Abstract:
A surgical instrument comprises an articulable end effector; a drive shaft connected to the end effector that drives the end effector; an electric motor connected to the drive shaft that drives the drive shaft; a battery unit for supplying power to the electric motor; at least one sensor for sensing a status of the instrument; and an alphanumeric display located on the instrument and in communication with the at least one sensor. The alphanumeric display is for displaying alphanumeric characters that display visually to a user of the instrument a status of the instrument based on an input from the at least one sensor.

Description:
PRIORITY CLAIM 
     The present application claims priority as a continuation under 35 U.S.C. §120 to U.S. nonprovisional patent application Ser. No. 11/343,545, filed Jan. 31, 2006, now U.S. Pat. No. 8,708,213, the entire disclosure of which is hereby incorporated by reference herein. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to the following U.S. patent and patent applications, which are incorporated herein by reference: 
     (1) U.S. patent application Ser. No. 11/343,498, now U.S. Pat. No. 7,766,210, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH USER FEEDBACK SYSTEM; 
     (2) U.S. patent application Ser. No. 11/343,573, now U.S. Pat. No. 7,416,101, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH LOADING FORCE FEEDBACK; 
     (3) U.S. patent application Ser. No. 11/344,035, now U.S. Pat. No. 7,422,139, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH TACTILE POSITION FEEDBACK; 
     (4) U.S. patent application Ser. No. 11/343,447, now U.S. Pat. No. 7,770,775, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH ADAPTIVE USER FEEDBACK; 
     (5) U.S. patent application Ser. No. 11/343,562, now U.S. Pat. No. 7,568,603, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH ARTICULATABLE END EFFECTOR; 
     (6) U.S. patent application Ser. No. 11/344,024, now U.S. Pat. No. 8,186,555, MOTOR-DRIVEN SURGICAL CUTTING AND FASTENING INSTRUMENT WITH MECHANICAL CLOSURE SYSTEM; 
     (7) U.S. patent application Ser. No. 11/343,321, now U.S. Patent Application Publication No. 2007/0175955 A1, SURGICAL CUTTING AND FASTENING INSTRUMENT WITH CLOSURE TRIGGER LOCKING MECHANISM; 
     (8) U.S. patent application Ser. No. 11/343,563, now U.S. Patent Application Publication No. 2007/0175951 A1, GEARING SELECTOR FOR A POWERED SURGICAL CUTTING AND FASTENING STAPLING INSTRUMENT; 
     (9) U.S. patent application Ser. No. 11/343,803, now U.S. Pat. No. 7,845,537, SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES; 
     (10) U.S. patent application Ser. No. 11/344,020, now U.S. Pat. No. 7,464,846, SURGICAL INSTRUMENT HAVING A REMOVABLE BATTERY; 
     (11) U.S. patent application Ser. No. 11/343,439, now U.S. Pat. No. 7,644,848, ELECTRONIC LOCKOUTS AND SURGICAL INSTRUMENT INCLUDING SAME; 
     (12) U.S. patent application Ser. No. 11/343,547, now U.S. Pat. No. 7,753,904, ENDOSCOPIC SURGICAL INSTRUMENT WITH A HANDLE THAT CAN ARTICULATE WITH RESPECT TO THE SHAFT; 
     (13) U.S. patent application Ser. No. 11/344,021, now U.S. Pat. No. 7,464,849, ELECTRO-MECHANICAL SURGICAL CUTTING AND FASTENING INSTRUMENT HAVING A ROTARY FIRING AND CLOSURE SYSTEM WITH PARALLEL CLOSURE AND ANVIL ALIGNMENT COMPONENTS; and 
     (14) U.S. patent application Ser. No. 11/343,546, now U.S. Patent Application Publication No. 2007/0175950 A1, DISPOSABLE STAPLE CARTRIDGE HAVING AN ANVIL WITH TISSUE LOCATOR FOR USE WITH A SURGICAL CUTTING AND FASTENING INSTRUMENT AND MODULAR END EFFECTOR SYSTEM THEREFOR. 
    
    
     BACKGROUND 
     This application discloses an invention that is related, generally and in various embodiments, to visual and audible feedback systems for motor-driven surgical instruments. 
     Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.). 
     Known surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes 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. 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 which, 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. 
     An example of a surgical stapler suitable for endoscopic applications is described in U.S. Pat. No. 5,465,895, which discloses an endocutter with distinct closing and firing actions. A clinician using this device is able to close the jaw members 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 with either single or multiple firing strokes, thereby severing and stapling the tissue. The simultaneous severing and stapling avoids complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple. 
     One specific advantage of being able to close upon tissue before firing is that the clinician is able to verify via an endoscope that the desired location for the cut has been achieved, including a sufficient amount of tissue has been captured between opposing jaws. Otherwise, opposing jaws may be drawn too close together, especially pinching at their distal ends, and thus not effectively forming closed staples in the severed tissue. At the other extreme, an excessive amount of clamped tissue may cause binding and an incomplete firing. 
     Endoscopic staplers/cutters continue to increase in complexity and function with each generation. One of the main reasons for this is the quest for lower force-to-fire (FTF) to a level that all or a great majority of surgeons can handle. One known solution to lower FTF it use CO 2  or electrical motors. These devices have not fared much better than traditional hand-powered devices, but for a different reason. Surgeons typically prefer to experience proportionate force distribution to that being experienced by the end-effector in the forming the staple to assure them that the cutting/stapling cycle is complete, with the upper limit within the capabilities of most surgeons (usually around 15-30 lbs). They also typically want to maintain control of deploying the staple and being able to stop at any time if the forces felt in the handle of the device feel too great or for some other clinical reason. These user-feedback effects are not suitably realizable in present motor-driven endocutters. As a result, there is a general lack of acceptance by physicians of motor-drive endocutters where the cutting/stapling operation is actuated by merely pressing a button. 
     With current surgical instruments, the status of the instrument is generally not provided to a user of the surgical instrument during a procedure. For example, with current mechanical endocutters, the presence of the staple cartridge, the position of the knife, the time elapsed since clamping, the magnitude of the firing force, etc. are generally not provided to the user. Without visual and/or audible feedback, each user must rely on his or her own “feel” to determine the status of the surgical instrument, thereby creating inefficiencies, inconsistencies, and potential damage to the surgical instrument. 
     SUMMARY 
     In one general respect, this application discloses a status module for use with a surgical instrument comprising a plurality of sensors. According to various embodiments, the status module comprises a housing, a plurality of contacts, a circuit, and a plurality of indicators. The housing is structured and arranged to releasably connect to the surgical instrument. Each individual contact is structured and arranged to be in electrical communication with a different sensor when the housing is connected to the surgical instrument. The circuit is in electrical communication with at least one of the contacts. At least one of the indicators is in electrical communication with the circuit. 
     In another general respect, this application discloses a surgical instrument. According to various embodiments, the surgical instrument comprises a plurality of sensors, and a status module releasably connected to the surgical instrument. The status module comprises a plurality of contacts, a circuit, and a plurality of indicators. Each individual contact is in electrical communication with a different sensor. The circuit is in electrical communication with at least one of the contacts. At least one of the indicators is in electrical communication with the circuit. 
     In another general aspect, the present invention is directed to a surgical instrument that comprises: an articulable end effector; a drive shaft connected to the end effector that drives the end effector; an electric motor connected to the drive shaft that drives the drive shaft; a battery unit for supplying power to the electric motor; at least one sensor for sensing a status of the instrument; and an alphanumeric display located on the instrument and in communication with the at least one sensor. The alphanumeric display is for displaying alphanumeric characters that display visually to a user of the instrument a status of the instrument based on an input from the at least one sensor. 
     In various implementations, the end effector comprises a removable cartridge, and the alphanumeric display visually indicates a status of the removable cartridge, such as whether the removable cartridge is loaded or whether the cartridge is spent, or whether the cartridge is positioned in the end effector. Also, the alphanumeric display may indicate an articulation angle of the end effector. 
     In various implementations, the end effector comprises first and second jaw members for clamping tissue therebetween. In such embodiments, the alphanumeric display may indicate a time elapsed since tissue was clamped in the end effector or it may provide information related a clamping force exerted by the end effector. Also, the end effector may comprise a cutting instrument that is for, when fired, cutting tissue clamped in the end effector, in which case the alphanumeric display may indicates a status of a cutting force exerted by the cutting instrument, whether the cutting force is within or outside an expected range, a percentage of a maximum firing force exerted by the cutting instrument, or a position of the cutting instrument in the end effector. Additionally, the alphanumeric display may be removably connected to the instrument. 
    
    
     
       DRAWINGS 
       Various embodiments of the disclosed invention are described herein by way of example in conjunction with the following figures. 
         FIGS. 1 and 2  are perspective views of a surgical cutting and fastening instrument according to various embodiments; 
         FIGS. 3-5  are exploded views of an end effector and shaft of the instrument according to various embodiments; 
         FIG. 6  is a side view of the end effector according to various embodiments; 
         FIG. 7  is an exploded view of the handle of the instrument according to various embodiments; 
         FIGS. 8 and 9  are partial perspective views of the handle according to various embodiments; 
         FIG. 10  is a side view of the handle according to various embodiments; 
         FIG. 11  is a schematic diagram of a circuit used in the instrument according to various embodiments; 
         FIGS. 12-13  are side views of the handle according to various embodiments; 
         FIGS. 14-22  illustrate different mechanisms for locking the closure trigger according to various embodiments; 
         FIGS. 23A-B  show a universal joint (“u-joint”) that may be employed at the articulation point of the instrument according to various embodiments; 
         FIGS. 24A-B  shows a torsion cable that may be employed at the articulation point of the instrument according to various embodiments; 
         FIGS. 25-31  illustrate a surgical cutting and fastening instrument with power assist according to various embodiments; 
         FIGS. 32-36  illustrate a surgical cutting and fastening instrument with power assist according to various embodiments; 
         FIGS. 37-40  illustrate a surgical cutting and fastening instrument with tactile feedback according to various embodiments; 
         FIGS. 41-42  illustrate various embodiments of a proportional sensor; 
         FIG. 43  illustrates various embodiments of a surgical instrument; 
         FIG. 44  is a schematic diagram of the surgical instrument of  FIG. 43 ; and 
         FIGS. 45-47  illustrate various embodiments of a portion of the surgical instrument of  FIG. 43 . 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that at least some of the figures and descriptions of the disclosed invention have been simplified to illustrate elements that are relevant for a clear understanding of the disclosed invention, while eliminating, for purposes of clarity, other elements. Those of ordinary skill in the art will recognize, however, that these and other elements may be desirable. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the disclosed invention, a discussion of such elements is not provided herein. 
       FIGS. 1 and 2  depict a surgical cutting and fastening instrument  10  according to various embodiments of the present invention. The illustrated embodiment is an endoscopic instrument and, in general, the embodiments of the instrument  10  described herein are endoscopic surgical cutting and fastening instruments. It should be noted, however, that according to other embodiments of the present invention, the instrument may be a non-endoscopic surgical cutting and fastening instrument, such as a laparoscopic instrument. 
     The surgical instrument  10  depicted in  FIGS. 1 and 2  comprises a handle  6 , a shaft  8 , and an articulating end effector  12  pivotally connected to the shaft  8  at 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. 
     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 a preferably 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 U.S. patent application Ser. No. 11/329,020, filed Jan. 10, 2006, entitled SURGICAL INSTRUMENT HAVING AN ARTICULATING END EFFECTOR, now U.S. Pat. No. 7,670,334, which is incorporated herein by reference. As explained in this incorporated application (now patent), movement of the end effector  12  through multiple angles relative to the longitudinal axis of the instrument shaft  8  is conventionally referred to as “articulation.” Articulation is typically accomplished by a pivot (or articulation) joint  14  being placed in the elongate shaft  8  just proximal to the end effector  12 . This allows the clinician to articulate the end effector  12  remotely to either side for better surgical placement of the staple lines and easier tissue manipulation and orientation. An articulating end effector  12  permits the clinician to more easily engage tissue in some instances, such as behind an organ. In addition, articulated positioning advantageously allows an endoscope to be positioned behind the end effector without being blocked by the elongate shaft. 
     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 effective stapling and severing of tissue clamped in the end effector  12 . The handle  6  includes a 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 as further described below, 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  26  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, such as, for example, an opposing jaw, etc. 
     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. 
     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 . The firing trigger  20  may then be actuated. The firing trigger  20  returns to the open position (shown in  FIGS. 1 and 2 ) when the clinician removes pressure, as described more fully below. A release button  160  on the handle  6 , and in this example, on the pistol grip  26  of the handle  6 , when depressed may release the locked closure trigger  18 . 
       FIG. 3  is an exploded view of the end effector  12  according to various embodiments. 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 a pivot point  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 (described further below) 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 point  25  into the clamped or closed position. If clamping of the end effector  12  is satisfactory, the operator may actuate the firing trigger  20 , which, as explained in more detail below, causes the knife  32  and sled  33  to travel longitudinally along the channel  22 , thereby cutting tissue clamped within the end effector  12 . The movement of the sled  33  along the channel  22  causes the staples 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. U.S. Pat. No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM, which is incorporated herein by reference, provides more details about such two-stroke cutting and fastening instruments. According to various embodiments, the sled  33  may be an integral part of the cartridge  34 , such that when the knife  32  retracts following the cutting operation, the sled  33  does not retract. 
     It should be noted that although the embodiments of the instrument  10  described herein employ an end effector  12  that staples the severed tissue, in other embodiments different techniques for fastening or sealing the severed tissue may be used. For example, end effectors that use RF energy or adhesives to fasten the severed tissue may also be used. U.S. Pat. No. 5,810,811, entitled ELECTROSURGICAL HEMOSTATIC DEVICE, which is incorporated herein by reference, discloses a cutting instrument that uses RF energy to fasten the severed tissue. U.S. patent application Ser. No. 11/267,811, entitled SURGICAL STAPLING INSTRUMENTS STRUCTURED FOR DELIVERY OF MEDICAL AGENTS, now U.S. Pat. No. 7,673,783, and U.S. patent application Ser. No. 11/267,383, entitled SURGICAL STAPLING INSTRUMENTS STRUCTURED FOR PUMP-ASSISTED DELIVERY OF MEDICAL AGENTS, now U.S. Pat. No. 7,607,557, both of which are also incorporated herein by reference, disclose cutting instruments that use adhesives to fasten the severed tissue. Accordingly, although the description herein refers to cutting/stapling operations and the like below, it should be recognized that this is an exemplary embodiment and is not meant to be limiting. Other tissue-fastening techniques may also be used. 
       FIGS. 4 and 5  are exploded views and  FIG. 6  is a side view of the end effector  12  and shaft  8  according to various 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 . When the main drive shaft  48  is caused to rotate by actuation of the firing trigger  20  (as explained in more detail below), 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/sled driving member  32  to travel longitudinally along the channel  22  to cut any tissue clamped within the end effector  12 . 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  is threaded on the helical drive screw  36 . The bearing  36  is also connected to the knife  32 . When the helical drive screw  36  forward rotates, the bearing  38  traverses the helical drive screw  36  distally, driving the cutting instrument  32  and, in the process, the sled  33  to perform the cutting/stapling operation. 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  34  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 . 
     Because of the lack of user feedback for the cutting/stapling operation, there is a general lack of acceptance among physicians of motor-driven surgical instruments where the cutting/stapling operation is actuated by merely pressing a button. In contrast, embodiments of the present invention provide a motor-driven endocutter with user-feedback of the deployment, force, and/or position of the cutting instrument in the end effector. 
       FIGS. 7-10  illustrate an exemplary embodiment of a motor-driven endocutter, and in particular the handle  6  thereof, that provides user-feedback regarding the deployment and loading force of the cutting instrument in the end effector. In addition, the embodiment may use power provided by the user in retracting the firing trigger  20  to power the device (a so-called “power assist” mode). As shown in the illustrated embodiment, the handle  6  includes exterior lower side pieces  59 ,  60  and exterior upper side pieces  61 ,  62  that fit together to form, in general, the exterior of the handle  6 . A battery  64 , such as a Li ion battery, may be provided in the pistol grip portion  26  of the handle  6 . The battery  64  powers a motor  65  disposed in an upper portion of the pistol grip portion  26  of the handle  6 . According to various embodiments, the motor  65  may be a DC brushed driving motor having a maximum rotation of, approximately, 5000 RPM. The motor  65  may drive a 90° bevel gear assembly  66  comprising a first bevel gear  68  and a second bevel gear  70 . The bevel gear assembly  66  may drive a planetary gear assembly  72 . The planetary gear assembly  72  may include a pinion gear  74  connected to a drive shaft  76 . The pinion gear  74  may drive a mating ring gear  78  that drives a helical gear drum  80  via a drive shaft  82 . A ring  84  may be threaded on the helical gear drum  80 . Thus, when the motor  65  rotates, the ring  84  is caused to travel along the helical gear drum  80  by means of the interposed bevel gear assembly  66 , planetary gear assembly  72  and ring gear  78 . 
     The handle  6  may also include a run motor sensor  110  in communication with the firing trigger  20  to detect when the firing trigger  20  has been drawn in (or “closed”) toward the pistol grip portion  26  of the handle  6  by the operator to thereby actuate the cutting/stapling operation by the end effector  12 . The sensor  110  may be a proportional sensor such as, for example, a rheostat or variable resistor. When the firing trigger  20  is drawn in, the sensor  110  detects the movement, and sends an electrical signal indicative of the voltage (or power) to be supplied to the motor  65 . When the sensor  110  is a variable resistor or the like, the rotation of the motor  65  may be generally proportional to the amount of movement of the firing trigger  20 . That is, if the operator only draws or closes the firing trigger  20  in a little bit, the rotation of the motor  65  is relatively low. When the firing trigger  20  is fully drawn in (or in the fully closed position), the rotation of the motor  65  is at its maximum. In other words, the harder the user pulls on the firing trigger  20 , the more voltage is applied to the motor  65 , causing greater rates of rotation. 
     The handle  6  may include a middle handle piece  104  adjacent to the upper portion of the firing trigger  20 . The handle  6  also may comprise a bias spring  112  connected between posts on the middle handle piece  104  and the firing trigger  20 . The bias spring  112  may bias the firing trigger  20  to its fully open position. In that way, when the operator releases the firing trigger  20 , the bias spring  112  will pull the firing trigger  20  to its open position, thereby removing actuation of the sensor  110 , thereby stopping rotation of the motor  65 . Moreover, by virtue of the bias spring  112 , any time a user closes the firing trigger  20 , the user will experience resistance to the closing operation, thereby providing the user with feedback as to the amount of rotation exerted by the motor  65 . Further, the operator could stop retracting the firing trigger  20  to thereby remove force from the sensor  110 , to thereby stop the motor  65 . As such, the user may stop the deployment of the end effector  12 , thereby providing a measure of control of the cutting/fastening operation to the operator. 
     The distal end of the helical gear drum  80  includes a distal drive shaft  120  that drives a ring gear  122 , which mates with a pinion gear  124 . The pinion gear  124  is connected to the main drive shaft  48  of the main drive shaft assembly. In that way, rotation of the motor  65  causes the main drive shaft assembly to rotate, which causes actuation of the end effector  12 , as described above. 
     The ring  84  threaded on the helical gear drum  80  may include a post  86  that is disposed within a slot  88  of a slotted arm  90 . The slotted arm  90  has an opening  92  at its opposite end  94  that receives a pivot pin  96  that is connected between the handle exterior side pieces  59 ,  60 . The pivot pin  96  is also disposed through an opening  100  in the firing trigger  20  and an opening  102  in the middle handle piece  104 . 
     In addition, the handle  6  may include a reverse motor (or end-of-stroke sensor)  130  and a stop motor (or beginning-of-stroke) sensor  142 . In various embodiments, the reverse motor sensor  130  may be a limit switch located at the distal end of the helical gear drum  80  such that the ring  84  threaded on the helical gear drum  80  contacts and trips the reverse motor sensor  130  when the ring  84  reaches the distal end of the helical gear drum  80 . The reverse motor sensor  130 , when activated, sends a signal to the motor  65  to reverse its rotation direction, thereby withdrawing the knife  32  of the end effector  12  following the cutting operation. 
     The stop motor sensor  142  may be, for example, a normally-closed limit switch. In various embodiments, it may be located at the proximate end of the helical gear drum  80  so that the ring  84  trips the switch  142  when the ring  84  reaches the proximate end of the helical gear drum  80 . 
     In operation, when an operator of the instrument  10  pulls back the firing trigger  20 , the sensor  110  detects the deployment of the firing trigger  20  and sends a signal to the motor  65  to cause forward rotation of the motor  65  at, for example, a rate proportional to how hard the operator pulls back the firing trigger  20 . The forward rotation of the motor  65  in turn causes the ring gear  78  at the distal end of the planetary gear assembly  72  to rotate, thereby causing the helical gear drum  80  to rotate, causing the ring  84  threaded on the helical gear drum  80  to travel distally along the helical gear drum  80 . The rotation of the helical gear drum  80  also drives the main drive shaft assembly as described above, which in turn causes deployment of the knife  32  in the end effector  12 . That is, the knife  32  and sled  33  are caused to traverse the channel  22  longitudinally, thereby cutting tissue clamped in the end effector  12 . Also, the stapling operation of the end effector  12  is caused to happen in embodiments where a stapling-type end effector is used. 
     By the time the cutting/stapling operation of the end effector  12  is complete, the ring  84  on the helical gear drum  80  will have reached the distal end of the helical gear drum  80 , thereby causing the reverse motor sensor  130  to be tripped, which sends a signal to the motor  65  to cause the motor  65  to reverse its rotation. This in turn causes the knife  32  to retract, and also causes the ring  84  on the helical gear drum  80  to move back to the proximate end of the helical gear drum  80 . 
     The middle handle piece  104  includes a backside shoulder  106  that engages the slotted arm  90  as best shown in  FIGS. 8 and 9 . The middle handle piece  104  also has a forward motion stop  107  that engages the firing trigger  20 . The movement of the slotted arm  90  is controlled, as explained above, by rotation of the motor  65 . When the slotted arm  90  rotates CCW as the ring  84  travels from the proximate end of the helical gear drum  80  to the distal end, the middle handle piece  104  will be free to rotate CCW. Thus, as the user draws in the firing trigger  20 , the firing trigger  20  will engage the forward motion stop  107  of the middle handle piece  104 , causing the middle handle piece  104  to rotate CCW. Due to the backside shoulder  106  engaging the slotted arm  90 , however, the middle handle piece  104  will only be able to rotate CCW as far as the slotted arm  90  permits. In that way, if the motor  65  should stop rotating for some reason, the slotted arm  90  will stop rotating, and the user will not be able to further draw in the firing trigger  20  because the middle handle piece  104  will not be free to rotate CCW due to the slotted arm  90 . 
       FIGS. 41 and 42  illustrate two states of a variable sensor that may be used as the run motor sensor  110  according to various embodiments of the present invention. The sensor  110  may include a face portion  280 , a first electrode (A)  282 , a second electrode (B)  284 , and a compressible dielectric material  286  (e.g., EAP) between the electrodes  282 ,  284 . The sensor  110  may be positioned such that the face portion  280  contacts the firing trigger  20  when retracted. Accordingly, when the firing trigger  20  is retracted, the dielectric material  286  is compressed, as shown in  FIG. 42 , such that the electrodes  282 ,  284  are closer together. Since the distance “b” between the electrodes  282 ,  284  is directly related to the impedance between the electrodes  282 ,  284 , the greater the distance the more impedance, and the closer the distance the less impedance. In that way, the amount that the dielectric material  286  is compressed due to retraction of the firing trigger  20  (denoted as force “F” in  FIG. 42 ) is proportional to the impedance between the electrodes  282 ,  284 , which can be used to proportionally control the motor  65 . 
     Components of an exemplary closure system for closing (or clamping) the anvil  24  of the end effector  12  by retracting the closure trigger  18  are also shown in  FIGS. 7-10 . In the illustrated embodiment, the closure system includes a yoke  250  connected to the closure trigger  18  by a pin  251  that is inserted through aligned openings in both the closure trigger  18  and the yoke  250 . A pivot pin  252 , about which the closure trigger  18  pivots, is inserted through another opening in the closure trigger  18  which is offset from where the pin  251  is inserted through the closure trigger  18 . Thus, refraction of the closure trigger  18  causes the upper part of the closure trigger  18 , to which the yoke  250  is attached via the pin  251 , to rotate CCW. The distal end of the yoke  250  is connected, via a pin  254 , to a first closure bracket  256 . The first closure bracket  256  connects to a second closure bracket  258 . Collectively, the closure brackets  256 ,  258  define an opening in which the proximate end of the proximate closure tube  40  (see  FIG. 4 ) is seated and held such that longitudinal movement of the closure brackets  256 ,  258  causes longitudinal motion by the proximate closure tube  40 . The instrument  10  also includes a closure rod  260  disposed inside the proximate closure tube  40 . The closure rod  260  may include a window  261  into which a post  263  on one of the handle exterior pieces, such as exterior lower side piece  59  in the illustrated embodiment, is disposed to fixedly connect the closure rod  260  to the handle  6 . In that way, the proximate closure tube  40  is capable of moving longitudinally relative to the closure rod  260 . The closure rod  260  may also include a distal collar  267  that fits into a cavity  269  in proximate spine tube  46  and is retained therein by a cap  271  (see  FIG. 4 ). 
     In operation, when the yoke  250  rotates due to refraction of the closure trigger  18 , the closure brackets  256 ,  258  cause the proximate closure tube  40  to move distally (i.e., away from the handle end of the instrument  10 ), which causes the distal closure tube  42  to move distally, which causes the anvil  24  to rotate about the pivot point  25  into the clamped or closed position. When the closure trigger  18  is unlocked from the locked position, the proximate closure tube  40  is caused to slide proximally, which causes the distal closure tube  42  to slide proximally, which by virtue of the tab  27  being inserted in the window  45  of the distal closure tube  42 , causes the anvil  24  to pivot about the pivot point  25  into the open or unclamped position. In that way, by refracting and locking the closure trigger  18 , an operator may clamp tissue between the anvil  24  and channel  22 , and may unclamp the tissue following the cutting/stapling operation by unlocking the closure trigger  18  from the locked position. 
       FIG. 11  is a schematic diagram of an electrical circuit of the instrument  10  according to various embodiments of the present invention. When an operator initially pulls in the firing trigger  20  after locking the closure trigger  18 , the sensor  110  is activated, allowing current to flow therethrough. If the normally-open reverse motor sensor switch  130  is open (meaning the end of the end effector stroke has not been reached), current will flow to a single pole, double throw relay  132 . Since the reverse motor sensor switch  130  is not closed, the coil  134  of the relay  132  will not be energized, so the relay  132  will be in its non-energized state. The circuit also includes a cartridge lockout sensor switch  136 . If the end effector  12  includes a staple cartridge  34 , the sensor switch  136  will be in the closed state, allowing current to flow. Otherwise, if the end effector  12  does not include a staple cartridge  34 , the sensor switch  136  will be open, thereby preventing the battery  64  from powering the motor  65 . 
     When the staple cartridge  34  is present, the sensor switch  136  is closed, which energizes a single pole, single throw relay  138 . When the relay  138  is energized, current flows through the relay  138 , through the variable resistor sensor  110 , and to the motor  65  via a double pole, double throw relay  140 , thereby powering the motor  65  and allowing it to rotate in the forward direction. 
     When the end effector  12  reaches the end of its stroke, the reverse motor sensor  130  will be activated, thereby closing the switch  130  and energizing the relay  132 . This causes the relay  132  to assume its energized state (not shown in  FIG. 11 ), which causes current to bypass the cartridge lockout sensor switch  136  and variable resistor  110 , and instead causes current to flow to both the normally-closed double pole, double throw relay  140  and back to the motor  65 , but in a manner, via the relay  140 , that causes the motor  65  to reverse its rotational direction. 
     Because the stop motor sensor switch  142  is normally-closed, current will flow back to the relay  132  to keep it energized until the switch  142  opens. When the knife  32  is fully retracted, the stop motor sensor switch  142  is activated, causing the switch  142  to open, thereby removing power from the motor  65 . 
     In other embodiments, rather than a proportional-type sensor  110 , an on-off type sensor could be used. In such embodiments, the rate of rotation of the motor  65  would not be proportional to the force applied by the operator. Rather, the motor  65  would generally rotate at a constant rate. But the operator would still experience force feedback because the firing trigger  20  is geared into the gear drive train. 
       FIG. 12  is a side-view of the handle  6  of a power-assist motorized endocutter according to another embodiment. The embodiment of  FIG. 12  is similar to that of  FIGS. 7-10  except that in the embodiment of  FIG. 12 , there is no slotted arm  90  connected to the ring  84  threaded on the helical gear drum  80 . Instead, in the embodiment of  FIG. 12 , the ring  84  includes a sensor portion  114  that moves with the ring  84  as the ring  84  advances down (and back) on the helical gear drum  80 . The sensor portion  114  includes a notch  116 . The reverse motor sensor  130  may be located at the distal end of the notch  116  and the stop motor sensor  142  may be located at the proximate end of the notch  116 . As the ring  84  moves down the helical gear drum  80  (and back), the sensor portion  114  moves with it. Further, as shown in  FIG. 12 , the middle piece  104  may have an arm  118  that extends into the notch  116 . 
     In operation, as an operator of the instrument  10  retracts in the firing trigger  20  toward the pistol grip  26 , the run motor sensor  110  detects the motion and sends a signal to power the motor  65 , which causes, among other things, the helical gear drum  80  to rotate. As the helical gear drum  80  rotates, the ring  84  threaded on the helical gear drum  80  advances (or retracts, depending on the rotation). Also, due to the pulling in of the firing trigger  20 , the middle piece  104  is caused to rotate CCW with the firing trigger  20  due to the forward motion stop  107  that engages the firing trigger  20 . The CCW rotation of the middle piece  104  cause the arm  118  to rotate CCW with the sensor portion  114  of the ring  84  such that the arm  118  stays disposed in the notch  116 . When the ring  84  reaches the distal end of the helical gear drum  80 , the arm  118  will contact and thereby trip the reverse motor sensor  130 . Similarly, when the ring  84  reaches the proximate end of the helical gear drum  80 , the arm  118  will contact and thereby trip the stop motor sensor  142 . Such actions may reverse and stop the motor  65 , respectively, as described above. 
       FIG. 13  is a side-view of the handle  6  of a power-assist motorized endocutter according to another embodiment. The embodiment of  FIG. 13  is similar to that of  FIGS. 7-10  except that in the embodiment of  FIG. 13 , there is no slot in the arm  90 . Instead, the ring  84  threaded on the helical gear drum  80  includes a vertical channel  126 . Instead of a slot, the arm  90  includes a post  128  that is disposed in the channel  126 . As the helical gear drum  80  rotates, the ring  84  threaded on the helical gear drum  80  advances (or retracts, depending on the rotation). The arm  90  rotates CCW as the ring  84  advances due to the post  128  being disposed in the channel  126 , as shown in  FIG. 13 . 
     As mentioned above, in using a two-stroke motorized instrument, the operator first pulls back and locks the closure trigger  18 .  FIGS. 14 and 15  show one embodiment of a way to lock the closure trigger  18  to the pistol grip portion  26  of the handle  6 . In the illustrated embodiment, the pistol grip portion  26  includes a hook  150  that is biased to rotate CCW about a pivot point  151  by a torsion spring  152 . Also, the closure trigger  18  includes a closure bar  154 . As the operator draws in the closure trigger  18 , the closure bar  154  engages a sloped portion  156  of the hook  150 , thereby rotating the hook  150  upward (or CW in  FIGS. 14-15 ) until the closure bar  154  completely passes the sloped portion  156  into a recessed notch  158  of the hook  150 , which locks the closure trigger  18  in place. The operator may release the closure trigger  18  by pushing down on a slide button release  160  on the back or opposite side of the pistol grip portion  26 . Pushing down the slide button release  160  rotates the hook  150  CW such that the closure bar  154  is released from the recessed notch  158 . 
       FIG. 16  shows another closure trigger locking mechanism according to various embodiments. In the embodiment of  FIG. 16 , the closure trigger  18  includes a wedge  160  having an arrow-head portion  161 . The arrow-head portion  161  is biased downward (or CW) by a leaf spring  162 . The wedge  160  and leaf spring  162  may be made from, for example, molded plastic. When the closure trigger  18  is retracted, the arrow-head portion  161  is inserted through an opening  164  in the pistol grip portion  26  of the handle  6 . A lower chamfered surface  166  of the arrow-head portion  161  engages a lower sidewall  168  of the opening  164 , forcing the arrow-head portion  161  to rotate CCW. Eventually the lower chamfered surface  166  fully passes the lower sidewall  168 , removing the CCW force on the arrow-head portion  161 , causing the lower sidewall  168  to slip into a locked position in a notch  170  behind the arrow-head portion  161 . 
     To unlock the closure trigger  18 , a user presses down on a button  172  on the opposite side of the closure trigger  18 , causing the arrow-head portion  161  to rotate CCW and allowing the arrow-head portion  161  to slide out of the opening  164 . 
       FIGS. 17-22  show a closure trigger locking mechanism according to another embodiment. As shown in this embodiment, the closure trigger  18  includes a flexible longitudinal arm  176  that includes a lateral pin  178  extending therefrom. The arm  176  and pin  178  may be made from molded plastic, for example. The pistol grip portion  26  of the handle  6  includes an opening  180  with a laterally extending wedge  182  disposed therein. When the closure trigger  18  is retracted, the pin  178  engages the wedge  182 , and the pin  178  is forced downward (i.e., the arm  176  is rotated CW) by the lower surface  184  of the wedge  182 , as shown in  FIGS. 17 and 18 . When the pin  178  fully passes the lower surface  184 , the CW force on the arm  176  is removed, and the pin  178  is rotated CCW such that the pin  178  comes to rest in a notch  186  behind the wedge  182 , as shown in  FIG. 19 , thereby locking the closure trigger  18 . The pin  178  is further held in place in the locked position by a flexible stop  188  extending from the wedge  184 . 
     To unlock the closure trigger  18 , the operator may further squeeze the closure trigger  18 , causing the pin  178  to engage a sloped backwall  190  of the opening  180 , forcing the pin  178  upward past the flexible stop  188 , as shown in  FIGS. 20 and 21 . The pin  178  is then free to travel out an upper channel  192  in the opening  180  such that the closure trigger  18  is no longer locked to the pistol grip portion  26 , as shown in  FIG. 22 . 
       FIGS. 23A-B  show a universal joint (“u-joint”)  195 . The second piece  195 - 2  of the u-joint  195  rotates in a horizontal plane in which the first piece  195 - 1  lies.  FIG. 23A  shows the u-joint  195  in a linear (180°) orientation and  FIG. 23B  shows the u-joint  195  at approximately a 150° orientation. The u-joint  195  may be used instead of the bevel gears  52   a - c  (see  FIG. 4 , for example) at the articulation point  14  of the main drive shaft assembly to articulate the end effector  12 .  FIGS. 24A-B  show a torsion cable  197  that may be used in lieu of both the bevel gears  52   a - c  and the u-joint  195  to realize articulation of the end effector  12 . 
       FIGS. 25-31  illustrate another embodiment of a motorized, two-stroke surgical cutting and fastening instrument  10  with power assist according to another embodiment of the present invention. The embodiment of  FIGS. 25-31  is similar to that of  FIGS. 6-10  except that instead of the helical gear drum  80 , the embodiment of  FIGS. 25-31  includes an alternative gear drive assembly. The embodiment of  FIGS. 25-31  includes a gear box assembly  200  including a number of gears disposed in a frame  201 , wherein the gears are connected between the planetary gear  72  and the pinion gear  124  at the proximate end of the drive shaft  48 . As explained further below, the gear box assembly  200  provides feedback to the user via the firing trigger  20  regarding the deployment and loading force of the end effector  12 . Also, the user may provide power to the system via the gear box assembly  200  to assist the deployment of the end effector  12 . In that sense, like the embodiments described above, the embodiment of  FIGS. 25-31  is another power assist, motorized instrument  10  that provides feedback to the user regarding the loading force experienced by the cutting instrument  32 . 
     In the illustrated embodiment, the firing trigger  20  includes two pieces: a main body portion  202  and a stiffening portion  204 . The main body portion  202  may be made of plastic, for example, and the stiffening portion  204  may be made out of a more rigid material, such as metal. In the illustrated embodiment, the stiffening portion  204  is adjacent to the main body portion  202 , but according to other embodiments, the stiffening portion  204  could be disposed inside the main body portion  202 . A pivot pin  207  may be inserted through openings in the firing trigger pieces  202 ,  204  and may be the point about which the firing trigger  20  rotates. In addition, a spring  222  may bias the firing trigger  20  to rotate in a CCW direction. The spring  222  may have a distal end connected to a pin  224  that is connected to the pieces  202 ,  204  of the firing trigger  20 . The proximate end of the spring  222  may be connected to one of the handle exterior lower side pieces  59 ,  60 . 
     In the illustrated embodiment, both the main body portion  202  and the stiffening portion  204  include gear portions  206 ,  208  (respectively) at their upper end portions. The gear portions  206 ,  208  engage a gear in the gear box assembly  200 , as explained below, to drive the main drive shaft assembly and to provide feedback to the user regarding the deployment of the end effector  12 . 
     The gear box assembly  200  may include as shown, in the illustrated embodiment, six (6) gears. A first gear  210  of the gear box assembly  200  engages the gear portions  206 ,  208  of the firing trigger  20 . In addition, the first gear  210  engages a smaller second gear  212 , the smaller second gear  212  being coaxial with a large third gear  214 . The third gear  214  engages a smaller fourth gear  216 , the smaller fourth gear  216  being coaxial with a fifth gear  218 . The fifth gear  218  is a 90° bevel gear that engages a mating 90° bevel gear  220  (best shown in  FIG. 31 ) that is connected to the pinion gear  124  that drives the main drive shaft  48 . 
     In operation, when the user retracts the firing trigger  20 , a run motor sensor (not shown) is activated, which may provide a signal to the motor  65  to rotate at a rate proportional to the extent or force with which the operator is retracting the firing trigger  20 . This causes the motor  65  to rotate at a speed proportional to the signal from the sensor. The sensor is not shown for this embodiment, but it could be similar to the run motor sensor  110  described above. The sensor could be located in the handle  6  such that it is depressed when the firing trigger  20  is retracted. Also, instead of a proportional-type sensor, an on/off type sensor may be used. 
     Rotation of the motor  65  causes the bevel gears  66 ,  70  to rotate, which causes the planetary gear  72  to rotate, which causes, via the drive shaft  76 , the ring gear  122  to rotate. The ring gear  122  meshes with the pinion gear  124 , which is connected to the main drive shaft  48 . Thus, rotation of the pinion gear  124  drives the main drive shaft  48 , which causes actuation of the cutting/stapling operation of the end effector  12 . 
     Forward rotation of the pinion gear  124  in turn causes the bevel gear  220  to rotate, which causes, by way of the rest of the gears of the gear box assembly  200 , the first gear  210  to rotate. The first gear  210  engages the gear portions  206 ,  208  of the firing trigger  20 , thereby causing the firing trigger  20  to rotate CCW when the motor  65  provides forward drive for the end effector  12  (and to rotate CCW when the motor  65  rotates in reverse to retract the end effector  12 ). In that way, the user experiences feedback regarding loading force and deployment of the end effector  12  by way of the user&#39;s grip on the firing trigger  20 . Thus, when the user retracts the firing trigger  20 , the operator will experience a resistance related to the load force experienced by the end effector  12 . Similarly, when the operator releases the firing trigger  20  after the cutting/stapling operation so that it can return to its original position, the user will experience a CW rotation force from the firing trigger  20  that is generally proportional to the reverse speed of the motor  65 . 
     It should also be noted that in this embodiment the user can apply force (either in lieu of or in addition to the force from the motor  65 ) to actuate the main drive shaft assembly (and hence the cutting/stapling operation of the end effector  12 ) through retracting the firing trigger  20 . That is, retracting the firing trigger  20  causes the gear portions  206 ,  208  to rotate CCW, which causes the gears of the gear box assembly  200  to rotate, thereby causing the pinion gear  124  to rotate, which causes the main drive shaft  48  to rotate. 
     Although not shown in  FIGS. 25-31 , the instrument  10  may further include reverse motor and stop motor sensors. As described above, the reverse motor and stop motor sensors may detect, respectively, the end of the cutting stroke (full deployment of the knife  32  and sled  33 ) and the end of retraction operation (full retraction of the knife  32 ). A circuit similar to that described above in connection with  FIG. 11  may be used to appropriately power the motor  65 . 
       FIGS. 32-36  illustrate a two-stroke, motorized surgical cutting and fastening instrument  10  with power assist according to another embodiment. The embodiment of  FIGS. 32-36  is similar to that of  FIGS. 25-31  except that in the embodiment of  FIGS. 32-36 , the firing trigger  20  includes a lower portion  228  and an upper portion  230 . Both portions  228 ,  230  are connected to and pivot about a pivot pin  207  that is disposed through each portion  228 ,  230 . The upper portion  230  includes a gear portion  232  that engages the first gear  210  of the gear box assembly  200 . The spring  222  is connected to the upper portion  230  such that the upper portion is biased to rotate in the CW direction. The upper portion  230  may also include a lower arm  234  that contacts an upper surface of the lower portion  228  of the firing trigger  20  such that when the upper portion  230  is caused to rotate CW the lower portion  228  also rotates CW, and when the lower portion  228  rotates CCW the upper portion  230  also rotates CCW. Similarly, the lower portion  228  includes a rotational stop  238  that engages a lower shoulder of the upper portion  230 . In that way, when the upper portion  230  is caused to rotate CCW the lower portion  228  also rotates CCW, and when the lower portion  228  rotates CW the upper portion  230  also rotates CW. 
     The illustrated embodiment also includes the run motor sensor  110  that communicates a signal to the motor  65  that, in various embodiments, may cause the motor  65  to rotate at a speed proportional to the force applied by the operator when retracting the firing trigger  20 . The sensor  110  may be, for example, a rheostat or some other variable resistance sensor, as explained herein. In addition, the instrument  10  may include a reverse motor sensor  130  that is tripped or switched when contacted by a front face  242  of the upper portion  230  of the firing trigger  20 . When activated, the reverse motor sensor  130  sends a signal to the motor  65  to reverse direction. Also, the instrument  10  may include a stop motor sensor  142  that is tripped or actuated when contacted by the lower portion  228  of the firing trigger  20 . When activated, the stop motor sensor  142  sends a signal to stop the reverse rotation of the motor  65 . 
     In operation, when an operator retracts the closure trigger  18  into the locked position, the firing trigger  20  is retracted slightly (through mechanisms known in the art, including U.S. Pat. No. 6,978,921, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM and U.S. Pat. No. 6,905,057, entitled SURGICAL STAPLING INSTRUMENT INCORPORATING A FIRING MECHANISM HAVING A LINKED RACK TRANSMISSION, both of which are incorporated herein by reference) so that the user can grasp the firing trigger  20  to initiate the cutting/stapling operation, as shown in  FIGS. 32 and 33 . At that point, as shown in  FIG. 33 , the gear portion  232  of the upper portion  230  of the firing trigger  20  moves into engagement with the first gear  210  of the gear box assembly  200 . When the operator retracts the firing trigger  20 , according to various embodiments, the firing trigger  20  may rotate a small amount, such as five degrees, before tripping the run motor sensor  110 , as shown in  FIG. 34 . Activation of the sensor  110  causes the motor  65  to forward rotate at a rate proportional to the retraction force applied by the operator. The forward rotation of the motor  65  causes, as described above, the main drive shaft  48  to rotate, which causes the knife  32  in the end effector  12  to be deployed (i.e., begin traversing the channel  22 ). Rotation of the pinion gear  124 , which is connected to the main drive shaft  48 , causes the gears  210 - 220  in the gear box assembly  200  to rotate. Since the first gear  210  is in engagement with the gear portion  232  of the upper portion  230  of the firing trigger  20 , the upper portion  230  is caused to rotate CCW, which causes the lower portion  228  to also rotate CCW. 
     When the knife  32  is fully deployed (i.e., at the end of the cutting stroke), the front face  242  of the upper portion  230  trips the reverse motor sensor  130 , which sends a signal to the motor  65  to reverse rotational direction. This causes the main drive shaft assembly to reverse rotational direction to retract the knife  32 . Reverse rotation of the main drive shaft assembly causes the gears  210 - 220  in the gear box assembly to reverse direction, which causes the upper portion  230  of the firing trigger  20  to rotate CW, which causes the lower portion  228  of the firing trigger  20  to rotate CW until the front face  242  of the upper portion  230  trips or actuates the stop motor sensor  142  when the knife  32  is fully retracted, which causes the motor  65  to stop. In that way, the user experiences feedback regarding deployment of the end effector  12  by way of the user&#39;s grip on the firing trigger  20 . Thus, when the user refracts the firing trigger  20 , the operator will experience a resistance related to the deployment of the end effector  12  and, in particular, to the loading force experienced by the knife  32 . Similarly, when the operator releases the firing trigger  20  after the cutting/stapling operation so that it can return to its original position, the user will experience a CW rotation force from the firing trigger  20  that is generally proportional to the reverse speed of the motor  65 . 
     It should also be noted that in this embodiment the user can apply force (either in lieu of or in addition to the force from the motor  65 ) to actuate the main drive shaft assembly (and hence the cutting/stapling operation of the end effector  12 ) through retracting the firing trigger  20 . That is, retracting the firing trigger  20  causes the gear portion  232  of the upper portion  230  to rotate CCW, which causes the gears of the gear box assembly  200  to rotate, thereby causing the pinion gear  124  to rotate, which causes the main drive shaft assembly to rotate. 
     The above-described embodiments employed power-assist user feedback systems, with or without adaptive control (e.g., using a sensor  110 ,  130 , and  142  outside of the closed loop system of the motor, gear drive train, and end effector) for a two-stroke, motorized surgical cutting and fastening instrument. That is, force applied by the user in retracting the firing trigger  20  may be added to the force applied by the motor  65  by virtue of the firing trigger  20  being geared into (either directly or indirectly) the gear drive train between the motor  65  and the main drive shaft  48 . In other embodiments of the present invention, the user may be provided with tactile feedback regarding the position of the knife  32  in the end effector  12 , but without having the firing trigger  20  geared into the gear drive train.  FIGS. 37-40  illustrate a motorized surgical cutting and fastening instrument  10  with such a tactile position feedback system. 
     In the illustrated embodiment of  FIGS. 37-40 , the firing trigger  20  may have a lower portion  228  and an upper portion  230 , similar to the instrument  10  shown in  FIGS. 32-36 . Unlike the embodiment of  FIG. 32-36 , however, the upper portion  230  does not have a gear portion that mates with part of the gear drive train. Instead, the instrument  10  includes a second motor  265  with a threaded rod  266  threaded therein. The threaded rod  266  reciprocates longitudinally in and out of the motor  265  as the motor  265  rotates, depending on the direction of rotation. The instrument  10  also includes an encoder  268  that is responsive to the rotations of the main drive shaft  48  for translating the incremental angular motion of the main drive shaft  48  (or other component of the main drive assembly) into a corresponding series of digital signals, for example. In the illustrated embodiment, the pinion gear  124  includes a proximate drive shaft  270  that connects to the encoder  268 . 
     The instrument  10  also includes a control circuit (not shown), which may be implemented using a microcontroller or some other type of integrated circuit, that receives the digital signals from the encoder  268 . Based on the signals from the encoder  268 , the control circuit may calculate the stage of deployment of the knife  32  in the end effector  12 . That is, the control circuit can calculate if the knife  32  is fully deployed, fully retracted, or at an intermittent stage. Based on the calculation of the stage of deployment of the end effector  12 , the control circuit may send a signal to the second motor  265  to control its rotation to thereby control the reciprocating movement of the threaded rod  266 . 
     In operation, as shown in  FIG. 37 , when the closure trigger  18  is not locked into the clamped position, the firing trigger  20  rotated away from the pistol grip portion  26  of the handle  6  such that the front face  242  of the upper portion  230  of the firing trigger  20  is not in contact with the proximate end of the threaded rod  266 . When the operator retracts the closure trigger  18  and locks it in the clamped position, the firing trigger  20  rotates slightly towards the closure trigger  18  so that the operator can grasp the firing trigger  20 , as shown in  FIG. 38 . In this position, the front face  242  of the upper portion  230  contacts the proximate end of the threaded rod  266 . 
     As the user then retracts the firing trigger  20 , after an initial rotational amount (e.g., 5 degrees of rotation) the run motor sensor  110  may be activated such that, as explained above, the sensor  110  sends a signal to the motor  65  to cause it to rotate at a forward speed proportional to the amount of retraction force applied by the operator to the firing trigger  20 . Forward rotation of the motor  65  causes the main drive shaft  48  to rotate via the gear drive train, which causes the knife  32  and sled  33  to travel down the channel  22  and sever tissue clamped in the end effector  12 . The control circuit receives the output signals from the encoder  268  regarding the incremental rotations of the main drive shaft assembly and sends a signal to the second motor  265  to cause the second motor  265  to rotate, which causes the threaded rod  266  to retract into the motor  265 . This allows the upper portion  230  of the firing trigger  20  to rotate CCW, which allows the lower portion  228  of the firing trigger to also rotate CCW. In that way, because the reciprocating movement of the threaded rod  266  is related to the rotations of the main drive shaft assembly, the operator of the instrument  10 , by way of his/her grip on the firing trigger  20 , experiences tactile feedback as to the position of the end effector  12 . The retraction force applied by the operator, however, does not directly affect the drive of the main drive shaft assembly because the firing trigger  20  is not geared into the gear drive train in this embodiment. 
     By virtue of tracking the incremental rotations of the main drive shaft assembly via the output signals from the encoder  268 , the control circuit can calculate when the knife  32  is fully deployed (i.e., fully extended). At this point, the control circuit may send a signal to the motor  65  to reverse direction to cause retraction of the knife  32 . The reverse direction of the motor  65  causes the rotation of the main drive shaft assembly to reverse direction, which is also detected by the encoder  268 . Based on the reverse rotation detected by the encoder  268 , the control circuit sends a signal to the second motor  265  to cause it to reverse rotational direction such that the threaded rod  266  starts to extend longitudinally from the motor  265 . This motion forces the upper portion  230  of the firing trigger  20  to rotate CW, which causes the lower portion  228  to rotate CW. In that way, the operator may experience a CW force from the firing trigger  20 , which provides feedback to the operator as to the retraction position of the knife  32  in the end effector  12 . The control circuit can determine when the knife  32  is fully retracted. At this point, the control circuit may send a signal to the motor  65  to stop rotation. 
     According to other embodiments, rather than having the control circuit determine the position of the knife  32 , reverse motor and stop motor sensors may be used, as described above. In addition, rather than using a proportional sensor  110  to control the rotation of the motor  65 , an on/off switch or sensor can be used. In such an embodiment, the operator would not be able to control the rate of rotation of the motor  65 . Rather, it would rotate at a preprogrammed rate. 
       FIG. 43  illustrates various embodiments of a surgical instrument  300 . The surgical instrument  300  may be similar to the surgical instrument  10  described hereinabove, but also includes a status module  302  releasably connected thereto. Although the status module  302  is shown in  FIG. 43  as being connected to the exterior lower side piece  60  of the handle  6 , it is understood that the status module  302  may be connected to the surgical instrument  300  at any suitable location. According to various embodiments, the handle  6  of the surgical instrument  300  defines a recess structured and arranged to receive the status module  302 . 
     The surgical instrument  300  comprises a plurality of sensors  304  (shown schematically in  FIG. 44 ), wherein the plurality of sensors  304  includes, for example, an articulation angle sensor, an anvil position sensor, a cartridge sensor, a closure trigger sensor, a closure force sensor, a firing force sensor, a knife position sensor, a lockout condition sensor, or any combination thereof. Each sensor  304  may be in electrical communication with a different contact  306  (shown schematically in  FIG. 44 ) positioned proximate the exterior of the surgical instrument  300 . 
     The sensors  304  may be embodied in any suitable manner. For example, the articulation angle sensor may be embodied as, for example, a potentiometer that comprises a portion of the articulation control  16  and outputs a signal that indicates the relative articulation angle of the end effector  12 . The anvil position sensor may be embodied as, for example, the anvil closure sensor  2004  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The cartridge sensor may be embodied as, for example, the cartridge present sensor  2010  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The closure trigger sensor may be embodied as, for example, the closure trigger sensor  2002  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The closure force sensor may be embodied as, for example, the anvil closure load sensor  2006  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The firing force sensor may be embodied as, for example, the firing trigger sensor  110  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The knife position sensor may be embodied as, for example, the knife position sensor  2008  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. The lockout condition sensor may be embodied as, for example, the cartridge lockout sensor  136  or the cartridge present sensor  2010  disclosed in U.S. patent application Ser. No. 11/343,803, entitled SURGICAL INSTRUMENT HAVING RECORDING CAPABILITIES, now U.S. Pat. No. 7,845,537. 
     According to various embodiments, the status module  302  comprises a housing  308  structured and arranged to releasably connect to the surgical instrument  300 . The status module  308  comprises a plurality of contacts  310  (shown schematically in  FIG. 44 ), wherein each individual contact  310  is structured and arranged to be in electrical communication with a different sensor  304  of the surgical instrument  300  when the housing  308  is connected to the surgical instrument  300 . For example, when the status module  302  is connected to the surgical instrument  300 , each contact  310  of the status module  302  may be aligned with a respective corresponding contact  306  of the surgical instrument  300 , thereby placing each contact  310  of the status module  302  in electrical communication with a different sensor  304 . 
     The status module  302  further comprises a circuit  312  (shown schematically in  FIG. 44 ) in communication with at least one of the contacts  310 , and a plurality of indicators  314  (shown schematically in  FIG. 44 ). At least one of the indicators  314  is in electrical communication with the circuit  312 . The circuit  312  comprises a drive circuit, and is structured and arranged to drive at least one of the indicators  314 . According to various embodiments, the circuit  312  may further comprise, as shown schematically in  FIG. 44 , a switch  316 , a counter  318 , a transmitter  320 , or any combination thereof. 
     The switch  316  is in electrical communication with at least one of the indicators  314 , and may be utilized to disable the respective indicator  314  that is in electrical communication therewith. According to various embodiments, the switch  316  may comprise a portion of the status module  302  other than the circuit  312 , or a portion of the surgical instrument  300  other than the status module  302 . For such embodiments, the switch  316  may be in electrical communication with the circuit  312 . 
     The counter  318  may be utilized to determine the number of firings, the number of firings remaining, the post-clamping wait time, etc. According to various embodiments, the counter  318  may comprise a portion of the status module  302  other than the circuit  312 . According to other embodiments, the counter  318  may comprise a portion of the surgical instrument  300  other than the status module  302 . For such embodiments, the counter  318  may be in electrical communication with the circuit  312 . 
     The transmitter  320  may be utilized to wirelessly transmit information sensed by the plurality of sensors  304  to a wireless receiver (not shown) associated with a monitor (not shown) that may be viewed by a user of the surgical instrument  300  while the user is performing a procedure. The information may be wirelessly transmitted continuously or periodically. The displayed information may include, for example, firing progress information, compression load information, knife load information, number of firings, procedure time, compression wait time, battery level, etc. According to other various embodiments, the transmitter  320  may comprise a portion of the status module  302  other than the circuit  312 , or a portion of the surgical instrument  300  other than the status module  302 . For such embodiments, the transmitter  320  may be in electrical communication with the circuit  312 . 
       FIGS. 45-47  illustrate various embodiments of the status module  302 . As shown, the status module  302  may comprise different types of indicators  314 . According to various embodiments, the indicators  314  may comprise one or more visual indicators such as, for example, a light emitting diode, a multi-color light emitting diode, a display, etc. or any combination thereof. The display may comprise, for example, an alpha numeric display, a dot matrix display, a liquid crystal display, etc. According to various embodiments, at least one of the indicators  314  may comprise an audible indicator such as, for example, an audio output device. The audible output device may be embodied as, for example, a speaker, and may be in electrical communication with the switch  316 . According to various embodiments, the indicators  314  may comprise at least one visual indicator and at least one audible indicator. 
     In operation, the indicators  314  may provide visual and audible feedback to a user of the surgical instrument  300 . For example, as shown in  FIG. 45 , an indicator  314  (e.g., a light emitting diode) may be utilized to indicate whether the closure trigger  18  is in the locked position, whether a predetermined post-clamping wait period has been completed, whether a staple cartridge  34  is loaded, etc. Different indicators  314  may emit different colors of light. As used in  FIGS. 45 and 46 , different hatching indicates different colors. An indicator  314  (e.g., a multi-color light emitting diode) may be utilized for multiple status indications of a particular function of the surgical instrument  300 . For example, to indicate the status of the staple cartridge  34 , a multi-color light emitting diode may emit green light if a loaded staple cartridge  34  is in the channel  22 , yellow light if a spent staple cartridge  34  is in the channel  22 , or red light if a staple cartridge  34  is not in the channel  22 . Similarly, to indicate the status of a cutting force being exerted by the surgical instrument  300 , a multi-color light emitting diode may emit green light if the cutting force being exerted is in a normal range, yellow light if the cutting force being exerted is in an elevated range, or red light if the cutting force being exerted is in a high load range. It is understood that the indicators  314  may be utilized for multiple status indications of other functions of the surgical instrument  300  such as, for example, battery level. 
     As shown in  FIG. 45 , a line of indicators  314  (e.g., light emitting diodes) may be utilized to indicate the progression of the knife  32 , the percentage of the maximum closure force being exerted, the percentage of the maximum firing force being exerted, the current articulation angle of the end effector  12 , etc. Such indications may provide a user of the surgical instrument  300  with feedback concerning the forces involved in operating the surgical instrument  300  and feedback as to how close the surgical instrument  300  is operating to its maximum capacity. Although only one line of indicators  314  is shown in  FIG. 45 , it is understood that the status module  302  may comprise any number of lines of indicators  314 . 
     As shown in  FIG. 46 , the status module  302  may comprise indicators  314  (e.g., light emitting diodes) arranged in two circular orientations. For such embodiments, the status module  302  may be capable of providing more concurrent information to a user of the surgical instrument  300  than the status module  302  shown in  FIG. 45 . Although two circular arrangements of indicators are shown in  FIG. 46 , it is understood that the status module  302  may comprise any number of indicators  314  arranged in any number of orientations. For example, the status module  302  may comprises indicators  314  arranged in a pyramid pattern. 
     As shown in  FIG. 47 , the indicators  314  of the status module  302  may comprise a line of light emitting diodes and at least one display (e.g., a liquid crystal display). For such embodiments, the status module  302  may be capable of providing more concurrent information to a user of the surgical instrument  300  than the status module  302  shown in  FIG. 45  or  FIG. 46 . For example, the light emitting diodes may show reaction force at the anvil  24  and staple cartridge  22 , the battery level, the articulation angle, etc. in the form of a bar graph. The display may show information concerning closure forces, firing forces, the number of firings remaining, post-clamping wait time, stroke progression, articulation angle, etc. in the form of digits. 
     While several embodiments of the invention have been described, it should be apparent, however, that various modifications, alterations and adaptations to those embodiments may occur to persons skilled in the art with the attainment of some or all of the advantages of the invention. For example, according to various embodiments, a single component may be replaced by multiple components, and multiple components may be replaced by a single component, to perform a given function or functions. This application is therefore intended to cover all such modifications, alterations and adaptations without departing from the scope and spirit of the disclosed invention as defined by the appended claims. 
     Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.