapter assembly 200. The knob housing 202 includes an electrical connector 312 and a storage device 310 coupled thereto. The storage device 310 is configured to store various operating parameters pertaining to the adapter assembly 200. Adapter assembly 200 is configured to convert rotation of coupling shafts (not explicitly shown) of handle assembly 100 into axial translations useful for operating trocar assembly 270 of adapter assembly 200, anvil assembly 500, and/or staple driver 434 or knife assembly 444 of reload 400.

[0036] Adapter assembly 200 further includes the trocar assembly 270 removably supported in a distal end of outer tube 206. Trocar assembly 270 includes a trocar member 274 and a drive screw 276 operably received within trocar member 274 for axially moving trocar member 274 relative to outer tube 206. A distal end 274b of trocar member 274 is configured to selectively engage anvil assembly 500, such that axial movement of trocar member 274, via a rotation of drive screw 276, results in a concomitant axial movement of anvil assembly 500.

[0037] With reference to FIG. 4, a clamping transmission assembly 240 includes first rotatable proximal drive shaft 212 coupled to one of the motors 152, a second rotatable proximal drive shaft 281, a rotatable distal drive shaft 282, and a coupling member 286, each of which are supported within the outer tube 206 of adapter assembly 200. Clamping transmission assembly 240 functions to extend/retract trocar member 274 of trocar assembly 270 of adapter assembly 200, and to open/close the anvil assembly 500 when anvil assembly 500 is connected to trocar member 274.

[0038] With reference to FIG. 5, the adapter assembly 200 includes a stapling transmission assembly 250 for interconnecting one of the motors 152 and a second axially translatable drive member of reload 400, wherein the stapling transmission assembly 250 converts and transmits a rotation of one of the motors 152 to an axial translation of an outer flexible band assembly 255 of adapter assembly 200, and in turn, the staple driver 434 of reload 400 to fire staples 423 from the reload 400 and against anvil assembly 500.

[0039] The stapling transmission assembly 250 of adapter assembly 200 includes the outer flexible band assembly 255 secured to staple driver coupler 254. A second rotatable proximal drive shaft 220 is coupled to one of the motors 152 and is configured to actuate that staple driver coupler 254 , which converts rotational movement into longitudinal movement. Outer flexible band assembly 255 includes first and second flexible bands 255a, 255b laterally spaced and connected at proximal ends thereof to a support ring 255c and at distal ends thereof to a proximal end of a distal pusher 255d. Each of first and second flexible bands 255a, 255b is attached to support ring 255c and distal pusher 255d. Outer flexible band assembly 255 further includes first and second connection extensions 255e, 255f extending proximally from support ring 255c. First and second connection extensions 255 e, 255f are configured to operably connect outer flexible band assembly 255 to staple driver coupler 254 of stapling transmission assembly 250.

[0040] With reference to FIG. 6, staple driver 434 of reload 400 includes a staple cartridge 420 having a driver adapter 432 and a staple driver 434. A proximal end 432a of driver adapter 432 is configured for selective contact and abutment with distal pusher 255d of outer flexible band assembly 255 of stapling transmission assembly 250 of adapter assembly 200. In operation, during distal advancement of outer flexible band assembly 255, as described above, distal pusher 255d of outer flexible band assembly 255 contacts proximal end 432a of driver adapter 432 to advance driver adapter 432 and driver 434 from a first or proximal position to a second or distal position. Driver 434 includes a plurality of driver members 436 aligned with staple pockets 421 of staple cartridge 420 for contact with staples 423. Accordingly, advancement of driver 434 relative to staple cartridge 420 causes ejection of the staples 423 from staple cartridge 420.

[0041] Forces during an actuation of trocar member 274, closing of end effector 300 (e.g., a retraction of anvil assembly 500 relative to reload 400), and ejecting staples 423 from the reload 400 may be measured by the strain gauge 408b in order to monitor and control various processes, such as firing of staples 423 from reload 400; monitor forces during a firing and formation of the staples 423 as the staples 423 are being ejected from reload 400; optimize formation of the staples 423 (e.g., staple crimp height) as the staples 423 are being ejected from reload 400 for different indications of tissue; and monitor and control a firing of the annular knife of reload 400.

[0042] With reference to FIG. 7, the strain gauge 408b of adapter assembly 200 is disposed within a strain gauge housing 320. The strain gauge 408b measures and monitors the retraction of trocar member 274 as well as the ejection and formation of the staples 423 from the reload 400. During the closing of end effector 300, when anvil assembly 500 contacts tissue, an obstruction, a tissue-contacting surface of the reload 400, staple ejection, or the like, a reaction force is exerted on anvil assembly 500 which is in a generally distal direction. This distally directed reaction force is communicated from anvil assembly 500 to the strain gauge 408b. The strain gauge 408b then communicates signals to main controller circuit board 142 of power handle 101 of handle assembly 100. Graphics are then displayed on the screen 146 of handle assembly 100 to provide the user with real-time status information as shown in FIG. 10.

[0043] The trocar assembly 270 is axially and rotationally fixed within outer tube 206 of adapter assembly 200. With reference to FIG. 6, adapter assembly 200 includes a support block 292 fixedly disposed within outer tube 206. The strain gauge housing 320 is disposed between the support block 292 and a connector sleeve 290. The reload 400 is removably coupled to the connector sleeve 290.

[0044] In operation, strain gauge 408b of adapter assembly 200 measures and monitors the retraction of trocar member 274, which passes through the strain gauge 408b. The strain gauge 408b of adapter assembly 200 also measures and monitors ejection of the staples 423 from the reload 400, since the first and second flexible bands 255a, 255b also pass through the strain gauge 408b. During clamping, stapling and cutting, a reaction force is exerted on anvil assembly 500 and the reload 400, which is communicated to support block 292, which then communicates the reaction force to a strain sensor of the strain gauge 408b.

[0045] Strain sensor of strain gauge 408b may be any device configured to measure strain (a dimensionless quantity) on an object that it is adhered to (e.g., support block 292), such that, as the object deforms, a metallic foil of the strain sensor is also deformed, causing an electrical resistance thereof to change, which change in resistance is then used to calculate loads experienced by trocar assembly 270. Strain gauge 408b provides a closed-loop feedback to a firing/clamping load exhibited by first, second and third force/rotation transmitting/converting assemblies.

[0046] Strain sensor of strain gauge 408b then communicates signals to main controller circuit board 142. Graphics are then displayed on screen 146 of handle assembly 100 to provide the user with real-time information related to the status of the firing of handle assembly 100. Strain gauge 408b is also electrically connected to the electrical connector 312 (FIG. 3) via proximal and distal harness assemblies 314, 316.

[0047] For further details regarding the construction and operation of the circular stapler and its components, reference may be made to International Application Publication No. PCT/US2019/040440, filed on July 3, 2019, the entire contents of which being incorporated by reference herein.

[0048] FIG. 8 shows a method of operating the powered stapler 1. At step 700, the user commences a surgical procedure by positioning the adapter assembly 200, including the trocar member 274 and the anvil assembly 500, within the colorectal or upper gastrointestinal region. The user presses the toggle control button 30 to extend the trocar member 274 until it pierces tissue. During operation, the anvil assembly 500 (after being positioned by surgeon at the tissue site where anastomosis is being performed) is attached to the trocar member 274 and the user begins the clamping process on the tissue interposed between reload 400 and the anvil assembly 500 by pressing on the bottom of the toggle control button 30. After extension of the trocar member 274, the anvil assembly 500 that was previously positioned by surgeon is attached to the trocar member 274. At step 702, the surgeon then begins the clamping process on the tissue interposed between reload 400 and the anvil assembly 500 by pressing on the bottom portion of the toggle control button 30.

[0049] During clamping, the anvil assembly 500 is retracted toward the reload 400 until reaching a preset, fully clamped position. The preset clamped position varies for each of the different types of reloads (e.g., the distance is about 29 mm for 25 mm reloads). While clamping, the strain gauge 408b continuously provides measurements to the main controller 147 on the force imparted on the trocar member 274 as it moves the anvil assembly 500 to clamp tissue between the anvil assembly 500 and the reload 400.

[0050] FIG. 8A shows a clamping algorithm according to the present disclosure. The algorithm may be embodied as software instructions stored in memory and executable by a processor. With reference to FIG. 9, which schematically illustrates the travel distance and speed of the anvil assembly 500 as it is retracted by the first motor 152. At step 704, the anvil assembly 500 is retracted, i.e., moved proximally, from a first fully open position 601 at a first speed for a first segment from the fully open position 601 to a second position 602, which is closer to the reload 400. This is done in response to the user pressing the toggle control button 30.

[0051] At step 706, the anvil assembly 500 traverses proximally along a second segment from the second position 602 to a third position 603 at the second speed, which is slower than the first speed. As the anvil assembly 500 is traversing the second segment, at step 708, the main controller 147 continuously verifies whether the measured force is within predefined parameters to determine if the measured force exceeds a high force threshold limit prior to reaching a starting compression distance. This measurement is used to detect obstruction, a mismatch between the anvil assembly 500 and the reload 400, and/or misalignment of the anvil assembly 500 with the reload 400. If the force is higher than the high force threshold, then at step 710, the power handle 101 temporarily reverses the clamping transmission assembly 240 to retract the anvil assembly 500 to correct the misalignment. The main controller 147 then reattempts to continue clamping, i.e., moving the anvil assembly 500 proximally toward the reload 400, until a third position 603 is reached. If the third position 603 is not reached within a predetermined period of time, the main controller 147 then issues an error, including an alarm on the display screen 146 prompting the user to inspect the anvil assembly 500. After inspection and clearance of any obstruction, the user may then restart the clamping process.

[0052] Once the anvil assembly 500 reaches the third position 603, which is at the end of the second segment, the power handle 101 performs a rotation verification to check position of the anvil assembly 500. At step 712, the main controller 147 commences a controlled tissue compression (“CTC”) algorithm. The CTC algorithm has two phases — the first CTC phase starts from the third position 603, during which the anvil assembly 500 is driven proximally) at a varying speed based on a measured force until reaching a position between a fourth position 604 and a fifth position 605. The fourth position 604 denotes a maximum gap position, i.e., separation between the anvil assembly 500 and the reload 400, at which stapling and cutting may take place. Conversely, the fifth position 605 denotes a minimum gap position. The distance between the fourth and fifth positions 604 and 605 defines a clamp gap, which depends on the size of the reload 400 being used, i.e., thick vs thin type reload 400.

[0053] Advancement of the anvil assembly 500 between the third position 603 and the fourth position 604, at step 712, accounts for slow-changing and rapid-changing forces imparted on the tissue during compression with a second-order predictive force filter. As the predicted force approaches a target CTC force, the clamping speed is slowed to prevent over-shoot. When the measured force reaches the target CTC force and the clamp gap has not yet been achieved, clamping is stopped to allow for tissue relaxation. During tissue relaxation, after the measured force falls below the target clamping force, advancement recommences. The force exerted on tissue is derived from the strain measurements by the main controller 147 from the strain gauge 408b. This process continues until the fourth (i.e., maximum gap) position 604 is reached.

[0054] Once the fourth position 604 has been reached, the anvil assembly 500 is advanced proximally to a fifth (i.e., minimum gap) position 605, at step 714. After reaching the fourth position 604 and before advancing the anvil assembly 500 to the fifth position 605, the anvil assembly 500 may be stopped temporarily, which may be from about 0.5 seconds to about 2 seconds. The distance between the fourth position 604 to the fifth position 605 may be from about 0.002” to about 0.02”. The anvil assembly 500 is advanced proximally to the fifth position 605 based on measured force in the same manner as the clamping between the third position 603 and the fourth position 604. In particular, the anvil assembly 500 may be advanced from the fourth position 604 to the fifth position 605 using the same force feedback as used to advance to the fourth position 604.

[0055] At step 716, while the anvil assembly 500 is advanced between fourth and fifth positions 604 and 605, the controller 147 continuously monitors the force and compares the forces to a CTC minimum force, which is used as one of the verification checks that clamping was successfully completed. Once the measured force reaches the CTC minimum force, at step 718, the clamping process stops, and the position at which the anvil assembly 500 stopped between the minimum gap (i.e., fifth position 605) and maximum gap (i.e., fourth position 604) is stored in memory 141 as a final clamp position 607. If the CTC minimum force is never reached, then the clamping continues until reaching the fifth (i.e., minimum gap) position 605, and at step 719, this position is then stored in memory 141 as the final clamp position 607.

[0056] Once final clamp position 607 is reached, a notification that clamping is complete may be displayed on the screen 146 and audio tones may be output by the power handle 101. The anvil assembly 500 is maintained at the final clamp position 607 for a predetermined period of time, which may be from about 1 second to about 12 seconds and in embodiments, may be from about 2 seconds to about 6 seconds. The anvil assembly 500 maintains a preset force on the tissue, which may be from about 80 lbs to about 150 lbs, which in embodiments may be about 105 lbs.

[0057] Once the main controller 147 signals that tissue clamping was successful, the user initiates the stapling sequence by pressing one of the safety buttons 36 of the power handle 101, which acts as a safety and arms the toggle control button 30, allowing it to commence stapling. The user then presses down on the toggle control button 30, which moves the second rotation transmitting assembly 250 to convert rotation to linear motion and to eject and form staples from circular reload 400.

[0058] FIG. 8B shows a stapling algorithm according to the present disclosure. The algorithm may be embodied as software instructions stored in memory and executable by a processor. At step 720, the controller 147 receives minimum and maximum stapling force values, which may be stored in the storage device 402 of the reload 400 and used by the main controller 147 during the stapling sequence. The controller 147 may also receive minimum and maximum staple position values, which depend on the size of staples of the reload 400. In embodiments, these values may be stored in the memory 141 or any other storage device (e.g., server) accessible by the controller 147.

[0059] At step 722, the controller 147 calculates the target staple force as a function of the final clamp position 607. In particular, the target staple force is calculated using the following formula:

T ar get Staple Force

Final Clamp Pos. —Min. Clamp Pos. Max. Clamp Pos. —Min. Clamp Pos.

* Max. Staple Force — Min. Staple Force) + Min. Staple Force

[0060] In embodiments, a staple force factor may be used to multiply the difference between the maximum and minimum staple forces to tailor the target staple force based on the type and/or size of the reload 400 being used. In the above formula, when the final clamp position 607 is the same as the fifth (i.e., minimum gap) position 605, i.e., CTC minimum force was never reached, the target staple force is the minimum staple force. If the final clamp position 607 is larger than the minimum clamp gap, i.e., CTC minimum was reached before the minimum clamp gap is reached, then the target staple force is larger than the minimum staple force. Thus, the minimum staple force value is increased by an adjustment factor that is calculated by adding the result of the difference between maximum and minimum staple forces and multiplied by a ratio of the differences between clamp gap positions as shown in the formula.

[0061] The stapling process has three phases. The first phase is the staple detection process (i.e., from first position 608 to the second position 610) in which the controller 147 determines whether staples are present in the reload 400 based on strain measurement as the staple driver 434 contacts staples. At step 724, the staple driver 434 is initially advanced from a first position 608 (e.g., hard stop) at a first speed for a first segment from the first position 608 to a second position 610 (e.g., base position at which the staple driver 434 contacts the staples 423). [0062] The second phase is the intermediate zone (from the second position 610 to the third position 612) where the staples have contacted the anvil assembly 500 and have started bending. At step 726, the staple driver 434 is advanced from the second position 610, until the staple driver 434 reaches a third position 612 (e.g., minimum staple position), to eject the staples 423. During this phase, the staple driver 434 may be advanced at a second speed, slower than the first speed.

[0063] As the staples 423 are ejected from the reload 400 to staple tissue, the main controller 147 continually monitors the strain measured by the strain gauge 408b and determines whether the force corresponding to the measured strain is between the minimum stapling force and the maximum stapling force. Determination whether the measured force is below the minimum stapling force is used to verify that the staples 423 are present in the reload 400. In addition, a low force may be also indicative of a failure of the strain gauge 408b.

[0064] If the measured force is below the minimum stapling force, then the main controller 147 signals the first motor 152a to retract the driver 434 to the second position 610. The main controller 147 also displays a sequence on the screen 146 instructing the user the steps to exit stapling sequence and retract the anvil assembly 500. After removing the anvil assembly 500, the user may replace the circular adapter assembly 200 and the reload 400 and restart the stapling process.

[0065] If the measured force is above the maximum stapling force, which may be about 580 lbs., the main controller 147 stops the first motor 152a and displays a sequence on the screen 146 instructing the user the steps to exit the stapling sequence. However, the user may continue the stapling process without force limit detection by pressing on the toggle control button 30.

[0066] At step 728, the controller 147 compares the measured force to the target staple force calculated as the staple driver 434 is advanced to the third position 612. If the target staple force is not achieved prior to the staple driver 434 reaching the third (i.e., minimum staple) position 612, at step 738, the staples are ejected toward the maximum staple position at step 738.

[0067] If the target staple force is achieved prior to the staple driver 434 reaching the third (i.e., minimum staple) position 612, at step 730, the controller 147 then sets the target staple force to a maximum staple force, which may be about 580 lbs. At step 732, the controller 147 continues to advance the staple driver 434 to the third position 612. At step 734, the controller 147 compares the measured force for the maximum staple force. If the maximum staple force is not detected before the staple driver 434 reaches the minimum staple position, the staple driver 434 is stopped and the controller 147 identifies the stapling process as failed. At step 736, the controller 147 also displays an error message about the failed stapling attempt on the screen 146. If the maximum staple force is not reached, the controller 147 continues the stapling process to step 738. [0068] At step 738, staple formation occurs, during which the staple driver 434 is advanced from the third position 612 to a fourth position 614 (i.e., maximum staple position) which fully forms the staples. The stapling process is deemed complete if the measured staple force reaches the target staple force during advancement of the staple driver 434 between the minimum and maximum staple positions (i.e., between the third position 612 and the fourth position 614) and/or if the stapler driver 434 reaches the fourth position 614 with or without reaching the target staple force.

[0069] At step 740, the controller 147 determines whether the staple driver 434 reached the fourth position 614. If yes, then at step 742 the controller 147 outputs a message that the stapling process is complete and the powered stapler 1 may be used to perform the cutting sequence, during which the annular knife 444 is advanced to cut stapled tissue.

[0070] If the fourth position 614 has not been reached, then at step 744 the controller 147 compares the measured force to the target staple force as the staple driver 434 is advanced to the fourth position 614. If the target staple force is not yet reached, the controller 147 returns to step 740 and continues to advance the staple driver 434. If the target force is reached, then the controller 147 proceeds to step 742 and the stapling process is identified as complete as described above.

[0071] It will be understood that various modifications may be made to the embodiments of the presently disclosed adapter assemblies. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure.

[0072] In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer- readable media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

[0073] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.

[0074] Aspects of this disclosure may be further described by reference to the following examples:

[0075] Example 1. A surgical device comprising: a power source; a first motor and a second motor coupled to the power source; a reload including a plurality of staples and a staple driver movable by the second motor for pushing the plurality of staples from the reload; and an anvil approximated relative to the reload by the first motor; a sensor for measuring a clamp force imparted by the anvil and a staple force imparted by the staple driver; a controller for: determining a final clamp position during approximation of the anvil relative to the reload; calculating a target staple force as a function of the final clamp position; comparing the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil; and determining whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

[0076] Example 2. The surgical device according to example 1, wherein the controller determines the final clamp position based on the measured clamp force.

[0077] Example 3. The surgical device according to example 2, wherein the measured clamp force is monitored during the anvil moving from a maximum clamp position to a minimum clamp position.

[0078] Example 4. The surgical device according to example 3, wherein the controller determines the final clamp position by comparing the measured clamp force to a minimum force threshold and the final clamp position corresponds to a position at which the measured clamp force reaches a minimum force threshold.

[0079] Example s. The surgical device according to example 3, wherein the final clamp position corresponds to the maximum clamp position when the measured clamp force does not reach a minimum force threshold.

[0080] Example 6. The surgical device according to example 1, wherein the controller further receives a minimum staple force value and a maximum staple force value.

[0081] Example 7. The surgical device according to example 6, wherein the controller calculates the target staple force by increasing the minimum staple force value by an adjustment factor.

[0082] Example 8. The surgical device according to example 7 , wherein the controller calculates the adjustment factor as a function of the final clamp position. [0083] Example 9. The surgical device according to example 1, wherein the controller further receives a minimum staple position and a maximum staple position.

[0084] Example 10. The surgical device according to example 9, wherein the controller further compares the measured staple force to the target staple force during advancement of the staple driver from the minimum staple position to the maximum staple position.

[0085] Example 11. The surgical device according to example 9, wherein in response to the measured staple force reaching the target staple force prior to the staple driver reaching the minimum staple position the controller increases the target staple force to a maximum staple force value.

[0086] Example 12. A method for controlling a powered stapler, the method comprising: activating a first motor for approximating an anvil relative to a reload including a plurality of staples and a staple driver movable; measuring, at a sensor, a clamp force imparted by the anvil; determining a final clamp position during approximation of the anvil relative to the reload; calculating, at a controller, a target staple force as a function of the final clamp position; activating a second motor for advancing a staple driver relative to the reload to push the plurality of staples from the reload; measuring, at the sensor, a staple force imparted by the staple driver; comparing, at the controller, the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil; and determining, at the controller, whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

[0087] Example 13. The method according to example 12, further comprising:

[0088] determining, at the controller, the final clamp position based on the measured clamp force, wherein the measured clamp force is monitored during the anvil moving from a maximum clamp position to a minimum clamp position.

[0089] Example 14. The method according to example 13, further comprising: determining, at the controller, the final clamp position by comparing the measured clamp force to a minimum force threshold and the final clamp position corresponds to a position at which the measured clamp force reaches a minimum force threshold.

[0090] Example 15. The method according to example 13, wherein the final clamp position corresponds to the maximum clamp position when the measured clamp force does not reach a minimum force threshold.

[0091] Example 16. The method according to example 12, further comprising: receiving, at the controller, a minimum staple force value and a maximum staple force value. [0092] Example 17. The method according to example 16, further comprising: calculating, at the controller, the target staple force by increasing the minimum staple force value by an adjustment factor.

[0093] Example 18. The method according to example 17, further comprising: calculating, at the controller, the adjustment factor as a function of the final clamp position.

[0094] Example 19. The method according to example 12, further comprising: receiving, at the controller, a minimum staple position and a maximum staple position.

[0095] Example 20. The method according to example 19, further comprising: comparing, at the controller, the measured staple force to the target staple force during advancement of the staple driver from the minimum staple position to the maximum staple position, wherein in response to the measured staple force reaching the target staple force prior to the staple driver reaching the minimum staple position the controller increases the target staple force to a maximum staple force value.

Claims

WHAT IS CLAIMED IS:

1. A surgical device comprising: a power source (144); a first motor (152) and a second motor (152) coupled to the power source; a reload (400) including a plurality of staples (423) and a staple driver (430) movable by the second motor for pushing the plurality of staples from the reload; and an anvil (500) approximated relative to the reload by the first motor; a sensor (408b) for measuring a clamp force imparted by the anvil and a staple force imparted by the staple driver; a controller (147) for: determining a final clamp position during approximation of the anvil relative to the reload; calculating a target staple force as a function of the final clamp position (607); comparing the measured staple force to the target staple force during advancement of the staple driver to form the plurality of staples against the anvil; and determining whether formation of the plurality of staples against the anvil is complete based on a comparison of the measured staple force to the target staple force.

2. The surgical device according to claim 1 , wherein the controller determines the final clamp position based on the measured clamp force.

3. The surgical device according to claim 2, wherein the measured clamp force is monitored during the anvil moving from a maximum clamp position (604) to a minimum clamp position (605).

4. The surgical device according to claim 3, wherein the controller determines the final clamp position by comparing the measured clamp force to a minimum force threshold and the final clamp position corresponds to a position at which the measured clamp force reaches a minimum force threshold.

5. The surgical device according to claim 3, wherein the final clamp position corresponds to the maximum clamp position when the measured clamp force does not reach a minimum force threshold.

6. The surgical device according to any of the preceding claims, wherein the controller further receives a minimum staple force value and a maximum staple force value.

7. The surgical device according to claim 6, wherein the controller calculates the target staple force by increasing the minimum staple force value by an adjustment factor.

8. The surgical device according to claim 7, wherein the controller calculates the adjustment factor as a function of the final clamp position.

9. The surgical device according to any of the preceding claims, wherein the controller further receives a minimum staple position (612) and a maximum staple position (614).

10. The surgical device according to claim 9, wherein the controller further compares the measured staple force to the target staple force during advancement of the staple driver from the minimum staple position to the maximum staple position.

11. The surgical device according to claim 9, wherein in response to the measured staple force reaching the target staple force prior to the staple driver reaching the minimum staple position the controller increases the target staple force to a maximum staple force value.