SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS

[0001] This application is a continuation application claiming priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 14/496,775, entitled SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS, filed Sep. 25, 2014, now U.S. Patent Application Publication No. 2015/0038986, which is a continuation application claiming priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 12/647,134, entitled SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS, filed Dec. 24, 2009, which issued on Oct. 7, 2014 as U.S. Pat. No. 8,851,354, the entire disclosures of which are hereby incorporated by reference herein.

[0002] Surgical staplers are used to simultaneously make a longitudinal incision in tissue and apply lines of staples on opposing sides of the incision. Such instruments commonly include an end effector having a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples—one on each side of the knife channel. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument includes a plurality of reciprocating wedges that, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil. Simultaneously, a cutting instrument (or knife) is drawn distally along the jaw member so that the clamped tissue is cut and fastened (e.g., stapled) at the same time.

[0003] An example of a surgical stapler suitable for endoscopic applications is described in published U.S. Patent Application Publication No. 2004/0232196, entitled, SURGICAL STAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSING AND FIRING SYSTEMS, now U.S. Pat. No. 7,000,818, the disclosure of which is herein incorporated by reference in its entirety. In use, a clinician is able to close the jaw members of the stapler upon tissue to position the tissue prior to firing. Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can then fire the surgical stapler, thereby severing and stapling the tissue. The simultaneous severing and stapling actions avoid complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.

[0004] Motor-driven endocutters are known in the art. In such devices, an electric motor powers the cutting and fastening action of the instrument. It is also known to use an on-board battery, located in the handle of the instrument, to power the motor. Published U.S. Patent Application Publication No. 2007/0175952, entitled MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH LOADING FORCE FEEDBACK, now U.S. Pat. No. 7,416,101, the disclosure of which is herein incorporated by reference in its entirety, describes one such motor-driven surgical instrument.

[0005] In one general aspect, the present invention is directed to a surgical instrument with a tissue-clamping end effector, where actuation of the instrument is locked out when the thickness of the tissue clamped in the end effector is not within a specified thickness range. According to various embodiments, the end effector comprises a tissue thickness module that senses the thickness of the tissue clamped in the end effector. The surgical instrument also comprises a control circuit in communication (e.g., wireless communication) with the tissue thickness module. The control circuit prevents actuation of a working portion of the end effector when the thickness of the tissue clamped in the end effector is not within the specified thickness range. In that way, actuation of the instrument can be locked out when too much or too little tissue is clamped in the end effector. This prevents the instrument from firing in situations where it should not be fired.

[0006] According to various implementations, the end effector comprises: first and second opposing jaw members; and a disposable cartridge (such as a disposable staple cartridge) located in the first jaw member. The tissue thickness module may be part of the disposable cartridge, and may comprise a Hall effect sensor. The second jaw member may comprise a magnet, where the Hall effect sensor senses a magnetic field strength from the magnet that is indicative of the thickness of the tissue clamped in the end effector. The tissue thickness module communicates data to the control circuit, the data comprising: (i) data indicative of the thickness of the tissue clamped in the end effector; and (ii) data indicative of a cartridge type of the disposable cartridge. The control circuit may comprise a processing unit programmed to determine whether the tissue clamped in the end effector is within the specified thickness range for the disposable cartridge based on the data communicated to the control circuit by the tissue thickness module. In that connection, the control circuit may comprise solid state memory that stores thickness range data for one or more cartridge types. The processing unit may be programmed to determine whether the tissue clamped in the end effector is within the specified thickness range for the disposable cartridge based on the data communicated to the control circuit by the tissue thickness module by comparing the data indicative of the thickness of the tissue clamped in the end effector to stored thickness range data for the cartridge type of the disposable cartridge in the end effector.

[0015] Certain embodiments of the present invention will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments and that the scope of these embodiments is defined solely by the claims. The features illustrated or described in connection with one embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the appended claims.

[0016] In general, embodiments of the present invention are directed to a surgical instrument that prevents firing of the instrument if the thickness of the tissue clamped in the end effector of the instrument is outside of acceptable limits (e.g., too thick or too thin). That way, the instrument can be prevented from firing in situations when it should not be fired. If the tissue thickness is not within the acceptable limits for the instrument, the operator (e.g., clinician) can adjust the tissue thickness or change the cartridge, for example.

[0017] The instrument may be a motor-drive instrument or a hand-powered instrument, according to various embodiments. FIGS. 1 and 2 depict a motor-driven surgical cutting and fastening instrument 10 according to various embodiments of the present invention. The illustrated embodiment is a linear endoscopic instrument and, in general, the embodiments of the instrument 10 described herein are linear endoscopic surgical cutting and fastening instruments. It should be noted, however, that the invention is not so limited and that according to other embodiments of the present invention, the instrument may be another type of endoscopic instrument, such as a circular or curved endocutter. In addition, the instrument may be a non-endoscopic surgical cutting and fastening instrument, such as a laparoscopic or open instrument.

[0018] The surgical instrument 10 depicted in FIGS. 1 and 2 comprises a handle 6, a shaft 8, and an end effector 12 connected to the shaft 8. In various embodiments, the end effector 12 can be articulated about an articulation pivot 14. An articulation control 16 may be provided adjacent to the handle 6 to effect rotation of the end effector 12 about the articulation pivot 14. In the illustrated embodiment, the end effector 12 is configured to act as an endocutter for clamping, severing and stapling tissue, although, in other embodiments, different types of end effectors may be used, such as end effectors for other types of surgical devices, such as graspers, cutters, staplers, clip appliers, access devices, drug/gene therapy devices, ultrasound, RF or laser devices, etc. More details regarding RF devices may be found in U.S. Pat. No. 5,403,312 and U.S. patent application Ser. No. 12/031,573, entitled SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING RF ELECTRODES, filed Feb. 14, 2008, both of which are incorporated by reference in their entirety.

[0019] The handle 6 of the instrument 10 may include a closure trigger 18 and a firing trigger 20 for actuating the end effector 12. It will be appreciated that instruments having end effectors directed to different surgical tasks may have different numbers or types of triggers or other suitable controls for operating the end effector 12. The end effector 12 is shown separated from the handle 6 by the elongate shaft 8. In one embodiment, a clinician or operator of the instrument 10 may articulate the end effector 12 relative to the shaft 8 by utilizing the articulation control 16, as described in more detail in published U.S. Patent Application Publication No. 2007/0158385, entitled SURGICAL INSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No. 7,670,334, which is incorporated herein by reference in its entirety.

[0020] The end effector 12 includes in this example, among other things, a staple channel 22 and a pivotally translatable clamping member, such as an anvil 24, which are maintained at a spacing that assures, when the anvil 24 is in its clamped position, effective stapling and severing of tissue clamped in the end effector 12. The handle 6 includes a downwardly extending pistol grip 26, towards which a closure trigger 18 is pivotally drawn by the clinician to cause clamping or closing of the anvil 24 toward the staple channel 22 of the end effector 12 to thereby clamp tissue positioned between the anvil 24 and channel 22. The firing trigger 20 is farther outboard of the closure trigger 18. Once the closure trigger 18 is locked in the closure position, the firing trigger 20 may rotate slightly toward the pistol grip 26 so that it can be reached by the operator using one hand. Then the operator may pivotally draw the firing trigger 20 toward the pistol grip 12 to cause the stapling and severing of clamped tissue in the end effector 12. In other embodiments, different types of clamping members besides the anvil 24 could be used. The handle 6 may also include an upper portion 28 that may sit on top of the user's hand when the user grips the pistol grip portion 26 with his/her hand.

[0021] It will be appreciated that the terms “proximal” and “distal” are used herein with reference to a clinician gripping the handle 6 of an instrument 10. Thus, the end effector 12 is distal with respect to the more proximal handle 6. It will be further appreciated that, for convenience and clarity, spatial terms such as “vertical” and “horizontal” are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these terms are not intended to be limiting and absolute.

[0022] In operational use, the closure trigger 18 may be actuated first. Once the clinician is satisfied with the positioning of the end effector 12, the clinician may draw back the closure trigger 18 to its fully closed, locked position proximate to the pistol grip 26. Drawing back of the closure trigger 18 causes the anvil 24 to rotate downwardly, clamping the tissue between the anvil 24 and channel 27. The firing trigger 20 may then be actuated. Actuation of the firing trigger 20 causes the cutting instrument in the end effector 12 to sever the clamped tissue, and causes the fasteners in the end effector to fasten the severed tissue. The firing trigger 20 returns to the open position (shown in FIGS. 1 and 2) when the clinician removes pressure. A release button 19 on the handle 6, when depressed may release the locked closure trigger 18. The release button 19 may be implemented in various forms such as, for example, as disclosed in published U.S. Patent Application Publication No. 2007/0175955, entitled SURGICAL CUTTING AND FASTENING INSTRUMENT WITH CLOSURE TRIGGER LOCKING MECHANISM, which is incorporated herein by reference in its entirety.

[0023] The end effector 12 may include a cutting instrument, such as knife, for cutting tissue clamped in the end effector 12 when the firing trigger 20 is retracted by a user. The end effector 12 may also comprise means for fastening the tissue severed by the cutting instrument, such as staples, RF electrodes, adhesives, etc. More details regarding possible configurations of the end effector 12 may be found in the following patents and published patent applications, which are incorporated herein by reference in their entirety: U.S. Pat. No. 5,709,680; U.S. Pat. No. 5,688,270; U.S. Pat. No. 7,000,818; U.S. Patent Application Publication No. 2005/0173490, now U.S. Pat. No. 7,140,528; U.S. Patent Application Publication No. 2006/0025809, now U.S. Pat. No. 7,506,790; U.S. Patent Application Publication No. 2007/0102453, now U.S. Pat. No. 7,673,783; U.S. Patent Application Publication No. 2007/0102452, now U.S. Pat. No. 7,607,557; U.S. Patent Application Publication No. 2009/0206134, now U.S. Pat. No. 7,857,185; and U.S. Patent Application Publication No. 2009/0206124, now U.S. Pat. No. 7,819,298.

[0024] The instrument 10 may also comprise a closure system for closing (or clamping) the end effector upon closure (or retraction) of the closure trigger 18. More details regarding embodiments of an exemplary closure system for closing (or clamping) the anvil 24 of the end effector 12 by retracting the closure trigger 18 are provided in the following U.S. patent references, which are incorporated herein by reference in their entirety: U.S. Patent Application Publication No. 2004/0232196, now U.S. Pat. No. 7,000,818; U.S. Patent Application Publication No. 2007/0175956, now U.S. Pat. No. 7,644,848; U.S. Patent Application Publication. No. 2007/0158385, now U.S. Pat. No. 7,670,334; U.S. Patent Application Publication No. 2007/0175962, now U.S. Pat. No. 7,422,139; U.S. Pat. No. 7,464,849; and the references cited in the paragraph above.

[0025] A longitudinally movable or rotatable drive shaft located within the shaft 8 of the instrument 10 may drive/actuate the cutting instrument and the fastening means in the end effector 12. An electric motor, located in the pistol grip portion 26 of the handle 6 of the instrument 10, may be used to drive, directly or indirectly (via a gear drive train), the drive shaft. In various embodiments, the motor may be a DC brushed driving motor having a maximum rotation of, approximately, 25,000 RPM. In other embodiments, the motor may include a brushless motor, a cordless motor, a synchronous motor, a stepper motor, or any other suitable electric motor. A battery (or “power source” or “power pack”), such as a Li ion battery, may be provided in the pistol grip portion 26 of the handle 6 adjacent to the motor. The battery supplies electric power to the motor via a motor control circuit. According to various embodiments, a number of battery cells connected in series may be used as the power source to power the motor. In addition, the power source may be replaceable and/or rechargeable.

[0026] As described in more detail below, operation of the motor may be controlled by a processor or microcontroller-based control circuit, which may be located in the handle 6 of the instrument 10, near the motor and battery pack. The control circuit may receive input from the end effector 12 relating to the thickness of the tissue clamped between the opposing jaws (e.g., the staple channel 22 and the anvil 24) of the end effector 12. The control circuit may be in communication with the tissue thickness sensing module of the end effector 12 wirelessly or via a wired connection. If the control circuit determines that the clamped tissue is not within acceptable limits (e.g., too thick or too thin) based on the input from the tissue thickness sensing module, the control circuit may lockout operation of the motor, thereby preventing operation of the instrument. Before describing the control circuit, a description of the end effector 12 and the tissue thickness sensing module is provided.

[0027] FIG. 3 is a diagram of the end effector 12 according to various embodiments of the present invention. As shown in the illustrated embodiment, the end effector 12 may include, in addition to the previously mentioned channel 22 and anvil 24, a cutting instrument 32, a sled 33, a staple cartridge 34 that is removably seated in the channel 22, and a helical screw shaft 36. The cutting instrument 32 may be, for example, a knife. The anvil 24 may be pivotably opened and closed at pivot pins 25 connected to the proximate end of the channel 22. The anvil 24 may also include a tab 27 at its proximate end that is inserted into a component of the mechanical closure system to open and close the anvil 24. When the closure trigger 18 is actuated, that is, drawn in by a user of the instrument 10, the anvil 24 may pivot about the pivot pins 25 into the clamped or closed position, thereby clamping tissue between the channel 22 and the anvil 24. If clamping of the end effector 12 is satisfactory, the operator may actuate the firing trigger 20, which causes the knife 32 and sled 33 to travel longitudinally along the channel 22, thereby cutting the tissue clamped within the end effector 12. The movement of the sled 33 along the channel 22 causes the staples (not shown) of the staple cartridge 34 to be driven through the severed tissue and against the closed anvil 24, which turns the staples to fasten the severed tissue. In various embodiments, the sled 33 may be an integral component of the cartridge 34. U.S. Pat. No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM, which is incorporated herein by reference in its entirety, provides more details about such two-stroke cutting and fastening instruments. The sled 33 may be part of the cartridge 34, such that when the knife 32 retracts following the cutting operation, the sled 33 does not retract.

[0028] FIGS. 4-5 are exploded views and FIG. 6 is a side view of the end effector 12 and shaft 8 according to various, non-limiting embodiments. As shown in the illustrated embodiment, the shaft 8 may include a proximate closure tube 40 and a distal closure tube 42 pivotably linked by a pivot links 44. The distal closure tube 42 includes an opening 45 into which the tab 27 on the anvil 24 is inserted in order to open and close the anvil 24, as further described below. Disposed inside the closure tubes 40, 42 may be a proximate spine tube 46. Disposed inside the proximate spine tube 46 may be a main rotational (or proximate) drive shaft 48 that communicates with a secondary (or distal) drive shaft 50 via a bevel gear assembly 52. The secondary drive shaft 50 is connected to a drive gear 54 that engages a proximate drive gear 56 of the helical screw shaft 36. The vertical bevel gear 52b may sit and pivot in an opening 57 in the distal end of the proximate spine tube 46. A distal spine tube 58 may be used to enclose the secondary drive shaft 50 and the drive gears 54, 56. Collectively, the main drive shaft 48, the secondary drive shaft 50, and the articulation assembly (e.g., the bevel gear assembly 52a-c) are sometimes referred to herein as the “main drive shaft assembly.”

[0029] A bearing 38, positioned at a distal end of the staple channel 22, receives the helical drive screw 36, allowing the helical drive screw 36 to freely rotate with respect to the channel 22. The helical screw shaft 36 may interface a threaded opening (not shown) of the knife 32 such that rotation of the shaft 36 causes the knife 32 to translate distally or proximately (depending on the direction of the rotation) through the staple channel 22. Accordingly, when the main drive shaft 48 is caused to rotate by actuation of the firing trigger 20, the bevel gear assembly 52a-c causes the secondary drive shaft 50 to rotate, which in turn, because of the engagement of the drive gears 54, 56, causes the helical screw shaft 36 to rotate, which causes the knife driving member 32 to travel longitudinally along the channel 22 to cut any tissue clamped within the end effector. The sled 33 may be made of, for example, plastic, and may have a sloped distal surface. As the sled 33 traverses the channel 22, the sloped forward surface may push up or drive the staples in the staple cartridge through the clamped tissue and against the anvil 24. The anvil 24 turns the staples, thereby stapling the severed tissue. When the knife 32 is retracted, the knife 32 and sled 33 may become disengaged, thereby leaving the sled 33 at the distal end of the channel 22.

[0030] In the illustrated embodiment, the end effector uses a rotatable, helical screw shaft 36 to drive the cutting instrument 32. Such a helical drive screw may be used in embodiments where a rotating drive member is used. In other embodiments, a longitudinally reciprocating drive member may be used to power the cutting instrument. The end effector 12 may be modified accordingly to suit such a longitudinally reciprocating drive member. More details regarding such end effectors may be found in U.S. Pat. No. 7,140,528 and U.S. Pat. No. 7,000,819, which are incorporated herein by reference in their entirety.

[0031] According to various embodiments, the replaceable staple cartridge 34 may comprise a tissue thickness sensing module that senses the thickness of tissue clamped in the end effector 12 between the staple channel 22 (including the staple cartridge 34) and the anvil 24. According to various, non-limiting embodiments, as shown in FIG. 7, the tissue thickness sensing module 60 may be located at a distal end 62 of the staple cartridge 34, such that it is out of the way of the staples of the staple cartridge 34 when the staples are fired. FIG. 8 is a block diagram of the tissue thickness sensing module 60 according to various embodiments. As shown in FIG. 8, the tissue thickness sensing module 60 may comprise a tissue thickness sensor 64, a controller 65, a radio module 70, and a power source 74. The controller 65 may comprise a processor unit (CPU) 66 and a memory unit 68. In various embodiments, the tissue thickness sensor 64 may comprise a Hall effect sensor that detects the thickness of the tissue clamped in the end effector 12 based on the magnetic field from a magnet 78 located, for example, at a distal end 80 of the anvil 24, as shown in FIG. 7. When the clinician closes the anvil 24 by retracting the closure trigger 18, the magnet 78 rotates downwardly closer to the sensor 64, thereby varying the magnetic field detected by the sensor 64 as the anvil 24 rotates into the closed (or clamped position). The strength of the magnetic field from the magnet 78 and sensed by the sensor 64 is indicative of the distance between the channel 22 and the anvil 24, which is indicative of the thickness of the tissue clamped between the channel 22 and the anvil 24 when the end effector 12 is in the closed (or clamped) position.

[0032] The memory unit 68 of the controller 65 may comprise one or more solid state read only memory (ROM) and/or random access memory (RAM) units. In various embodiments, the CPU 66 and the memory unit(s) 68 may be integrated into a single integrated circuit (IC), or multiple ICs. The ROM memory unit(s) may comprise flash memory. The ROM memory unit(s) may store code instructions to be executed by the CPU 66 of the controller 65. In addition, the ROM memory unit(s) may store data indicative of the cartridge type of the cartridge 34. That is, for example, ROM memory unit(s) 68 may store data indicating the model type of staple cartridge 34. As explained further below, the motor control circuit in the handle 6 of the instrument 10 may utilize the tissue thickness information and the model type of the staple cartridge 34 to determine if the tissue clamped in the end effector 12 is too thick or too thin, based on the specified tissue thickness range for the particular staple cartridge 34. The radio module 70 may be a low-power, 2-way radio module that communicates wirelessly, using a wireless data communication protocol, with the motor control circuit in the handle 6 of the instrument 10. According to various embodiments, the radio module 70 may communicate with the motor control circuit using a communication frequency that is suitable for transmission through human tissue. The communications between the radio module 70 and the motor control circuit may use the MICS (Medial Implant Communication Service) frequency band (402-405 MHz), a suitable industrial, scientific and medical (ISM) radio band (such as 433 MHz center frequency or 915 MHz center frequency), or any other suitable, human-tissue-permeable frequency band. The power source 74 may comprise a suitable battery cell for powering the components of the tissue thickness sensing module 60, such as a Lithium-ion battery or some other suitable battery cell.

[0033] FIG. 9 is a diagram of the motor control circuit 100 according to various, non-limiting embodiments. The motor control circuit 100 may be located in the handle 6 of the instrument 10, in close proximity with the motor 104 and battery pack 106, and spaced away from the tissue thickness sensing module 60 in the end effector 12 by the shaft 8, for example. As such, the motor control circuit 100 may wirelessly communicate with the tissue thickness sensing module 60 as described herein, although in other embodiments, there may be a wired connection, with wires running through the shaft 8 between the motor control circuit 100 and the tissue thickness sensing module 60 to handle the communications therebetween.

[0034] As shown in FIG. 9, the motor control circuit 100 may comprise, according to various embodiments, a power switching circuit 101, a controller 108, and a radio module 110. The radio module 110 may communicate with the radio module 70 of the tissue thickness sensing module 60. Therefore, the radio module 100 may be a low, power module that operates at the same frequency as the radio module 70 and uses the same communication protocol. The radio modules 70, 100, as shown in FIG. 10, may both comprise, according to various embodiments, transmit and receive antennas 200, 202, an antenna switch 204, a transmit/receive switch 206, RF modulator/demodulator 208, a coder/decoder (codec) 210, and a baseband processor 212. The antennas 200, 2002 of the motor control circuit 100 and the tissue thickness sensing module 60 may be microstrip antennas, for example.

[0035] The power switching circuit 101 may comprise, according to various embodiments, a power switch 103 and a forward/reverse switch 102, that collectively connect the motor 104 and the battery pack 106 in order to connect power from the battery pack 106 to the motor 104. In various embodiments, the forward/reverse switch 102 may comprise a double-pole/double throw relay that, depending on its polarity, determines whether the motor 104 forward rotates or reverse rotates. The controller 108 may control the operation of the switches 102-103. In various embodiments, the controller 108 may be implemented as a microcontroller that comprises a processing unit (CPU) 114 and memory 116. The memory 116 may comprise solid state ROM and/or RAM memory units. The ROM memory unit(s) may comprise instruction code that is executed by the processing unit 114. The processing unit 114 and the memory 116 may be integrated into a single IC, or multiple ICs may be used. The controller 108 and radio module 112 of the motor control circuit 100 may be powered by the battery pack 106.

[0036] As shown in FIG. 9, the controller 108 may receive a number of inputs and, based on processing of those inputs, may control the switches 102-103, to thereby appropriately control the motor 104 of the instrument 10. The inputs to the controller 108 may include a fire input 120, a cutting instrument position input 122, and any other suitable inputs. The fire input 120 may indicate the status of the firing trigger 20, such as whether the clinician has retracted the firing trigger 20 to commence a cutting stroke by the knife in the end effector 12 and whether the clinician has let go of the firing trigger 20 to end the cutting stroke. The fire input 120 may be from a sensor, such as a proportional switch, responsive to the firing trigger 20. The cutting instrument position input 122 may indicate the position of the cutting instrument 34 in the end effector 12 in the course of the cutting stroke. The controller 108 may use this input to determine the position of cutting instrument 34 in the cutting stroke, such as whether the cutting instrument 34 is near or at the end of the cutting stroke. As the cutting instrument 34 approaches the end of the cutting stroke, the controller 108 may reduce the rotation rate of the motor 104, and may reverse the rotation of the motor 104 when the cutting instrument 34 reaches the end of the cutting stroke. The controller 108 may also reduce the rate of rotation of the motor 104 when the cutting instrument is close to its initial, home position at the proximate end of the end effector 12 when the cutting instrument is retracted, and may stop the motor 104 when the cutting instrument is fully retracted. More details regarding a proportional firing trigger switch are provided in the following U.S. patent references, which are incorporated herein by reference in their entirety: U.S. Patent Application Publication No. 2007/0175957, now U.S. Pat. No. 7,770,775; U.S. Patent Application Publication No. 2007/0175958, now U.S. Pat. No. 7,766,210; and U.S. Patent Application Publication No. 2007/0175959, now U.S. Pat. No. 7,568,603. More details regarding instruments with cutting instrument position sensors are provided in the following U.S. patent references, which are incorporated herein by reference in their entirety: U.S. patent application Ser. No. 12/235,782, now U.S. Pat. No. 8,210,411; and U.S. patent application Ser. No. 12/235,972, now U.S. Pat. No. 9,050,083.

[0037] Of course, the controller 108 also receives input data from the tissue thickness sensing module 60 via the radio module 110. The input data from the tissue thickness sensing module 60 may include: (i) the tissue thickness data as sensed by the sensor 64 of the tissue thickness sensing module 60; and (ii) the cartridge model data indicative of the model type of the staple cartridge 34, which is stored in the memory 68 of the tissue thickness sensing module 60. Based on this data, the controller 108 of the motor control circuit 100 may determine whether the tissue clamped in the end effector 12 is within the specified range for the specific staple cartridge 34. If the tissue thickness is within the specified range, the controller 108 may control the switches 102-103 such that power is connected to the motor 104 (assuming other input data is appropriate). On the other hand, if the tissue thickness is not within the specified range, the controller 108 may control the switch 103 such that power is not connected to the motor 104, thereby locking out the motor 104 based on the tissue thickness and preventing operation of the instrument 10.

[0038] FIG. 11 is a flowchart of a process executed by the controller 108 according to various embodiments. The process may be executed by the processing unit 114 by executing code stored in the memory 116. The process may start at step 150, where the controller 108 determines whether the thickness of the tissue clamped in the end effector 12 is within the specified range for the particular staple cartridge 34. The controller 108 may determine this by comparing the tissue thickness data from the sensor 64 to the specified range for the particular staple cartridge 34. The controller 108 may determine the specified thickness range for the staple cartridge using (i) the staple cartridge model data transmitted from the tissue thickness sensing module 60 and (ii) a look-up table (or other data storage structure) in the memory 116 of the controller, which table stores data indicating the specified thickness range for a number of staple cartridge model types. The specified thickness range may include a minimum thickness and a maximum thickness for each model type. For example, different cartridge model types may have different length staples. Longer staples may be able to accommodate more tissue in the end effector than cartridges with shorter staple lengths. As such, the upper thickness limit may be greater for cartridges with longer staples, and the lower thickness limit may be lower for cartridges with shorter staple lengths. If the clamped tissue thickness is less than the minimum thickness or greater than the maximum thickness for the model type of the cartridge 34, the tissue thickness is outside of the specified range.

[0039] If the tissue thickness is outside of the specified thickness range for the staple cartridge 34, the process advances to step 152, where the controller 108 controls the power switch 103 such that power switch 103 is in an open, non-conducting state, so that power from the battery pack 106 is not coupled to the motor 104. As such, the motor 104 does not receive power and is locked out of operation, thereby preventing actuation of the end effector 12. On the other hand, if the tissue thickness is within the specified thickness range for the staple cartridge 34, the process advances to step 154, where the controller 108 determines whether the firing trigger 20 is retracted based on the fire input 120. If it is not, the process advances to step 152 so that power from the battery pack 106 is not coupled to the motor 104. If, on the other hand, the firing trigger 20 is retracted, the process advances to step 156, where the controller 108 determines the position of the cutting instrument 34 in the cutting stroke based on the cutting instrument position input 22. If the position of the cutting instrument is in the forward stroke, the process advances to step 158, where the controller 108 outputs a control signal to the forward/reverse switch 102 to cause the forward/reverse switch 102 to be in a state that couples power to the motor 104 such that the motor 104 forward rotates. Conversely, if the position of the cutting instrument in the cutting stroke requires reverse rotation of the motor 104, the process advances to step 160, where the controller 108 outputs a control signal to the forward/reverse switch 102 to cause the forward/reverse switch 102 to be in a state that couples power to the motor 104 such that the motor 104 reverse rotates. The process may run in an ongoing manner throughout a surgical procedure involving the instrument 10. That way, if for some reason the tissue thickness goes out of range during the procedure, the controller 108 can take appropriate action in response to the real-time tissue thickness data received from the tissue thickness module 60.

[0040] Returning to FIG. 9, the controller 108 may also receive feedback from the motor 104 regarding conditions of the motor 104, such as rate of rotation, rotation direction, etc. The controller 108 may use the data in controlling the motor 104. Also, the controller 108 may output control signals to one or more output devices 124. The output devices 124 may comprise visual indicators, such as illuminators (e.g., light emitting diodes), and/or audible indicators, such as speakers. For example, the output devices 124 may comprise a number of LEDs located on the outside of the handle 6 of the instrument and visible to the operator of the instrument 10 when the instrument 10 is in use. One LED may be turned on when the clamped tissue thickness is in the specified thickness range for the staple cartridge; a second LED may be turned on when the clamped tissue thickness is outside the specified thickness range for the staple cartridge; a third LED may be turned on when the motor 104 is forward rotating; a fourth LED may be turned on when the motor 104 is reverse rotating; etc.

[0041] In addition, in other embodiments, the transmissions from the tissue thickness module 60 may be received by a receiver other than the motor control circuit 100. For example, with reference to FIG. 12, the transmissions from the tissue thickness module 60 may be received by a visual display unit 160 and/or a computer system 170. The visual display unit 160 may comprise a RF radio module 162 for communicating with the tissue thickness module 60. Images based on data from the tissue thickness module 60 may be displayed on the display 160. That way, the clinician may see real-time data regarding the thickness of the clamped tissue throughout a procedure involving the instrument 10. The visual display unit 160 may comprise a monitor, such as a CRT monitor, a plasma monitor, a LCD monitor, or any other suitable visual display monitor. Similarly, the computer system 170 may comprise a RF radio module 172 for communicating with the tissue thickness module 60. The computer system 170 may store the data from the tissue thickness module 60 in a memory unit (e.g., a ROM or hard disk drive) and may process the data with a processor.

[0042] The surgical instruments disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the surgical instrument, followed by cleaning or replacement of particular pieces, and subsequent reassembly. In particular, the surgical instrument can be disassembled, and any number of the particular pieces or parts of the device can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the surgical instrument can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of a surgical instrument can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned surgical instrument, are all within the scope of the present application.

[0043] Preferably, the surgical instrument described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility.

[0044] In various embodiments, some components of the instrument 10 may be part of a removable, replaceable pack that may be inserted into the instrument 10 after the instrument 10 has been sterilized. For example, with reference to FIG. 9, in various embodiments, the battery pack 106, the controller 108, and the radio module 110 may be part of a removable, replaceable pack 140 that may be inserted into the handle 6 of the instrument 10 after the instrument has been sterilized. For example, the removable, replaceable pack 140 may be transferred aseptically to the instrument 10 after the instrument has been sterilized. In such an embodiment, the pack 140 may have appropriate external connectors for connecting to the motor 104, the switching circuit 101, the inputs 120, 122, and output devices 124, etc. In such an embodiment, therefore, the pack 140 can be reused in multiple instruments 10. The cartridge 34 may be disposed of after each use.

[0045] The above embodiments were described in the context of linear endocutter devices with a staple cartridge. It should be noted that the tissue thickness module 60 and corresponding control circuit 100 may be used in any surgical instrument having an end effector used to clamp tissue where thickness of the clamped tissue is an important consideration in the procedure. For example, the tissue thickness module 60 and corresponding control circuit 100 may be used in circular endocutters or other types of cutting/fastening devices, such as laproscopic devices. Also, the tissue thickness module 60 and corresponding control circuit 100 does not need to be used in a device using staples to fasten the severed tissue, but could also be used in instruments using other means to fasten the severed tissue, as noted above. Also, the tissue thickness module 60 and corresponding control circuit 100 do not need to be used in instruments having a motor. In such embodiments, the instrument 10 may employ a mechanical lockout to prevent firing. One such lockout mechanism is described in published U.S. Patent Application Publication No. 2006/0025811, now U.S. Pat. No. 7,857,183, which is incorporated herein by reference in its entirety.

[0046] In various embodiments, therefore, the present invention is directed to a surgical instrument 10 that comprises a tissue-clamping end effector 12. In various embodiments, the end effector 12 comprises a moveable working instrument (e.g., a cutting instrument) 34 and a tissue thickness module 60 that senses the thickness of tissue clamped in the end effector 12. The surgical instrument 10 also comprises a control circuit 100 in communication with the tissue thickness module, where the control circuit prevents actuation of the working instrument when the thickness of the tissue clamped in the end effector is not within a specified thickness range. According to various implementations, the end effector comprises: first and second opposing jaw members 22, 24; and a disposable cartridge 34 (such as a disposable staple cartridge) located in the first jaw member 22, where the tissue thickness module is part of the disposable cartridge. Also, the tissue thickness module may comprise a Hall effect sensor 64, and the second jaw member comprises a magnet 78, where the Hall effect sensor senses a magnetic field strength from the magnet that is indicative of the thickness of the tissue clamped in the end effector when the end effector is in the closed (or clamped) position. In addition, the tissue thickness module communicates data to the control circuit, the data comprising: (i) data indicative of the thickness of the tissue clamped in the end effector; and (ii) data indicative of a cartridge type of the disposable cartridge.

[0047] The control circuit may comprise a processing unit 114 programmed to determine whether the tissue clamped in the end effector is within the specified thickness range for the disposable cartridge based on the data communicated to the control circuit by the tissue thickness module, including the data indicative of the thickness of the tissue clamped in the end effector and the data indicative of the cartridge type of the disposable cartridge. Additionally, the control circuit may comprise solid state memory 116 that stores thickness range data for one or more cartridge types. The processing unit may be programmed to determine whether the tissue clamped in the end effector is within the specified thickness range for the disposable cartridge based on the data communicated to the control circuit by the tissue thickness module by comparing the data indicative of the thickness of the tissue clamped in the end effector to stored thickness range data for the cartridge type of the disposable cartridge in the end effector.

[0048] In addition, the surgical instrument may further comprises an electric motor 104 that actuates the drive shaft 48, 50, and a battery pack 106 that supplies electrical power to the electric motor. The control circuit may prevent actuation of the electric motor when the thickness of the tissue clamped in the end effector is not within a specified thickness range.

[0049] Also, in various embodiments, the tissue thickness module is in wireless communication with the control circuit. The tissue thickness module may comprise a first radio module and the control circuit may comprise a second radio module, where the first radio module wirelessly communicates with the second radio module. In addition, the tissue thickness module may be in communication with a remote visual display unit or a remote computer system.

[0050] While this invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of the disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.