Powered surgical instrument

[0001] 1. Technical Field

[0002] The present disclosure relates to surgical instruments for fastening body tissue and, more particularly, to a powered surgical instrument having powered actuation capabilities.

[0003] 2. Background of Related Art

[0004] Surgical devices where tissue is first grasped or clamped between opposing jaw structure and then joined by surgical fasteners are well known in the art. In some instruments, a knife is provided to cut the tissue which has been joined by the fasteners. The fasteners typically include surgical staples and two part polymeric fasteners.

[0005] Instruments for this purpose may include two jaw members which are respectively used to capture or clamp tissue. Typically, one of the members carries a staple cartridge that houses a plurality of staples arranged in rows while the other member has an anvil that defines a surface for forming the staple legs as the staples are driven from the staple cartridge. Several instruments include clamps, handles and/or knobs to affect actuation along with rotation and articulation of an end effector. Such surgical instruments can require the user to exert a significant force in operating the handles, knobs, etc., which can create instability and undesired movement in operating the instruments.

[0006] Accordingly, surgical instruments that require less force to operate are desired. Surgical instruments that operate with more precision is also desired.

[0007] The present disclosure relates to a surgical instrument including a housing, an endoscopic portion, a drive motor, a drive tube, a firing rod and an end effector. The endoscopic portion extends distally from the housing and defines a first longitudinal axis. The drive motor is disposed at least partially within the housing. The drive tube is disposed in mechanical cooperation with the drive motor and is rotatable about a drive tube axis extending therethrough. The firing rod is disposed in mechanical cooperation with the drive tube and at least a portion of the firing rod is translatable with respect to the drive tube. The end effector is disposed adjacent a distal portion of the endoscopic portion.

[0008] The present disclosure also relates to a method of applying surgical fasteners to tissue. The method of this embodiment includes providing a powered surgical instrument which includes a housing, an endoscopic portion, a drive motor, a drive tube, a firing rod and an end effector. The drive motor is disposed at least partially within the housing. The drive tube is disposed in mechanical cooperation with the drive motor and is rotatable about a drive tube axis extending therethrough. The firing rod is disposed in mechanical cooperation with the drive tube and at least a portion of the firing rod is translatable with respect to the drive tube. The end effector is disposed adjacent a distal portion of the endoscopic portion. The method further includes rotating the drive tube about the drive tube axis and translating the firing rod with respect to the drive tube to affect a surgical function of the end effector.

[0009] The present disclosure further relates to a surgical instrument comprising a housing, an endoscopic portion extending distally from the housing and defining a longitudinal axis, an end effector disposed adjacent a distal portion of the endoscopic portion, the end effector being movable to an angled position with respect to the longitudinal axis, a drive motor disposed at least partially within the housing, the drive motor being arranged for driving a surgical function of the end effector, an articulation mechanism for moving the end effector to the angled position with respect to the longitudinal axis, and an articulation motor for driving the articulation mechanism.

[0010] The surgical instrument may include a drive tube disposed in mechanical cooperation with the drive motor, the drive tube being rotatable about a drive tube axis extending therethrough, and a firing rod disposed in mechanical cooperation with the drive tube, at least a portion of the firing rod being translatable with respect to the drive tube. A clutch is disposed between the drive motor and the drive tube, in certain embodiments. The clutch may include a clutch plate and a spring. The clutch plate is desirably arranged to mate with an interface disposed on a proximal face of the drive tube. A manual articulation knob may also be included for driving the articulation mechanism.

[0011] The end effector is desirably rotatable about the longitudinal axis with respect to the housing, in certain embodiments. The surgical instrument desirably includes a user interface including at least one switch that controls the end effector. A power source is desirably disposed at least partially within the housing and arranged to provide power to the drive motor. In certain embodiments, the end effector is part of a disposable loading unit having a body portion.

[0021] Embodiments of the presently disclosed powered surgical instrument are now described in detail with reference to the drawings, in which like reference numerals designate identical or corresponding elements in each of the several views. As used herein the term “distal” refers to that portion of the powered surgical instrument, or component thereof, farther from the user while the term “proximal” refers to that portion of the powered surgical instrument or component thereof, closer to the user.

[0022] A powered surgical instrument, e.g., a surgical stapler, in accordance with the present disclosure is referred to in the figures as reference numeral 100. Referring initially to FIG. 1, powered surgical instrument 100 includes a housing 110, an endoscopic portion 140 defining a first longitudinal axis A-A extending therethrough, and an end effector 160, defining a second longitudinal axis B-B extending therethrough. Endoscopic portion 140 extends distally from housing 110 and end effector 160 is disposed adjacent a distal portion 142 of endoscopic portion 140.

[0023] With reference to FIG. 2, an enlarged view of housing 110 is illustrated according to an embodiment of the present disclosure. In the illustrated embodiment, housing 110 includes a handle portion 112 having at least one switch 114 thereon (two switches 114a and 114b illustrated as a toggle switch are shown). Handle portion 112, which defines a handle axis H-H, is configured to be grasped by the hand of a user. Each switch 114a and 114b is shown as being disposed at a suitable location on handle portion 112 to facilitate its depression by a user's finger or fingers.

[0024] Referring to FIG. 3, a proximal area 118 of housing 110 includes a user interface 120. In the illustrated embodiment, user interface 120 includes two lights 124a, 124b. It is envisioned that lights 124a, 124b provide information/feedback (e.g., visual feedback) to its user. For example, illumination of first light 124a may indicate that a staple cartridge is loaded properly and illumination of second light 124b may indicate that second switch 114b (FIG. 2) has been initiated and that end effector 160 is ready to use. It is also envisioned that a screen (not explicitly shown in this embodiment) may be disposed on housing 110 to provide information/feedback to a user. The screen may comprise a LCD screen or other screen incorporated into housing 110.

[0025] FIGS. 2-4 illustrate an articulation mechanism 170, including an articulation housing 172, a powered articulation switch 174 and a manual articulation knob 176. The knob 176 is desirably configured to indicate the angle of the end effector 160. For example, the angular displacement of the knob 176, which has an elongated shape, with respect to axis A-A indicates the angle of the end effector with respect to axis A-A. Actuation of articulation mechanism 170 (e.g., translating powered articulation switch 174 or pivoting manual articulation knob 176) causes end effector 160 to move from its first position, where longitudinal axis B-B is substantially aligned with longitudinal axis A-A, towards a position in which longitudinal axis B-B is disposed at an angle to longitudinal axis A-A. Preferably, a plurality of articulated positions is achieved.

[0026] Additionally, articulation housing 172 and powered articulation switch 174 are mounted to a rotating housing assembly 180. Rotation of a rotation knob 182 about first longitudinal axis A-A causes housing assembly 180 as well as articulation housing 172 and powered articulation switch 174 to rotate about first longitudinal axis A-A, and thus causes corresponding rotation of distal portion 224 of firing rod 220 and end effector 160 about first longitudinal axis A-A. Further details of articulation housing 172, powered articulation switch 174, manual articulation knob 176 and providing articulation to end effector 160 are described in detail in commonly-owned U.S. patent application Ser. No. 11/724,733 entitled “Surgical Stapling Apparatus with Powered Articulation” filed on Mar. 15, 2007 by Marczyk and U.S. Pat. No. 6,953,139 to Milliman et al., the contents of both of which are hereby incorporated by reference in their entirety. It is envisioned that any combinations of limit switches, proximity sensors (e.g., optical and/or ferromagnetic), linear variable displacement transducers and shaft encoders (disposed within housing 110, for instance) may be utilized to control and/or record an articulation angle of end effector 160 and/or position of firing rod 220.

[0027] FIGS. 4-8 illustrate various internal components of powered surgical instrument 100, including a drive motor 200 (FIG. 4), a drive tube 210 (FIGS. 4-7) and a firing rod 220 (including proximal portion 222 (FIGS. 5, 6 and 8) and distal portion 224 (FIGS. 4 and 5)). Drive tube 210 is rotatable about drive tube axis C-C extending therethrough (FIG. 4). Drive motor 200 is disposed in mechanical cooperation with drive tube 210 and is configured to rotate drive tube 210 about drive gear axis C-C. In a disclosed embodiment, drive motor 200 may be a motor or a gear motor, which may include gearing incorporated within its housing.

[0028] With reference to FIGS. 4-6, a firing rod coupling 190 is illustrated. Firing rod coupling 190 provides a link between proximal portion 222 and distal portion 224 of firing rod 220. Specifically, firing rod coupling 190 enables rotation of distal portion 224 of firing rod 220 with respect to proximal portion 222 of firing rod 220. Thus, firing rod coupling 190 enables proximal portion 222 of firing rod 220 to remain stationary (discussed below with reference to alignment plate 350), while allowing rotation of distal portion 224 of firing rod 220 (e.g., upon rotation of rotation knob 182, discussed above).

[0029] Drive tube 210 rotates in response to rotation of drive motor 200. As drive tube 210 rotates, firing rod 220 is translated proximally and/or distally, as described below. With reference to FIGS. 5 and 6, proximal portion 222 of firing rod 220 includes a threaded portion 226, which extends through an internally-threaded portion 212 of drive tube 210. This relationship between firing rod 220 and drive tube 210 causes firing rod 220 to move distally and/or proximally (in the directions of arrows D and E) along threaded portion 212 of drive tube 210 upon rotation of drive tube 210. For example, as drive tube 210 rotates in a first direction (e.g., clockwise), firing rod 220 moves proximally (FIG. 5 illustrates firing rod 220 disposed adjacent its proximal-most position), and as drive tube 210 rotates in a second direction (e.g., counter-clockwise), firing rod 220 moves distally (FIG. 6 illustrates firing rod 220 adjacent its distal-most position).

[0030] With continued reference to FIGS. 5 and 6, firing rod 220 is distally and proximally translatable within particular limits. Specifically, a first end 222a of proximal portion 222 of firing rod 220 acts as a mechanical stop in combination with an alignment plate 350. That is, upon retraction when firing rod 220 is translated proximally, first end 222a contacts a distal surface 351 of alignment plate 350, thus preventing continued proximal translation of firing rod 220 (FIG. 5). Additionally, threaded portion 226 of proximal portion 222 of firing rod 220 acts as a mechanical stop in combination with alignment plate 350. That is, when firing rod 220 is translated distally, threaded portion 226 contacts a proximal surface 353 of alignment plate 350, thus preventing further distal translation of firing rod 220 (FIG. 6).

[0031] As drive tube 210 is rotated by drive motor 200, proximal portion 222 of firing rod 220 is constricted from substantial rotation by alignment plate 350 (FIG. 8). Alignment plate 350 includes an aperture 352 therethrough, which has a non-round cross-section. The non-round cross-section of aperture 352 prevents rotation of proximal portion 222 of firing rod 220, thus limiting proximal portion 222 of firing rod 220 to axial translation therethrough. Further, a proximal bearing 354 (FIGS. 4-7) and a distal bearing 356 (FIGS. 4-6) are disposed at least partially around drive tube 210 for facilitation of rotation of drive tube 210, while helping align drive tube 210 within housing 110. In further embodiments, additional tubes may be added. To reduce the length of the drive tube and/or increase the torque, the drive tube can incorporate an external thread which mates with another tubular member. This allows the telescoping, multi-layered tube to travel axially so that the firing rod will travel more axially, while the assembly has the same overall length. Furthermore, inner threaded tubes can also be utilized in a similar manner.

[0032] Distal translation of firing rod 220 (corresponding with a counter-clockwise rotation of drive tube 210, for instance) can cause jaw members 162, 164 (see FIG. 1) of end effector 160 to grasp or clamp tissue held therebetween. Additional distal translation of firing rod 220 may cause surgical fasteners to be ejected from end effector 160 (e.g., via cam bars and/or an actuation sled (neither of which are explicitly shown in this embodiment)) to fasten tissue and may also cause a knife (not explicitly shown in this embodiment) to sever tissue. Proximal translation of firing rod 220 (corresponding with a clockwise rotation of drive tube 210, for instance) can cause jaw members 162, 164 and/or knife to retract or return to their pre-fired positions. Further details of firing and otherwise actuating end effector 160 are described in detail in commonly-owned U.S. Pat. No. 6,953,139 to Milliman et al. (the '139 Milliman patent), the disclosure of which is hereby incorporated by reference herein in its entirety.

[0033] According to an embodiment of the present disclosure, end effector 160 includes a cartridge assembly (e.g., jaw member 164) and an anvil assembly (e.g., jaw member 162) including an anvil portion for deploying surgical fasteners into body tissue and forming the surgical fasteners. Cartridge assembly 164 houses a plurality of staples. At least one of anvil assembly 162 and cartridge assembly 164 is movable in relation to one another between an open position where anvil assembly 162 is spaced from cartridge assembly 164 and an approximated or clamped position where anvil assembly 162 is in juxtaposed alignment with cartridge assembly 164. In an embodiment, the staples are housed in cartridge assembly 164 to apply linear rows of staples to body tissue.

[0034] It is further envisioned that end effector 160 is attached to a mounting portion 166, which is pivotably attached to a body portion 168. Body portion 168 may be integral with endoscopic portion 140 of powered surgical instrument 100, or may be removably attached thereto to provide a replaceable, disposable loading unit (DLU) or single use loading unit (SULU). The loading unit may be connectable to endoscopic portion 140 through a bayonet connection. It is envisioned that the loading unit has at least one articulation link connected to mounting portion 166 of the loading unit and the articulation link is connected to a linkage rod so that the end effector 160 is articulated as the linkage rod is translated in the distal-proximal direction along first longitudinal axis A-A. Other means of connecting end effector 160 to endoscopic portion 140 to allow articulation may be used. For example, a flexible tube or a plurality of pivotable members may be used.

[0035] A loading unit may incorporate (or be configured to incorporate) various end effectors, such as vessel sealing devices, linear stapling devices, circular stapling devices, cutters, etc. Such end effectors may be coupled to endoscopic portion 140 of powered surgical instrument 100. An intermediate flexible shaft may be included between handle portion 112 and loading unit. An example of a flexible shaft is described in detail in commonly-owned U.S. patent application 11/786,934 entitled “Powered Surgical Instrument” filed on an even date herewith by Zemlok, the contents of which are hereby incorporated by reference in their entirety. It is envisioned that the incorporation of a flexible shaft may facilitate access to and/or within certain areas of the body.

[0036] Further, where various loading units can be used, a digital control module (DCM) 130 (FIG. 4) can control the force being applied to firing rod 220 so that firing rod 220 can drive the particular end effector 160 that is on the loading unit in use at the time. For clarity, wires are not shown in the Figures connecting DCM 130 to various components of powered surgical instrument 100, but such wires are contemplated by the present disclosure. The loading unit may also include a mechanical or electronic sensor, e.g., 132, that indicates to DCM 130 which end effector is on the loading unit. In an embodiment, DCM 130 is also capable of storing information relating to the force applied to firing rod 220 and/or end effector 160 via sensors or by measuring the voltage and current being drawn by the motor. Additionally, the voltage and current from drive motor 200 may be measured to provide information and/or feedback regarding the state of powered surgical instrument 100. For instance, if the user is attempting to clamp down on tissue that is too thick, the voltage and/or current can be measured to determine the clamping energy. If predetermined energy limitations are exceeded, this information can be provided to the user and/or the power can be interrupted or ceased. It is envisioned that such a feature helps prevent damage to the mechanisms in the instrument.

[0037] In an embodiment of the disclosure, anvil assembly 162 of end effector 160 includes a cam surface for being engaged by a drive assembly of end effector 160. Here, the drive assembly includes a drive beam, which desirably has a knife for cutting tissue. The drive beam has a cam roller positioned to engage the cam surface, and a flange positioned to engage the cartridge assembly to affect approximation of the anvil assembly 162 and cartridge assembly 164 with respect to one another when the drive beam is advanced distally. In addition, when advanced further in the distal direction, the drive beam engages an actuation member for deploying the surgical fasteners from the cartridge assembly, as disclosed in the Milliman '139 patent.

[0038] Any combination of sensors may be positioned within powered surgical instrument 100 to determine its operating stage, e.g., articulation, rotation, clamping, firing of end effector 160, etc. For example, limit switches 230 and 232 (FIG. 4), proximity sensors (e.g., linear and/or ferromagnetic), potentiometers, linear variable displacement transducers (LVDT), shaft encoders, etc., may be used to help control and/or record the location of firing rod 220 (e.g., limit switch 232) and may be used to detect a properly loaded staple cartridge (e.g., limit switch 230).

[0039] With reference to FIGS. 5 and 6, indicators 320a, 320b are illustrated on firing rod 220 and help determine the speed of firing rod 220 and the location of firing rod 220 with respect to drive tube 210 and/or housing 110. For instance, limit switch 230 may be activated by sensing indicators 320a and/or 320b (e.g., bumps, grooves, indentations, etc.) passing thereby to determine position of firing rod 220, speed of firing rod 220 and mode of powered surgical instrument 100 (e.g., clamping, grasping, firing, sealing, cutting, retracting). The indicators may have a variety of shapes and many equally spaced features similar to those shown can be used. The position of firing rod 220, for example, may be indicated on a screen of user interface 120. Further, the feedback received from indicators 320a, 320b may be used to determine when firing rod 220 should stop its axial movement (e.g., when drive motor 200 should cease) depending on the size of the particular loading unit attached thereto.

[0040] With reference to FIG. 7, a drive motor shaft 202 is shown extending from drive motor 200 and a planetary gear 204. Drive motor shaft 202 is in mechanical cooperation with clutch 300. Drive motor shaft 202 is rotated by drive motor 200, thus resulting in rotation of clutch 300. Clutch 300 includes a clutch plate 302 and a spring 304 and is shown having wedged portions 306 disposed on clutch plate 302, which are matable with an interface (e.g., wedges 214) disposed on a proximal face 216 of drive tube 210. Spring 304 is illustrated between planetary gear 204 and drive tube 210. Specifically, and in accordance with the embodiment illustrated in FIG. 7, spring 304 is illustrated between clutch plate 302 and a clutch washer 308. Additionally, drive motor 200 is mounted on a motor mount 310. As illustrated in FIG. 7, motor mount 310 is adjustable proximally and distally with respect to housing 110 via slots 312 disposed in motor mount 310 and protrusions 314 disposed on housing 110.

[0041] In an embodiment of the disclosure, a clutch is formed between the drive tube 210 and the drive motor 200. Wedged portions 306 of clutch 300 are configured and arranged to slip with respect to wedges 214 of proximal face 216 of drive tube 210 unless a threshold force is applied to clutch plate 302 clutch spring 304. Further, when spring 304 applies the threshold force needed for wedged portions 306 and wedges 214 to engage without slipping, drive tube 210 will rotate upon rotation of drive motor 200. It is envisioned that wedged portions 306 and/or wedges 214 are configured to slip in one and/or both directions (i.e., clockwise and/or counter-clockwise) with respect to one another until a threshold force is attained.

[0042] It is further envisioned that drive motor shaft 202 includes a D-shaped cross-section, which includes a substantially flat portion and a rounded portion. Thus, while drive motor shaft 202 is translatable with respect to clutch plate 302, drive motor shaft 202 will not “slip” with respect to clutch plate 302 upon rotation of drive motor shaft 202. That is, rotation of drive motor shaft 202 will result in a relatively slip-less rotation of clutch plate 302.

[0043] While not explicitly illustrated in the accompanying figures, user interface 120 may include a plurality of switches. User interface may display the “mode” (e.g., rotation, articulation or actuation), which may be communicated to user interface via a sensor, “status” (e.g., angle of articulation, speed of rotation, or type of actuation) and “feedback,” such as whether staples have been fired. It is also envisioned that switch can be used to let a user input different tissue types, and various sizes and lengths of staple cartridges. Further, switches on user interface may include arrows thereon and may be used for selecting the direction, speed and/or torque at which drive tube 210 is rotated by drive motor 200. It is also envisioned that at least one switch can be used for selecting an emergency mode that overrides various settings, for example.

[0044] Additionally, and with reference to FIGS. 1 and 2, switches 114a, 114b may be used for starting and/or stopping movement of drive motor 200. Other functions for switches 114a, 114b are also anticipated as well as having more or fewer switches 114. In a particular embodiment, a switch 114c may be included (FIGS. 1, 2 and 4), wherein depression thereof may mechanically and/or electrically initiate actuation or firing of end effector 160. Further, at least one switch 114 may include one or more microelectronic membrane switches, for example. Such a microelectronic membrane switch includes a relatively low actuation force, small package size, ergonomic size and shape, low profile, the ability to include molded letters on the switch, symbols, depictions and/or indications, and a low material cost. Additionally, switches 114 (such as microelectronic membrane switches) may be sealed to help facilitate sterilization of powered surgical instrument 100, as well as helping to prevent particle and/or fluid contamination.

[0045] As an alternative to, or in addition to switches 114, other input devices may include voice input technology, which may include hardware and/or software incorporated in DCM 130, or a separate digital module connected to DCM 130. The voice input technology may include voice recognition, voice activation, voice rectification and/or embedded speech. The user may be able to control the operation of the instrument in whole or in part through voice commands, thus freeing one or both of the user's hands for operating other instruments. Voice or other audible output may also be used to provide the user with feedback.

[0046] In an embodiment, spring 304 may be used in the feedback and control of powered surgical instrument 100. As described above, DCM 130 may be connected to one or more switches 114 and one or more display screens to provide feedback to the user and for helping to control the operation of powered surgical instrument 100. DCM 130 may be a digital board incorporated in housing 110 of powered surgical instrument 100. Spring 304 may include a pressure transducer that can interact with DCM 130 to control the force being applied to drive tube 210.

[0047] It is also envisioned that user interface 120 includes different colors and/or intensities of text on screen and/or on switches for further differentiation between the displayed items. User feedback can also be included in the form of pulsed patterns of light, acoustic feedback (e.g., buzzers, bells or beeps that may be sounded at selected time intervals), verbal feedback, and/or haptic vibratory feedback (such as an asynchronous motor or solenoids), for example. The visual, auditory or haptic feedback can be increased or decreased in intensity. For example, the intensity of the feedback may be used to indicate that the forces on the instrument are becoming excessive. Additionally, switches may be positioned at different heights from one another and/or may included raised indicia or other textural features (e.g., concavity or convexity) to allow a user to depress an appropriate switch without the need to look at user interface 120.

[0048] Additionally, user interface 120 may include a separate display screen or screens and input devices (such as switches or buttons), or the input devices may be incorporated in whole or in part in screen. For example, a touch screen liquid crystal display (LCD) may be used to allow the user to provide input while viewing operational feedback. The touch screen LCD may include resistive, capacitive or surface acoustic wave controls. This approach may enable facilitation of sealing screen components to help sterilize powered surgical instrument 100, as well as preventing particle and/or fluid contamination. In certain embodiments, screen is pivotably or rotatably mounted to powered surgical instrument 100 for flexibility in viewing screen during use or preparation. Screen may be hinged or ball-and-socket mounted to powered surgical instrument 100, for example.

[0049] In a disclosed embodiment, at least some of the information monitored by the various sensors in powered surgical instrument 100 may be provided to a video screen or monitoring system in an operating room. For instance, the data may be transmitted to a receiver for the operating room monitoring system from a communication transmitter incorporated in or associated with powered surgical instrument 100, via technology including Blue Tooth, ANT3, KNX, Z Wave, X10, wireless USB, WiFi, IrDa, Nanonet, Tiny OS, ZigBee, radio frequency, UHF and VHF. Such features may facilitate monitoring by the user of powered surgical instrument 100 or other operating room or hospital personnel or remotely located persons.

[0050] It is also envisioned that any combination of battery cells 400 (FIG. 4), a battery pack, fuel cell and/or high-energy capacitor may be used to provide power to powered surgical instrument 100. For example, capacitors may be used in conjunction with a battery pack. Here, capacitors can be used for a burst of power when energy is desired/required more quickly than can be provided with a battery on its own (e.g., when clamping thick tissue, rapid firing, clamping, etc.), as batteries are typically slow-drain devices from which current cannot be quickly drawn. It is envisioned that batteries can be connected to capacitors to charge the capacitors.

[0051] It is also envisioned that battery pack includes at least one disposable battery. The disposable battery may be between about 9 volts and about 30 volts and may be useful in a disposable surgical instrument. Other power-supplying means are also contemplated including electric power. In alternative embodiments a cord is provided to connect instrument 100 to a generator and/or line voltage.

[0052] In a disclosed embodiment, the DCM is connected to drive motor 200 and is configured and arranged to monitor the battery impedance, voltage, temperature and/or current draw and to control the operation of powered surgical instrument 100. The load or loads on battery 400, transmission, drive motor 200 and drive components of powered surgical instrument 100 are determined to control a motor speed if the load or loads indicate a damaging limitation is reached or approached. For example, the energy remaining in battery 400, the number of firings remaining, whether battery 400 must be replaced or charged, and/or approaching the potential loading limits of powered surgical instrument 100 may be determined.

[0053] The DCM can be configured and arranged to control or help control the operation of drive motor 200 to respond to the monitored information. Pulse modulation of the battery voltage can be used as an electronic clutch for controlling the torque output. For example, the DCM can regulate the voltage or pulse modulate the voltage to adjust the power and/or torque output to prevent system damage or optimize energy usage. An electric braking circuit may be used for controlling drive motor 200, which uses the existing back electromotive force (EMF) of rotating drive motor 200 to counteract and substantially reduce the momentum of drive tube 210. The electric braking circuit may improve the control of drive motor 200 and/or drive tube 210 for stopping accuracy and/or shift location of powered surgical instrument 100. Sensors for monitoring components of powered surgical instrument 100 and to help prevent overloading of powered surgical instrument 100 may include thermal-type sensors, such as thermal sensors, thermistors, thermopiles, thermo-couples and/or thermal infrared imaging and provide feedback to the DCM. The DCM may control the components of powered surgical instrument 100 in the event that limits are reached or approached and such control can include cutting off the power from the battery pack 400, temporarily interrupting the power or going into a pause mode, pulse modulation to limit the energy used, and the DCM can monitor the temperature of components to determine when operation can be resumed. The above uses of the DCM may be used independently of or factored with current, voltage, temperature and/or impedance measurements.

[0054] It is envisioned that end effector 160 is reusable, can accept a staple cartridge and/or is part of a disposable loading unit. Further details of a disposable or replaceable loading unit are described in detail in commonly-owned U.S. Pat. No. 5,752,644 to Bolanos et al., the entire contents of which are hereby incorporated by reference herein. Disposable and/or replaceable loading units can include end effectors with or without articulation, as disclosed in the '139 Milliman patent.

[0055] A disposable or replaceable loading unit incorporating a surgical end effector 160, in certain embodiments of the present disclosure, includes sensors positioned within the loading unit to determine the position of various components and/or operation of end effector 160, such as articulation, rotation, clamping and firing of end effector 160. For example, electrical contacts, proximity sensors, optical sensors, photo diodes, and/or mechanical or metallic sensors may be used to control and/or record information concerning the end effector 160. The location of the anvil assembly 162 and cartridge assembly 164 with respect to one another, the articulated or non-articulated position of end effector 160, rotation of end effector 160, and/or correct loading of the loading unit, staple cartridge and/or components of the staple cartridge may also be determined.

[0056] An identification system may also be included to determine and communicate to the DCM various information, including the speed, power, torque, clamping, travel length and strength limitations for operating the particular end effector 160. The DCM may also determine the operational mode and adjust the voltage, clutch spring loading and stop points for travel of the components. More specifically, the identification system may include a component (e.g., a microchip, emitter or transmitter) in end effector 160 that communicates (e.g., wirelessly, via infrared signals, etc.) with the DCM, or a receiver therein. It is also envisioned that a signal may be sent via firing rod 220, such that firing rod 220 functions as a conduit for communications between the DCM and end effector 160.

[0057] The loading unit, in certain embodiments according to the present disclosure, includes an axial drive assembly that cooperates with firing rod 220 to approximate anvil assembly 162 and cartridge assembly 164 of end effector 160, and fire staples from the staple cartridge. The axial drive assembly may include a beam that travels distally through the staple cartridge and may be retracted after the staples have been fired, as disclosed in certain embodiments of the '139 Milliman patent. By way of example, the sensors discussed above may be used to determine if the staples have been fired from the staple cartridge, whether they have been fully fired, whether and the extent to which the beam has been retracted proximally through the staple cartridge and other information regarding the operation of the loading unit. In certain embodiments of the present disclosure, the loading unit incorporates components for identifying the type of loading unit, and/or staple cartridge loaded on the instrument 100, including infra red, cellular, conductive identification (which may utilize the firing rod as a conduit) or radio frequency identification chips (such as Sensormatic or similar technology). The type of loading unit and/or staple cartridge may be received by an associated receiver within the DCM, or an external device in the operating room for providing feedback, control and/or inventory analysis. The power or battery pack 400 can incorporate a component for identifying the type of power pack 400 loaded with powered surgical instrument 100 or for sending feedback concerning the status of power pack 400.

[0058] In certain embodiments of the present disclosure, powered surgical instrument 100 includes disposable or replaceable loading units incorporating a surgical end effector 160 and a reusable portion including a housing 110 and endoscopic portion 140 that is removably attached to the loading unit. The reusable portion may be configured for sterilization and re-use in a subsequent surgical procedure. In an embodiment, the components of the housing 110 are sealed against infiltration of particulate and/or fluid contamination and help prevent damage of the component by the sterilization process. Power pack 400, in certain embodiments according to the present disclosure, comprises a rechargeable battery. The rechargeable battery can be connected to contacts accessible at housing 110 of the instrument 100, for example, or, rechargeable battery may be rechargeable through an inductive charging interface sealed within housing 110. The inductive charging interface may eliminate shorting of contacts and provides an internal battery that may be hermetically or liquid resistance sealed.

[0059] The present disclosure also relates to a method of applying surgical fasteners to tissue. The method includes the use of powered surgical instrument 100, as described above.

[0060] It will be understood that various modifications may be made to the embodiments disclosed herein. Sensors, feedback and control systems are desirably incorporated into the surgical instrument, in certain preferred embodiments, as disclosed above and as disclosed in U.S. patent application Ser. No. 11/786,934 entitled “Powered Surgical Instrument” by Zemlok, filed on an even date herewith, the disclosure of which is hereby incorporated by reference herein in its entirety.

[0061] As a further example, a movable handle (not explicitly shown in this embodiment) may be employed to control various functions of powered surgical instrument 100. Therefore, the above description should not be construed as limiting, but merely as exemplifications of various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.