WO2021016699A1

WO2021016699A1 - Surgical instrument with tactile feedback

Info

Publication number: WO2021016699A1
Application number: PCT/CA2019/051583
Authority: WO
Inventors: Oliver Russell WOLFOND; Sam Gerald Norman KESHEN
Original assignee: So Medical Inc.
Priority date: 2019-07-26
Filing date: 2019-11-06
Publication date: 2021-02-04

Abstract

A surgical instrument comprises an outer shaft, an inner shaft at least partially disposed within the outer shaft, a handle, and a coupling assembly having a predetermined threshold that couples the handle to the outer shaft in one of an engaged configuration and disengaged configuration. In the engaged configuration, rotation of the handle supplies a torque to the outer shaft. In the disengaged configuration, the handle rotates independently of the outer shaft. The inner shaft has a probe end, a transfer end opposite the probe end, and is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end. The coupling assembly couples the handle to the outer shaft (i) in the engaged configuration when the mechanical force is greater than a threshold and (ii) in the disengaged configuration when the mechanical force is less than or equal to the threshold.

Description

TITLE: SURGICAL INSTRUMENT WITH TACTILE FEEDBACK

FIELD

[001] This disclosure relates generally to surgical instruments, and more specifically to surgical instruments that provide tactile or other feedback.

INTRODUCTION

[002] Spine degeneration, deformity or trauma often requires surgical intervention. For example, a surgical procedure known as spinal fusion may be performed as a means of thoracic, lumbar or sacral spine stabilization. This surgical procedure sees a user locating a number of screws into pedicles, narrow bony processes that extend from opposite sides of each vertebrae, in order to attach a stabilizing device to the spine. Pilot holes are usually made in the pedicles to receive the screws.

[003] Instruments for making pilot holes in anatomical structures, such as pedicles or other bones, are known.

SUMMARY

[004] This summary is intended to introduce the reader to the more detailed description that follows and not to limit or define any claimed or as yet unclaimed invention. One or more inventions may reside in any combination or sub-combination of the elements or process steps disclosed in any part of this document including its claims and figures.

[005] In accordance with one broad aspect, there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly having at least one threshold, the coupling assembly coupling the handle to the outer shaft at the second shaft end in one of an engaged configuration and a disengaged configuration, wherein, in the engaged configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the disengaged configuration, the handle rotates about the longitudinal axis independently of the outer shaft; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end; wherein the coupling assembly couples the handle to the outer shaft in the engaged configuration when the mechanical force is greater than the at least one threshold; and wherein the coupling assembly couples the handle to the outer shaft in the disengaged configuration when the mechanical force is less than or equal to the at least one threshold.

[006] In some embodiments, the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end. In such embodiments, the at least one cutting edge may cut a pilot hole as the handle is rotated about the longitudinal axis. The pilot hole may be made in a bone.

[007] In some embodiments, the inner shaft is movable along the interior channel in response to the mechanical force received at the probe end.

[008] In some embodiments, a displacement of the inner shaft measured along the longitudinal axis is at least partially based on a magnitude of the mechanical force received at the probe end.

[009] In some embodiments, the coupling assembly comprises a biasing member, wherein the biasing member is compressible along the longitudinal axis from at least a first length to a threshold length in response to the mechanical force transferred from the transfer end of the inner shaft. For example, the biasing member may be a coil spring.

[0010] In accordance with another broad aspect there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor; wherein the actuator couples the handle to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

[0011] In some embodiments, in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

[0012] In some embodiments, the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end. In such embodiments, the at least one cutting edge may cut a pilot hole as the handle is rotated about the longitudinal axis. The pilot hole may be made in a bone.

[0013] In some embodiments, the transfer end of the inner shaft is secured to the sensor.

[0014] In some embodiments, the sensor is a strain gauge. [0015] In some embodiments, the first and second thresholds are adjustable.

[0016] In accordance with another broad aspect there is provided a surgical instrument comprising: a shaft having a first shaft end, a second shaft end opposite the probe end along a longitudinal axis of the shaft; a handle rotatable about the longitudinal axis; and a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the handle to the shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the shaft, and wherein, in the second configuration, a torque supplied from the handle to the shaft is limited, wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising a detected parameter from the sensor, the actuator couples the handle to the shaft in one of the first configuration and the second configuration when the detected parameter is greater than the first threshold; and the actuator couples the handle to the shaft in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the second threshold.

[0017] In some embodiments, in the second configuration, the torque is limited through disengagement of the handle with the shaft.

[0018] In some embodiments, the shaft has at least one cutting edge provided on an exterior surface of the shaft proximate the first shaft end. In such embodiments, the at least one cutting edge may cut a pilot hole as the handle is rotated about the longitudinal axis. The pilot hole may be made in a bone.

[0019] In some embodiments, the sensor comprises an accelerometer located within the shaft.

[0020] In some embodiments, the sensor comprises an ultrasound transceiver located within the shaft proximate the first shaft end. [0021] In some embodiments, the sensor comprises a magnetic permeability sensor located within the shaft proximate the first shaft end.

[0022] In some embodiments, the sensor comprises a pair of electrically isolated capacitive sensors, wherein at least one of the pair of capacitive sensors is located at the first shaft end, and wherein the controller determines a capacity differential between the pair of capacitive sensors.

[0023] In some embodiments, the sensor comprises a pair of electrically isolated electrodes, wherein at least one of the pair of electrodes is located at the first shaft end, and wherein the controller determines a conductivity differential between the pair of electrodes.

[0024] In some embodiments, the first and second thresholds are adjustable.

[0025] In accordance with another broad aspect there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the handle to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold.

[0026] In some embodiments, in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

[0027] In some embodiments, the controller determines the magnitude of the mechanical force based on the separation and a calibration index.

[0028] In some embodiments, the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end. In such embodiments, the at least one cutting edge may cut a pilot hole as the handle is rotated about the longitudinal axis. The pilot hole may be made in a bone.

[0029] In some embodiments, the position sensor is an optical position sensor.

[0030] In some embodiments, the position sensor is a capacitive position sensor.

[0031] In some embodiments, the position sensor is an inductive position sensor.

[0032] In some embodiments, the first and second thresholds are adjustable [0033] In accordance with another broad aspect there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly having at least one threshold, the coupling assembly coupling the motor to the outer shaft at the second shaft end in one of an engaged configuration and a disengaged configuration, wherein, in the engaged configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the disengaged configuration, the motor rotates about the motor axis independently of the outer shaft; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end; wherein the coupling assembly couples the motor to the outer shaft in the engaged configuration when the mechanical force is greater than the at least one threshold; and wherein the coupling assembly couples the motor to the outer shaft in the disengaged configuration when the mechanical force is less than or equal to the at least one threshold.

[0034] In accordance with another broad aspect there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor; wherein the actuator couples the motor to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

[0035] In some embodiments, in the second configuration, the torque is limited through disengagement of the motor with the outer shaft.

[0036] In accordance with another broad aspect there is provided a surgical instrument comprising: a shaft having a first shaft end, a second shaft end opposite the probe end along a longitudinal axis of the shaft; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the shaft is limited, wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising a detected parameter from the sensor, the actuator couples the motor to the shaft in one of the first configuration and the second configuration when the detected parameter is greater than the first threshold; and the actuator couples the motor to the shaft in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the second threshold.

[0037] In some embodiments, in the second configuration, the torque is limited through disengagement of the motor with the shaft.

[0038] In accordance with another broad aspect there is provided a surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the motor to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold.

[0039] In some embodiments, in the second configuration, the torque is limited through disengagement of the motor with the outer shaft.

[0040] It will be appreciated by a person skilled in the art that a method or apparatus disclosed herein may embody any one or more of the features contained herein and that the features may be used in any particular combination or sub- combination.

[0041] These and other aspects and features of various embodiments will be described in greater detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] For a better understanding of the described embodiments and to show more clearly how they may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:

[0043] FIG. 1 is an illustration of an example implant secured to a portion of a spinal column for structural reinforcement;

[0044] FIG. 2A is an illustration of a vertebra having a pair of properly aligned screws in respective pedicles;

[0045] FIG. 2B is an illustration of a vertebra having one properly aligned screw and one misaligned screw in respective pedicles;

[0046] FIG. 3A is a side elevation view of a surgical instrument, according to a first example embodiment, with a coupling assembly in a disengaged configuration; [0047] FIG. 3B is a cross-sectional view of the surgical instrument of FIG. 3A taken along line A-A

[0048] FIG. 3C is a front perspective view of the surgical instrument of FIG. 3A;

[0049] FIG. 3D is a rear perspective view of the surgical instrument of FIG.

3A;

[0050] FIG. 3E is an enlarged cross-sectional view of the surgical instrument of FIG. 3B taken at portion S;

[0051] FIG. 4A is a side elevation view of the surgical instrument of FIG. 3A with the coupling assembly in an engaged configuration;

[0052] FIG. 4B is a cross-sectional view of the surgical instrument of FIG. 4A taken along line C-C;

[0053] FIG. 4C is a front perspective view of the surgical instrument of FIG. 4A;

[0054] FIG. 4D is a rear perspective view of the surgical instrument of FIG.

4A;

[0055] FIG. 4E is an enlarged cross-sectional view of the surgical instrument of FIG. 4B taken at portion D;

[0056] FIG. 5 is a partial side elevation view of the surgical instrument of FIG. 3A with a handle and an outer shaft of the surgical instrument omitted to show internal components;

[0057] FIG. 6A is a front perspective view of the handle of the surgical instrument of FIG. 3A;

[0058] FIG. 6B is a front elevation view of the handle of FIG. 6A;

[0059] FIG. 6C is a cross-sectional view of the handle of FIG. 6B taken along line E-E; [0060] FIG. 7 A is a front perspective view of the surgical instrument of FIG. 3A with the outer shaft omitted to show internal components;

[0061] FIG. 7B is another front perspective view of the surgical instrument of FIG. 7A;

[0062] FIG. 8A is a side elevation view of the surgical instrument of FIG. 3A with the handle and the outer shaft omitted to show internal components;

[0063] FIG. 8B is a rear perspective view of the surgical instrument of FIG. 8A;

[0064] FIG. 9A is a side elevation view of the surgical instrument of FIG. 4A with the handle and the outer shaft omitted to show internal components;

[0065] FIG. 9B is a rear perspective view of the surgical instrument of FIG. 9A;

[0066] FIG. 10A is a side elevation view of a surgical instrument, according to a second example embodiment, with a coupling assembly in a disengaged configuration;

[0067] FIG. 10B is a cross-sectional view of the surgical instrument of FIG. 10A taken along line F-F\

[0068] FIG. 11 A is a side elevation view of a surgical instrument, according to a third example embodiment, with a coupling assembly in a disengaged configuration;

[0069] FIG. 11 B is a cross-sectional view of the surgical instrument of FIG. 11 A taken along line G-G;

[0070] FIG. 11 C is a front perspective view of the surgical instrument of FIG. 11 A; [0071] FIG. 12A is a partial side elevation view of a surgical instrument, according to a fourth example embodiment, with an outer shaft having a sensor located therein;

[0072] FIG. 12B is a cross-sectional view of the surgical instrument of FIG. 12A taken along line H-H;

[0073] FIG. 13A is a side elevation view of a surgical instrument, according to a fifth example embodiment, with a shaft having a sensor located therein;

[0074] FIG. 13B is a cross-sectional view of the surgical instrument of FIG. 13A taken along line /-/; and

[0075] FIG. 13C is a side perspective view of the surgical instrument of FIG.

13A;

[0076] FIG. 14 is a side elevation view of a surgical instrument, according to a sixth example embodiment, with an outer shaft having a curved portion;

[0077] FIG. 15A is a front perspective view of a surgical instrument, according to a seventh example embodiment, with a coupling assembly located externally of a handle of the surgical instrument;

[0078] FIG. 15B is a side elevation view of the surgical instrument of FIG. 15A;

[0079] FIG. 16A is a side elevation view of a surgical instrument, according to an eighth example embodiment, with a coupling assembly in a disengaged configuration;

[0080] FIG. 16B is a cross-sectional view of the surgical instrument of FIG. 16A taken along line J-J;

[0081] FIG. 17A is a side elevation view of an outer shaft of the surgical instrument of FIG. 16A; [0082] FIG. 17B is a cross-sectional view of the outer shaft of FIG. 17A taken along line K-K\

[0083] FIG. 18A is a side elevation view of an inner shaft of the surgical instrument of FIG. 16A;

[0084] FIG. 18B is a cross-sectional view of the inner shaft of FIG. 18A taken along line L-L;

[0085] FIG. 19A is a side elevation view of a handle of the surgical instrument of FIG. 16A; and

[0086] FIG. 19B is a cross-sectional view of the handle of FIG. 19A taken along line M-M.

[0087] The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the teaching of the present specification and are not intended to limit the scope of what is taught in any way.

DETAILED DESCRIPTION

[0088] Various apparatuses, methods and compositions are described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover apparatuses and methods that differ from those described below. The claimed inventions are not limited to apparatuses, methods and compositions having all of the features of any one apparatus, method or composition described below or to features common to multiple or all of the apparatuses, methods or compositions described below. It is possible that an apparatus, method or composition described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus, method or composition described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) and/or owner(s) do not intend to abandon, disclaim, or dedicate to the public any such invention by its disclosure in this document. [0089] Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limiting the scope of the example embodiments described herein.

[0090] The terms "an embodiment," "embodiment," "embodiments," "the embodiment", "the embodiments", "one or more embodiments", "some embodiments", and "one embodiment" mean "one or more (but not all) embodiments of the present invention(s)", unless expressly specified otherwise.

[0091] The terms "including", "comprising", and variations thereof mean "including but not limited to", unless expressly specified otherwise. A listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. The terms "a", "an", and "the" mean "one or more", unless expressly specified otherwise.

[0092] Spine deformity or trauma often requires surgical repair. For example, a surgical procedure known as spinal fusion may be performed as a means of thoracic, lumbar and sacral spine stabilization. Spinal fusion involves immobilizing spinal segments to prevent motion and allow for healing. This surgical procedure involves a surgeon placing a number of screws into pedicles, narrow bony processes that extend from opposite sides of each vertebra, in order to attach a stabilizing device to the spine. Pedicles are the strongest parts of the vertebra and, as a result, provide the greatest mechanical integrity for anchoring the stabilization device.

[0093] Typically, the pedicles are first cannulated by a tool commonly referred to as a“pedicle finder” to provide a tunnel or pilot hole for receiving the screws. For example, FIG. 1 illustrates an implant 10 (i.e. stabilizing device) secured to a portion of a patient’s spine 20 with a plurality of screws 30 to secure it to the spine 20. Pedicle finders are generally handheld, blunt-tipped metal trocars, which can cut bone via torsional force applied by the surgeon (i.e. similar to a screwdriver). While pedicle finders are functional in their simplicity, this same property invites the possibility for significant error.

[0094] Due to the anatomy of the spine, a medial or lateral trajectory of the pedicle finder can result in a breach through the inner or outer walls of the pedicle. If not detected, placement of the screw inside this pilot hole can result in irritation of the neurovascular structures housed within the canal or lateral to the spinal column, and/or decreased integrity of screw. In some cases, improperly placed pedicle screws may require additional surgical intervention. FIG. 2A illustrates a vertebra 40 with two correctly aligned pedicle screws 50A and 50B therein. The pedicle screws 50A and 50B are aligned such that the shank of each screw is enclosed within the vertebra 40; that is, the shank of each screw does not emerge from the vertebra other than where it is connected to the screw head. FIG. 2B illustrates a vertebra 60 with one correctly aligned pedicle screw 70A and one misaligned pedicle screw 70B therein. The misaligned pedicle screw 70B breaches the wall of the vertebra 60 at multiple points and passes through the spinal canal 80. Such a misalignment not only decreases the structural integrity of a stabilizing device (e.g. implant 10 of FIG. 1 ) supported by the misaligned pedicle screw 70B, but also has the potential to cause symptomatic irritation of the nerves within the canal. [0095] Nerve irritation from misaligned screws can create significant discomfort and disability to the patient, including, but not limited to, drop-foot, pain, or sensory dysfunction. These complications are costly, as they can lead to increased post-operative length of stay, additional medical imaging, and can require surgical revision and/or replacement of the stabilization device. Decreased mechanical stability of the stabilization device (e.g. implant 10 of FIG. 1 ) may result in decreased rates of fusion or complete failure which may require surgical revision.

[0096] Surgeons use a variety of equipment and techniques to improve the positioning of screws and pilot holes. In some cases, computer-assisted spinal navigation is used to guide the surgeon through the procedure. However, computer-assisted spinal navigation has proven to have a steep learning curve in addition to requiring a significant amount of time and expense. In other cases, X- ray imaging or other medical imaging techniques are used to aid surgical navigation. Such techniques can be expensive and may expose the patient and surgeon to unnecessary radiation. Due to the lack of simple to use, safe, and cost- effective surgical navigation tools, many surgeons rely entirely on their experience and knowledge of anatomy in order to align and position screws.

[0097] The exemplary embodiments of this disclosure generally provide surgical instruments for making pilot holes in vertebrae. The surgical instruments described herein generally have a coupling assembly that is movable between an engaged configuration and a disengaged configuration. In the engaged configuration, rotation of the instrument’s handle or a motor supplies a torque to the instrument’s outer shaft. In the disengaged configuration, the instrument’s handle or motor rotates independently of the instrument’s outer shaft. For example, when the coupling assembly is in the disengaged configuration, the user does not have the ability to deliver torque to the outer shaft by rotating the handle, or alternatively, the torque is limited by a mechanical or electromechanical mechanism, such as a torque limiter. Similarly, in cases where a motor is used, the motor does not have the ability to deliver torque to the outer shaft when the coupling assembly is in the disengaged configuration.

[0098] In some of the surgical instruments described herein, the coupling assembly moves between the engaged and disengaged configurations based on a mechanical force detected at the instrument’s probe end relative to at least one predetermined threshold. A mechanical force supplied to the probe end of the instrument is provided by the bone and varies according to the bone’s density at the probe end as the pilot hole is made. During procedures where the bone is breached, the soft tissue surrounding the bone’s wall can supply a mechanical force to the probe end that is generally lower than the mechanical force provided by the denser bone. In some example instruments described herein, the coupling assembly is moved between the engaged and disengaged configurations based on sensory inputs, other than mechanical force, such as acceleration, sound, vibration, conductivity, etc.

[0099] Although the example embodiments of the present disclosure are adapted for surgical procedures to the spine, this is an example of one of many possible uses. The surgical instruments may be adapted for use in other orthopedic procedures in which keeping instrumentation inside a bony channel is important or in other surgical disciplines where there may be a need to detect immediate changes in a tissue density. One such use may be the placement of camera ports in the abdomen for laparoscopic surgery.

First Example Embodiment

[00100] FIGS. 3A to 4E illustrate an example surgical instrument 100 for making pilot holes. As will be described in more detail below, the surgical instrument 100 can provide a user (e.g. a surgeon) with real-time tactile feedback while forming a pilot hole in a bone or other anatomical structures. This tactile feedback may allow the user to improve the location or orientation of the pilot hole, thereby improving surgical outcomes and increasing patient safety. [00101] The surgical instrument 100 has an outer shaft 102, a handle 104, a coupling assembly 106, and an inner shaft 108. The outer shaft 102 has a first shaft end 102a and a second shaft end 102b opposite the first shaft end 102a along a longitudinal axis 110 defined by the outer shaft 102. The outer shaft 102 may be formed from metal, metal alloy or plastic based on suitability for the intended use. For example, for surgical use, the outer shaft 102 may be formed from bio-compatible metals, such as titanium, titanium alloy or stainless steel. In the illustrated example, the outer shaft 102 has a generally circular cross-section along its longitudinal axis. The generally circular cross-section of the outer shaft 102 will be convenient for making a pilot hole with a generally circular or elliptical pilot hole. However, the cross-section of the outer shaft 102 may have other configurations, e.g., triangular, hexagonal, etc., in some embodiments.

[00102] The outer shaft 102 defines an interior channel 112 that extends between the first and second shaft ends 102a and 102b. In the illustrated example, the interior channel 112 has a generally circular cross-section along its longitudinal axis. In one or more alternative embodiments, the cross-section of the interior channel 112 may have other configurations, e.g. triangular, rectangular, etc.

[00103] The handle 104 is rotatable about the longitudinal axis 110 in either a clockwise or a counterclockwise direction. The coupling assembly 106 couples the handle 104 to the outer shaft 102 at the second shaft end 102b in one of an engaged configuration and a disengaged configuration. FIGS. 3A to 3E show the coupling assembly 106 in the disengaged configuration. As will be described in more detail below, when the coupling assembly 106 is in the disengaged configuration, the handle 104 rotates about the longitudinal axis 110 independently of the outer shaft 102. Accordingly, rotation of the handle 104 (e.g. by the user turning the handle 104) does not rotate the outer shaft 102.

[00104] FIGS. 4A to 4E show the coupling assembly 106 in the engaged configuration. As will be described in more detail below, when the coupling assembly 106 is in the engaged configuration, the handle 104 rotates about the longitudinal axis 110 concurrently with the outer shaft 102. Accordingly, rotation of the handle 104 (e.g. by the user turning the handle 104) concurrently rotates the outer shaft 102.

[00105] The inner shaft 108 is at least partially disposed within the interior channel 112. The inner shaft 108 has a probe end 108a and a transfer end 108b opposite the probe end 108a along the longitudinal axis 110. The inner shaft 108 is arranged to transfer a mechanical force received at the probe end 108a to the coupling assembly 106 via the transfer end 108b. In the illustrated example, the inner shaft 108 is moveable along the interior channel 112 in response to the mechanical force received at the probe end 108a.

[00106] As with the outer shaft 102, the inner shaft 108 may be formed from metal, metal alloy or plastic based on suitability for the intended use. For example, for surgical use, the inner shaft 108 may be formed from a bio-compatible metal such as titanium, titanium alloy or stainless steel.

[00107] In the illustrated example, the inner shaft 108 has a generally circular cross-section along its longitudinal axis. In one or more alternative embodiments, the cross-section of the interior channel 112 may have other configurations, e.g. triangular, rectangular, etc. Preferably, the cross-section of the inner shaft 108 generally corresponds to the cross-section of the interior channel 112, e.g. as shown. This correspondence may allow for smooth travel of the inner shaft 108 along the interior channel 112.

[00108] For surgical instruments adapted to make pilot holes, the outer shaft 102 has at least one cutting edge 114 provided on an exterior surface of the outer shaft 102, to form flutes or other rotary cutting elements (e.g., burrs, abrasives, etc.). The at least one cutting edge 114 is generally provided on a cutting region proximate the first shaft end 102a, e.g. as shown, but in some embodiments can be provided along the entire length of the outer shaft 102. [00109] As the outer shaft 102 rotates about the longitudinal axis 110, the at least one cutting edge 1 14 cuts the pilot hole. As best shown in FIGS. 3C to 3D and 4C to 4D, the outer shaft 102 has three cutting edges 114a, 114b, and 114c spaced circumferentially around the exterior surface of the outer shaft 102. The cutting edges 114a, 114b and 114c extend generally longitudinally from the first shaft end 102a. In the illustrated example, the cutting edges 114a, 114b and 114c are equally spaced circumferentially around the exterior surface of the outer shaft 102, and are not angled. In some alternative embodiments, more or fewer cutting edges with different spacing between each edge may be provided.

[00110] For example, in some embodiments, the at least one cutting edge

114 is wrapped around the exterior surface of the outer shaft 102 in a helical configuration. In some embodiments, the at least one cutting edge 114 is provided on the inner shaft 108 at the probe end 108a. In some embodiments, the outer shaft 102 and the inner shaft 108 both have at least one cutting edge provided thereon. In some embodiments, the at least one cutting edge 114 may be omitted from the surgical instrument 100 for applications that do not involve cutting.

[00111] The coupling assembly 106 has at least one threshold. The threshold is a predetermined value that, when crossed, causes the coupling assembly 106 to move from one of the engaged and disengaged configuration to the other of the engaged or disengaged configuration. For the surgical instrument 100 of FIGS. 3A to 4E, the at least one threshold is a threshold force.

[00112] In the engaged configuration, the coupling assembly 106 couples the handle 104 to the outer shaft 102 in a fixed rotatable manner when a mechanical force applied to the probe end 108a is greater than the threshold force. As described above, in the engaged configuration, the handle 104 fixedly rotates about the longitudinal axis 110 concurrently with the outer shaft 102. In this way, the user is able to deliver torque to the outer shaft 102 by rotating the handle 104 about the longitudinal axis 110. [00113] Conversely, in the disengaged configuration the coupling assembly 106 couples the handle 104 to the outer shaft 102 in a freely rotatable manner when the mechanical force is less than or equal to the threshold force. As described above, in the disengaged configuration, the handle 104 freely rotates about the longitudinal axis 110 independently of the outer shaft 102. In this way, the user is unable to deliver torque to the outer shaft by rotating the handle 104 about the longitudinal axis 110.

[00114] For example, as the surgical instrument 100 is making a pilot hole in a bone, a mechanical force received at the probe end 108a is provided through contact with the bone. Bone density can vary at different locations within a particular bone. Thus, the mechanical force provided by the bone to probe end 108a while making the pilot hole may vary with position and/or depth within the bone. Generally, the denser a particular region of bone is, the higher the force that particular region will supply to the probe end 108a. When the probe end 108a breaches the bone while forming the pilot hole a transition of media occurs. The probe end 108a may experience change in mechanical force like a step function as the probe end 108a transitions from contact with the bone to softer tissue surround the bone. This transition of media may result is a significant, if not total, loss in mechanical force supplied to the probe end 108a.

[00115] When the coupling assembly 106 is in the engaged configuration, the user can deliver torque to the outer shaft 102 by rotating the handle 104 about the longitudinal axis 110, thereby rotating of the at least one cutting edge 114 (e.g. cutting edges 114a, 114b and 114c) defined on the exterior surface of the outer shaft 102. Accordingly, the user is able to make, or continue to make, a pilot hole by rotating the handle 104 as long as the coupling assembly 106 is, or remains, in the engaged configuration.

[00116] However, when a mechanical force received at the probe end 108a falls below the threshold while forming the pilot hole, the coupling assembly 106 moves to the disengaged configuration and the user loses his or her ability to deliver torque to the outer shaft 102 through rotation of the handle 104, due to the free rotational coupling. In this way, the user can recognize, in real-time, when a mechanical force received at the probe end 108a crosses the threshold. This lack of force at the probe end 108a may be caused, for example, when a breach, or near breach, of the bone occurs, or when the pilot hole is being made in a region of bone having low density. This tactile feedback can allow the user to alter his or her trajectory so that the pilot hole can be made in a region of bone that offers sufficient mechanical integrity to support a stabilizing device (e.g. implant 10 of FIG. 1 ). The loss of the ability to deliver toque to the outer shaft 102 via the handle 104 may also prevent the user from continuing to rotate the outer shaft 102 once a breach of the bone wall has occurred, thereby decreasing the risk of inadvertent tissue damage and/or damage to neurovascular structures.

[00117] Each surgical instrument 100 may have a coupling assembly 106 with a unique threshold. In some cases, the surgical instrument 100 selected for use may be application specific. For example, a surgical instrument 100 having a coupling assembly 106 with a different threshold may be used for a younger patient than an older patient. In some cases, the preferred threshold across patients may vary with bone composition of the particular patient (i.e. degree of osteopenia and/or osteoporosis). In some cases, the threshold may also be varied for different types of surgical procedures. For example, a surgical instrument 100 having a coupling assembly 106 with a different threshold may be used for spinal surgery than hip surgery. As will be described in more detail below, in some embodiments, the threshold of each coupling assembly 106 is adjustable.

[00118] The handle 104 may be one of a number of suitable three- dimensional shapes, e.g. conical, cylindrical, etc. In the illustrated example, the handle 104 is generally spherical. The generally spherical handle 104 may provide a grip for the user’s hand, thereby simplifying rotation. In some embodiments, an outer surface of the handle 104 is rubberized to improve grip. In some embodiments, the handle 104 is at least partially covered with a coarse material to improve grip.

[00119] Reference is now made to FIGS. 5 to 9B to more clearly illustrate internal components of the surgical instrument 100. Referring to FIG. 5, the coupling assembly 106 has a coupling body 116 and a spring 118 extending longitudinally from a first spring end 118a to a second spring end 118b. The coupling body 116 has an axial bore (not shown) defined therethrough which permits passage of the inner shaft 108. In the illustrated example, the coupling body 116 has a star-shaped cross-section (best shown in FIGS. 8B and 9B).

[00120] The coupling body 116 can be secured to the spring 118 at the first spring end 118a in a number of suitable ways, e.g. by mechanical fasteners, adhesive, or a combination thereof. The coupling assembly 106 also has a flange portion that projects radially around the coupling body 116. The flange portion may be an inner ring 120. As shown in FIG. 5, the inner shaft 108 passes through the inner ring 120, the coupling body 116, and the spring 118.

[00121] The coupling body 116 is fixed to the inner shaft 108 proximate the transfer end 108b. The inner shaft 108 rotates and translates in unison with the coupling body 116 and the inner ring 120. In some embodiments, the inner shaft 108 and the coupling body 116 may be integrally formed. In one or more alternative embodiments, the engagement body 116 may be secured to the inner shaft 108 in such a way that permits the inner shaft 108 to translate along the longitudinal axis 110 in unison with the coupling body 116, but rotate about the longitudinal axis 110 independently of the coupling body 116 (e.g., via radial tongue-and-groove mating).

[00122] Referring to FIGS. 6A to 6C, the handle 104 has a first handle end

104a and a second handle end 104b opposite the first handle end 104a. The handle 104 has a first recessed portion 122 extending from the first handle end 104a toward the second handle end 104b. The first recessed portion 122 has an outer wall 122a and a base 122b that together define a cylindrical handle cavity 124. The handle 104 also has a second recessed portion 126 extending from the base 122b of the first receded portion 122 toward the second handle end 104b. The second recessed portion 126 defines a longitudinally extending spring socket 128 and a longitudinally extending inner shaft socket 130 axially aligned with the spring socket 128.

[00123] The handle 104 also has a coupling collar 132 extending upwardly and perpendicularly from the base 122b of the first recessed portion 122. As best shown in FIG. 6A, the coupling collar 132 has an elongate aperture 134 defined therethrough. In the illustrated example, the elongate aperture 134 has a star shaped cross-section, with rounded vertices. As best shown in FIG. 6C, the elongate aperture 134, the spring socket 128 and the inner shaft socket 130 are axially aligned to define a contiguous passageway.

[00124] With reference to FIG. 5 and FIGS. 6A to 6C, the star-shaped coupling body 116 of the coupling assembly 106 generally corresponds with the star-shaped elongate aperture 134 of the coupling collar 132 located within the handle cavity 124.

[00125] As shown in FIGS. 7A to 7B, the star-shaped elongate aperture 134 receives the star-shaped coupling body 116 in a mating engagement. In this way, the coupling collar 132 may be characterized as a‘female’ connector and the coupling body 116 may be characterized a‘male’ connector. When the coupling body 116 is at least partially received within the elongate aperture 134 of coupling collar 132, rotation of the handle 104 about the longitudinal axis 110 concurrently rotates the inner ring 120. As best shown in FIGS. 3E and 4E, when the coupling body 116 is at least partially received in the elongate aperture 134, e.g., as described above, the spring 118 sits in the spring socket 128. [00126] Although the illustrated example uses star-shaped ‘male’ and

‘female’ connectors, many other configurations may provide similar rotational engagement, e.g. rectangular, hexagonal, etc.

[00127] With reference to FIGS. 8A to 8B and 9A to 9B, the coupling assembly 106 also has an outer ring 136 aligned axially with the inner ring 120. As will be described in more detail below, the outer ring 136 is rotationally engaged to the outer shaft 102. In this way, rotation of the outer ring 136 about the longitudinal axis 110 concurrently rotates the outer shaft 102.

[00128] Referring to FIGS. 8A to 8B, as shown the outer ring 136 is adjacent, but does not surround any portion of the inner ring 120. In this arrangement, the coupling assembly 106 is in the disengaged position. Thus, rotating the handle 104 about the longitudinal axis 110 concurrently rotates the inner ring 120 about the longitudinal axis 1 10, but not the outer ring 136.

[00129] As best shown in FIG. 8B, the inner ring 120 has an outer circumferential surface 138 and the outer ring 136 has an inner circumferential surface 140. The inner and outer rings 120 and 136 are rotationally engaged (i.e. rotate in unison) when the outer circumferential surface 138 of the inner ring 120 at least partially surrounds the inner circumferential surface 140 of the outer ring 136. In the illustrated example, the outer and inner circumferential surfaces 138 and 140 have corresponding intermeshing teeth, or grooves and notches, that engage when overlaid (e.g. similar to interlocking teeth of gears). Other configurations may be used to rotationally engage the inner and outer rings 120 and 136.

[00130] Referring to FIGS. 9A to 9B, the inner ring 120 is shown partially disposed within the outer ring 136. In this arrangement, the outer circumferential surface 138 at least partially surrounds the inner circumferential surface 140. As described above, when the inner ring 120 is at least partially disposed within the outer ring 136, the inner and outer rings 120 and 136 are rotationally engaged (i.e. rotate together). In this arrangement, the coupling assembly 106 is in the engaged configuration. Accordingly, rotating the handle 104 about the longitudinal axis 110 concurrently rotates the inner and outer rings 120 and 136, thereby rotating the outer shaft 102.

[00131] Referring again to FIGS. 3E and 4E, the outer ring 136 of the coupling assembly 106 is rotationally engaged to the outer shaft 102 at the second shaft end 102b via a conical-shaped sleeve 142. The sleeve 142 has an axial bore 144 defined therethrough that receives the second shaft end 102b. The outer shaft 102 can be secured to the sleeve 142 in a number of suitable ways, e.g. by adhesive provided along the bore 144, mechanical fasteners, etc.

[00132] With reference to FIGS. 8A to 8B and 9A to 9B, the outer ring 136 has a pair of slots 146a and 146b defined in an outer circumferential surface thereof. The sleeve 142 has a pair of projections (not shown) that fit into corresponding slots 146a and 146b. When the projections are respectively received in slots 146a and 146b, the outer ring 136 is rotationally engaged with the sleeve 142. Since the sleeve 142 is also rotationally engaged to the outer shaft 102, e.g. as described above, the outer ring 136 is rotationally engaged with the outer shaft 102 via the sleeve 142. Accordingly, rotating the outer ring 136 concurrently rotates the outer shaft 102 when in this configuration.

[00133] In one or more alternative embodiments, the outer ring 136 and the sleeve 142 may be integrally formed. In such embodiments, the outer ring 136 is directly rotationally engaged with the outer shaft 102. Furthermore, other configurations of the sleeve 142, besides the illustrated conical-shaped sleeve 142, may provide similar function.

[00134] Referring again to FIGS. 3E and 4E, the handle 104 has a threaded retaining cap 148 removably connected at the first handle end 104a. When connected, the cap 148 allows the sleeve 142 to rotate within the handle cavity 124 (i.e. about the outer wall 122a), but prevents the sleeve 142 from coming out of the handle cavity 124. As a result, the retaining cap 148 keeps the outer shaft 102 connected to the coupling assembly 106 within the handle 104. In addition, the retaining cap 148 can prevent the components of the coupling assembly 106 from coming out of the handle cavity 124.

[00135] Referring now to FIGS. 6A and 6C, the handle 104 has a threaded section 150 that projects from the first handle end 104a around the handle cavity 124. The retaining cap 148 mates with the threaded section 150 via threads to partially enclose the handle cavity 124, thereby preventing the sleeve 142 from coming out of the handle cavity 124. This threaded engagement allows the retaining cap to be removed from the handle 104. For example, removing the retaining cap 148 may facilitate disassembly for sterilization of parts, general maintenance, replacement of parts, spring calibration, etc. The use of other fasteners, such as ball and groove joints, and/or press or snap fits may be used in place of the threaded retaining cap 148 and threaded section 150 to provide analogous function.

[00136] Referring to FIGS. 3A to 3E, the coupling assembly 106 is shown in the disengaged configuration. The coupling assembly 106 is in the disengaged configuration since no portion of the inner ring 120 is disposed within the outer ring 136 (best shown in FIG. 3E). Accordingly, the inner ring 120 and the outer ring 136 are not rotationally engaged and, as a result, rotation of the handle 104 about the longitudinal axis 1 10 will not supply torque to the outer shaft 102.

[00137] With reference to FIGS. 3A to 3D, the probe end 108a of the inner shaft 108 protrudes from the outer shaft 102 at the first shaft end 102a when the coupling assembly 106 is in the disengaged configuration. This arrangement allows the probe end 108a to be an initial point of contact for the surgical instrument 100. As best shown in FIG. 3E, the spring 118 sits in the spring socket 128. The second spring end 118b abuts the spring socket 128 at a rear end thereof, thereby biasing the inner shaft 108 so that the probe end 108a protrudes from the first shaft end 102a. A first distance Di measured along the longitudinal axis 110 from the first shaft end 102a to the probe end 108a is between 0.5 and 15 mm when the coupling assembly 106 is in the disengaged configuration. In the illustrated example, the first distance Di is about 2.5 mm. The first distance Di may be modified by varying a length of inner shaft 108, varying a length of the outer shaft 102, and/or varying a length of the spring 118.

[00138] Within continued reference to FIG. 3E, the spring 118 also biases the coupling body 118 away from a back wall of the elongate aperture 134. Put alternatively, the spring 118, in its natural or non-compressed state, prevents complete insertion of the coupling body 118 within the elongate aperture 134 (see gap G in FIG. 3E).

[00139] As described above, when a pilot hole is being made within a bone using the surgical instrument 100, the surgical instrument 100 is pressed against the bone, and a corresponding mechanical force results at the probe end 108a of the inner shaft 108 due to resistance of the bone tissue to the applied force. The mechanical force from the bone is proportionate to a density of the bone at a location of the probe end 108a. A location with higher bone density will apply a greater mechanical force than a location with lower bone density. When a breach, or near breach, of the bone occurs, the mechanical force supplied to the probe end 108a may drop significantly, or even entirely in cases where the probe end 108a breaches the bone wall.

[00140] Referring to FIGS. 4A to 4E, the coupling assembly 106 is shown in the engaged configuration. The coupling assembly 106 is in the engaged configuration since the inner ring 120 is partially disposed within the outer ring 136, as shown in FIG. 4E. Accordingly, the inner ring 120 and the outer ring 136 are rotationally engaged and, as a result, rotation of the handle 104 about the longitudinal axis 1 10 supplies torque to the outer shaft 102. [00141] A mechanical force Fp is supplied to the probe end 108a. For illustrative purposes, the mechanical force Fp represents an example mechanical force that may be supplied to the probe end 108a by a bone while making a pilot hole therein. The mechanical force Fp received at the probe end 108a has caused the inner shaft to move along the interior channel 112 in a direction from the first shaft end 102a to the second shaft end 102b. In this way, the inner shaft 108 transfers the mechanical force Fp received at the probe end 108a to the spring 118 of the coupling assembly 106.

[00142] With reference to FIG. 4B, the mechanical force Fp has caused the inner shaft 108 to partially retract within the outer shaft 102 when compared to the position of the inner shaft 108 in FIG. 3B. Since the spring 118 biases the inner shaft 108 in the protruded arrangement shown in FIG. 3B, the spring 118 compresses as the inner shaft 108 retracts within the outer shaft 102.

[00143] As described above, the coupling body 116 is secured to the inner shaft 108 in such a way that allows the coupling body 116 to move together with the inner shaft 108 along the longitudinal axis 110. Accordingly, the mechanical force Fp, by causing the inner shaft 108 to move along the interior channel 112 also causes the coupling body 116 to move further (i.e. retract) into the elongate aperture 134 of the coupling collar 132. As a result, the inner ring 120 moves toward the outer ring 136. FIG. 4E shows the coupling body 116 fully received within the elongate aperture 134 (i.e. the coupling body 116 contacts the back wall of the elongate aperture 134). In contrast, as shown in FIG.3E, the coupling body 116 is partially received within the elongate aperture 134 due to the gap G provided by the spring 118.

[00144] In the illustrated example, the threshold of the coupling assembly 106 is generally equal to a compression mechanical force required to compress the spring 118 from a first spring length Lsi to a threshold spring length (not shown). The threshold spring length may be characterized as the spring length at which the inner ring 120 becomes at least partially disposed within the outer ring 136. Spring length is measured along the longitudinal axis 110 between the first and second spring ends 118a and 118b.

[00145] Referring to FIG. 4E, the inner ring 120 is partially disposed within the outer ring 136. As described above, in this arrangement, the inner and outer rings 120 and 136 are rotationally engaged. The spring 118 compresses along the longitudinal axis 110 as inner shaft 108 retracts within the outer shaft 102. With reference to FIGS. 3E and 4E, the spring 118 has compressed from a first spring length Lsi (FIG. 3E) to second spring length I_s2 (FIG. 4E) in response to the mechanical force Fp received at the probe end 108a.

[00146] The mechanical force Fp is greater than the threshold of the coupling assembly 106 since the second spring length I_s2 is shorter than the threshold spring length. That is, the spring 118 has compressed beyond the threshold spring length. In the illustrated example, the mechanical force Fp received at the probe end 108a has compressed the spring 118 from the first spring length Lsi to the second spring length I_s2, passing the threshold spring length on the way.

[00147] The coupling assembly 106 moves from the disengaged configuration to the engaged configuration when the spring length crosses the threshold spring length. In this way, the engaged configuration of the coupling assembly 106 is provided across a range of mechanical forces that are greater than the threshold. For example, the mechanical force Fp may decrease while forming the pilot hole. Flowever, if the decreased mechanical force does not drop below the threshold, the coupling assembly 106 will remain in the engaged configuration. Similarly, the disengaged configuration of the coupling assembly 106 is provided across a range of mechanical forces that are less than the threshold.

[00148] The spring 118 has a spring stiffness. The threshold of the coupling assembly 106 is at least partially dependent upon the spring stiffness. A spring 118 with a higher spring stiffness will require a higher mechanical force for compression than a spring 118 with a lower spring stiffness. As a result, the spring 118 with the higher spring stiffness will generally have a higher threshold than the spring 118 with the lower spring stiffness. The spring 118 selected for use in the coupling assembly 106 may be based on the intended application of the surgical instrument 100. For example, when a surgical instrument 100 is to be used for spinal surgery, the spring 118 may have the higher spring stiffness, thereby requiring higher mechanical force to maintain the coupling assembly 106 in the engaged configuration. In effect, increasing or decreasing the spring stiffness of the spring 118 is a way of adjusting a sensitivity of the surgical instrument 100.

[00149] A second distance D2 measured along the longitudinal axis 110 from the first shaft end 102a to the probe end 108a is between 0 and 5 mm in the engaged configuration. In the illustrated example, the second distance D2 is about 0.5 mm. A displacement of the inner shaft 108 measured along the longitudinal axis 110 is at least partially based on a magnitude of the mechanical force received at the probe end 108a and the spring stiffness. For example, in comparison of FIGS. 3A and 4A, the mechanical force Fp has displaced the inner shaft 108 a distance of about 2 mm along the interior channel 112 (Di = 2.5 mm; D2 = 0.5 mm; D2 - Di = 2.0 mm).

[00150] As a magnitude of the mechanical force received at the probe end

108a decreases, the spring 420 decompresses, returning toward its natural or non- compressed state (i.e. first spring length Lsi). When a magnitude of the mechanical force received at probe end 108a drops below the threshold, the spring length expands and crosses the threshold spring length, thereby moving the coupling assembly 106 from the engaged configuration to the disengaged configuration.

[00151] As the user is rotating the handle 104 to deliver torque to the outer shaft 104, he or she is alerted when the probe end 108a has breached the bone wall, or entered a region of bone with an inadequate bone density. For example, the rotation of the handle 104 independently of the outer shaft 102 may serve as the alert. Moreover, in the disengaged configuration, the user loses the ability to deliver torque to outer shaft 102 by rotating the handle 104 about the longitudinal axis. In this way, the user may be prevented from continuing to make the pilot hole until his or her trajectory is appropriately adjusted. The surgical instrument 100 provides the user with a simple and effective means of surgical navigation while making pilot holes, thereby improving surgical outcomes and/or increasing patient safety.

[00152] In some embodiments, the surgical instrument 100 also has a drive motor (not shown). The drive motor has a motor axis of rotation that can be coaxially with the longitudinal axis 110 defined by the outer shaft 102. The drive motor is preferably located adjacent to the handle 104. Accordingly, the drive motor can be used to rotate the handle 104 about the longitudinal axis 100. In some cases, the drive motor is coupled to and operated by a computing system (not shown).

[00153] In the illustrated example, the handle 104 has an optional end plate 152 at the second handle end 104b. The end plate 152 is preferably made from a rigid material, such a metal or a dense plastic. The end plate 152 provides a hard surface for the user to strike with a hammer or mallet for impacting the probe end 108a into the bone. The end plate 152 can improve the structural integrity of the handle 104. The end plate 152 can also prevent the transfer end 108b of the inner shaft 108 from breaking through from the handle 104 at the second handle end 104b, e.g. in situations where the mechanical force received at the probe end 108a is exceedingly high.

[00154] In the illustrated example, the end plate 152 is press fitted into a plate cavity 154 defined in the handle 104 at the second handle end 104b. The end plate 152 may be removed from the handle 104 to facilitate sterilization of internal parts. As shown in FIG. 6C, when secured within the plate cavity 154, the end plate 152 closes the contiguous passage formed though the elongate aperture 134, the spring socket 128 and the inner shaft socket 130. In some embodiments, the end plate 152 is removably mounted to the handle 104. The end plate 152 can also be used to tailor the weight of the handle 104.

[00155] Referring to FIG. 3E and 4E, the coupling assembly 106 is fully disposed within the handle 104. In this arrangement, the handle 104 can protect internal components from damage, improve ergonomics, and/or enhance the aesthetic appearance of the surgical instrument 100.

Second Example Embodiment

[00156] FIGS. 10A to 10B illustrate another example surgical instrument, referred to generally as 200. The surgical instrument 200 shown in FIGS. 10A to 10B is analogous to the surgical instrument 100 shown in FIGS. 3A to 4E, except for differences in the handle 204 and the coupling assembly 206. Unless otherwise noted, like-numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 100 shown in FIGS. 3A to 4E. For example, outer shaft 202 is analogous to outer shaft 102.

[00157] Referring to FIG. 10B, the coupling assembly 206 has a position sensor 256, a spring 258 having a spring stiffness, and an actuator 260 having a controller 262 communicatively coupled to the position sensor 256. As will be described in more detail below, the actuator 260 couples the handle 204 to the outer shaft 202 at the second shaft end 202b in one of an first configuration and a second configuration. The controller 262 can control the operation of the actuator 260 to provide the first and second configurations.

[00158] In the first configuration, the handle 204 rotates about the longitudinal axis 210 concurrently with the outer shaft 202. Accordingly, rotation of the handle 204 (e.g. by the user turning the handle 204) concurrently rotates the outer shaft 202. The first configuration may be characterized as an“engaged configuration”, e.g. as described above with reference to FIGS. 3A-4E.

[00159] In the second configuration, a torque supplied from the handle 204 to the outer shaft 202 is limited. That is, in the second configuration, a torque provided to the handle 204 (e.g. by the user turning the handle 204) is not fully transferred to the outer shaft 202. As described in more detail below, the coupling assembly 206 may have a torque limiter to provide this functionality. In some embodiments, the controller 262 may have the torque limiter. In some cases, in the second configuration, no torque is supplied from the handle 204 to the outer shaft 202 (i.e. the handle 204 rotates about the longitudinal axis 210 independently of the outer shaft 202). In such cases, the torque may be limited through disengagement of the handle 204 with the outer shaft 202. FIG. 10B exemplifies such a case in which no torque is supplied from the handle 204 to the outer shaft 202. Accordingly, the second configuration shown in FIG. 10B may be characterized as a“disengaged configuration”.

[00160] The inner shaft 208 is arranged to transfer a mechanical force received at the probe end 208a to the spring 258 via the transfer end 208b. The spring 258 extends longitudinally from a first spring end 258a to a second spring end 258b. In the illustrated example, the spring 258 is disposed within the interior channel 212 and located between the transfer end 208b of the inner shaft 208 and the position sensor 256. The transfer end 208a of the inner shaft 208 can be secured to the spring 258 at the first spring end 258a in a number of suitable ways, e.g. by mechanical fasteners, adhesive, or a combination thereof. Similarly, the position sensor 256 can be secured to the spring 258 at the second spring end 258b in a number of suitable way, e.g. by mechanical fasteners, adhesive, or a combination thereof.

[00161] Referring to FIGS. 10A to 10B, the coupling assembly 206 is shown in the second configuration. In the second configuration, the probe end 208a of the inner shaft 208 protrudes from the outer shaft 202 at the first shaft end 202a. As shown in FIG. 10B, the second spring end 258b abuts the position sensor 256, thereby biasing the inner shaft 208 so that probe end 208a protrudes from the first shaft end 202a. This arrangement allows the probe end 208a to be an initial point of contact for the surgical instrument 200.

[00162] A mechanical force received at the probe end 208a may cause the inner shaft 208 to move along the interior channel 212 in a direction from the first shaft end 202a to the second shaft end 202b. In this way, the inner shaft 208 transfers the mechanical force received at the probe end 208a to the spring 258 via the transfer end 208b. Since the spring 258 biases the inner shaft 208 in the protruded arrangement shown in FIG. 10B, the spring 258 compresses as the inner shaft 208 retracts within the outer shaft 202.

[00163] The spring 258 is compressible along the longitudinal axis 210 in proportion to a magnitude of the mechanical force received at the probe end 208a. A mechanical force with a higher magnitude will cause greater compression of the spring 258 than a mechanical force with a lower magnitude. With reference to FIG. 10B, as the spring 258 compresses, the transfer end 208b moves closer to the position sensor 256. Conversely, as the spring 258 decompresses the transfer end 208 moves farther from the position sensor 256. In this way, a position of the transfer end 208b of the inner shaft 208, relative to the position sensor 256, is at least partially based on a magnitude of the mechanical force received at the probe end 208a.

[00164] The position sensor 256 can detect a position of the transfer end 208b of the inner shaft 208 relative to the position sensor 256. For example, the position sensor 256 can detect a distance S between the position sensor 256 and the transfer end 208b, or a deflection of the inner shaft 208 along the length of the interior channel 212. In the illustrated example, the position sensor 256 is an optical position sensor 256. The optical position sensor 256 is arranged to direct a light beam (e.g., a laser) having a known intensity toward the transfer end 208b of the inner shaft 208, and detect the distance S based on the intensity of the light reflected back to the optical light sensor 256 from the transfer end 208b. The spring 258 is configured and arranged so that it obstructs neither the light beam directed by the optical position sensor 256 nor the light reflected back to the optical light sensor 256.

[00165] In some embodiments, the position sensor 256 may be a capacitive sensor or an inductive sensor, which can measure a capacitance or inductance induced by the inner shaft 208 within a predetermined portion of the interior channel 212 (e.g., as the inner shaft is displaced within the interior channel 212, the capacitance or inductance may increase, and be measured to determine the amount of deflection). In such embodiments, the spring 258 may be positioned or oriented other than as shown, to accommodate the capacitive or inductive sensor.

[00166] The controller 262 may be, e.g., a microcontroller or other processor, which receives a signal comprising the distance S (i.e. the distance between the transfer end 208b and the position sensor 256) from the position sensor 256. The controller 262 can determine a magnitude of the mechanical force based at least in part on the distance S as determined from the signal. For example, the controller 262 may covert the distance S to a force magnitude using a calibration index or the like, based on the spring stiffness. One way to generate the calibration index would be to supply a plurality mechanical forces with known magnitudes to the probe end 208a and plot the correspond separation S for each magnitude. The calibration index can be updated periodically, or as desired, to accommodate for changes to the spring stiffness over time. Alternatively, or in addition, the spring 258 may be replaced after each procedure or after a pre-determ ined number of procedures.

[00167] In some embodiments, the spring 258 is replaceable with one of a plurality of springs, with each spring having its own unique spring stiffness. In such embodiments, a calibration index may be generated and/or provided for each spring. The spring 258 may be selected based for a spring stiffness suitable for the intended application of the surgical instrument 200. Although the coupling assembly 208 has a spring in the illustrated example (e.g. spring 258), the coupling assembly 208 may have other types of biasing members, e.g. a metal bellow, a coned-disc washer (also known as a Belleville washer), a strut, etc. When used, the Belleville washer may provide more precise measurements than other types of biasing members.

[00168] The controller 262 can be programmed to have at least one threshold value, or simply threshold. For example, the controller 262 may have a first threshold and second threshold. In such example, the first and second thresholds may be equal or may be varied as desired. In the illustrated example, the threshold is a threshold force. As will be described in more detail below, the at least one threshold may be adjustable. The controller 262 directs the actuator 260 to move based on a magnitude of the mechanical force received at the probe end 208a in relation to the threshold. That is, when the magnitude of the mechanical force is greater than the at least one threshold, the controller causes the actuator 260 to couple the handle 204 to the outer shaft 202 in the first configuration. Conversely, when the magnitude of the mechanical force is less than or equal to the at least one threshold, the controller causes the actuator 260 to couple the handle 204 to the outer shaft 202 in the second configuration. In some cases, a hysteresis may be provided to reduce or eliminate undesired switching between the first and second configurations when the magnitude of the mechanical force is close to the at least one threshold. For example, in order to avoid oscillation when the force is just slightly above the at least one threshold, the controller may have a disengage threshold that is lower than an engage threshold. The measured force would therefore drop lower than the threshold force (e.g., threshold force less hysteresis value, equaling a hysteresis threshold force), prior to re-engaging. [00169] The coupling assembly 206 moves from the second configuration to the first configuration when the actuator 260 and the handle 204 become rotationally engaged (i.e. rotate together). Referring to FIG. 10B, the handle 204 has a recessed portion 264 extending from the first handle end 204a toward the second handle end 204b. The recessed portion 264 has an outer wall 264a and a base 264b that together define a cylindrical handle cavity 266. The base 264b of the recessed portion 264 has an aperture 268 defined therein. In the illustrated example, the aperture 268 has a star-shaped cross-section.

[00170] With continued reference to FIG. 10B, the actuator 260 has a coupling body 270 that projects outwardly therefrom. In the illustrated example, the coupling body 270 has a star-shaped cross-section. The star-shaped coupling body 270 of the actuator 260 generally corresponds with the star-shaped aperture 268 of the handle 204. The star-shaped coupling body 270 is located so that it may extend into and be received by the star-shaped aperture 268.

[00171] In the illustrated example, the aperture 268 of the handle 204 may be characterized as a‘female’ connector and the coupling body 270 of the actuator 260 may be characterized a‘male’ connector. It will be appreciated that in one or more alternative embodiments, the ‘female’ and ‘male’ connectors may be inverted. For example, the base 264b of the recessed portion 264 may have a coupling body projecting therefrom (‘male’ connector) and the actuator 260 may have an aperture defined therein (‘female’ connector).

[00172] When the coupling body 270 of the actuator 260 is at least partially received within the aperture 268 of the handle 204, the actuator 260 and the handle 204 become rotationally engaged. Due to this engagement, rotation of the handle 204 about the longitudinal axis 210 concurrently rotates the outer shaft 202.

Referring to FIG. 10B, the coupling assembly 106 is in the second configuration since no portion of the coupling body 270 is disposed within the aperture 268. In other words, in the illustrated example, the actuator 260 and the handle 204 are not rotationally engaged.

[00173] Although the illustrated example uses star-shaped ‘male’ and ‘female’ connectors, many other configurations can provide similar rotational engagement, e.g. rectangular, hexagonal, etc.

[00174] The actuator 260 is rotationally secured to the outer shaft 202 at the second shaft end 202b. That is, rotation of the actuator 260 about the longitudinal axis 210 causes the outer shaft 202 to rotate concurrently about the longitudinal axis 210. Thus, in the first configuration, when handle 204 and the actuator 260 are rotationally engaged, e.g. as described above, rotation of the handle 204 delivers toque to the outer shaft 202 via the actuator 260.

[00175] The outer shaft 202 can be rotationally secured to the actuator 260 in a number of suitable ways. For example, as shown in FIG. 10B, a flange section 272 projects outwardly from the second shaft end 202b. The flange section 272 has a radial portion 272a and a longitudinal portion 272b extending generally perpendicularly from the radial portion 272a at a distal edge thereof. The radial portion 272a and longitudinal portion 272b together define a cylindrical outer shaft cavity 274.

[00176] With continued reference to FIG. 10B, the longitudinal portion 272b of the flange section 272 is received within the handle cavity 266. Although the outer wall 264a of the recessed portion 264 overlies the longitudinal portion 272b of the flange section 272, the flange section 272 and the handle 204 rotate independently in the second configuration. In the second configuration, rotation of the handle 204 about the longitudinal axis 210 rotates the outer wall 264a about the longitudinal portion 272b.

[00177] The actuator 260 can be rotationally engaged with the longitudinal portion 272b of the flange section 272 in a number of ways. For example, the longitudinal portion 272b may have a pair of longitudinally extending slits (not shown) defined in an interior surface thereof. Each slit may receive one of a corresponding pair of tabs (not shown) that project outwardly from the actuator 260. Respective engagement between the pair of slits and tabs can rotationally engage the actuator 260 and the flange section 272 without preventing the actuator 260 from moving (i.e. actuation) along the longitudinal axis 210 (i.e. the tabs can move longitudinally within the slits).

[00178] In the illustrated example, the flange section 272 is integrally formed with the outer shaft 202. In one or more alternative embodiments, the flange section 272 may be secured to the second shaft end 202b in other suitable ways, e.g. by mechanical fasteners, adhesive, threaded engagement, or a combination thereof.

[00179] The coupling assembly 208 may also have an energy storage module 276 (e.g. a battery) for energizing the actuator 260, the controller 262 and/or the position sensor 256. The energy storage module 276 can be located at any suitable location within the surgical instrument 200; however, it will be appreciated that locating the energy storage module 276 close to the actuator 260 and/or the position sensor 256 may be convenient. As shown in FIG. 10B, the energy storage module 276 is located between the position sensor 256 and the actuator 260 within the handle cavity 266. In some embodiments, the position sensor 256, the controller 262 and the energy storage 276 are mounted or connected to a circuit board (not shown). In such embodiments, the circuit board couples the position sensor 256, the controller 262 and the energy storage module 276.

[00180] Those skilled in the art will appreciate that the energy storage module 276, the controller 262, the sensor 256, and/or the circuit board may also be rotationally engaged with the longitudinal portion 272b, e.g. in a similar as the actuator 260 described above. [00181] In an alternative embodiment (not shown), the components within the handle 104 (e.g. the actuator 260, the controller 262, the sensor 256, the energy storage module 276 and/or the circuit board) may be located together in a removably housing unit. The housing unit may be rotationally engaged with the longitudinal portion 272b, e.g. as described above. For example, the housing unit may facilitate charging the energy storage module 276, maintenance, and/or replacement of parts.

[00182] The controller 262 generally may be a processor with on-board memory. The processor may be any suitable microcontroller or other processor that can provide sufficient processing power depending on the configurations, purposes and requirements of the surgical instrument 200. In some embodiments, the controller 262 may have an external memory module coupled to processor. In such embodiments, the external memory module may also be coupled to the processor via the circuit board. The on-board memory and the external memory may include both volatile and non-volatile memory, which are collectively referred to herein as‘memory’.

[00183] The at least one threshold of the coupling assembly 206 is stored in the memory. The memory can store the calibration index or calibration indices (described above). The processor can instruct the memory to write and/or retrieve data.

[00184] In some embodiments, the controller 262 may have an input device for entering information, updating calibration indices and making requests. For example, the input device may be a communications interface (e.g., Universal Serial Bus) or a physical input device, such as one or more buttons, a touchscreen or any combination of these. In such embodiments, the input device may be used to adjust the at least one threshold of the coupling assembly 206. For example, once set, the adjusted threshold may replace the previously stored threshold in the memory. [00185] The controller 262 may also have a wireless transmitter configured to couple the controller 262 to a peripheral device. For example the wireless transmitter may be at least one of a Wi-Fi™ module, a Bluetooth™ module and a near-field communication (NFC) module configured to couple the controller 262 to the peripheral device, e.g. a database, a laptop, a smart phone, etc. In such embodiments, the peripheral device may be used to adjust the at least one threshold of the coupling assembly 206. For example, once set, the adjusted threshold may replace the previously stored threshold in the memory. This ability to adjust the at least one threshold via the controller 262 can allow the surgical instrument 200 to be tailored or‘fine-tuned’ for specific applications.

[00186] In the illustrated example, the coupling assembly 206 is partially disposed within the handle 204. Only the spring 258 is external to the handle 204. As shown in FIG. 10B, the position sensor 256 and the actuator 260 are fully disposed within the handle 204. In particular, the position sensor 256 and the actuator 260 sit within the handle cavity 266. In this arrangement, the handle 204 can protect internal components from damage, reduce occurrences of tampering, and/or enhance the aesthetic appearance of the surgical instrument 200.

[00187] With continued reference to FIGS. 10A to 10B, the retaining cap 248 is press fitted with the handle 204 at the second handle end 204a. When secured, the retaining cap 248 can hold the flange portion 272 within the handle cavity 266, thereby preventing the outer shaft 202 from dislocating the handle 204 at the second shaft end 202b. The retaining cap 248 may also be threadedly engaged with the handle 204, e.g. similar to the retaining cap 148 and the handle 104 of FIG. 3E. The retaining cap 248 can also be removable secured to the handle 204 with pins, bolts, clips or a combination thereof.

Third Example Embodiment

[00188] FIGS. 11A to 11 C illustrate another example surgical instrument, referred to generally as 300. The surgical instrument 300 shown in FIGS. 11 A to 11 C is similar to the surgical instrument 200 shown in FIGS. 10A to 10B, except for differences to the coupling assembly 306. Unless otherwise noted, like- numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 200 shown in FIGS. 10A to 10B, or example surgical instrument 100 (if not shown in FIGS. 10A to 10B).

[00189] Referring to FIG. 11 B, the inner shaft 308 is arranged to transfer a mechanical force received at the probe end 308a to the sensor 356 via the transfer end 308b. Unlike the inner shafts 108 and 208 of respective example surgical instruments 100 and 200 described above, the inner shaft 308 of surgical instrument 300 does not transfer the mechanical force through movement along the interior channel 312. Instead, the inner shaft 308 transfers the mechanical force received at the probe end 308a through direct contact between the transfer end 308b and the sensor 356.

[00190] As shown in FIG. 11 B, the transfer end 308b of the inner shaft 308 is secured to the sensor 356. The transfer end 308b can be secured to the sensor 356 in a number of suitable ways, e.g. with mechanical hardware (e.g. threaded fasteners, clips, or the like), adhesive, or a combination thereof.

[00191] As shown in FIG. 11 C, the probe end 308a of the inner shaft 308 protrudes slightly from the outer shaft 302 at the first shaft end 302a. This arrangement allows the probe end 308a to be an initial point of contact for the surgical instrument 300. A length of the inner shaft 308 can be adjusted to vary a distance that the inner shaft 308 protrudes from the outer shaft 302 at the first shaft end 302a.

[00192] Since the transfer end 308b of the inner shaft 308 is secured to the sensor 356, e.g. as described above, the inner shaft 308 does not retract within the outer shaft 302 in response to a mechanical force received at the probe end 308a. Although FIGS. 11 A to 11 C show the coupling assembly 306 in the second configuration, the location of the inner shaft 308 relative to the outer shaft 302 remains the same in the first configuration. Since the probe end 308a does not move, a breach may be detected with minimal penetration into the area of unwanted penetration, thereby improving sensitivity of the surgical instrument 300.

[00193] The sensor 356 can be any sensor capable of detecting a mechanical force (i.e. load) supplied to the sensor 356 by the transfer end 308b. In the illustrated example, the sensor 356 is a strain gauge (e.g. MEMS strain gauge). As shown in FIG. 11 B, the strain gauge 356 is located to receive a mechanical force transferred by the transfer end 308b. A mechanical force with a higher magnitude will provide a greater strain on the strain gauge (i.e. resulting in a higher voltage reading) than a mechanical force with a lower magnitude.

[00194] The controller 362 can determine a magnitude of the mechanical force based at least in part on the signal received from the sensor 356. For example, during operation, the controller 362 receives a signal comprising a detected voltage from the strain gauge 356. The controller 362 can covert the detected voltage to the strain magnitude using a calibration index or the like. One way to generate the calibration index would be to supply a plurality of mechanical forces with known magnitudes to the probe end 308a and plot the correspond voltage for each magnitude.

[00195] Like the example surgical instrument 200 shown in FIGS. 10A to 10B, the controller 362 moves the actuator 360 based on a magnitude of the mechanical force received at the probe end 308a in relation to the at least one threshold. The actuator 360 couples the handle 304 to the outer shaft 302 in the first configuration when the magnitude of the mechanical force is greater than the at least one threshold. Conversely, the actuator 360 couples the handle 304 to the outer shaft 302 in the second configuration when the magnitude of the mechanical force is less than or equal to the at least one threshold. [00196] The at least one threshold of surgical instrument 300 may be set or adjusted as desired for particular applications, e.g. via the controller 362.

[00197] In some embodiments, the controller 362 may also determine a rate of change of the magnitude of the mechanical force, an integral of the magnitude over a given period, or both. In such embodiments, the at least one threshold may comprise multiple thresholds or a weighted average.

[00198] Referring to FIG. 11 B, the coupling assembly 306 is fully disposed within the handle 304. In this arrangement, the handle 304 can protect internal components from damage, reduce occurrences of tampering, and/or enhance the aesthetic appearance of the surgical instrument 300.

Fourth Example Embodiment

[00199] FIGS. 12A to 12B illustrate another example surgical instrument, referred to generally as 400. The surgical instrument 400 shown in FIGS. 12A to 12B is similar to the surgical instrument 300 shown in FIGS. 11A to 11 C, except for the location of the sensor 456. Unless otherwise noted, like-numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 300 shown in FIGS. 11A to 11 C, or example surgical instrument 100 (if not shown in FIGS. 11A to 11 C). FIGS. 12A to 12B show only a portion of the surgical instrument 400 to improve clarity.

[00200] The sensor 456 (e.g. strain gauge 456) of coupling assembly 406 is located within the outer shaft 402. As shown in FIG. 12B, the sensor 456 is spaced apart from the actuator (not shown) by a distance Ds-c measured along the longitudinal axis 410. In the illustrated example, the sensor 456 is coupled to the controller of the actuator by a wire 478. In one or more alternative embodiments, the sensor 456 may be wirelessly connected to the controller, e.g. through Wi-Fi, Bluetooth, NFC, etc. [00201] In the illustrated example, the interior channel 412 has a first portion 412a and a second portion 412b. The first portion 412a has a smaller diameter than the second portion 412b. A transition wall 412c is defined at the junction between the first and second portions 412a and 412b. The strain gauge 456 is located within the second portion 412b and secured to the transition wall 412c. The wire 478 couples the sensor 456 to the controller 462 by passing through the second portion 412b.

[00202] The strain gauge 456 (or another type of sensor) can be located at any suitable position within the outer shaft 402. For example, the sensor 456 can be located closer to the second shaft end (not shown) than the first shaft end 402a. In the illustrated example, the sensor is located closer to the first shaft end 402a than the second shaft end. Locating the sensor 456 away from the other components of the coupling assembly may provide one or more advantages. For example, the other components (e.g. battery, actuator, and/or controller) may be replaced without having to replace the sensor 456. Alternatively, or in addition, the length of the inner shaft 408 can be reduced (see the length of the inner shaft 308 shown in FIG. 11 B compared to the length of the inner shaft 408 shown in FIG. 12B). This may simplify manufacturing, and/or reduce material cost and weight of the surgical instrument 400.

[00203] Although the surgical instrument 400 shown in FIGS. 12A to 12B uses the strain gauge 456, the surgical instrument 400 may be modified by replacing the strain gauge 456 with the position sensor 356 and spring 358 of the surgical instrument 200 shown in FIGS. 10A to 10B.

Fifth Example Embodiment

[00204] FIGS. 13A to 13C illustrate another example surgical instrument, referred to generally as 500. The surgical instrument 500 shown in FIGS. 13A to 13C is similar to the surgical instrument 300 shown in FIGS. 11A to 11 C, except for the location of the sensor 556 and the absence of an inner shaft. Unless otherwise noted, like-numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 300 shown in FIGS. 11 A to 11 C, or example surgical instrument 100 (if not shown in FIGS. 11A to 11 C).

[00205] The sensor 556 of coupling assembly 506 is located within the shaft 502. As shown in FIG. 13B, the sensor 556 is spaced apart from the controller 562 by a distance Ds-c measured along the longitudinal axis 510. In the illustrated example, the sensor 556 is coupled to the controller 562 of the actuator 560 by a wire 580. In one or more alternative embodiments, the sensor 556 may be wirelessly connected to the controller 562, e.g. through Wi-Fi, Bluetooth, NFC, etc.

[00206] The sensor 556 may be one of a variety of sensor types. In the illustrated example, the sensor 556 is a 3-axis accelerometer. The 3-axis accelerometer can detect magnitude and direction of acceleration, as a vector quantity, which can be used to gauge vibration. For example, the acceleration data may be processed by software running on the controller 562 to determine a density of the material at, or near to, the probe end 502a of the surgical instrument 500. The actuator 560 can then engage or disengage the handle 504, e.g. as described above, when significant density changes are experienced, such as at the interface between bone and soft tissue surround the bone.

[00207] In an alternative embodiment, the sensor 556 is an ultrasound transceiver. In such embodiments, the ultrasound transceiver is preferably located at, or proximate, the first shaft end 502a. The ultrasonic transceiver may determine a density of the material and/or a proximity to material interfaces (e.g. the bone/tissue interface) at, or around, the first shaft end 502a. For example, by measuring the reflection of ultrasonic pulses directed by the transceiver, the proximity to the bone/tissue interface may be determined. As a result, the handle 504 may disengage the outer shaft 502 at the second shaft end 502b. e.g., as described above, before a breach of the bone into the surround tissue.

[00208] In some embodiments, it may be beneficial to include a channel and or lens between the sensor 556 and the first shaft end 502a for improved signal quality.

[00209] In another alternative embodiment, the sensor 556 is a magnetic permeability sensor. In such embodiments, the magnetic permeability sensor is preferably located at, or proximate, the first shaft end 502a. The dielectric properties of bone differ from that of blood, the soft tissue surrounding the bone, etc. Accordingly, the magnetic permeability sensor is capable of determining the proximity of the first shaft end 502a to a material interface (e.g. the bone/tissue interface). As a result, the handle 504 may disengage the outer shaft 502 at the second shaft end 502b. e.g., as described above, before a breach of the bone into the surround tissue.

[00210] In yet another alternative embodiment, the sensor 556 comprises a pair of electrically isolated capacitive sensors. At least one of the pair of capacitive sensors is located at the first shaft end 502a. In such embodiments, the controller 562 can determine a capacity differential between the pair of capacitive sensors. The capacitance of bone differs from that of blood, the soft tissue surrounding the bone, etc. Accordingly, the capacity differential is a means of determining the proximity of the first shaft end 502a to a material interface (e.g. the bone/tissue interface). As a result, the handle 504 may disengage the outer shaft 502 at the second shaft end 502b. e.g., as described above, before a breach of the bone into the surround tissue. In one such example, the exterior surface of shaft 102 may be one of the two capacity sensors, and an electrically isolated metal probe, pin, or cutting head, at the first shaft end 102a may be the other of the two capacity sensors. [00211] In still yet another alternative embodiment, the sensor 556 comprises a pair of electrically isolated electrodes. At least one of the pair of electrodes is located at the first shaft end 502a. In such embodiments, the controller 562 can determine a conductivity differential between the pair of electrodes. The conductivity of bone differs from that of blood, the soft tissue surrounding the bone, etc. Accordingly, the conductivity differential is a means of determining the proximity of the first shaft end 502a to a material interface (e.g. the bone/tissue interface). As a result, the handle 504 may disengage the outer shaft 502 at the second shaft end 502b. e.g., as described above, before a breach of the bone into the surround tissue. In one such example, the exterior surface of shaft 102 may be one of the two electrodes, and an electrically isolated metal probe, pin, or cutting head, at the first shaft end 102a may be the other of the two electrodes.

[00212] Referring to FIG. 13B, the surgical instrument 500 does not have an inner shaft. The sensors 556, e.g. as described above, can operate without an inner shaft to detect a mechanical force. Since the surgical instrument 500 lacks an inner shaft, the shaft 502 also may lack an interior channel defined therein to receive the inner shaft. This lack of an inner shaft and interior channel may simplify manufacturing of the surgical instrument 500. The first shaft end 502a is an initial point of contact for the surgical instrument 500. In the illustrated example, the first shaft end 502a has a rounded contact tip 503.

[00213] As shown in FIG. 13B, the shaft 102 defines an internal cavity 582 extending from a first cavity end 582a to a second cavity end 582b at the controller 562. The sensor 556 can be secured to the first cavity end 582a in a number of suitable ways, e.g. by mechanical fasteners, adhesive, or a combination thereof. The wire 580 couples the sensor 556 to the controller 562 by passing through the internal cavity 582. In embodiments where the sensor 556 and the controller 562 are wirelessly connected, it will be appreciated that the internal cavity 582 may be omitted. [00214] During operation, the controller 562 receives a signal comprising a detected parameter from the sensor 556. In some embodiments, the coupling assembly 506 may also include filters, amplifiers, or a combination thereof to process the signal. It will be appreciated that the detected parameter will vary according to the type of sensor 556 used in the coupling assembly 506. In the illustrated example, the detected parameter is an acceleration since the sensor 556 is the 3-axis accelerometer. For example, when the sensor 556 is the pair of electrodes, the detected parameter may be a conductivity differential.

[00215] The controller 562 has a at least one threshold (e.g. stored in the memory of controller 565). Like the detected parameter, the at least one threshold will vary according to the type of sensor 556 used in the coupling assembly 506. In the illustrated example, the at least one threshold is an acceleration threshold since the sensor 556 is the 3-axis accelerometer. Similarly, when the sensor 556 is the pair of electrodes, the at least one threshold may be a conductivity differential threshold.

[00216] The controller 562 moves the actuator 560 based on the detected parameter in relation to the at least one threshold. The actuator 560 couples the handle 504 to the shaft 502 in one of the first configuration and the second configuration when the detected parameter is greater than the at least one threshold. Conversely, the actuator 560 couples the handle 504 to the shaft 102 in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the at least one threshold.

[00217] In some embodiments, the controller 562 may determine a rate of change of the detected parameter, an integral of the detected parameter over a given period, or both. In such embodiments, the at least one threshold may comprise multiple thresholds or a weighted average.

[00218] In some embodiments, the threshold may be derived from a series of data points (e.g. a series of acceleration values, a series of conductivity differentials, etc.). In such embodiments, the controller’s processor may use algorithms, which may involve integral or differential analysis of the series of values, to determine whether the threshold is crossed.

[00219] In other embodiments, the controller’s processor may rely on a trained neural network to determine whether the threshold is crossed. In such embodiments, the neural network may be trained using known methods, such as ‘reinforcement learning’ or‘supervised learning.’ For example, a model could be trained by using collected input sensor data (accelerometer values, strain gauge readings, capacitive sensor data, etc.), labeled, for example, according to known positions within a subject material, like bone, or at the moment that a breach of a bone-tissue interfaces occurs while making a pilot hole, or according to the proximity of the first shaft end 502a to the bone-tissue interface. The trained neural network operating within the processor may continually assess the input data stream and output a binary classification and/or a probability. The binary classification may be a decision to engage or disengage the handle 504 from the shaft 502. Alternatively, or in addition, the trained neural network may output a probability of being in a passing or failing state of a given criteria, or multiple criteria, such as breaching the bone-tissue interface. In such embodiments, the threshold may be based on the binary classification, or it may be a probability threshold.

[00220] In the illustrated example, the actuator 560 couples the handle 504 to the shaft 102 in the second configuration when the detected acceleration is greater than the acceleration threshold. Conversely, the actuator 560 couples the handle 504 to the shaft 102 in the first configuration when the detected acceleration is less than or equal to the acceleration threshold. For example, in cased where the surgical instrument 500 is used to make a pilot hole, the user may lose his or her ability to supply toque to the shaft 502 via the handle 504 when the detected acceleration (i.e. vibration) exceeds the threshold. [00221] With continued reference to FIGS. 13A to 13C, the shaft 502 has a tapered portion 584 tapering toward the first shaft end 502a. In cases where the surgical instrument 500 is used to make a pilot hole, the tapered portion 584 can provide for improved cutting. The tapered portion 584 can also simply removal of the shaft 502 from the pilot hole. In other cases, the tapered portion 584 may improve maneuverability of the surgical instrument 500 in difficult to access areas.

[00222] A tapering angle qt and/or a length LT of the tapering portion 584 can be tailored to specific applications. The tapered portion 584 shown in FIG. 13A to 13C can be similarly applied to any of the other example surgical instruments presented herein.

Sixth Example Embodiment

[00223] FIG. 14 illustrates another example surgical instrument, referred to generally as 600. The surgical instrument 600 shown in FIG. 14 is similar to the surgical instrument 300 shown in FIGS. 11A to 11 C, except that the outer shaft 602 has a curved portion 686 proximate the first shaft end 602a. Unless otherwise noted, like-numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or performing similar function as those in the example surgical instrument 300 shown in FIGS. 11A to 11 C, or example surgical instrument 100 (if not shown in FIGS. 1 1A to 11 C).

[00224] In cases where the surgical instrument 600 is used to make a pilot hole, the curved portion 686 can provide improved cutting. In other cases, the curved portion 686 may improve maneuverability of the surgical instrument 600 in difficult to access areas. An angle 0c and/or a length Lc of the curved portion 686 can be tailored to specific applications. The curved portion 686 shown in FIG. 14 can be similarly applied to any of the other example surgical instruments presented herein.

Seventh Example Embodiment [00225] FIGS. 15A to 15B illustrate another example surgical instrument, referred to generally as 700. The surgical instrument 700 shown in FIGS. 15A to 15B is similar to the surgical instrument 100 shown in FIGS. 3A to 4E, except that the coupling assembly 706 is external to the handle 704. Unless otherwise noted, like-numbered elements (i.e. , elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 100 shown in FIGS. 3A to 4E.

[00226] Referring to FIGS. 15A to 15B, the handle 704 has an extension shaft 788 extending outwardly from the handle 704 to a distal end 788a. Rotation of the handle 704 about the longitudinal axis 710 concurrently rotates the extension shaft 788. In the illustrated example, the handle 704 is integrally formed with the extension shaft 788. In one or more alternative embodiments, the handle 704 and the extension shaft 788 can be connected in a number of suitable ways, e.g. by mechanical fasteners, adhesive, or any combination thereof. As best shown in FIG. 15B, the coupling assembly 706 couples the distal end 788a of the extension shaft 788 to the outer shaft 702 in one of the first or second configurations (e.g. one of the engaged and disengaged configuration described with reference to FIGS. 3A- 4E).

[00227] A length LE of the extension shaft 788 measured from the distal end

788a to the handle 704 can be tailored to specific applications. In this way, the overall length of the surgical instrument is adjustable by varying the length LE of the extension shaft 788 without having to modify any of the other components.

[00228] The coupling assembly 706 is shown schematically in FIGS. 15A to 15B. The coupling assembly 706 can be one of the coupling assemblies 106, 206,

306, 506 of surgical instruments 100, 200, 300 and 500 shown in FIGS. 3A to 4E, FIGS. 10A to 10B, FIGS. 11 A to 11 C, and FIGS. 13A to 13C, respectively. [00229] In one or more alternative embodiments, the coupling assembly 706 may be characterized a“torque limiter”. The torque limiter 706 may limit the amount of torque applied to the outer shaft 702 via the handle 704 by having two or more members which slip or uncouple relative to each other. Example torque limiters 706 may be, but are not limited to, ball and detents, clutches, friction plates, magnets and/or the like.

[00230] In some cases, the torque limiter 706 may provide one or more advantages over the engaged and disengaged configuration described above. For example, in some cases, maintaining some level handle engagement to the outer shaft can increase stability and precision yet still allow the user to be made aware of when a given threshold has been crossed. In other cases, the user may prefer torque limiting over handle disengagement (i.e. the disengaged configuration) to prevent application of high torque yet still maintain the ability to supply a reduced amount of torque.

Eighth Example Embodiment

[00231] FIGS. 16A to 19B illustrate another example surgical instrument, referred to generally as surgical instrument 800. The surgical instrument 800 shown in FIGS. 16A and 16B is analogous to the surgical instrument 100 shown in FIGS. 3A to 4E, except for differences in the handle 804 and the coupling assembly 806. Unless otherwise noted, like-numbered elements (i.e., elements having reference numerals that share two least-significant digits, or two least significant digits and an alphabetic character where applicable) have similar structure and/or perform similar function as those in the example surgical instrument 100 shown in FIGS. 3A to 4E. For example, outer shaft 802 is analogous to outer shaft 102.

[00232] The surgical instrument 800 has an outer shaft 802, a handle 804, a coupling assembly 806, and an inner shaft 808. The outer shaft 802 has a first shaft end 802a and a second shaft end 802b opposite the first shaft end 802a along a longitudinal axis 810 defined by the outer shaft 802. The outer shaft 802 defines an interior channel 812 that extends between the first and second shaft ends 802a and 802b. In the illustrated example, the interior channel 812 has a generally circular cross-section along its longitudinal axis.

[00233] The handle 804 is rotatable about the longitudinal axis 810 in either a clockwise or a counterclockwise direction. The coupling assembly 806 couples the handle 804 to the outer shaft 802 at the second shaft end 802b in one of an engaged configuration and a disengaged configuration. As will be described in more detail below, the handle 804 cooperates with the coupling assembly 106 in moving between the engaged configuration and disengaged configuration.

[00234] FIGS. 16A and 16B show the coupling assembly 806 in the disengaged configuration. As will be described in more detail below, when the coupling assembly 806 is in the disengaged configuration, the handle 804 rotates about the longitudinal axis 810 independently of the outer shaft 802. Accordingly, rotation of the handle 804 (e.g. by the user turning the handle 804) does not rotate the outer shaft 802. On the other hand, when the coupling assembly 806 is in the engaged configuration, the handle 804 rotates about the longitudinal axis 810 concurrently with the outer shaft 802. Accordingly, rotation of the handle 804 (e.g. by the user turning the handle 104) concurrently rotates the outer shaft 802.

[00235] The inner shaft 808 is at least partially disposed within the interior channel 812. The inner shaft 808 has a probe end 808a and a transfer end 808b opposite the probe end 808a along the longitudinal axis 810. The inner shaft 108 is arranged to transfer a mechanical force received at the probe end 808a to the coupling assembly 806 via the transfer end 808b. In the illustrated example, the inner shaft 108 is moveable along the interior channel 812 in response to the mechanical force received at the probe end 808a.

[00236] In the illustrated example, the inner shaft 808 has a generally circular cross-section along its longitudinal axis. In one or more alternative embodiments, the cross-section of the interior channel 812 may have other configurations, e.g. triangular, rectangular, etc. Preferably, the cross-section of the inner shaft 808 generally corresponds to the cross-section of the interior channel 812, e.g. as shown. This correspondence may allow for smooth travel of the inner shaft 808 along the interior channel 812.

[00237] For surgical instruments adapted to make pilot holes, the outer shaft 802 has a cutting edge 814 provided on an exterior surface of the outer shaft 802, to form flutes or other rotary cutting elements (e.g., burrs, abrasives, etc.). The cutting edge 814 is generally provided on a cutting region proximate the first shaft end 802a, e.g. as shown, but in some embodiments can be provided along the entire length of the outer shaft 802. In some embodiments, the cutting edge 814 may be omitted from the surgical instrument 800 for applications that do not involve cutting.

[00238] The coupling assembly 806 has at least one threshold. The threshold is a predetermined value that, when crossed, causes the coupling assembly 806 to move from one of the engaged and disengaged configuration to the other of the engaged or disengaged configuration. For the surgical instrument 800 of FIGS. 16A and 16B, the at least one threshold is a threshold force.

[00239] In the engaged configuration, the coupling assembly 806 couples the handle 804 to the outer shaft 802 in a fixed rotatable manner when a mechanical force applied to the probe end 808a is greater than the threshold force. As described above, in the engaged configuration, the handle 804 fixedly rotates about the longitudinal axis 810 concurrently with the outer shaft 802. Accordingly, the user is able to deliver torque to the outer shaft 802 by rotating the handle 804 about the longitudinal axis 810, thereby rotating of the cutting edge 814 defined on the exterior surface of the outer shaft 802.

[00240] Conversely, in the disengaged configuration the coupling assembly 806 couples the handle 804 to the outer shaft 802 in a freely rotatable manner when the mechanical force is less than or equal to the threshold force. As described above, in the disengaged configuration, the handle 804 freely rotates about the longitudinal axis 810 independently of the outer shaft 802. In this way, the user is unable to deliver torque to the outer shaft by rotating the handle 804 about the longitudinal axis 810.

[00241] The user is able to make, or continue to make, a pilot hole by rotating the handle 804 as long as the coupling assembly 806 is, or remains, in the engaged configuration. However, when a mechanical force received at the probe end 808a falls below the threshold while forming the pilot hole, the coupling assembly 806 moves to the disengaged configuration and the user loses his or her ability to deliver torque to the outer shaft 802 through rotation of the handle 804, due to the free rotational coupling.

[00242] Reference is now made to FIGS. 17A to 19B to more clearly illustrate components of the surgical instrument 800. Referring to FIGS. 17A and 17B, the outer shaft 802 has a coupling collar 890 extending longitudinally from the second shaft end 802b. In the illustrated example, the coupling collar 890 is integral with the outer shaft 802. In alternative embodiments, the coupling collar 890 may be coupled to the second shaft end 802b in other suitable ways, e.g. by mechanical fasteners, adhesive, or a combination thereof. As shown in FIG. 17B, the coupling collar 890 has a recessed portion 892 extending from an open coupling collar end 890a toward an opposed coupling collar end 890b. The recessed portion 892 has an outer wall 892a and a base wall 892b that define a coupling collar cavity 894.

[00243] Referring to FIG. 17A, the coupling collar cavity 894 has a first portion 894a proximate the first coupling collar end 890a, a second portion 894b proximate the second coupling collar end 890b, and an intermediate portion 894c between the first and second portions 894a and 894b. The first and second portions 894a and 894b of the coupling collar cavity 894 may have the same or similar diameter. However, the intermediate portion 894c of the coupling collar cavity 894 has a diameter smaller than the diameters of the first and second portions 894a and 894b of the coupling collar cavity 894. To provide for the smaller diameter of the intermediate portion 894c of the coupling collar cavity 894, the outer wall 892a of the recessed portion 892 widens (or projects inwardly), e.g. as shown at portion 896.

[00244] With reference to FIGS. 16B and 17B, the opposed coupling collar end 890b has an aperture 898 that extends through the base 892b of the recessed portion 892. The aperture 898 is located so that it aligns with the inner channel 812 of the outer shaft 802 to define a contiguous passageway between the inner channel 812 and the coupling collar cavity 894.

[00245] In the illustrated example, the outer shaft 802 has a tapered portion 899 at the second shaft end 802b. The tapered portion 899 may smooth the transition from the coupling collar 890 to the outer shaft 802. Alternatively, such a tapered portion may not be provided.

[00246] Referring to FIGS. 19A and 19B, the handle 804 has a first handle end 804a and a second handle end 804b opposite the first handle end 804a. The handle 804 has a first handle recessed portion 822 extending from the first handle end 804a toward the second handle end 804b. The first handle recessed portion 822 has an outer wall 822a and a base wall 822b that define a first handle cavity 824. The handle 804 also has a second handle recessed portion 823 extending from the second handle end 804b toward the first handle end 804. The second handle recessed portion 823 has an outer wall 823a and a base wall 823b that define a second handle cavity 825.

[00247] The handle 804 also has an internal bore 827 that extends through bases 822b and 823b of the first and second handle recessed portions 822 and 823, respectively. In this way, the internal bore 827 connects the first and second handle cavities 824 and 825 to define a contiguous passageway therethrough. [00248] With reference to FIGS. 17A and 19B, the coupling collar 890 may be located (i.e. inserted) within the first handle cavity 824. As shown in FIG. 16B, the coupling body 890 abuts the base wall 822b of the first handle recessed portion 822. This engagement prevents the coupling body 890 from passing through the internal bore 827 of the handle 804.

[00249] Referring to FIGS. 18A and 18B, the inner shaft 808 has a coupling body 891 extending longitudinally from the transfer end 808b. In the illustrated example, the coupling body 891 is integral with the inner shaft 808. In alternative embodiments, the coupling body 891 may be coupled to the transfer shaft end 808b in other suitable ways, e.g. by mechanical fasteners, adhesive, or a combination thereof.

[00250] Referring still to FIGS. 18A and 18B, the coupling body 891 has a first coupling body end 891 a and a second coupling body end 891 b opposite the first coupling body end 891 a. The coupling body 891 has a first flange 895 and a spaced apart second flange 897 that project radially outwardly therefrom. The first flange 895 is located at the second coupling body end 891 b. The first and second flanges 895 and 897 extend generally the same distance from the coupling body 891 , e.g. as shown in FIGS. 18A and 18B.

[00251] With reference to FIGS. 18A and 19B, the coupling body 891 may be located within the handle 804 through the second handle cavity 825. The coupling body 891 may be located within the handle 804 either before or after the coupling collar 890 has been located in the first handle cavity 824. In cases where the coupling collar 890 has been previously located in the first handle cavity 824, the coupling body 891 can be inserted into the handle 804 via the second handle cavity 825 so that the inner shaft 808 passes into the inner channel 812 of the outer shaft

802.

[00252] Returning to FIGS. 18A and 18B, the coupling body 891 has a ledge 885 that projects radially outwardly therefrom at the first coupling body end 891 a. The ledge 885 extends beyond a maximum radial extent of each of first and second flanges 895 and 897. Said another way, the ledge 885 has a larger diameter than the first and second flanges 895 and 897.

[00253] Referring again to FIG. 16B, the ledge 885 is sized so that it will not pass through the internal bore 827 of the handle 804. Accordingly, as shown, due to the engagement between the ledge 885 of the coupling body 891 and the base wall 823b of the second handle recessed portion 823, the first coupling body end 891 b is spaced apart from (i.e. does not make contact with) the base wall 892b of the recessed portion 892. Thus, when the coupling assembly 808 is in the disengaged configuration, e.g. as shown, rotation of the handle 804 does not result in friction between the coupling collar 890 and coupling body 891 , thereby permitting free rotation.

[00254] The second flange 897 of the coupling body 891 (see FIG. 18A) is sized so that it may fittingly mate with the internal bore 827 of the handle 804 (see FIG. 19B). Mating between the second flange 897 of the coupling body 891 and the internal bore 827 of the handle 804 rotationally couples the handle 804 to the coupling body 891 , thereby rotationally coupling the handle 804 to the inner shaft 808. That is, when the second flange 897 is mated with the internal bore 827, the inner shaft 808 rotates concurrently with the handle 804 about longitudinal axis 810. The second flange 897 of the coupling body 891 and the internal bore of the handle 804 are mated whether the coupling assembly 806 is in the disengaged configuration (as shown in FIG. 16B) or in the engaged configuration.

[00255] The first flange 895 of the coupling body 891 (see FIG. 18A) is sized so that is generally corresponds with (i.e. has roughly the same diameter) as the intermediate portion 894c of the coupling collar cavity 894 (see FIG. 17B). When the first flange is at least partially located within the intermediate portion 894c of the coupling collar cavity 894, the first flange 895 meshes with the outer wall 892a of recessed portion 892. Mating between the first flange 895 of the coupling body 891 and the outer wall 892a at the intermediate portion 894c of the coupling collar cavity 894 rotationally couples the coupling collar 890 to the coupling body 891 , thereby rotationally coupling the handle 804 to the outer shaft 802.

[00256] Referring again to FIGS. 16A and 16B, the handle 804 has a retaining cap 848 removably connected at the first handle end 804a. When connected, the retaining cap 848 prevents the coupling collar 890 from departing the first handle cavity 824. As a result, the retaining cap 848 keeps the outer shaft 802 connected to the coupling assembly 806 within the handle 804. The handle 104 has an end plate 852 removably connected at the second handle end 804b. The end plate 152 is preferably made from a rigid material, such as metal or a dense plastic. The end plate 152 provides a hard surface for the user to strike with a hammer or mallet for impacting the probe end 808a into the bone. The end plate 852 can improve the structural integrity of the handle 804. The end plate 852 can also be used to tailor the weight of the handle 804.

[00257] The retaining cap 848 and end plate 852 may be secured to respective ends of the handle 804 in a number of suitable ways, e.g. by mechanical fasteners, press or snap fit, ball and groove joints, threaded engagement, or a combination thereof. In the illustrated examples, the retaining cap 848 and the end plate 852 are secured together to respective ends of the handle 804 by screws 889 that extend from the retaining cap 848 through handle 804 to the end plate

852. The retaining cap 848 and/or the end plate 852 may be removed from the handle 804, e.g. by loosening or removing screws 889. For example, removing the retaining cap 848 and/or the end cap 852 may facilitate disassembly for sterilization of parts, general maintenance, replacement of parts, spring calibration, etc.

[00258] Referring again to FIG. 16B, the coupling assembly 808 also includes a spring 818 that extends from a first spring end to a second spring end generally perpendicularly from the end plate 852. The second spring end may be secured (e.g. by mechanical fasteners, or the like) to end plate 852 at portion 883 so that the spring 818 extends generally perpendicularly therefrom.

[00259] Rod 887 has a notch 879 along its longitudinal axis. Notch 879 delineates between a first portion of rod 887 that has a diameter that fits within socket 893, and a second portion of rod 887 that has a larger diameter such that the second portion does not fit within socket 893. Accordingly, the notch 879 prevents coupling body 891 from translating further along the longitudinal axis 812 toward the end plate 852.

[00260] As perhaps best shown in FIG. 18B, the coupling body 891 has an elongate aperture (e.g. socket 893) extending from the first coupling body end 891a toward the second coupling body end 891 b.

[00261] Referring again to FIG. 16B, the end plate 852 has a stabilizing rod 877 or shaft extending generally perpendicularly therefrom. The stabilizing rod 877 extends through the spring 818. When the end plate 852 is secured to the second handle end 804b, e.g. as described above, the rod 887 is received within the socket 893.

[00262] In the engaged configuration, spring 818 is compressed by a force that is translated from probe end 808a of inner shaft 808 to transfer end 808b and assembly 806, thereby causing flange 895 to frictionally or otherwise engage portion 896 and thereby allow a rotational force applied to handle 804 to be imparted to the outer shaft 802.

[00263] In the disengaged configuration, spring 818 extends due to a diminished or absent force applied to probe end 808a. Extension of spring 818 causes portion 896 to come out of contact with flange 895, thereby preventing or impairing a rotational force applied to handle 804 from being imparted to the outer shaft 802. [00264] In the example embodiment shown in FIGS. 16A to 19B, coupling collar 890, coupling body 891 and spring 818 collectively form coupling assembly 808 that cooperates with handle 804 to deliver rotational force.

[00265] The example surgical instruments illustrated herein generally have a handle (e.g. handle 104 in FIG. 3A, handle 204 in FIG. 10A, etc.). For example, a user grips the handle to rotate it about the longitudinal axis. In one or more alternative embodiments, the handle 104 may be replaced with a motor (not shown). The motor has a motor axis of rotation that is generally coaxial with a longitudinal axis defined by the outer shaft. A coupling assembly (e.g. coupling assembly 106 in FIG. 3B, coupling assembly 206 if FIG. 10B, etc.), couples the motor (i.e. instead of the handle) to the outer shaft at the second end in one of the engaged and disengaged configurations. In the engaged configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis. Conversely, in the disengaged configuration, the motor rotates about the motor axis independently of the outer shaft. In some cases, the motor can be driven autonomously, e.g. by a computer.

[00266] In some embodiments, a locking mechanism may be provided that fixes the coupling assembly in the engaged configuration. For example, the locking mechanism may be a slider element that forces the coupling assembly into the engaged configuration.

[00267] As used herein, the wording“and/or” is intended to represent an inclusive - or. That is,“X and/or Y” is intended to mean X or Y or both, for example. As a further example,“X, Y, and/or Z” is intended to mean X or Y or Z or any combination thereof.

[00268] While the above description describes features of example embodiments, it will be appreciated that some features and/or functions of the described embodiments are susceptible to modification without departing from the spirit and principles of operation of the described embodiments. For example, the various characteristics which are described by means of the represented embodiments or examples may be selectively combined with each other. Accordingly, what has been described above is intended to be illustrative of the claimed concept and non-limiting. It will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto. The scope of the claims should not be limited by the preferred embodiments and examples, but should be given the broadest interpretation consistent with the description as a whole.

ITEMS

Item 1 : A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly having at least one threshold, the coupling assembly coupling the handle to the outer shaft at the second shaft end in one of an engaged configuration and a disengaged configuration, wherein, in the engaged configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the disengaged configuration, the handle rotates about the longitudinal axis independently of the outer shaft; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end; wherein the coupling assembly couples the handle to the outer shaft in the engaged configuration when the mechanical force is greater than the at least one threshold; and wherein the coupling assembly couples the handle to the outer shaft in the disengaged configuration when the mechanical force is less than or equal to the at least one threshold.

Item 2: The surgical instrument of any preceding item, wherein:

the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end.

Item 3: The surgical instrument of any preceding item, wherein:

the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the outer shaft.

Item 4: The surgical instrument of any preceding item, wherein:

the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a helical configuration. Item 5: The surgical instrument of any preceding item, wherein:

the inner shaft has at least one cutting edge provided at the probe end.

Item 6: The surgical instrument of any preceding item, wherein:

in the engaged configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis.

Item 7: The surgical instrument of any preceding item, wherein:

the pilot hole is made in a bone. Item 8: The surgical instrument of any preceding item, wherein:

in the disengaged configuration, the probe end protrudes from the outer shaft.

Item 9: The surgical instrument of any preceding item, wherein:

the inner shaft is movable along the interior channel in response to the mechanical force received at the probe end.

Item 10: The surgical instrument of any preceding item, wherein:

a displacement of the inner shaft measured along the longitudinal axis is at least partially based on a magnitude of the mechanical force received at the probe end.

Item 11 : The surgical instrument of any preceding item, wherein:

a distance measured along the longitudinal axis from the first shaft end to the probe end is between 0.5 and 15 mm in the disengaged configuration.

Item 12: The surgical instrument of any preceding item, wherein:

the coupling assembly comprises a biasing member, wherein the biasing member is compressible along the longitudinal axis from at least a first length to a threshold length in response to the mechanical force transferred from the transfer end of the inner shaft.

Item 13: The surgical instrument of any preceding item, wherein:

the threshold of the coupling assembly is generally equal to a compression mechanical force required to compress the biasing member to the threshold length, and wherein, the coupling assembly couples the handle to the outer shaft in the engaged configuration when the biasing member is compressed to at least the threshold length.

Item 14: The surgical instrument of any preceding item, wherein: the coupling assembly further comprises i) an outer ring rotationally engaged with the outer shaft at the second shaft end; and ii) an inner ring rotationally engaged with the handle, wherein the inner ring is axially aligned with the outer ring and moves along the longitudinal axis with the inner shaft, and wherein the inner ring is rotationally engaged with the outer ring when the inner ring is at least partially disposed within the outer ring.

Item 15: The surgical instrument of any preceding item, wherein:

the outer ring has an inner circumferential surface and the inner ring has an outer circumferential surface, and wherein the inner and outer circumferential surfaces rotationally engage when the inner ring at least partially disposed within the outer ring.

Item 16: The surgical instrument of any preceding item, wherein:

the biasing member is a coil spring.

Item 17: The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a metal or a metal alloy. Item 18: The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a plastic.

Item 19: The surgical instrument of any preceding item, wherein:

the outer shaft comprises a tapered portion tapering toward the first shaft end.

Item 20: The surgical instrument of any preceding item, wherein:

the outer shaft comprises a curved portion proximate the first shaft end.

Item 21 : The surgical instrument of any preceding item, wherein:

the handle is generally spherical. Item 22: The surgical instrument of any preceding item, wherein:

outer shaft has a generally circular cross-section. Item 23: The surgical instrument of any preceding item, wherein:

the coupling assembly is at least partially disposed within the handle.

Item 24: The surgical instrument of any preceding item, wherein:

the coupling assembly is fully disposed within the handle.

Item 25: The surgical instrument of any preceding item, wherein:

the coupling assembly is external to the handle.

Item 26: The surgical instrument of any preceding item, wherein:

the handle comprises an extension shaft extending outwardly from the handle to a distal end, wherein rotation of the handle about the longitudinal axis concurrently rotates the extension shaft about the longitudinal axis, and wherein the coupling assembly couples the distal end of the extension shaft to the outer shaft in one of the engaged and disengaged configurations.

Item 27: The surgical instrument of any preceding item further comprising: a drive motor, wherein the drive motor rotates the handle about the longitudinal axis. Item 28: A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor; wherein the actuator couples the handle to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

Item 29: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

Item 30: The surgical instrument of any preceding item, wherein: the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end.

Item 31 : The surgical instrument of any preceding item, wherein:

Item 32: The surgical instrument of any preceding item, wherein:

the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a helical configuration.

Item 33: The surgical instrument of any preceding item, wherein:

the inner shaft has at least one cutting edge provided at the probe end. Item 34: The surgical instrument of any preceding item, wherein:

in the first configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis.

Item 35: The surgical instrument of any preceding item, wherein:

the pilot hole is made in a bone.

Item 36: The surgical instrument of any preceding item, wherein:

the transfer end of the inner shaft is secured to the sensor. Item 37: The surgical instrument of any preceding item, wherein:

the coupling assembly further comprises an energy storage module for energizing the actuator and the sensor.

Item 38: The surgical instrument of any preceding item, wherein: the first and second thresholds are adjustable.

Item 39: The surgical instrument of any preceding item, wherein:

the sensor is a strain gauge.

Item 40: The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a metal or a metal alloy.

Item 41 : The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a plastic.

Item 42: The surgical instrument of any preceding item, wherein:

the outer shaft comprises a tapered portion tapering toward the first shaft end. Item 43: The surgical instrument of any preceding item, wherein:

the outer shaft comprises a curved portion proximate the first shaft end.

Item 44: The surgical instrument of any preceding item, wherein:

the handle is generally spherical.

Item 45: The surgical instrument of any preceding item, wherein:

the outer shaft has a generally circular cross-section.

Item 46: The surgical instrument of any preceding item, wherein:

the coupling assembly is at least partially disposed within the handle.

Item 47: The surgical instrument of any preceding item, wherein:

the coupling assembly is fully disposed within the handle. Item 48: The surgical instrument of any preceding item, wherein:

the coupling assembly is external to the handle.

Item 49: The surgical instrument of any preceding item, wherein:

the handle comprises an extension shaft extending outwardly from the handle to a distal end, wherein rotation of the handle about the longitudinal axis concurrently rotates the extension shaft about the longitudinal axis, and wherein the actuator couples the distal end of the extension shaft to the outer shaft in one of the first and second configurations.

Item 50: The surgical instrument of any preceding item, wherein:

the sensor is located within the outer shaft and is spaced apart from the actuator by a distance measured along the longitudinal axis. Item 51 : The surgical instrument of any preceding item, wherein:

the sensor is located closer to the first shaft end than the second shaft end.

Item 52: The surgical instrument of any preceding item, wherein:

the sensor is located closer to the second shaft end than the first shaft end.

Item 53: The surgical instrument of any preceding item further comprising: a drive motor, wherein the drive motor rotates the handle about the longitudinal axis. Item 54: A surgical instrument comprising:

a shaft having a first shaft end, a second shaft end opposite the probe end along a longitudinal axis of the shaft; a handle rotatable about the longitudinal axis; and a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the handle to the shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the shaft, and wherein, in the second configuration, a torque supplied from the handle to the shaft is limited, wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising a detected parameter from the sensor, the actuator couples the handle to the shaft in one of the first configuration and the second configuration when the detected parameter is greater than the first threshold; and the actuator couples the handle to the shaft in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the second threshold.

Item 55: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the handle with the shaft.

Item 56: The surgical instrument of any preceding item, wherein:

at least one cutting edge is provided on an exterior surface of the shaft proximate the first shaft end. Item 57: The surgical instrument of any preceding item, wherein:

the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the shaft. Item 58: The surgical instrument of any preceding item, wherein:

the at least one cutting edge is wrapped around the exterior surface of the shaft in a helical configuration. Item 59: The surgical instrument of any preceding item, wherein:

the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis when the actuator is in the first configuration.

Item 60: The surgical instrument of any preceding item, wherein:

the pilot hole is made in a bone.

Item 61 : The surgical instrument of any preceding item, wherein:

Item 62: The surgical instrument of any preceding item, wherein:

the energy storage module is at least partially disposed within the handle.

Item 63: The surgical instrument of any preceding item, wherein:

the energy storage module is fully disposed within the handle.

Item 64: The surgical instrument of any preceding item, wherein:

The first and second thresholds are adjustable. Item 65: The surgical instrument of any preceding item, wherein:

the shaft comprises a tapered portion tapering toward the first shaft end.

Item 66: The surgical instrument of any preceding item, wherein:

the shaft comprises a curved portion proximate the first shaft end. Item 67: The surgical instrument of any preceding item, wherein:

the handle is generally spherical. Item 68: The surgical instrument of any preceding item, wherein:

the shaft has a generally circular cross-section.

Item 69: The surgical instrument of any preceding item, wherein:

the actuator is fully disposed within the handle.

Item 70: The surgical instrument of any preceding item, wherein:

the sensor comprises an accelerometer located within the shaft.

Item 71 : The surgical instrument of any preceding item, wherein:

the sensor comprises an ultrasound transceiver located within the shaft proximate the first shaft end.

Item 72: The surgical instrument of any preceding item, wherein:

the sensor comprises a magnetic permeability sensor located within the shaft proximate the first shaft end.

Item 73: The surgical instrument of any preceding item, wherein:

the sensor comprises a pair of electrically isolated capacitive sensors, wherein at least one of the pair of capacitive sensors is located at the first shaft end, and wherein the controller determines a capacity differential between the pair of capacitive sensors.

Item 74: The surgical instrument of any preceding item, wherein: the sensor comprises a pair of electrically isolated electrodes, wherein at least one of the pair of electrodes is located at the first shaft end, and wherein the controller determines a conductivity differential between the pair of electrodes. Item 75: The surgical instrument of any preceding item further comprising: a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

Item 76: A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the handle to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold. Item 77: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

Item 78: The surgical instrument of any preceding item, wherein: the controller determines the magnitude of the mechanical force based on the separation and a calibration index.

Item 79: The surgical instrument of any preceding item, wherein:

Item 80: The surgical instrument of any preceding item, wherein: the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the outer shaft.

Item 81 : The surgical instrument of any preceding item, wherein:

the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a corkscrew-like configuration.

Item 82: The surgical instrument of any preceding item, wherein:

the inner shaft has at least one cutting edge provided at the probe end.

Item 83: The surgical instrument of any preceding item, wherein:

in the first configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis. Item 84: The surgical instrument of any preceding item, wherein:

the pilot hole is made in a bone.

Item 85: The surgical instrument of any preceding item, wherein:

the transfer end of the inner shaft is secured to the biasing member.

Item 86: The surgical instrument of any preceding item, wherein:

the coupling assembly further comprises an energy storage module for energizing the actuator and the position sensor. Item 87: The surgical instrument of any preceding item, wherein:

the first and second thresholds are adjustable.

Item 88: The surgical instrument of any preceding item, wherein:

the position sensor is an optical position sensor. Item 89: The surgical instrument of any preceding item, wherein:

the position sensor is a capacitive position sensor. Item 90: The surgical instrument of any preceding item, wherein:

the position sensor is an inductive position sensor.

Item 91 : The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a metal or a metal alloy.

Item 92: The surgical instrument of any preceding item, wherein:

the inner shaft is formed from a plastic.

Item 93: The surgical instrument of any preceding item, wherein:

Item 94: The surgical instrument of any preceding item, wherein:

the outer shaft comprises a curved portion proximate the first shaft end. Item 95: The surgical instrument of any preceding item, wherein:

the handle is generally spherical.

Item 96: The surgical instrument of any preceding item, wherein:

the outer shaft has a generally circular cross-section.

Item 97: The surgical instrument of any preceding item, wherein:

the coupling assembly is at least partially disposed within the handle.

Item 98: The surgical instrument of any preceding item, wherein: the actuator and position sensor are fully disposed within the handle.

Item 99: The surgical instrument of any preceding item, wherein:

the coupling assembly is external to the handle.

Item 100: The surgical instrument of any preceding item, wherein:

Item 101 : The surgical instrument of any preceding item further comprising: a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

Item 102: A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly having at least one threshold, the coupling assembly coupling the motor to the outer shaft at the second shaft end in one of an engaged configuration and a disengaged configuration, wherein, in the engaged configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the disengaged configuration, the motor rotates about the motor axis independently of the outer shaft; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end; wherein the coupling assembly couples the motor to the outer shaft in the engaged configuration when the mechanical force is greater than the at least one threshold; and wherein the coupling assembly couples the motor to the outer shaft in the disengaged configuration when the mechanical force is less than or equal to the at least one threshold.

Item 103: A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor wherein the actuator couples the motor to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

Item 104: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the motor with the outer shaft. Item 105: A surgical instrument comprising:

a shaft having a first shaft end, a second shaft end opposite the probe end along a longitudinal axis of the shaft; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the shaft is limited, wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising a detected parameter from the sensor, the actuator couples the motor to the shaft in one of the first configuration and the second configuration when the detected parameter is greater than the first threshold; and the actuator couples the motor to the shaft in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the second threshold. Item 106: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the motor with the shaft.

Item 107: A surgical instrument comprising:

an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the motor to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold. Item 108: The surgical instrument of any preceding item, wherein: in the second configuration, the torque is limited through disengagement of the motor with the outer shaft.

Claims

CLAIMS:

1. A surgical instrument comprising:

2. The surgical instrument of claim 1 , wherein the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end.

3. The surgical instrument of claim 2, wherein the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the outer shaft.

4. The surgical instrument of claim 2, wherein the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a helical configuration.

5. The surgical instrument of any one of claims 1 to 4, wherein the inner shaft has at least one cutting edge provided at the probe end.

6. The surgical instrument of claim 2 or any one of claims 3 to 5 when dependent from claim 2, wherein, in the engaged configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis.

7. The surgical instrument of claim 6, wherein the pilot hole is made in a bone.

8. The surgical instrument of any one claims 1 to 7, wherein, in the disengaged configuration, the probe end protrudes from the outer shaft.

9. The surgical instrument of any one of claims 1 to 8, wherein the inner shaft is movable along the interior channel in response to the mechanical force received at the probe end.

10. The surgical instrument of claim 9, wherein a displacement of the inner shaft measured along the longitudinal axis is at least partially based on a magnitude of the mechanical force received at the probe end.

11. The surgical instrument of claim 8 or claim 9, wherein a distance measured along the longitudinal axis from the first shaft end to the probe end is between 0.5 and 15 mm in the disengaged configuration.

12. The surgical instrument of any one of claims 9 to 11 , wherein the coupling assembly comprises a biasing member, wherein the biasing member is compressible along the longitudinal axis from at least a first length to a threshold length in response to the mechanical force transferred from the transfer end of the inner shaft.

13. The surgical instrument of claim 12, wherein the at least one threshold of the coupling assembly is generally equal to a compression mechanical force required to compress the biasing member to the threshold length, and wherein, the coupling assembly couples the handle to the outer shaft in the engaged configuration when the biasing member is compressed to at least the threshold length.

14. The surgical instrument of claim 13, wherein the coupling assembly further comprises i) an outer ring rotationally engaged with the outer shaft at the second shaft end; and ii) an inner ring rotationally engaged with the handle, wherein the inner ring is axially aligned with the outer ring and moves along the longitudinal axis with the inner shaft, and wherein the inner ring is rotationally engaged with the outer ring when the inner ring is at least partially disposed within the outer ring.

15. The surgical instrument of claim 14, wherein the outer ring has an inner circumferential surface and the inner ring has an outer circumferential surface, and wherein the inner and outer circumferential surfaces rotationally engage when the inner ring at least partially disposed within the outer ring.

16. The surgical instrument of any one of claims 12 to 15, wherein the biasing member is a coil spring.

17. The surgical instrument of any one of claims 1 to 16, wherein the inner shaft is formed from a metal or a metal alloy.

18. The surgical instrument of any one of claims 1 to 16, wherein the inner shaft is formed from a plastic.

19. The surgical instrument of any one of claims 1 to 18, wherein the outer shaft comprises a tapered portion tapering toward the first shaft end.

20. The surgical instrument of any one of claims 1 to 19, wherein the outer shaft comprises a curved portion proximate the first shaft end.

21 . The surgical instrument of any one of claims 1 to 20, wherein the handle is generally spherical.

22. The surgical instrument of any one of claims 1 to 21 , wherein outer shaft has a generally circular cross-section.

23. The surgical instrument of any one of claims 1 to 22, wherein the coupling assembly is at least partially disposed within the handle.

24. The surgical instrument of any one of claims 1 to 23, wherein the coupling assembly is fully disposed within the handle.

25. The surgical instrument of any one of claims 1 to 22, wherein the coupling assembly is external to the handle.

26. The surgical instrument of claim 25, wherein the handle comprises an extension shaft extending outwardly from the handle to a distal end, wherein rotation of the handle about the longitudinal axis concurrently rotates the extension shaft about the longitudinal axis, and wherein the coupling assembly couples the distal end of the extension shaft to the outer shaft in one of the engaged and disengaged configurations.

27. The surgical instrument of any one of claims 1 to 26, further comprising a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

28. A surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor; wherein the actuator couples the handle to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

29. The surgical instrument of claim 28, wherein, in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

30. The surgical instrument of claim 28 or claim 29, wherein the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end.

31. The surgical instrument of claim 30, wherein the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the outer shaft.

32. The surgical instrument of claim 30, wherein the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a helical configuration.

33. The surgical instrument of any one of claims 28 to 32, wherein the inner shaft has at least one cutting edge provided at the probe end.

34. The surgical instrument of claim 30 or any one of claims 31 to 33 when dependent from claim 30, wherein, in the first configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis.

35. The surgical instrument of claim 34, wherein the pilot hole is made in a bone.

36. The surgical instrument of any one of claims 28 to 35, wherein the transfer end of the inner shaft is secured to the sensor.

37. The surgical instrument of any one of claims 28 to 36, wherein the coupling assembly further comprises an energy storage module for energizing the actuator and the sensor.

38. The surgical instrument of any one of claims 28 to 37, wherein the first and second thresholds are adjustable.

39. The surgical instrument of any one of claims 28 to 38, wherein the sensor is a strain gauge.

40. The surgical instrument of any one of claims 28 to 39, wherein the inner shaft is formed from a metal or a metal alloy.

41. The surgical instrument of any one of claims 28 to 39, wherein the inner shaft is formed from a plastic.

42. The surgical instrument of any one of claims 28 to 41 , wherein the outer shaft comprises a tapered portion tapering toward the first shaft end.

43. The surgical instrument of any one of claims 28 to 42, wherein the outer shaft comprises a curved portion proximate the first shaft end.

44. The surgical instrument of any one of claims 28 to 43, wherein the handle is generally spherical.

45. The surgical instrument of any one of claims 28 to 44, wherein the outer shaft has a generally circular cross-section.

46. The surgical instrument of any one of claims 28 to 45, wherein the coupling assembly is at least partially disposed within the handle.

47. The surgical instrument of any one of claims 28 to 46, wherein the coupling assembly is fully disposed within the handle.

48. The surgical instrument of any one of claims 28 to 47, wherein the coupling assembly is external to the handle.

49. The surgical instrument of claim 48, wherein the handle comprises an extension shaft extending outwardly from the handle to a distal end, wherein rotation of the handle about the longitudinal axis concurrently rotates the extension shaft about the longitudinal axis, and wherein the actuator couples the distal end of the extension shaft to the outer shaft in one of the first and second configurations.

50. The surgical instrument of any one of claims 28 to 46, wherein the sensor is located within the outer shaft and is spaced apart from the actuator by a distance measured along the longitudinal axis.

51 . The surgical instrument of claim 50, wherein the sensor is located closer to the first shaft end than the second shaft end.

52. The surgical instrument of claim 51 , wherein the sensor is located closer to the second shaft end than the first shaft end.

53. The surgical instrument of any one of claims 28 to 52, further comprising a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

54. A surgical instrument comprising:

55. The surgical instrument of claim 54, wherein, in the second configuration, the torque is limited through disengagement of the handle with the shaft.

56. The surgical instrument of claim 54 or claim 55, wherein at least one cutting edge is provided on an exterior surface of the shaft proximate the first shaft end.

57. The surgical instrument of claim 56, wherein the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the shaft.

58. The surgical instrument of claim 56, wherein the at least one cutting edge is wrapped around the exterior surface of the shaft in a helical configuration.

59. The surgical instrument of any one of claims 56 to 58, wherein, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis when the actuator is in the first configuration.

60. The surgical instrument of claim 59, wherein the pilot hole is made in a bone.

61 . The surgical instrument of any one of claims 54 to 60, wherein the coupling assembly further comprises an energy storage module for energizing the actuator and the sensor.

62. The surgical instrument of claim 61 , wherein the energy storage module is at least partially disposed within the handle.

63. The surgical instrument of claim 62, wherein the energy storage module is fully disposed within the handle.

64. The surgical instrument of any one of claims 54 to 63, wherein the first and second thresholds are adjustable.

65. The surgical instrument of any one of claims 54 to 64, wherein the shaft comprises a tapered portion tapering toward the first shaft end.

66. The surgical instrument of any one of claims 54 to 65, wherein the shaft comprises a curved portion proximate the first shaft end.

67. The surgical instrument of any one of claims 54 to 66, wherein the handle is generally spherical.

68. The surgical instrument of any one of claims 54 to 67, wherein the shaft has a generally circular cross-section.

69. The surgical instrument of any one of claims 54 to 68, wherein the actuator is fully disposed within the handle.

70. The surgical instrument of any one of claims 54 to 69, wherein the sensor comprises an accelerometer located within the shaft.

71 . The surgical instrument of any one of claims 54 to 69, wherein the sensor comprises an ultrasound transceiver located within the shaft proximate the first shaft end.

72. The surgical instrument of any one of claims 54 to 69, wherein the sensor comprises a magnetic permeability sensor located within the shaft proximate the first shaft end.

73. The surgical instrument of any one of claims 54 to 69, wherein the sensor comprises a pair of electrically isolated capacitive sensors, wherein at least one of the pair of capacitive sensors is located at the first shaft end, and wherein the controller determines a capacity differential between the pair of capacitive sensors.

74. The surgical instrument of any one of claims 54 to 69, wherein the sensor comprises a pair of electrically isolated electrodes, wherein at least one of the pair of electrodes is located at the first shaft end, and wherein the controller determines a conductivity differential between the pair of electrodes.

75. The surgical instrument of any one of claims 54 to 74, further comprising a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

76. A surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a handle rotatable about the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the handle to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, the handle rotates about the longitudinal axis concurrently with the outer shaft, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the handle to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the handle to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold.

77. The surgical instrument of claim 76, wherein, in the second configuration, the torque is limited through disengagement of the handle with the outer shaft.

78. The surgical instrument of claim 76 or claim 77, wherein the controller determines the magnitude of the mechanical force based on the separation and a calibration index.

79. The surgical instrument of any one of claims 76 to 78, wherein the outer shaft has at least one cutting edge provided on an exterior surface of the outer shaft proximate the first shaft end.

80. The surgical instrument of claim 79, wherein the at least one cutting edge comprises a plurality of cutting edges spaced around the exterior surface of the outer shaft.

81. The surgical instrument of claim 79, wherein the at least one cutting edge is wrapped around the exterior surface of the outer shaft in a helical configuration.

82. The surgical instrument of any one of claims 79 to 81 , wherein the inner shaft has at least one cutting edge provided at the probe end.

83. The surgical instrument of claim 79 or any one of claims 80 to 82 when dependent from claim 79, wherein, in the first configuration, the at least one cutting edge cuts a pilot hole as the handle is rotated about the longitudinal axis.

84. The surgical instrument of claim 83, wherein the pilot hole is made in a bone.

85. The surgical instrument of any one of claims 76 to 84, wherein the transfer end of the inner shaft is secured to the biasing member.

86. The surgical instrument of any one of claims 76 to 85, wherein the coupling assembly further comprises an energy storage module for energizing the actuator and the position sensor.

87. The surgical instrument of any one of claims 76 to 86, wherein the first and second thresholds are adjustable.

88. The surgical instrument of any one of claims 76 to 87, wherein the position sensor is an optical position sensor.

89. The surgical instrument of any one of claims 76 to 87, wherein the position sensor is a capacitive position sensor.

90. The surgical instrument of any one of claims 76 to 87, wherein the position sensor is an inductive position sensor.

91 . The surgical instrument of any one of claims 76 to 90, wherein the inner shaft is formed from a metal or a metal alloy.

92. The surgical instrument of any one of claims 76 to 90, wherein the inner shaft is formed from a plastic.

93. The surgical instrument of any one of claims 76 to 92, wherein the outer shaft comprises a tapered portion tapering toward the first shaft end.

94. The surgical instrument of any one of claims 76 to 93, wherein the outer shaft comprises a curved portion proximate the first shaft end.

95. The surgical instrument of any one of claims 76 to 94, wherein the handle is generally spherical.

96. The surgical instrument of any one of claims 76 to 95, wherein the outer shaft has a generally circular cross-section.

97. The surgical instrument of any one of claims 76 to 96, wherein the coupling assembly is at least partially disposed within the handle.

98. The surgical instrument of any one of claims 76 to 97, wherein the actuator and position sensor are fully disposed within the handle.

99. The surgical instrument of any one of claims 76 to 96, wherein the coupling assembly is external to the handle.

100. The surgical instrument of claim 99, wherein the handle comprises an extension shaft extending outwardly from the handle to a distal end, wherein rotation of the handle about the longitudinal axis concurrently rotates the extension shaft about the longitudinal axis, and wherein the actuator couples the distal end of the extension shaft to the outer shaft in one of the first and second configurations.

101. The surgical instrument of any one of claims 76 to 100, further comprising a drive motor, wherein the drive motor rotates the handle about the longitudinal axis.

102. A surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly having at least one threshold, the coupling assembly coupling the motor to the outer shaft at the second shaft end in one of an engaged configuration and a disengaged configuration, wherein, in the engaged configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the disengaged configuration, the motor rotates about the motor axis independently of the outer shaft; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the coupling assembly via the transfer end; wherein the coupling assembly couples the motor to the outer shaft in the engaged configuration when the mechanical force is greater than the at least one threshold; and wherein the coupling assembly couples the motor to the outer shaft in the disengaged configuration when the mechanical force is less than or equal to the at least one threshold.

103. A surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the sensor via the transfer end; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and wherein the controller determines the mechanical force based at least in part on a signal received from the sensor wherein the actuator couples the motor to the outer shaft in the first configuration when the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the outer shaft in the second configuration when the mechanical force is less than or equal to the second threshold.

104. The surgical instrument of claim 103, wherein, in the second configuration, the torque is limited through disengagement of the motor with the outer shaft.

105. A surgical instrument comprising:

a shaft having a first shaft end, a second shaft end opposite the probe end along a longitudinal axis of the shaft; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a sensor and an actuator having a controller communicatively coupled to the sensor, the actuator coupling the motor to the shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the shaft is limited, wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising a detected parameter from the sensor, the actuator couples the motor to the shaft in one of the first configuration and the second configuration when the detected parameter is greater than the first threshold; and the actuator couples the motor to the shaft in the other of the first configuration and the second configuration when the detected parameter is less than or equal to the second threshold.

106. The surgical instrument of claim 105, wherein, in the second configuration, the torque is limited through disengagement of the motor with the shaft.

107. A surgical instrument comprising: an outer shaft having a first shaft end, a second shaft end opposite the first shaft end along a longitudinal axis of the outer shaft, the outer shaft defining an interior channel between the first and second shaft ends; a motor having a motor axis of rotation, wherein the motor axis of rotation is generally coaxial with the longitudinal axis; a coupling assembly comprising a position sensor, a biasing member, and an actuator having a controller communicatively coupled to the position sensor, the actuator coupling the motor to the outer shaft at the second shaft end in one of a first configuration and a second configuration, wherein, in the first configuration, rotation of the motor about the motor axis concurrently rotates the outer shaft about the longitudinal axis, and wherein, in the second configuration, a torque supplied from the handle to the outer shaft is limited; and an inner shaft at least partially disposed within the interior channel, the inner shaft having a probe end and a transfer end opposite the probe end along the longitudinal axis, wherein the inner shaft is arranged to transfer a mechanical force received at the probe end to the biasing member via the transfer end, whereby the biasing member is compressible proportionately to a magnitude of the mechanical force; wherein the position sensor detects a separation between the transfer end and the position sensor; wherein the controller has a first threshold and a second threshold, wherein the controller controls operation of the actuator, and upon receiving a signal comprising the separation from the position sensor, the controller determines the magnitude of the mechanical force based at least in part on the separation; wherein the actuator couples the motor to the shaft in the first configuration when the magnitude of the mechanical force is greater than the first threshold; and wherein the actuator couples the motor to the shaft in the second configuration when the magnitude of the mechanical force is less than or equal to the second threshold.

108. The surgical instrument of claim 107, wherein, in the second configuration, the torque is limited through disengagement of the motor with the outer shaft.