Handheld surgical instrument and method for supplying tactile feedback to a user during a kickback event

One embodiment relates to a handheld surgical instrument that comprises a rotary surgical end effector and a coupler configured to cause rotation of the same. The handheld surgical instrument further comprises a motor, which is configured to drive a motor output region. The handheld surgical instrument further comprises a transmission, which defines a transmission input region that interfaces with the motor output region and a transmission output region coupled to the transmission input region. The transmission output region is operably coupled to the coupler, and the transmission is configured to alter the speed of the coupler relative to the motor output region. The motor output region and the transmission input region interface one another at a motor-transmission interface, and the motor-transmission interface comprises a motor-transmission backlash such that drive of the motor output region within the motor-transmission backlash does not cause rotation of the rotary surgical end effector.

TECHNICAL FIELD

This disclosure relates to a method and handheld surgical instrument comprising a drive system and a coupler operably engaged with the drive system to perform a feedback function while not performing or terminating an operational function.

SUMMARY OF THE DISCLOSURE

One embodiment relates to a handheld surgical instrument configured to provide tactile feedback in the event of kickback. The handheld surgical instrument comprises a rotary surgical end effector and a coupler configured to operably couple to the rotary surgical end effector to cause rotation of the same. The handheld surgical instrument further comprises a motor, which comprises a motor shaft defining a motor output region. The motor is configured to drive the motor output region. The handheld surgical instrument further comprises a transmission, which defines a transmission input region that interfaces with the motor output region and a transmission output region coupled to the transmission input region. The transmission output region is operably coupled to the coupler, and the transmission is configured to alter the speed of the coupler relative to the motor output region. The motor output region and the transmission input region interface one another at a motor-transmission interface, and the motor-transmission interface comprises a motor-transmission backlash such that drive of the motor output region within the motor-transmission backlash does not cause rotation of the rotary surgical end effector. The handheld surgical instrument further comprises a sensor configured to generate a grip event signal and a controller operably engaged with the sensor to receive the grip event signal from the sensor. The controller is configured to determine a grip event based on the grip event signal, and the controller is further configured to oscillate the motor shaft to perform a feedback function without rotating the rotary surgical end effector.

Another embodiment relates to a handheld surgical instrument configured to provide tactile feedback to a user during a kickback event. The handheld surgical instrument comprises a coupler configured to operably couple to a surgical end effector. The handheld surgical instrument further comprises a drive system, which comprises an output member operably engaged with the coupler for actuating the surgical end effector to perform an operational function. The handheld surgical instrument further comprises a first sensor configured to generate a grip event signal and a controller operably engaged with the first sensor to receive the grip event signal from the first sensor. The controller is configured to determine a grip event based on the grip event signal, and the controller is further configured to oscillate the output member in first and second directions to perform a feedback function while not causing the surgical end effector to perform the operational function.

Still another embodiment relates to a method for providing feedback to a user of a handheld surgical instrument comprising a drive system having backlash, a coupler operably engaged with the drive system, a surgical end effector operably engaged with the coupler to perform an operational function, a first sensor configured to generate at least one grip event signal, and a controller communicating with the first sensor and the drive system. The method comprises the steps of detecting a grip event based on the grip event signal and oscillating the drive system within the backlash without rotating or oscillating the surgical end effector upon detection of the grip event.

BACKGROUND OF THE DISCLOSURE

A common surgical tool used in orthopedic surgery is a surgical drill. The typical surgical drill includes a housing that contains a motor. The surgical drill further includes a coupling assembly that releasably couples a drill bit to the motor so that a surgeon may actuate the motor to rotate the drill bit. As implied by its name, the surgical drill is configured to drill bores in the tissue against which the drill bit is applied. One type of surgical procedure in which it is necessary to drill a bore is a trauma procedure to repair a broken bone.

A disadvantage of the surgical drill is that the drill bit may become suddenly bound, pinched, or misaligned, such that the surgeon may experience kickback in the form of torque being transferred from the drill bit through the handpiece to the surgeon. Debris may impede the rotation of the drill bit, and the kickback can create discomfort for the surgeon and decrease the ability of the surgeon to control the surgical drill, particularly when the surgical drill is used to perform high-speed drilling or high-torque reaming in high-density bone applications.

DETAILED DESCRIPTION

Referring toFIGS. 1 and 2, a handheld surgical instrument10, for use with a surgical end effector12, is shown for performing an operational function and a feedback function to treat a patient in a health care setting. As described in detail below, the handheld surgical instrument10may comprise a coupler14and a drive system18having a motor24, transmission26, and an output member16(implemented as a rotary front-end assembly) operably engaged with the coupler14.

The operational function may be associated with a desired surgical function of the handheld surgical instrument10. For example, the operational function may be drilling, sawing, cutting, or other functions dependent on the configuration of the handheld surgical instrument10and/or the surgical end effector12. Typically, the operational function referred to herein is rotary cutting.

In this exemplary embodiment, the handheld surgical instrument10may be realized as a rotary handpiece, and the associated surgical end effector12may comprise a rotary surgical end effector, such as a drill bit. The coupler14may be configured to operably couple to the rotary surgical end effector to cause rotation of the same. The coupler14may comprise a chuck engaged to the drive system18, such that the drill bit can be rotated for performing high-speed drilling or high-torque reaming in large bone applications. The coupler14can be configured to transmit torque to the surgical end effector12in any suitable rotational or linear direction. For example, where the handheld surgical instrument is a drill, the coupler14is configured to provide torque to the drill bit.

The rotary handpiece10may comprise an output member16comprised of, among other things, a spindle that rotates in response to actuation of the motor24. Attached to the front end of the spindle is the coupler14. The coupler14releasably holds a device to the spindle so that the device rotates in unison with the spindle. Generally, two types of devices are releasably coupled to the output member16. The first type of device is the actual surgical end effector, for example, the drill bit or the reamer. The surgical end effector may have a shaft, and the proximal end or rear end of the shaft may be releasably held to the output member by the coupler. The second type of device coupled to a rotary handpiece is a front-end attachment, such as a speed-altering surgical attachment. The attachment has a housing with opposed front and rear ends. An input shaft extends from the attachment rear end. The attachment front end has its own output spindle and complementary coupling assembly. Where the attachment is a speed-altering surgical attachment, a gear assembly is located between the input shaft and the output spindle of the speed-altering surgical attachment. The gear assembly contains gears that typically increase the torque/decrease the speed of the rotational motion applied to the attached surgical end effector through the attachment output spindle. The actual surgical end effector is coupled to the attachment spindle. The attachment reduces or increases speed of the rotational moment output by the handpiece that is applied to the surgical end effector. Typically, a speed-altering surgical attachment is used to reduce speed and increase torque of the attached surgical end effector. Another embodiment of the speed-altering surgical attachment increases speed and reduces torque of the attached surgical end effector.

In the case where the handheld surgical instrument is provided with a removable attachment which receives torque from the surgical handpiece, the attachment may define the coupler. For drilling procedures, the attachment may comprise a keyless drill chuck attachment, a keyed drill chuck attachment, a modified trinkle drill attachment, a standard trinkle drill attachment, a bur attachment, or the like. For reaming procedures, the attachment may comprise a modified trinkle reamer attachment, a standard trinkle reamer attachment, a keyed reamer chuck attachment, a reamer attachment, a right angle drive modified trinkle reamer attachment, a right angle drive reamer attachment, or the like. For sawing procedures, the attachment may comprise a sagittal attachment. However, it is contemplated that the attachment can comprise other drilling attachments, reaming attachments, or saw attachments.

The surgical end effectors associated with the attachments, as described above, can comprise: micro burs, wires, pins, reamers, radiolucent drill bits, micro blades, or the like. However, in other embodiments, the surgical end effector can comprise other cutting accessories.

Referring toFIGS. 1 and 2, the coupler14is of the type configured to operably couple directly to the surgical end effector12, and the drive system18comprises the output member16operably engaged with the coupler14for actuating the surgical end effector12to perform an operational function. The drive system18may be configured to transmit torque through the coupler14to the surgical end effector12to perform the operational function. As described in detail below, the handheld surgical instrument comprises multiple interfaces between driving members used to drive the surgical end effector to perform the operational function, and movement of those driving members within the cumulative backlash of the interfaces can provide tactile feedback without moving the surgical end effector and performing the operational function.

The motor24comprises a motor shaft that defines a motor output region42, and the motor24may be configured to drive the motor output region42. The motor24may be implemented in the form of an inrunner brushless DC electric motor (BLDC motor) as best shown inFIGS. 2 and 3. The motor output region42may be in the form of an output shaft. The BLDC motor24can further comprise an external stator46with a plurality of windings or coils48, which are in spaced radial arrangement with the rotor44. The coils48are configured to receive a direct current and become energized to provide electromagnets and create an alternating magnetic field that attracts and repels the permanent magnets of the rotor44to generate rotational torque and drive the motor24to actuate the surgical end effector12to perform the operational function.

It will be appreciated that the drive system can comprise other motors of any suitable type or configuration. For example, the motor could be an outrunner BLDC motor, a brushed electric motor, or any other suitable motor for transmitting torque to the surgical end effector in the rotational direction, a reciprocating linear direction, or any other motion. It will also be appreciated that one motor (not shown) could be used to perform the operational function OF, and a different motor (not shown) could be used to perform the feedback function.

The transmission output region comprises one or more drive heads as detailed in the description forFIG. 8. The output member16may be implemented as a rotating front-end assembly that defines an output member input region29operably coupled to the transmission output region25such that drive of the transmission output region25causes drive of the output member input region. The coupler14may be implemented as the distal end of the rotating front-end assembly.

The drive system18may further comprise a transmission26defining a transmission input region27operably coupled to the motor output region42to cause drive of the transmission input region27. The transmission26further defines a transmission output region25operably coupled to the transmission input region27such that drive of the transmission input region27is configured to cause drive of the transmission output region25. The transmission output region25is operably coupled to the output member16such that drive of the transmission output region25is configured to cause drive of the output member16and alter the speed of said output member16relative to said motor24. The motor output region42and the transmission input region27interface one another at a motor-transmission interface, and the motor-transmission interface has a motor-transmission backlash such that drive of the motor output region42within the motor-transmission backlash does not cause drive of the transmission input region27.

The transmission26comprises a plurality of gears meshed with one another at a plurality of internal transmission interfaces, and at least one of the internal transmission interfaces comprises an internal transmission backlash. In this embodiment, the transmission26comprises a planetary gear train that defines a plurality of stages interfacing with one another at a plurality of internal transmission interfaces, and at least one of the internal transmission interfaces comprises an internal transmission backlash such that drive of the transmission within the internal transmission backlash does not cause drive of the output member16.

The transmission26can be configured to increase or reduce the torque output generated by the motor24and transmit the torque through the coupler14to the surgical end effector12or attachment to perform the operational function. In the illustrated embodiment, the transmission26is disposed in the distal region23of the handheld surgical instrument10. The handheld surgical instrument10may further comprise a clutch, which may be in the form of the clutch224illustrated inFIGS. 5B, 6A, and 6B.

The handheld surgical instrument10may further comprise a battery50(as shown inFIG. 4A) and/or external power (not shown) to supply energy to the drive system18, a controller20, an input device22, and the like. The drive system18can be supplied with a predetermined maximum draw for transmitting torque to the surgical end effector12to perform the highest-torque and/or highest speed drilling or reaming associated with the handheld surgical instrument10. The battery50can be lithium-ion battery. However, it is contemplated that the battery50can be various other batteries. In one embodiment, a visual indicator28, such as an LED, may be coupled to the battery50as described in detail below. The battery may have a microcontroller that is capable of determining of a status of the battery, such as the state of charge, a level of degradation, a number of uses, etc. The microcontroller of the battery may be configured to trigger the visual indicator based on the status of the battery, such as illuminating the LED when the state of charge or level of wear is below a predetermined threshold.

The input device22may comprise first and/or second variable-speed trigger buttons34a,34brealized as physical, movable components configured to be depressed, switched, toggled, and the like to generate one or more input signals IS (as shown inFIG. 4A) associated with performing one or more operational functions OF. The first and second variable-speed trigger buttons34a,34b, may generate the input signals IS in a way that is proportional to how much the user depresses the first and/or second variable-speed trigger buttons34a,34b. Those having ordinary skill in the art will appreciate that the input signal IS could be realized in a number of different ways depending on the specific configuration of the input device22. For example, the input signal IS could be realized as a variable signal, a digital or analog signal, a waveform, and the like. Thus, as will be appreciated from the subsequent description below, either via the input signal IS directly or by the controller20, an output signal or waveform used to drive the drive system18could affect performance of the operational function in a number of different ways. In other embodiments, the input device can comprise one, three, four, five, or more buttons or other suitable types of input devices.

The handheld surgical instrument10can further comprise one or more non-tactile indicators. The non-tactile indicator can comprise an audible indicator, the visual indicator28, or other suitable indicator mounted in any suitable location or configuration on the handheld surgical instrument10. In this exemplary embodiment, the visual indicator28can comprise a light emitter70, such as an LED (not shown) and a ring-shaped light guide72coupled to the battery. It is contemplated that the handheld surgical instrument may comprise any number of other suitable visual indicators mounted to any location of the handheld surgical instrument, such as the handle or proximal portion of handheld surgical instrument. In other embodiments, the handheld surgical instrument may not comprise visual indicators.

The handheld surgical instrument10can further comprise one or more sensors configured to detect any number of conditions associated with an event and generate a grip event signal. In this exemplary embodiment, the event is a grip event when the surgical end effector12becomes bound, pinched, or misaligned while the surgical end effector is being actuated for performing an operational function such that debris impedes the motion of the surgical end effector and kickback transfers torque from the surgical end effector through the transmission and the motor to the user. For example, the grip event may comprise the surgical end effector becoming bound, pinched, or misaligned when drilling into high-density bone such that debris impedes the rotation or other cutting motion of the surgical end effector12and the kickback can create discomfort for the user and decrease the ability of the user to control the handheld surgical instrument10. The handheld surgical instrument10, can comprise first and second sensors30,32configured to detect two conditions associated with an event and generate first and second event signals ES1, ES2(as shown inFIGS. 4B and 4C) indicative of those conditions, as described in greater detail below.

In this exemplary embodiment, the first sensor30may comprise a gyroscope36configured to detect rotation of the handheld surgical instrument10at an angular velocity and generate a first event signal ES1associated with the same. The second sensor32can comprise a current sensor38, which is configured to detect a current supplied to the drive system18to actuate the drive system18to transmit torque to the surgical end effector12for performing the operational function, and the current sensor38can generate a second event signal ES2associated with the same. It is contemplated that the handheld surgical instrument can comprise one, three, four, five or more sensors. The handheld surgical instrument can comprise other suitable sensors configured to detect conditions associated with a low battery level, drive system slippage, or any other event. The detection of a grip event, i.e., a kickback event, can be accomplished in any suitable way, and the hardware and methods of detecting a kickback event described in U.S. Pat. No. 7,681,659, POWER TOOL ANTI-KICKBACK SYSTEM WITH ROTATIONAL RATE SENSOR issued Mar. 23, 2010 and incorporated herein by reference in its entirety.

As described in detail below, the controller20is operably engaged with each sensor to receive a grip event signal from each sensor, and the controller20is configured to determine a grip event based on the same. The controller20is further configured to oscillate the drive system18in first and second directions within a cumulative backlash of the handheld surgical instrument to perform a feedback function without causing the surgical end effector12to perform the operational function. As shown inFIG. 5B, the cumulative backlash may include backlash at the motor-transmission interface1000, backlash at interfaces between driving members integral to the motor24, backlash at interfaces1002,1008between gears of the transmission26, and backlash at a transmission-output member interface1004. As shown inFIG. 5B, in embodiments where the handheld surgical instrument includes a clutch, the cumulative backlash may include backlash at a transmission-clutch interface1004(FIG. 28A).

In one embodiment, the controller20may be configured to control the current supplied to the coils48and oscillate the motor shaft42of the drive system to perform the feedback function without rotating the rotary surgical end effector12. The controller20may be configured to control the current supplied to the coils48for selectively commutating any portion of the motor24, the transmission60, the clutch, the output member16, or other suitable portions of the handheld surgical instrument within respective backlashes at interfaces between those components of the handheld surgical instrument or within backlashes internal to the components to perform a feedback function, while not moving the surgical end effector12and performing the operational function.

For example, the current supplied to the coils48can be insufficient to create a magnetic flux for fully commutating the motor24and performing the operational function, but the current may be sufficient to only partially commutate the motor24and perform the feedback function. When the motor24performs the feedback function, the rotor44can oscillate back-and-forth in first and second directions between spaced apart coils48, thereby causing the BLDC motor24to “vibrate” to generate haptic feedback FB without applying sufficient torque and rotational movement through the drive system to the coupler14and moving the surgical end effector12. Depending on the frequency at which the rotor44vibrates, the resulting feedback generated by the rotor44could be audible feedback and/or haptic feedback.

Continuing the previous example, the rotor44can be configured to vibrate at different predetermined frequencies, durations, and the like to generate different types of haptic feedback. Those having ordinary skill in the art will appreciate that audible feedback occurs within a range of frequencies which are detectable by the human ear. Moreover, it will be appreciated that oscillation of the drive system, such as vibration of the rotor44can simultaneously generate both audible feedback and haptic feedback of different intensities. For example, feedback FB generated by the rotor44could be haptic feedback realized as vibrations translated to and felt by the user at the hand grip or handle of the handheld surgical instrument10as described in greater detail below, and also as audible feedback realized as a relatively quiet hum or buzzing noise. Conversely, feedback generated by the rotor44could be audible feedback realized as a relatively loud tone, and also as haptic feedback realized as vibrations translated to but not necessarily felt by the user at the input device22.

The motor output region42and the transmission input region27interface one another at a motor-transmission interface, which may be implemented as the motor-transmission interface1000shown inFIG. 5B. The motor-transmission interface1000may have a motor-transmission backlash such that drive of the motor output region42within the motor-transmission backlash may perform the feedback function and provide tactile feedback while not causing rotation of the rotary surgical end effector12to perform the operational function.

Referring toFIG. 4A, the controller20is in electrical communication with the input device22to receive the input signal IS from the input device22. Based on the input signal IS, the controller20can determine an operational function OF commanded by the user, and the controller20may generate an operate signal OS associated with the operational function OF. The drive system18can receive the operate signal OS from the controller20and supply sufficient current to the coils to fully commutate the motor24and transmit torque through the coupler14to the surgical end effector12to perform the associated operational function OF.

The input device22may comprise the first and second variable-speed trigger buttons34a,34b. The first variable-speed trigger button34amay be fully depressed without depressing the second variable-speed trigger button34b, such that the input device22generates an associated input signal IS received by the controller20. Based on the input signal IS, the controller20may determine that the operational function OF commanded by the user is the highest-speed and/or highest-torque for drilling or reaming in a first direction, and the controller20may generate an operate signal OS based on the input signal IS. Conversely, when the second variable-speed trigger button34bis fully depressed without depressing the first variable-speed trigger button34a, the input device22may generate another input signal IS received by the controller20. Based on this input signal IS, the controller20may determine that the operational function OF commanded by the user is the highest-speed and/or highest-torque drilling or reaming in a second direction that is opposite to the first direction, and the controller20may generate the associated operate signal OS. It is contemplated that one or both buttons34a,34bcan be only partially depressed to generate other input signals IS, and based on these input signals IS, the controller20may determine that the operational function OF commanded by the user is less than the highest-speed and/or highest-torque drilling or reaming. In other embodiments, the controller20can determine any number of other operational functions OF commanded by the user for the associated handheld surgical instrument10and the controller20may generate the associated operate signal OS based on the input signal IS. The drive system18can receive the operate signal OS from the controller20, such that the drive system18is actuated to transmit torque through the coupler14to the surgical end effector12for performing the associated operational function OF.

Referring toFIGS. 4B and 4C, the controller20can be in further electrical communication with the sensors30,32to receive the event signals ES1, ES2from the sensors30,32and generate a feedback signal FS based on the event signals ES1, ES2. Continuing with the previous example, the sensors30,32may comprise the gyroscope36and the current sensor38configured to generate the first and second event signals ES1, ES2respectively associated with the measured angular velocity of the handheld surgical instrument10and the current supplied from the battery to the motor24.

Based on the first event signal ES1, the controller20may determine that the handheld surgical instrument10is being rotated at a threshold angular velocity of at least 500 degrees per second. It is contemplated that the controller can determine that the threshold angular velocity associated with the grip event can be above or below 500 degrees per second. In other embodiments, the controller20can determine that the grip event has occurred when the gyroscope36measures an angular velocity equal to a first threshold angular velocity, and the controller20can determine that the grip event has terminated when the gyroscope measures an angular velocity equal to a second threshold angular velocity different from the first threshold angular velocity.

Based on the second event signal ES2, the controller20may determine that current is being supplied from the battery50to the drive system18. Because the current sensor38generates the second event signal ES2for indicating rotation or other cutting motion of the surgical end effector12associated with a grip event, the current sensor38can be used in combination with the gyroscope36to prevent the false detection of a grip event. In particular, if the gyroscope36were acting alone without the assistance of the current sensor38, the gyroscope36could falsely detect a grip event when the handheld surgical instrument10, is merely waved in the air at the predetermined angular velocity associated with a grip event, without the input device22, e.g., button, being actuated to supply power from the battery to the drive system18for rotating the surgical end effector12and thus creating the possibility of a grip event. In view of these determinations, the controller20may further determine that a grip event has occurred and generate a feedback signal FS.

Referring toFIG. 4B, the controller20may generate the feedback signal FS to actuate the drive system18to perform the feedback function FF, without actuating the drive system18to generate torque transmitted to the surgical end effector12for performing the operational function OF. In particular, when the controller20simultaneously receives the input signal IS and the first and second event signals ES1, ES2associated with the predetermined event, the controller20does not generate the operate signal OS. Rather, the controller20may generate only the feedback signal FS to actuate the drive system18to perform the feedback function FF and terminate the operational function OF. The operational function OF can be terminated by stopping the drive system18. For example, a brake device (not shown) may be utilized to slow or at least momentarily halt motion of the drive system18when the controller20determines that a grip event has occurred based on the first and second event signals ES1, ES2from the first and second sensors30,32.

While the operate signal OS could comprise any suitable configuration sufficient to actuate the drive system18to generate torque to perform the associated operational function OF, the feedback signal FS does not actuate the drive system18to generate the torque needed to perform the operational function OF. Put another way, the controller20is configured to actuate the drive system18to generate torque transmitted to the surgical end effector12for performing an operational function OF (seeFIG. 4A) and independently actuate the drive system18to perform one or more feedback functions FF (seeFIGS. 4B and 4C). Continuing the previous non-limiting example, the operate signal OS may be associated with the highest-torque and/or highest-speed drilling and reaming associated with the handheld surgical instrument10. This operate signal OS can require that the drive system18be supplied with a maximum draw from the battery50or other electrical source for transmitting the necessary torque to the surgical end effector to perform the highest-torque and highest-speed drilling and reaming associated with the handheld surgical instrument10. The feedback signal FS can require that the drive system18be supplied with a draw from the battery50that is one-tenth of the maximum available draw from the battery50or other electrical source. It is contemplated that feedback signal FS can require that the drive system18be supplied with a draw more or less than one-tenth of the maximum available draw from the battery50or other electrical source.

The drive system18may be configured to perform the feedback function FF to provide feedback to the user by oscillating the rotor44in first and second directions, when the drive system18receives the feedback signal FS from the controller20, such that the drive system18vibrates the handheld surgical instrument10to provide haptic feedback. The haptic feedback can indicate to the user that the grip event occurred and the controller20terminated the operational function OF to protect the user, the patient, and the handheld surgical instrument. In addition, the haptic feedback can indicate to the user that the operational function OF did not end as a result of a low or discharged battery or any damage to the handheld surgical instrument10.

Continuing with the previous example, the drive system18can perform the feedback function FF in response to receiving the feedback signal FS from the controller20. While the operate signal OS could commutate the motor24to fully rotate the rotor and subsequently drive the motor24to generate rotational torque transmitted to the surgical end effector12to perform the operational function OF, the feedback signal FS can be insufficient to fully commutate the motor24in the same manner. The feedback signal can be sufficient to vibrate the motor24to generate haptic feedback HF and perform the feedback function FF for reasons other than the grip event.

The controller20may be configured to control the drive system18to generate haptic feedback HF that can be used to indicate a status condition to the user. By way of non-limiting example, haptic feedback HF could be used to indicate the grip event while also verifying proper functionality of the drive system18and charge status of a battery50, such as may be advantageously implemented in connection with a diagnostics and/or service mode of the handheld surgical instrument10. In one embodiment, the controller20may be configured to generate a plurality of different haptic waveforms, which may be used to perform the feedback function FF by vibrating the drive system18at different frequencies, durations, intensities, and the like, so as to generate correspondingly different haptic feedback HF. The specific type of haptic feedback HF generated by the drive system18could be used to provide the user with a number of different types of tactile feedback FB and, thus, could advantageously afford the handheld surgical instrument10with enhanced functionality in use. By way of illustration, haptic feedback HF could be implemented as a short “burst” of vibration directed toward the user so as to indicate activation of the input device22during a grip event when the operational function of the drive system is terminated. For example, the controller can implement the feedback function FF for the same amount of time that the user actuates the input device22, e.g., button, for generating the input signal. However, the duration of the feedback function FF can be longer or shorter than the time that the input device22is actuated by the user.

Referring toFIG. 4C, the controller20can further transmit the feedback signal FS to non-tactile indicators. In this non-limiting example, the controller20can transmit the feedback signal FS to the visual indicator28to actuate the visual indicator28to provide feedback FB when the controller20determines an event based on the first and second event signals ES1, ES2. Where the visual indicator28comprises the light emitter70and/or the ring-shaped light guide72, the feedback signal FS can actuate the light emitter70to emit a constant light through the entire ring-shaped light guide72or a portion of the same. However, the feedback signal FS can actuate the light emitter70to intermittently emit light at regular or irregular predetermined frequencies. The feedback signal FS may actuate the light emitter to emit one or more colors indicating feedback associated with the event. For example, the feedback signal FS may actuate the light emitter to intermittently emit a red light to indicate a kickback or grip event, intermittently emit a yellow light to indicate slippage of the drive train18, or continuously emit a solid red light to indicate a low battery. It is contemplated that the controller20can generate other feedback signals FS to actuate the light emitter to emit any color at any frequency, actuate other visual indicators having other configurations, or actuate other non-tactile indicators to provide any type of feedback FB to the user.

The controller20may have one or more microprocessors for processing instructions or for processing an algorithm stored in memory to control operation of the drive system18and/or generation of the input signal IS, the feedback signal FS and/or the operate signal OS, such as via the drive system18. Additionally or alternatively, the controller20may comprise one or more microcontrollers, field programmable gate arrays, systems on a chip, discrete circuitry, and/or other suitable hardware, software, or firmware that is capable of carrying out the operational and feedback functions OF, FF described herein.

The controller20may generate the operate signal OS and the feedback signal FS in the form of separate waveforms or output signals. The operate signal OS and the feedback signal FS may be pulse-width modulation signals. However, these signals could be of any suitable type or configuration sufficient to drive the drive system18for performing the operational function and oscillate the drive system18for performing the feedback function FF and provide feedback FB as noted above.

FIGS. 5A, 5B, 6A and 6Billustrate a rotary handheld surgical instrument200constructed in accordance with one embodiment. It should be appreciated that other constructions are also possible. Handheld surgical instrument200has a housing202in which in a motor204is seated. In one embodiment of the handheld surgical instrument200, motor204is a DC motor. In other embodiments, motor204may be an AC motor, or a pneumatic or hydraulically driven motor. Integral with the motor204is rotating output shaft in the motor output region206. Handheld surgical instrument housing202is shaped to have a generally cylindrical head208in which motor204is fitted.

A transmission216is connected to the exposed distally located front end of the motor output region206. The transmission216includes gears that reduce the speed and increase the torque of the rotational moment output by the motor output region206. The transmission216has two rotating drive heads266,272(as shown inFIGS. 7-8). Owing to the arrangement of the gears forming the transmission216, the rotation of motor output region206causes drive heads266,272to simultaneously rotate at different speeds. Transmission216thus functions as a speed reduction assembly that outputs rotational force at two separate speeds.

The handheld surgical instrument200further comprises a clutch224defining a clutch input region that is operably coupled to the transmission output region such that drive of the transmission output region is configured to cause drive of the clutch input region. The clutch in the first position may be configured to interface the clutch input region with one of the two gear sets at a first transmission-clutch interface having a first transmission-clutch backlash such that drive of the transmission output region within the first transmission-clutch backlash does not cause drive of the clutch input region. The clutch in the second position may be configured to interface the clutch input region with the other one of the two gear sets at a second transmission-clutch interface having a second transmission-clutch backlash such that drive of the transmission output region within the second transmission-clutch backlash does not cause drive of the clutch input region.

In an exemplary embodiment, the clutch input region may be implemented in the form of pins (as shown inFIG. 6B, 364) that are operably coupled to the transmission output region, which may be implemented in the form of gear sets or drive heads (as shown inFIG. 8, 266, 272), such that the drive of the drive heads is configured to cause drive of the pins364. The pins364are movable to a first position where one of the two gear sets266,272is operably coupled to the pins364and configured to cause drive of the pins364. The pins364are further movable to a second position where the other one of the two gear sets266,272is operably coupled to the pins364and configured to cause drive of the pins364. The clutch224further defines a clutch output region operably coupled to the output member.

The transmission output region and the clutch input region interface one another in at least one transmission-clutch interface having a transmission-clutch backlash such that drive of the transmission output region within at least one transmission-clutch backlash does not cause drive of clutch input region. Continuing the previous embodiment, when the clutch input region (as shown inFIG. 6B, 364) is in position to engage either one of the two drive heads266,272of the transmission output region, there will be a backlash between pin364and drive head266or drive head272at the backlash interface1004(as shown inFIG. 5B).

The clutch output region may be statically fixed to the output member, when driven drives the output member through a spindle222(as shown inFIG. 6A). Backlash can occur at the interface between the pins of the clutch input region and the drive heads of the transmission output region. Backlash can occur anywhere internal to the clutch, for instance the pins (as shown inFIG. 6B, 222) and the clutch output region (as shown inFIG. 12, 304).

Referring toFIGS. 5B, 6A and 6B, the spindle222is rotatably mounted to the housing forward of transmission216. A clutch224selectively connects one of the two transmission drive heads266,272to spindle222so that the spindle and connected drive head rotate in unison.

A mount226releasably holds the coupler, which is in the form of a speed-altering surgical attachment500(as shown inFIG. 28A) or a surgical end effector228(as shown inFIG. 27), to the spindle222of the output member. In the embodiment ofFIG. 28A, the surgical end effector228may be implemented as an acetabular reamer. However, other embodiments of the surgical end effector are contemplated. Surgical end effector228has a distal end tissue working head230, which may be implemented in the form of an acetabular reamer head. Extending proximally from tissue working head230, surgical end effector228has an elongated shaft232. A mounting head234is attached to the proximal end of shaft232. Coupling head234is formed with geometric features that facilitate the rotational coupling of surgical end effector228to spindle222and minimize wobble of the end effector relative to the handheld surgical instrument200.

Handheld surgical instrument200is constructed so that the distal end of spindle222is formed with a bore300(as shown inFIG. 11) for receiving the attachment/end effector coupling head234(as shown inFIG. 7). Coupler226locks the end effector coupling head234in spindle bore300. As a consequence of this engagement, the coupling head234, and therefore the whole of surgical end effector228, rotates in unison with the spindle222.

Transmission216, now described by reference toFIGS. 6A, 8 and 9, includes a first set of three planet gears242(two shown). Planet gears242are each rotatably mounted to a generally disc-shaped planet carrier244. Planet gears242and planet carrier244, as with the remaining planet gears and planet carriers of transmission216, are housed in a generally tubular-shaped ring gear246. Ring gear246has a smooth outer wall and a toothed inner wall (teeth not illustrated). The teeth of planet gears242, as well as the teeth of the remaining planet gears254,262, engage the teeth of ring gear146.

Ring gear246is statically mounted in the handheld surgical instrument housing head208forward of motor204. To facilitate the static mounting of ring gear246, the ring gear is formed with two proximally extending feet248. The feet seat in openings formed in an internal structural web250of the housing to block rotation of the ring gear (openings not identified).

Planet gears242seat over and engage a pinion gear251disposed over motor output region206(identified inFIG. 6A). Thus, the rotation of motor output region206causes the rotation of planet gears242and planet carrier244.

A first sun gear252is integrally mounted to planet carrier244. In this embodiment, first sun gear252is positioned concentric with planet carrier244and extends distally forward from planet carrier244. Sun gear252engages a second set of three planet gears254(two shown). Planet gears254are rotatably disposed around a second planet carrier256. A tubular post258is integrally attached, concentric with and extends distally forward from second planet carrier256. A set of teeth disposed around the proximal end base of post258form a second sun gear260.

Second sun gear260engages a third set of planet gears, four planet gears262(one shown). Planet gears262are rotatably attached to and disposed around a third planet carrier264. A first drive head266is formed integrally with and extends axially forward from the third planet carrier. The first drive head266has a generally circular outer profile. The outer surface of drive head266is further shaped to have a plurality of longitudinally extending inwardly concaved, notches268. The notches268, which are circumferentially spaced apart, are located around the whole of the circumference of drive head266. Planet carrier264is further formed to have an axially extending through bore270. Bore270extends completely through both the planet carrier264and drive head266.

A second drive head272is positioned distally forward of, and concentric with, drive head266. Drive head272has the same outer diameter as drive head266. Drive head272defines notches274that have the same profile of notches268of the first drive head266. A tubular-shaped stem276extends proximally rearward from drive head272. In many embodiments of the invention, second drive head272and stem276are integrally formed. When transmission216is assembled, post258of the second planet carrier256is disposed in bore270of third planet carrier264and drive head266. Stem276similarly is disposed in bore270. More particularly, stem276is dimensioned to be tightly press fit over post258. Thus, drive head272rotates in unison with the second planet carrier256. Collectively, post278and stem276are shaped so that there is a longitudinal separation between drive heads266,272.

Drive head266and stem276are further collectively shaped so that the outer surface of the stem is spaced inwardly of the adjacent bore270defining the inner wall of the drive head. This arrangement allows stem276to rotate freely relative to the drive head268. Adjacent the proximal end of stem276, a bearing assembly277extends between post258and an adjacent inner circular wall internal to planet carrier264. More particularly, the planet carrier internal wall against which the outer race of bearing assembly277seats defines an elongated groove279that is concentric with and has a larger outer diameter than planet carrier bore270. A retaining ring280disposed proximal to the bearing assembly277holds the bearing assembly in position. Retaining ring280is snap fitted in a groove281also formed in the interior of planet carrier264. The planet carrier264is formed so that groove281is between the proximal end opening of bore270and groove279and is of greater diameter than groove279.

Drive head272has a nose271. Nose271extends forward of the portion of the drive head formed with notches274. An O-ring269is disposed over nose271. O-ring269is fitted over the drive head nose271portion immediately distal to the portion of the nose that defines notches274.

A bearing assembly275rotatably holds planet carrier264to the static ring gear246. Bearing assembly275has an outer race (not illustrated) seated in the perimeter of a counterbore247that forms the open end of ring gear246. The inner race of bearing assembly275(not illustrated) seats against an annular step278formed in the outer perimeter of the third planet carrier264. A retaining ring267holds bearing assembly275and, by extension, the moving components of gear train216in ring gear246. Retaining ring267is snap fitted in a groove273formed in the inner wall of the ring gear246that defines counterbore247.

As shown inFIG. 5B, the motor output region may be implemented as the pinion gear251, which interfaces with the transmission input region, which may be implemented as the first set of planet gears,242, at the motor-transmission interface having a first backlash interface1000. Also in this embodiment, the transmission may have a backlash interface1002between the first sun gear252and the second planet gears254and a backlash interface1008between the second sun gear260and the third set of planet gears264.

Referring toFIGS. 10 and 11, the spindle222may be implemented in the form of a single piece of metal that has circular sections of different diameters. At the most proximal end, spindle222comprises the coupler in the form of a head282defining a bore284with a hexagonal cross-sectional profile. However, it is contemplated that the bore can have a cross-section profile in the form of any suitable shape. Bore284is configured to closely slip fit receive the proximal end of the surgical end effector coupling head234fitted to the surgical end effector228. The close fitting is required because the inner surfaces285of the head282that define bore284are the surfaces that transmit the torque to the surgical end effector228.

Extending distally from head282, spindle222has a collar286. Collar286is shaped to have an outer diameter greater than that of head282. Immediately proximal of the distal end of the collar286, the collar is shaped to have a groove288that extends circumferentially around the outer surface of the collar. Collar286is further formed to define an opening290that extends laterally through the collar. Opening290is located to extend through an arcuate section of the collar286that defines the base of groove288. Opening290extends from a base of a recess291cut into the outer surface of collar286.

Spindle222further comprises the output member formed as a stem292that projects distally from collar286. Stem292has a number of sections with different outer diameters. A proximal section293adjacent collar286has a diameter approximately equal to that of sleeve head282. Stem section293is formed to have two diametrically opposed receiving slots294. Each receiving slot294is in a plane that, relative to the longitudinal axis of spindle222, extends diagonally forward. In some embodiments of the invention, each slot294is in a plane that, relative to the longitudinal axis of the spindle222, is at an angle of approximately 450. Thus, as seen inFIG. 10, when viewing a slot294from the front, a slot294appears to have a curved profile.

Distally from section293, the stem292is further formed to have a circumferential groove296. Forward of groove296stem292has an intermediate section295. Section295has a diameter slightly less than that of proximal section293. The reduced diameter of stem section295allows below discussed wave spring357(as shown inFIG. 26) to freely flex.

Forward of section295, spindle stem292is formed with a distal end section297. Stem section297has an outer diameter between the diameters of sections293and295. The inner race of a bearing assembly353(as shown inFIG. 6A) tightly fits over stem section297. A groove298extends circumferentially around the outer surface of stem292. Groove298is located immediately proximal to the distal end of stem section297, which is also the distal end of spindle222.

Spindle222is further formed to have a bore300that extends from the distal end, through stem292and collar286to bore284. Bore300is concentric and contiguous with bore284. In preferred embodiments, bore300has a circular cross sectional profile, though that need not always be the case. Bore300is dimensioned to facilitate the close slip fitting of a coupling head234of the surgical end effector228as discussed below.

A pin301(as shown inFIG. 26) is fitted in spindle opening290(as shown inFIG. 11), so as to be directed to the longitudinal center axis of the spindle222. Pin301extends into bore300.

Referring toFIGS. 12 and 13, a generally tubular-shaped clutch output region304is tightly fitted to the spindle222. Clutch output region304may have a constant outer diameter. The clutch output region304is further formed to have a proximal end bore306that extends distally forward from the proximal end of the coupler. In this exemplary embodiment, proximal end bore306extends approximately half way through the length of the coupler. Clutch output region304also has a distal end bore308that extends rearward from the distal end of the clutch output region. Distal end bore308has a diameter that facilitates the compression fitting of sleeve head282in the bore308.

Between the proximal end bore306and distal end bore308, clutch output region304is formed to have a circular void space307. The outer perimeter of void space307is defined by a circular flange309that extends inwardly from the inner walls of clutch output region304that define bores306and308and space307. Flange309has a distally-directed, laterally-extended annular face against which the proximally-directed face of sleeve head282abuts. Clutch output region304is further formed to have four longitudinally extending slots314. Each slot314extends from the outer surface of the clutch output region304into the proximal end bore306. Slots314are uniformly spaced apart from each other around the perimeter of the clutch output region304.

Clutch output region304itself is shaped to have an outer diameter that is slightly greater than the outer diameter of spindle collar286. When the spindle head282is inserted in the clutch output region304, the distal end face of the clutch output region forms an annular step around the proximal end of the spindle collar286.

Referring back toFIG. 6A, it can be seen that when surgical handheld instrument200is assembled, the spindle222and clutch output region304sub-assembly are fitted in the housing208so that gear train drive heads266,272of the transmission output region are disposed in the proximal end bore306of the clutch output region. Clutch output region304is shaped so that the inner wall that defines the proximal end bore306is spaced away from the drive heads266,272. Drive head nose271seats in clutch output region void space307. O-ring269abuts the adjacent inner face of clutch output region flange309.

Transmission216, clutch output region304, and spindle222are substantially disposed in a rotary housing310that extends distally forward from the front of handheld surgical instrument housing202. The rotary housing310, now described by reference toFIGS. 14-16, is formed from a single piece of metal that has a number of circular cross-sectional sections. The most proximal section of the rotary housing310is a base312. The outer surface of rotary section base312adjacent the proximal end of the rotary section is formed with threading317(seen inFIG. 15only). Base312is formed with an open ended bore316. Bore316is dimensioned to facilitate the loose slip fitting of the base over transmission ring gear246. When handheld surgical instrument200is assembled, base threading317engages complementary threading318formed around an inner wall of housing208(as shown inFIG. 6A). This threaded engagement holds rotary housing310to the handheld surgical instrument housing208.

Extending distally of the threaded section, rotary housing base312is formed with a section320with a smooth outer wall. Forward of base section320, the rotary housing310has a flange322that extends radially outward of base312. Flange322is the structural component of the rotary housing310that stops proximal movement of the rotary housing when the housing is screw fitted to the handheld surgical instrument housing208. Rotary housing310is further formed to define four slots324that extend through base section320and flange322. Slots324are uniformly spaced apart from one another about the circumference. The slots324function as spaces for receiving a fastening tool (not illustrated) used to screw secure the rotary housing310to the handheld surgical instrument housing208during manufacture.

Forward of flange322, rotary housing310forms a clutch sleeve326. Clutch sleeve326has a diameter slightly less than that of base312. The clutch sleeve326is formed to have four slots328uniformly spaced apart from one another about the circumference. Slots328extend diagonally downwardly around the outer circumference of the clutch sleeve326. Four holes330are uniformly spaced apart from one another about the circumference of the clutch sleeve326. Holes330are in a common circumferential section of the clutch sleeve located proximal to the proximal ends of slots328. Holes330are provided to facilitate manufacture and disassembly of the handheld surgical instrument200.

A groove332is formed in the clutch sleeve326to extend circumferentially around the outer surface of the sleeve. Groove332is located proximally rearward of the forward distal end of the clutch sleeve326. The outer surface of the clutch sleeve326located distal to groove332and extending to the distal end of the clutch sleeve is provided with threading334(seen inFIG. 15).

Projecting distally forward of clutch sleeve326, rotary housing310has a coupling neck336. Coupling neck336has a diameter less than that of clutch sleeve326. The coupling neck336is formed to define four slots338uniformly spaced apart from one another. Slots338extend longitudinally along the coupling neck336and are generally located in the most distal portion of the coupling neck338.

A head340forms the most distal section of rotary housing310. Head340extends forward from and has a diameter less than that of coupling neck336. Head340is formed with an inwardly directed circumferential lip342. Lip342defines the open distal end of the rotary housing, (distal end opening not identified).

Rotary housing310is further formed so that extending axially and distally forward from bore316there is a bore346that extends to the distal end of the housing. Bore346has sections of different diameters. The diameters of the different bore sections (not identified) are generally sized relative to each other in the same manner as the outer diameters of the clutch sleeve326and coupling neck336, and head340correspond to each other. The rotary housing310is further formed to have a groove348that extends inwardly from a housing inner wall that defines one of the sections of bore346. Specifically, groove348is formed in the housing clutch sleeve326so as to be immediately distal to the circular slice of the sleeve326in which outer circumference groove332is formed.

Bearing assemblies352,353, seen best inFIGS. 6B and 26, rotatably hold the spindle and outer coupler sub-assembly to the rotary housing310. The outer race of bearing assembly352(outer race not illustrated) seats against the bore346defined by the inner wall of the housing clutch sleeve326. The proximal end of the bearing race seats against the stepped inner annular surface of the rotary housing between the clutch sleeve326and the coupling neck336. The proximally-directed face of the outer race of bearing assembly352abuts a retaining ring354disposed in bore346. Retaining ring354is snap fitted in rotary housing groove348.

The inner race of bearing assembly (not illustrated) is press fit over spindle collar286. When the handheld surgical instrument200is assembled, the proximal end of the inner race of bearing assembly is disposed against the annular portion of the distally directed face of the adjacent clutch output region304. As discussed above, the outer race of bearing assembly352is blocked from distal movement by the adjacent inner walls of the rotary housing310. Thus, the abutment of the clutch output region304against the inner race of bearing assembly352by extension blocks distal movement of the spindle and outer coupler sub-assembly.

Bearing assembly353extends between the distal front end of spindle stem292and the adjacent inner wall of the rotary housing head340. The outer race of bearing assembly (not illustrated) seats against the inner wall of the rotary housing310within the housing head340. The bearing assembly outer race also abuts the proximally-directed surface of rotary housing lip342. The distally directed face of the inner race of bearing assembly353seats against a retaining ring355. Retaining ring355is snap fitted into groove298of spindle stem292. Thus, collectively, rotary housing lip342and retaining ring355block forward movement of bearing assembly353.

Washers356and357and retaining ring358cooperate to prevent proximal movement of bearing assembly353. Two washers356are provided. The more distal of the two washers356is disposed against the proximally-directed face of the bearing assembly353. Washer357, which is flexible wave washer, is sandwiched between the distal and proximal washers356. The retaining ring358seats in spindle groove296. The retaining ring358extends above the outer surface of the surrounding spindle sleeve292. When handheld surgical instrument200is assembled, the exposed portion of the retaining ring358blocks proximal movement of washers356and357and, therefore, similar movement of bearing assembly353. Wave washer357is provided to ensure that, in the event of manufacturing variations, the distal washer356is disposed against the bearing assembly353.

Washers356are L-shaped. The short vertical sections of the washers (not identified) are disposed around the outer surface of the spindle stem292. The washer356closest to bearing assembly353is positioned so its vertical section is against the inner race of the bearing assembly. This arrangement holds the washer356off the inner race of the bearing assembly353. The washer356adjacent retaining ring358is positioned so that its vertical section abuts the retaining ring.

When the spindle and clutch output region sub-assembly is so positioned, transmission output region drive heads266,272are both seated in the clutch output region proximal end bore306. Slots314are formed in the clutch output region304so as to extend over the drive heads266,272. Also, the components of this embodiment are dimensioned so that when the spindle222is seated in the rotary housing310, the most distal end of the spindle projects a slight distance forward of the surrounding distal end of the rotary housing.

Referring now toFIGS. 6A and 21, the clutch224includes a circular inner shifter360disposed inside the rotary housing clutch sleeve326over the clutch output region304. As best seen inFIGS. 20 and 21, inner shifter has a base361. Extending distally forward from base361, the inner shifter360is shaped to have a head362. Head362has an outer diameter less than that of base361. A constant diameter bore363extends axially through the inner shifter360from the proximal end of base361to the distal end of head362.

Inner shifter360is shaped so that when the clutch output region304is seated in bore363, the shifter is able to move longitudinally along the length of the outer coupler. Clutch224includes four torque pins364uniformly spaced apart from one another about the circumference and extending radially inwardly from the inner shifter base361. Each torque pin364is seated in a laterally extending opening365formed in the inner shifter base361. Each torque pin364extends through an associated one of the clutch output region slots314. Torque pins364are of sufficient length so end tips of the pins can seat in notches268and274of transmission drive heads266,272, respectively.

Referring toFIGS. 20 and 21, a shifter housing366disposed over the inner shifter360longitudinally moves the inner shifter360over the clutch output region304. The shifter housing366is generally in the form of a constant outer diameter, ring-shaped structure. Shifter housing366is further formed to, at the proximal end, have an inwardly extending lip368. A groove370extends inwardly from the annular inner wall of the shifter housing366that defines the center opening372through the housing. Groove370is located proximal to the distal end face of the shifter housing366. The shifter housing366is further formed to define two diametrically opposed spherical indentations374on the outer surface.

Shifter housing366is disposed in the rotary housing clutch sleeve326. Inner shifter head362is positioned inside the shifter housing366. A bearing assembly376is disposed between the outer circumferential wall of the inner shifter head362and the adjacent inner wall of the shifter housing366. The proximal end of bearing assembly376abuts the adjacent distally-directed annular surface of the inner shifter base361that projects radially beyond head362. The outer perimeter of the distally directed face of bearing assembly376abuts a retaining ring378fitted to the shifter housing366. Specifically, retaining ring378is snap fitted in shifter housing groove370. Thus, the capture of the opposed ends of bearing assembly376by the inner shifter base361and retaining ring378lock the inner shifter360and shifter housing366together for longitudinal movement. Bearing assembly376allows the inner shifter360and shifter housing366to axially rotate relative to each other.

Referring toFIGS. 22 and 23, a shift ring382rotatably mounted over the rotary housing clutch sleeve326is manually actuated to set the longitudinal position of the shifter housing366and, by extension, the inner shifter360. The shift ring382is generally in the form of a tubular member. Indentations384formed in the outer surface of the shift ring382facilitate the finger grasping of the ring. The shift ring382is further shaped to define an axially extending through bore386. Bore386is dimensioned to allow the shift ring382to rotate over the underlying rotary housing clutch sleeve326. At the proximal end, shifter ring defines a first counterbore388that forms the proximal end opening into bore386. A second counterbore390is located between the first counter bore388and bore386. The second counterbore390has a diameter between that of bore386and counterbore388.

At the distal end, shift ring382is formed to have a third counterbore392. The third counterbore392forms the distal end opening into bore386. The second and third counterbores390and392, respectively, are of identical diameter. The inner wall of shift ring382that defines bore386is further formed to define two longitudinally extending, diametrically opposed concave grooves394. Each groove394extends from the second counterbore390to the third counterbore392.

When handheld surgical instrument200is assembled, ball bearings396transfer the rotational motion of shift ring382into axial motion that displaces the shifter housing366. Each ball bearing396is seated in opposed ones of the rotary housing clutch sleeve slots328. Two ball bearings396are provided; there are four slots328. The additional slots328aid component orientation during assembly of the handheld surgical instrument200. Inside the rotary sleeve310, each ball bearing396seats in a separate one of the indentations374formed in the shifter housing366. Outside of rotary housing310, each ball bearing396seats in a separate one of the grooves394formed in clutch input region382.

When handheld surgical instrument200is assembled, rotary housing flange322seats in the clutch input region first counterbore388. O-rings398extend between the outer circumferential face of rotary housing310and the inner walls of clutch input region382. A first O-ring398is seated in the annular space of clutch input region second counterbore390. The second O-ring398is seated is seated in the clutch input region third counterbore392. Both O-rings398extend over the smooth outer surface of the rotary housing clutch sleeve326.

Referring toFIGS. 24 and 25, a shift ring nut400holds the shift ring382to the rest of the handheld surgical instrument200. Shift ring nut400is generally tubular-shaped. The shift ring400is formed to have a base402with a generally constant outer diameter. Forward of base402, shift ring nut400has a head404. Extending distally forward, the outer diameter of the shift ring head404tapers inwardly. The shift ring nut400is further formed to define two opposed flats406in the proximal end of the outer surface of base402. Flats406receive a fastening tool used to screw secure the shift nut400to the rotary housing310during assembly.

Bore408extends axially through the shift ring nut400from the proximal end to the distal end. The shift ring nut400is further formed to have an inwardly stepped annular lip410that extends inwardly from the inner circular wall that defines bore408. The inner round face of lip410is formed with threading411(as shown inFIG. 24). The shift ring nut400is screw secured to the rotary housing by engaging shift ring nut threading411with threading334on the rotary housing clutch sleeve326.

Clutch224is then set to couple the spindle222to one of the gear train drive heads266,272so that the spindle rotates with the selected drive head. Specifically, the clutch224is set so that torque pins364of the clutch input region seat in the notches268,274of the drive head266,272of the transmission output region, respectively, with which the spindle is to be connected. The setting of the torque pins364, e.g., the longitudinal positioning of the torque pins364, is performed by rotating clutch shift ring382. The rotation of shift ring382results in the helical movement of ball bearings396in rotary housing slots328. The longitudinal displacement of ball bearings396results in an identical longitudinal displacement of the shifter housing366. The longitudinal movement of the shifter housing366causes a like movement of the inner shifter360.

Since torque pins364are integral with inner shifter360, longitudinal displacement of the inner shifter results in the selective seating of the pins in either the notches268of the proximally located drive head266or notches274of the distally located drive head272.

Handheld surgical instrument200is now ready for operating. The depression of trigger switch212results in the actuation of motor204. Motor output region206rotates. Transmission216reduces the rotation moment output by shaft to two different speeds. Specifically, the gears internal to the gear train cause drive head266to rotate at a first reduced speed. Drive head272is caused to rotate at a second reduced speed less than the first reduced speed.

Depending on the setting of the clutch224, the torque pins364are seated in the notches268,274of one of the drive heads266,272, respectively. The torque pins364thus rotate at the speed of the drive head266,272with which the pins are engaged. The torque pins364extend through the clutch output region slots314. Consequently, the rotation of the torque pins results in a like movement of the clutch output region304and, therefore, the output member via spindle222. Since the coupling head boss482is relatively closely fitted in the spindle bore284, and these components have non-circular cross sectional profiles, rotary motion of the spindle222is transferred by boss482to the coupling head234and the rest of the surgical end effector228.

Referring toFIGS. 28A and 29, the coupler may be implemented in the form of a speed-altering surgical attachment500. The speed-altering surgical attachment500is operably engaged with the output member such that drive of the output member implemented in the form of an output drive shaft574causes drive of the speed-altering surgical attachment500, which in turn actuates the surgical end effector228to perform an operational function. The speed-altering surgical attachment500alters the speed of the surgical end effector relative to the motor.

Referring toFIG. 28B, the speed-altering surgical attachment500includes a housing502. An intermediate shaft504extends rearwardly from the housing502. Intermediate shaft504is shaped to have a proximal end mounting head506with the same features as surgical end effector mounting head234. Internal to the housing is a mounting assembly508represented by a phantom rectangle. Mount508is designed to releasably hold the proximal end of a surgical end effector (not illustrated) for rotation. The exact structure of the mount508is not relevant to this embodiment. Mount508may include the features of mounting assembly226. Alternatively, mount508may be provided with features to hold mounting heads other than the described mounting head234for rotation. These include mounting heads with trinkle fittings, Hudson® fittings and modified trinkle fittings that are known in the surgical art.

Intermediate shaft504rotates mount508. In this exemplary embodiment, intermediate shaft504and the spindle of mount508are the same component, and attachment500thus serves as a means for connecting a surgical end effector with a head different from mounting head234to the handheld surgical instrument. In this exemplary embodiment, the speed-altering surgical attachment rotates at the speed at which the handheld surgical instrument spindle222rotates. In other embodiments, such as the embodiment illustrated inFIG. 28A, there is a speed reducer or speed increaser gear assembly internal to the attachment housing502for transferring the rotational moment received by the input shaft506to the mounting head. The Applicants' Assignee's U.S. Pat. No. 5,993,454, DRILL ATTACHMENT FOR A SURGICAL DRILL, issued Nov. 30, 1999, and incorporated herein by reference in its entirety, shows one such assembly. This type of speed-altering surgical attachment may be provided with a spindle and mount substantially identical to the spindle222and mount226of the exemplary embodiment of the handheld surgical instrument.

The gear train and drive heads of this speed-altering surgical attachment may be of different design. For example, in some embodiments, the gear train may have three or more drive heads, each or which, in response to the single input rotational moment, operates at a different rotational speed. In some embodiments, the gear train has gears that cause one or more drive heads to rotate at speeds faster than those at which the motor output region206rotates.

The means by which the motor204rotates motor output region206may likewise vary from what has been described.

Similarly, the structure of the clutch224may differ from what has been described. For instance, some embodiments may have few or more laterally extending members, clutch pins, or other torque transmitting components, for simultaneously engaging a gear train drive head266,272and the spindle222. In some embodiments, clutch224may even include a single one of these members.

In some embodiments, the inner shifter and/or outer shifter may be arranged so that the points at which longitudinal motion are transferred to this sub assembly (indentions374in the described embodiment) are within the longitudinal slice in which the lateral member that transfers torque from one of the drive heads to the spindle is located. Such construction can further reduce the overall longitudinal length of the clutch.

Also, in some embodiments, the clutch pins may be integrally attached to the spindle. In these embodiments of the invention, the spindle itself is displaced in order to cause the clutch pins to engage the appropriate gear train drive head.

Similarly, in other embodiments, means other than a rotating shift ring may be employed to set the position of the clutch pins. In some embodiments, a switch member movably mounted to the handheld surgical instrument housing to move longitudinally is the surgeon-actuated component that is displaced to set the position of the clutch pins.

Also, the structure of the mounting assembly226and complementary speed-altering surgical attachment/surgical end effector mounting head may vary from what has been described. There is no requirement that in all embodiments the surfaces of the spindle that output torque and complementary mounting head boss482have a hexagonal or even a polygonal cross sectional profile. It is believed that a polygonal cross sectional geometry is the most efficient for ensuring torque transfer to the mounting head.

Similarly, the mounting head body484may have a geometry different from what has been described and illustrated. There is no requirement that in all embodiments this component and the complementary spindle bore have circular cross-sectional profiles. In some embodiments, these components may even have one or more planar faces. It is believed though such geometry is an optimal geometry for reducing mounting head wobble. Similarly, there is no requirement that in all embodiments of the invention, the indentation defined by the mounting head body for receiving the locking member associated with the handheld surgical instrument mounting assembly be an annular groove. In some embodiments, one or more indentations are provided in the mounting head body for receiving the complementary locking member integral with the complementary handheld surgical instrument mounting assembly.

In some embodiments, the mounting body may not have any geometric features for receiving complementary mounting assembly locking members. Also, there may embodiments wherein the geometric features for facilitating the engagement of the handheld surgical instrument mount with the mounting head project beyond the surface of the mounting head body.

Similarly, there may be embodiments in which the mounting head body has a diameter that is identical with that of the distally adjacent speed-altering surgical attachment/surgical end effector shaft. In still other embodiments, the surgical attachment/surgical end effector shaft may have a diameter greater than that of the mounting head.

Likewise, an surgical attachment/surgical end effector mounting head of this embodiment may be constructed with geometric features different from slots488and beveled faces492to facilitate the alignment of the mounting head in the spindle bore. Some embodiments may not even be provided with any of these features.

Other mounts may, instead of holding a speed-altering surgical attachment/surgical end effector mounting head to the spindle, serve only to cause the mounting head to be driven by the spindle. Moreover, manufacturers of handheld surgical instruments often provide removable speed-altering surgical attachments for mounting to handheld surgical instruments that have their own speed reduction gear assemblies. The ability to selectively couple a speed-altering surgical attachment to a surgical tool makes it possible for a surgeon to even further increase the torque available to the cutting tool coupled to the handheld surgical instrument. Often, these speed-altering surgical attachments are designed to reduce the speed and increase the torque by a pre-set whole number ratio. For example, speed-altering surgical attachments with internal gear assemblies that decrease speed of the motor drive shaft by 3:1 or 4:1 have been provided. (It should be understood that the above ratio refers to the relationship of the input shaft speed to the output shaft speed. The reciprocal of these ratios give the relationship between torque input and torque output.)

Moreover, manufacturers of handheld surgical instruments often provide removable speed-altering surgical attachments for mounting to handheld surgical instruments that have their own speed reduction gear assemblies. The ability to selectively couple a speed-altering surgical attachment to a surgical tool makes it possible for a surgeon to even further increase the torque available to the surgical end effector coupled to the handheld surgical instrument. Often these speed-altering surgical attachments are designed to reduce the speed/increase the torque by a pre-set whole number ratio. For example, speed-altering surgical attachments with internal gear assemblies that decrease speed of the motor drive shaft by 3:1 or 4:1 have been provided. It should be understood that the above ratios refer to the relationship of the input shaft speed to the output shaft speed. The reciprocal of these ratios gives the relationship between torque input and torque output.

Referring toFIG. 29, one embodiment of an attachment gear assembly500is intended for use with a handheld surgical instrument for increasing the torque of the surgical end effector attached to the handheld surgical instrument. The gear assembly can be used to obtain a 2:1 reduction of motor speed wherein the output force is both centered around the axis around which the input force is applied and in the same direction as the direction of the input force.

Referring toFIGS. 28A and 32, the speed-altering surgical attachment500comprises an intermediate shaft524defining a shaft input region528operably coupled to an output member implemented in the form of a spindle222such that drive of the spindle222is configured to cause drive of the shaft input region528. The intermediate shaft524further defines a shaft output region529. A gear train530defines a gear train input region531operably coupled to the shaft output region529such that drive of the shaft output region529is configured to cause drive of the gear train input region531. The gear train530further defines a gear train output region533operably coupled to the gear train input region531and the surgical end effector228such that drive of the gear train input region531is configured to cause drive of the gear train output region533and actuation of the surgical end effector228.

The shaft output region529of the intermediate shaft524interfaces with the gear train input region531at shaft-gear train interface1006, and the shaft-gear train interface1006comprises a shaft-gear train backlash such that drive of the shaft output region529within the shaft-gear train backlash does not cause drive of the gear train input region531. In this embodiment, the gear train input region529may be implemented in the form of planet gears548coupled to the shaft output region, which may be implemented in the form of an input sun gear542(as shown inFIG. 30). The gear train output region533may comprise an output sun gear588operably coupled to the planet gears560and the surgical end effector228(as shown inFIG. 27) such that drive of the planet gears560is configured to cause drive of the output sun gear588and actuation of the surgical end effector228.

Referring toFIG. 28A, the shaft output region529interfaces with the gear train input region531at a shaft-gear train interface having shaft-gear train backlash1006(as shown inFIG. 28A) such that drive of the shaft output region529within the shaft-gear train backlash1006does not cause drive of the gear train input region531.

The speed-altering surgical attachment500is mounted to the front end of the handheld surgical instrument200so as to seat in a collar integral with the front of the hand held surgical instrument. The gear train530internal to the speed-altering surgical attachment500transfers the rotational power developed by shaft532to a chuck510mounted to the front of the speed-altering surgical attachment. Chuck510may be used to hold the surgical end effector228. In the depicted embodiment, the surgical end effector228is a drill bit.

Referring toFIGS. 29 to 32, the speed-altering surgical attachment500includes an input housing514which contains most of the components of the attachment. Input Housing514is formed to have a narrow diameter stem section516. Stem section516is the portion of the housing514that is inserted into the handheld surgical instrument200. The outer surface of stem516is formed to attach the speed-altering surgical attachment500to the handheld surgical instrument, an anti-rotation key that stops movement of the attachment (key not illustrated). Input housing514is further formed to have a head520that is integral with and extends coaxially forward from stem516. In the depicted embodiment, head520has an outer diameter greater than that of stem516. A multi-section bore522extends through input housing514from the end of the stem516coupled to handheld surgical instrument200to the front end of the head520.

The intermediate shaft524is rotatably mounted in the portion of housing bore522that extends from the open end of the housing stem516to the portion of the head520adjacent the stem. Two spaced apart bearing assemblies528rotatably connect intermediate shaft524to input housing514.

The intermediate shaft524is formed with a bore526that extends axially through the intermediate shaft. Intermediate shaft524is further formed to have an end539(as shown inFIG. 32), closest to handheld surgical instrument200that is shaped to have a polygonal shaped outer surface. When the speed-altering surgical attachment500is coupled to a handheld surgical instrument200, the drive shaft end539seats in a complementary-profiled opening formed in the head of spindle222(as shown inFIG. 6B). Consequently, the rotation of spindle222causes a like rotation of intermediate shaft524.

Intermediate shaft524is formed to have a head provided with gear teeth that form an input sun gear542. The intermediate shaft524also has a nose section544located forward of the input sun gear542. The outer diameter of nose section544is less than the outer diameter of the input sun gear542.

The input sun gear542engages three input planet gears548that are rotatably mounted to the input housing514. More specifically, the input planet gears548, which are uniformly spaced about the longitudinal axis of intermediate shaft524, are mounted to the planet carrier538. The planet carrier538is ring-shaped and located around intermediate shaft524. Planet carrier538is press fit in a stepped section of housing bore522located in the portion of the head520of the housing adjacent stem516. In the depicted embodiment of the invention, the forward and rear outer edges of planet carrier538are formed with inwardly directed steps551to facilitate the mounting of the carrier in input housing514. Each of the input planet gears548is rotatably mounted to fixed axle pin554. Axle pins554are press fit in bores555that extend through planet carrier538.

A circularly shaped ring gear556surrounds the input planet gears548. Ring gear556has an inner surface with teeth558that engage input planet gears548. The outer wall of ring gear556is smooth. Ring gear556is further designed so that its outer diameter is less than the diameter of the adjacent inner wall of input housing514that defines the section of the housing bore522in which the ring gear is seated. Thus, there is a small interstitial space between the outer wall of the ring gear556and the adjacent inner wall of the input housing514. In some embodiments, the gap between the inner wall of the input housing514and the outer wall of the ring gear512is approximately between 0.007 and 0.011 inches (0.18 and 0.28 mm). Thus, ring gear556“floats” relative to input housing514.

The gear assembly of this embodiment includes a second set of planet gears or output planet gears560that also engage ring gear556. The output planet gears560are fitted to an output housing562that is mounted in and extends forward from the open end of input housing head520. The output housing562is a generally ring-shaped structure with a bore564that extends axially through it. Output housing bore564extends coaxially with input housing bore522. The rear end of output housing562is seated in the front end of the input housing bore522. The outer surface of the middle section of output housing562is provided with threading566. The threading566engages threading568provided around the inner wall of input housing514. The output housing562is further formed to have an outwardly extending annular lip563located forward of the surface on which threading566is formed. Lip563extends over the open forward end of input housing514to limit the extent to which the output housing562is seated in input housing bore522.

The output planet gears560are seated against the rearwardly directed face of output housing562. The output planet gears560are rotatably mounted over fixed axle pins571. The axle pins571are press fit into bores (not identified) that extend into the output housing562from the rearwardly directed face of the housing562. It will be further noted that, within the ring gear556, two ring-shaped washers572are located between input and output planet gears548and560, respectively. Washers572are provided to prevent the output planet gears560from separating from the output housing562.

An output drive shaft574is located in output housing bore564. The output drive shaft574has an elongated stem section576that extends out of the front end of the output housing562. Two bearing assemblies578that extend between the inner wall of the output housing562that defines bore564and the stem section576rotatably mount the output drive shaft574in the output housing562. The rear face of the rearward of the two bearing assemblies578abuts an inwardly directed step580internal to output housing562. A retaining ring582prevents the bearings from coming out of the front end of output housing bore564. The outer perimeter of retaining ring582is seated in an annular groove586formed in the inner wall of output housing562that defines bore564. Two washers587are located between the front face of the forward-most bearing assembly578and the adjacent surface of chuck510.

The output drive shaft574has a toothed head that functions as an output sun gear588. Output sun gear588is shaped to have a diameter greater than that of the stem576with which it is integrally formed. Owing to its large diameter, output sun gear588blocks outward movement of the input planet gears548so as to prevent the input planet gears from coming out of the planet carrier538.

It will also be noted that, in the illustrated embodiment, output drive shaft574has a bore592that extends axially through the shaft. FromFIG. 29it can be seen that the nose section544of intermediate shaft524extends into the adjacent open end of bore592of output drive shaft574. A flexible quad ring594is seated in an annular groove596formed contiguously with bore592inside output drive shaft574. Quad ring594is fitted over the portion of the nose section544that extends into bore592. The quad ring594provides a barrier to prevent lubricating material disposed inside the gear assembly from flowing outside the speed-altering surgical attachment500along the inner walls of either the intermediate shaft506,524or the output drive shaft574.

The output drive shaft574engages chuck510. Internal to the embodiment of the chuck are jaws that hold the surgical end effector228in place. (The jaws and other components internal to the chuck510are not illustrated.) One type of chuck510integral with speed-altering surgical attachment500is a “Jacobs” chuck. The jaws rotate in unison with the output drive shaft574so as to cause a like movement of the surgical end effector228.

The gear train530comprises a plurality of gears meshed with one another at a plurality of internal gear train interfaces, and at least one of the internal gear train interfaces comprises an internal gear train backlash such that drive of the gear train input region within the internal gear train backlash does not cause the surgical end effector to perform the operational function.

The gear train530comprises a plurality of gears542,548,556,560, and588meshed with one another at a plurality of internal gear interfaces1006,1010,1012(as shown inFIGS. 30 and 31), and at least one of the internal gear train interfaces comprises an internal gear train backlash such that drive of the gear train input region within the internal gear train backlash does not cause the surgical end effector to perform the operational function.

Referring toFIG. 28A, when the handheld surgical instrument200is actuated, the rotation of the output member comprising spindle222causes the intermediate shaft524to rotate. The movement of the intermediate shaft524and the input sun gear542integral therewith causes the input planet gears548to rotate around their axes. The rotation of the input planet gears548causes the ring gear556, which is not fixed, to rotate. Actuation of the ring gear556, in turn, forces the output planet gears560to rotate around their axes. The movement of the output planet gears560forces the rotation of the output sun gear588and output drive shaft574. The rotation of the output drive shaft causes the like movement of the surgical end effector228coupled to it by the chuck510.

It should be recognized that the foregoing description is directed to specific embodiment and that other embodiments may vary from what has been described. For example, there is no requirement that the speed-altering surgical attachment comprise input and output drive shafts dimensioned to cause a 2:1 reduction between input and output rotational speeds. In other embodiments, the drive shafts524,574can be dimensioned to cause the output drive shaft to spin faster than the intermediate shaft. Moreover, the components from which the speed-altering surgical attachment are assembled may vary from what has been described. For example, in some embodiments the input planet gears may be directly mounted to the housing in which the planet gears are contained. Still other embodiments may have a single housing.

Also, there is no requirement that the axes along which the input and output planet gears548,560, respectively, rotate lie along a common radial line that extends outward from the center of the speed-altering surgical attachment500. While this alignment is depicted inFIG. 29, it is not required in all embodiments. Moreover, there need not always be a 1:1 ratio in the number of input planet gears to the number of output planet gears.

Also, only one particular type of mount was shown in association with the handheld surgical instrument for holding a complementary surgical end effector. It is contemplated that other mounts may be used with this speed-altering surgical attachment.

It should likewise be recognized that, some embodiments of the speed-altering surgical attachment500may be permanently fitted to the handheld surgical instrument200. Also, the term surgical end effector should be understood to encompass other forms of surgical tools such as burs and wire drivers.

FIGS. 5B, 28A, 30, and 31illustrate the different interfaces that may have backlash when the coupler is implemented in the form of a speed-altering surgical attachment. Interface1000(as shownFIG. 5B) between the motor output region251and the transmission input region242may have backlash. Interface1002(as shown inFIG. 28A) between internal gears of the transmission may have backlash. Interface between gear sets252,254may have backlash. Interface between gear sets256,262may have backlash.

FIGS. 28A, 30, and 31depicts an exemplary embodiment of backlash at interfaces1006,1010,1012within a speed-altering surgical attachment500affixed to a handheld surgical instrument200. It is contemplated that movement of the motor within the cumulative backlash for all interfaces between driving components of the handheld surgical instrument can provide a feedback function while not driving the surgical end effector and performing the operational function.

FIG. 30is a view of interface1006between sun gear542and planet gears548(only one of the three points referenced) having backlash.FIG. 30also shows interface1010between the planet gears548and the ring gear556(only one of three points referenced) having backlash.FIG. 31shows interface1010between the ring gear556and the output planet gears560(only one of three points referenced) having backlash. Interface1012between the output planet gears560and the output sun gear588(only one of three points referenced) has backlash. It should be recognized that the foregoing description is directed to specific embodiments and that other embodiments may vary from what has been described. It is contemplated that oscillating the drive system18between the first and second directions for the feedback signal FS will fall less than the cumulative backlash starting from the motor-transmission interface1000through the last possible interface before the surgical end effector228, which will be embodiment specific.

Referring toFIG. 35, a method100for providing feedback to a user of the handheld surgical instrument10ofFIGS. 1-4Cis illustrated. The method100commences at step102with the step of detecting a grip event. In particular, the gyroscope36may detect the angular velocity of the handheld surgical instrument10, and the current sensor38may detect that the input device22was actuated to supply current from the battery50to the drive system18. However, the handheld surgical instrument can comprise one, three, four, or more sensors of any suitable type for detecting any condition associated with the grip event.

At step104, the operational function OF of the handheld surgical instrument10may be terminated when the grip event is detected. In particular, the controller20may receive the first and second grip event signals ES1, ES2from the gyroscope36and current sensor38. The controller20may determine that the grip event occurred when the controller20determines that the first grip event signal ES1indicates that the handheld surgical instrument is being rotated by the predetermined threshold angular velocity, e.g., 500 degrees per second, and the second signal ES2generated by the current sensor38indicates that current is being supplied to the drive system18. In other examples, the controller20may determine that a grip event has occurred in response to receiving other signals from any suitable sensor indicating that one or more thresholds associated with a grip event have been satisfied.

When the controller determines that the grip event has occurred, the controller20may terminate the operational function OF of the surgical end effector12by stopping the output member16. For example, the controller20may terminate sending the operate signal OS to the drive system18in order to stop the binding, pinching, or misalignment that is impeding rotation or other cutting motion of the surgical end effector12. In other embodiments, the controller20may further terminate the operational function OF by actuating a braking device (not shown) to stop or slow movement of the surgical end effector12.

At step106, the controller20may control the drive system18upon detection of the grip event to perform the feedback function by oscillating the drive system18between the first and second directions, without moving the surgical end effector12and causing the surgical end effector12to perform the operational function OF. More specifically, the controller20may actuate one or more components of the motor24or the transmission26to oscillate within the tolerances between surfaces that engage one another such that the oscillation of one component does not move the other component and the coupler14.

This method allows the user to know that the drill stopped moving because of a kickback event. By having a different modality of indication between a status of the battery and kickback events, confusion is eliminated. This is because visual indicators on batteries may often be used to communicate status on the battery. If the same visual indicator were to be used to indicate the triggering of an anti-kickback event, the user may be confused as to whether the battery status stopped the device from operating or the kickback event stopped the device from operating.

Several embodiments have been discussed in the foregoing description. However, the embodiments discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described. It will be further appreciated that the terms “include,” “includes,” and “including” have the same meaning as the terms “comprise,” “comprises,” and “comprising.”

Embodiments of the disclosure can be described with reference to the following numbered clauses, with specific features laid out in the dependent clauses:

I. A handheld surgical instrument to provide tactile feedback to a user during a kickback event, the handheld surgical instrument comprising:an input device configured to generate an input signal;a drive system;a coupler configured to receive a surgical end effector, said coupler operably engaged with said drive system;said drive system configured to perform:an operational function, anda feedback function, separate from said operational function, to provide feedback to a user; anda controller in communication with said drive system and said input device, said controller configured to control said drive system to perform said operational function in response to receiving said input signal from said input device, and said controller configured to oscillate said output member to perform a feedback function while not causing the surgical end effector to perform an operational function.

II. The handheld surgical instrument of clause I wherein said controller is configured to terminate said operational function of said drive system when said drive system performs said feedback function.

III. The handheld surgical instrument of any one of clauses I or II further comprising:a gyroscope configured to detect movement of the handheld surgical instrument and generate a first grip event signal based on the movement of the handheld surgical instrument being associated with a grip event; anda current sensor configured to detect a supply current to said drive system and generate a second grip event signal based on said supply current being associated with the grip event;said controller generating a feedback signal when said controller receives said first and second grip.

IV. The handheld surgical instrument of any one of clauses I, II, or III wherein said gyroscope is configured to detect rotation of the handheld surgical instrument at a rate of at least 500 degrees per second.

V. A method for providing feedback to a user of a handheld surgical instrument comprising a drive system, a coupler operably engaged with the drive system, a surgical end effector operably engaged with the coupler to perform an operational function, a first sensor configured to generate at least one grip event signal, and a controller communicating with the first sensor and the drive system, the method comprising the steps of:detecting a grip event based on the at least one grip event signal;terminating the operational function of the handheld surgical instrument when said grip event is detected; andcontrolling the drive system, with the controller, to oscillate the drive system in first and second directions, without causing the surgical end effector to perform the operational function, upon detection of the grip event.

VI. The method of clause V further comprising actuating said drive system to perform said feedback function while not actuating the surgical end effector to perform said operational function.

VII. A method for providing feedback to a user of a handheld surgical instrument comprising a drive system, a coupler operably engaged with the drive system, a surgical end effector operably engaged with the coupler, a first sensor configured to generate at least one grip event signal, and a controller communicating with the first sensor and the drive system, the method comprising the steps of:detecting a grip event based on the at least one grip event signal; andgenerating tactile feedback upon detection of the grip event.

VIII. A method for providing feedback to a user of a handheld surgical instrument comprising a drive system, a coupler operably engaged with the drive system, a removable battery coupled to the handheld surgical instrument, a surgical end effector operably engaged with the coupler, a first sensor configured to generate at least one grip event signal, and a controller communicating with the first sensor and the drive system, the method comprising the steps of:detecting a grip event based on the at least one grip event signal;generating tactile feedback upon detection of the grip event; andgenerating a visual indicator based on the status of the removable battery.