Patent Publication Number: US-2022218348-A1

Title: Surgical cutting instrument that analyzes tissue thickness

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 16/298,546, entitled SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS, filed Mar. 11, 2019, now U.S. Patent Application Publication No. 2019/0269407, which is a continuation application claiming priority under 35 U.S.C. § 120 to U.S. patent application Ser. No. 15/059,533, entitled SURGICAL CUTTING INSTRUMENT THAT ANALYZES TISSUE THICKNESS, filed Mar. 3, 2016, now U.S. Patent Application Publication No. 2016/0183944, which 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, which issued on Apr. 12, 2016 as U.S. Pat. No. 9,307,987, 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. 
    
    
     BACKGROUND 
     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. 
     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. 
     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. 
     SUMMARY 
     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. 
     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. 
    
    
     
       FIGURES 
       Various embodiments of the present invention are described herein by way of example in connection with the following figures, wherein: 
         FIGS. 1-2 and 12  are views of a surgical instrument according to various embodiments of the present invention; 
         FIGS. 3-5  are exploded views of the end effector and shaft of a surgical instrument according to various embodiments of the present invention; 
         FIGS. 6-7  are views of the end effector according to various embodiments of the present invention; 
         FIG. 8  is a block diagram of a tissue thickness module according to various embodiments of the present invention; 
         FIG. 9  is a block diagram of a motor control circuit according to various embodiments of the present invention; 
         FIG. 10  is a block diagram of a radio module according to various embodiments of the present invention; and 
         FIG. 11  is flow chart of a process executed by the motor control circuit according to various embodiments of the present invention. 
     
    
    
     DESCRIPTION 
     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. 
     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. 
     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. 
     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. 
     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. 
     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&#39;s hand when the user grips the pistol grip portion  26  with his/her hand. 
     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. 
     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. 
     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. Nos. 5,709,680; 5,688,270; 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. 
     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. Nos. 7,422,139; 7,464,849; and the references cited in the paragraph above. 
     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. 
     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. 
       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. 
       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  52   b  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  52   a - c ) are sometimes referred to herein as the “main drive shaft assembly.” 
     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  52   a - 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 . 
     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. Nos. 7,140,528 and 7,000,819, which are incorporated herein by reference in their entirety. 
     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. 
     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. 
       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. 
     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. 
     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 . 
     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. 
     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 . 
       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. 
     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 . 
     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. 
     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. 
     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. 
     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. 
     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. 
     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. 
     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. 
     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. 
     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. 
     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. 
     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.