Patent ID: 12201307

While the disclosure is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure.

DETAILED DESCRIPTION

Surgical bone drill systems may include a surgical bone drill bit configured to engage and drill holes into or through bone of a subject (e.g., a patient). In operation, the drill bit may be inserted to a surgical site through tissue of the subject and to the bone in which a hole is to be drilled. In some cases, the drill bit may be configured to provide an electrical stimulation to the tissue near the drill bit (e.g., the drill bit may be a neuromonitoring bone drill bit), where the electrical stimulation in or passing through the tissue may be sensed by a sensor or detector and the sensed measurements may be utilized for determining an integrity of the bone before, during, or after drilling the hole, monitoring for nerve location or damage, or other assessments and monitoring. When the bone in which a hole is being drilled is a pedicle of the vertebra, determining the integrity of the bone may be considered a “pedicle integrity assessment”. Example systems, devices, and connections of systems and devices related to neuromonitoring are disclosed in: U.S. Pat. No. 7,657,308, filed Feb. 18, 2005, and titled SYSTEM AND METHODS FOR PERFORMING DYNAMIC PEDICLE INTEGRITY ASSESSMENTS; and U.S. Pat. No. 8,442,621, filed on Jun. 3, 2009, and titled SURGICAL TRAJECTORY MONITORING SYSTEM AND RELATED METHODS, which are hereby incorporated in their entirety for any and all purposes.

When inserting a neuromonitoring bone drill bit into the subject, an exposed cutting portion (e.g., a fluted portion) of the drill bit may physically contact tissue of the subject, which may inadvertently damage the tissue of the subject when the tissue is unintendedly contacted. Likewise, inadvertent or unwanted electrical connection between the drill bit and nearby tissue can cause errant neuromonitoring results. As such, protecting against undesired electrical or physical contact between the drill bit and tissue of the subject can be desirable. An illustrative neuromonitoring surgical bone drill bit assembly configured to block a cutting portion of a drill bit from unintended contact (e.g., physical contact, electrical contact, or both) between the drill bit and a subject's tissue may include a surgical bone drill bit having a neuromonitoring connection, and at least a portion of the drill bit may be covered by a retractable shield.

In the illustrative drill bit assembly, the neuromonitoring connection may be a conductive area in electrical communication with a cutting portion of the drill bit and configured to receive or otherwise attach to a neuromonitoring clip in communication with a neuromonitoring system for delivering electrical stimulation through the drill bit to a bone structure of the subject. The drill bit assembly may electrically insulate a conductive path from the neuromonitoring connection to a distal end of the cutting portion of the drill bit.

Part of the drill bit assembly configured to electrically insulate the conductive path may include the retractable shield. In some cases, the retractable shield may be distally-biased to cover a cutting portion of the drill bit. Further, the retractable shield may be configured to resist tissue from contacting the drill bit, where such contact may damage tissue or interfere with neuromonitoring results or bone or pedicle integrity assessments. When the cutting portion of the drill bit is driven into the bone of the subject, the shield may engage the bone as the drill bit advances into the bone such that the shield retracts relative to a distal end of the drill bit.

The shield may be locked or unlocked using a locking system. When locked, the shield may be prevented from retracting relative to the distal end of the drill bit. When unlocked, the shield may be biased toward the distal end of the drill bit and may be able to retract relative to the distal end of the drill bit.

In some cases, the locking system may include a lock actuator configured to be actuated to lock the shield in place or unlock the shield. In one example, the lock actuator may be adjusted from a lock position to an unlock position by moving the lock actuator in a proximal direction relative to the distal end of the drill bit. Proximally moving the lock actuator may result in withdrawing a lock mechanism (e.g., an elongated member, such as a pin, or other suitable lock mechanism) to permit movement of the shield. Although not required, the lock actuator may be secured in the unlock position by twisting or rotating the lock actuator after proximally withdrawing the shield actuator or by taking other action to secure the lock actuator in the unlock position. Further, although the locking system is described herein as including a lock actuator or other lock components that withdraw proximally to adjust from a lock position to an unlock position, it is contemplated that distal movement or other suitable movement may be utilized to adjust the lock actuator or other suitable components of the lock system from a lock position to an unlock position.

In some instances, the lock actuator may be automatically released from the unlock position. In one example, inertia or other forces of the surgical bone drill system may be utilized to automatically release the lock actuator from the unlock position. For example, inertia of the surgical bone drill system as drilling stops or as a drill bit rotational direction is reversed may cause the lock actuator to automatically release from the secured unlock position. Alternatively or additionally, the lock actuator may be released from the secured unlock position manually by reversing the steps used to secure the lack actuator in the unlock position or by taking other actions.

In one illustrative example of using the drill bit assembly configured to physically and electrically shield portions of the drill bit, the neuromonitoring drill bit may be utilized with a drill to form a neuromonitoring (e.g., an electromyography (EMG)) drill. Before or after connecting the drill bit assembly to the drill, the drill bit assembly may be inserted into a navigational sleeve that facilitates navigating to a desired surgical location.

To monitor a condition of a target bone or nerves around the target bone, a neuromonitoring clip in communication with a neuromonitoring system may be coupled to the drill bit assembly and the drill bit assembly may be inserted into a tool guide at a surgical site, where the tool guide may or may not be held by a surgical robot. As the drill bit is inserted into the subject at the surgical site (e.g., using navigational feedback), the lock actuator may be in a lock position and the shield may be biased toward and prevented from retracting relative to a distal end of the drill bit. Once the drill bit has been positioned adjacent a target bone of the subject, a surgeon or other medical professional may adjust the lock actuator to an unlock position and drill a pilot hole along a trajectory guided by the robot or a surgical navigation system. During drilling of the pilot hole, nerve health or pedicle integrity may be monitored using feedback in response to the electrical stimulation provided to the target bone by the drill bit.

As the drill bit passes into the bone of the subject, the shield may automatically retract or withdraw with respect to the distal end of the drill bit. For example, the user applies force to push the spinning drill bit into bone, but the distal end of the shield is unable to enter the bone as much as the drill bit. Consequently, as the drill bit enters the bone, the length of the drill assembly that remains outside of the bone decreases. To compensate for this decrease, the drill assembly outside of the bone reduces in length (e.g., because of a sliding relationship between two or more components). As the drill bit is withdrawn from the bone (e.g., once the pilot hole is sufficiently drilled or to clear debris from drill bit fluting), the shield moves toward the distal end of the drill bit in response to a bias force acting on the shield. As a result, the cutting portion of the drill bit is covered by the shield as the drill bit is backed out of the bone. In some cases, the lock actuator may automatically or manually return to the lock position once the drill bit stops rotating or reverses rotation. As the shield automatically extends distally over the drill bit, the surgeon may remove the drill from the surgical site and the tool guide without unintentionally contacting the cutting portion and the electrically conductive portion of the drill bit to the tissue of the subject.

Turning to the figures,FIG.1depicts a schematic box diagram of the surgical bone drill system100in communication with a neuromonitoring system102(e.g., an electromyography (EMG) system or other suitable neuromonitoring system). Although the neuromonitoring system102is depicted, other suitable electrical stimulation and monitoring systems may be utilized to monitor a health of tissue of a subject at or adjacent the surgical site. As depicted inFIG.1, the drill system100may include a surgical bone drill104and a surgical bone drill bit assembly106, where the drill bit assembly106may be inserted into and coupled to the drill104such that actuation of the drill104causes at least a portion of the drill bit assembly106to rotate.

The neuromonitoring system102may be in communication (e.g., electrical communication) with the drill bit assembly106or other portion of the surgical bone drill system100in electrical communication with a drill bit of the drill bit assembly106. In some cases, the neuromonitoring system102may be mechanically, electrically, or mechanically and electrically coupled to the drill bit assembly106, as discussed herein or otherwise.

The neuromonitoring system102may be any suitable neuromonitoring system configured to electrically stimulate tissue of a subject and monitor the electrical stimulation. As discussed, in some cases, the neuromonitoring system102may be an EMG system. Although other systems are contemplated, example EMG systems and bone integrity assessments are disclosed in U.S. Patent Application Publication No. US 2005/0004623, filed on Oct. 30, 2002, and titled SYSTEM AND METHODS FOR PERFORMING PERCUTANEOUS PEDICLE INTEGRITY ASSESSMENTS, which is hereby incorporated by reference in its entirety for any and all purposes.

Application of the electrical stimulation (e.g., electrical signals or other suitable electrical stimulation) may be accomplished in any suitable manner including, but not limited to, applying voltage or current pulses of varying magnitude or frequency to the drill bit assembly106. Further, the neuromonitoring system102may monitor the electrical stimulation through the subject's body directly or indirectly (e.g., through detecting muscle activity or otherwise indirectly detecting) with a detector to assess an integrity of a bone in which the drill bit assembly106is being used to drill a hole and determine whether any nerves adjacent the bone may be innervating as a result of applying the stimulation signal to the drill bit assembly106. In one example, the neuromonitoring system102may use evoked muscle action potential (EMAP) monitoring techniques, where EMG responses of muscle groups associated with identified nerves are measured. Alternatively or additionally, the subject's response to the electrical stimulation may be visually monitored.

FIG.2is a schematic perspective view of an illustrative configuration of a surgical bone drill bit assembly206having a distal end portion208and a proximal end210. Among other components, the drill bit assembly206may include a shield212, a drill bit sleeve213, a neuromonitoring connection portion218, a lock actuator220, and a drill bit shank222of a surgical bone drill bit223. In some cases, the shield212in combination with the sleeve213or other components of the drill bit assembly206may be configured to electrically insulate a conductive path extending from the neuromonitoring connection portion218to a distal end of the surgical drill bit223.

In some cases, the sleeve213may be configured to extend over a drill bit of the drill bit assembly206and may include a cover214, a spacer215, a contoured portion216, other suitable components, or combinations thereof. The sleeve213may be formed as a single component or may be multiple components longitudinally extending along a drill bit of the drill bit assembly206. As depicted inFIG.2, the sleeve213may include the cover214, the spacer215, and the countered portion216.

In some cases, the shield212and the cover214may be configured to enter a surgical site inside of a subject during use of the drill bit assembly206with a drill (e.g., the drill104or other suitable drill). Further, the contoured portion216, the neuromonitoring connection218, the lock actuator220, and the drill bit shank222may be configured to remain proximal of the surgical site, outside of the subject, but this is not required. Other configurations of the components of the drill bit assembly206are contemplated

Turning to individual components of the drill bit assembly206depicted inFIG.2, the drill bit shank222may be located at the proximal end210of the drill bit assembly206and may be configured to be inserted into and engaged by a drill. Although not required, the drill bit shank222may have a male keyed configuration that is intended to be received in a female keyed configuration of a drill. In some cases, the drill bit shank222may be part of the drill bit223, but this is not required and the drill bit shank222may be one or more components separate from and in rotatable communication with the drill bit223, such that when a drill engaging the drill bit shank222causes rotation of the drill bit shank222, the drill bit223also rotates.

The lock actuator220may have any suitable configuration or location along the drill bit assembly206that facilitates a user locking or unlocking the shield212in response to movement of the lock actuator220. In one example, the lock actuator220may be located proximal of the shield212, but this is not required.

The neuromonitoring connection portion218may be located at any suitable location along the drill bit assembly206such that the neuromonitoring connection portion218may be in electrical communication with a drill bit of the drill bit assembly206and configured to facilitate an electrical connection between an electrical stimulation and monitoring system (e.g., the neuromonitoring system102or other suitable neuromonitoring system) and the drill bit assembly206. In some cases, the neuromonitoring connection portion218may be a conductive area that is configured to attach to a neuromonitoring clip mechanically and electrically coupling the drill bit assembly206to the neuromonitoring system or other electrical stimulation and monitoring system. Although not required, the neuromonitoring clip connection portion218may be in contact (e.g., electrical contact, physical contact, or both) with the drill bit223and may rotate with the drill bit223relative to the coupled neuromonitoring clip.

The contoured portion216or grip portion of the sleeve213may be located any suitable location along the drill bit assembly206such that a user (e.g., a surgeon or other medical provider in a procedure room) may grasp the contoured portion216between at least two digits of their hand during use of the drill bit assembly206. The contoured portion216may have one or more contoured portions configured for receiving a user's grip. For example, the contoured portion216of the drill bit assembly206may have a longitudinal and circumferential concave profile, as depicted inFIG.2, two longitudinally concave profiles circumferentially spaced from one another on opposing radial sides of the drill bit assembly206, two or more longitudinally concave profiles circumferentially spaced unequal distances from one another, indents, protrusions or both that are configured to facilitate gripping the contoured portions, other suitable profiles that facilitate gripping the drill bit assembly206, or combinations thereof. In one example use of the contoured portion216, a user may hold the drill connected to the drill bit assembly206with a first hand and grip the contoured portion216with two digits (e.g., between a thumb and an index finger, or other set of digits) with a second hand to stabilize the drill bit223at a target location while the drill bit223rotates with respect to the contoured portion216.

The cover214of the sleeve213may be located at least partially distally of the neuromonitoring connection218and may be comprised of one or more components along the drill bit assembly206to at least partially electrically insulate a conductive path of the drill bit assembly206between the neuromonitoring connection218and a distal end of the drill bit. In some cases, the cover214may be located proximal of the shield212. Although not required, the cover214may be configured to receive at least a portion of the shield212or otherwise facilitate movement or sliding of the shield212in responses to forces acting on the shield212.

The shield212may be located at the distal end portion208of the drill bit assembly206and may extend proximally therefrom so as to cover a distal end of the drill bit223of the drill bit assembly206. As discussed, the shield212may be configured to retract or withdraw by sliding or moving proximally along or with respect to a distal end portion of a drill bit of the drill bit assembly206as the drill bit is advanced into a subject's bone or other tissue and then automatically extend distally as the drill bit is withdrawn from the subject's bone or other tissue to cover a portion of the drill bit that had been inserted into the subject's bone or other tissue. As the shield212retracts or withdraws along a distal end of the drill bit223, the sleeve213(e.g., the cover214or other portion of the sleeve213) may receive the shield212.

The shield212may have any suitable configuration that facilitates longitudinally moving or sliding (e.g., withdrawing or retracting and extending) the shield212along the drill bit223of the drill bit assembly206. In one example configuration of the shield212, the shield212may have a first portion212a(e.g., a reduced diameter portion or other portion), a second portion212b(e.g., an expanded diameter portion), and a third portion212c(e.g., a tip portion), but the shield212is not required to have three portions. When included, the first portion212amay be configured to be received within an inner diameter of the cover214as the shield212withdraws proximally and the second portion212bmay form or act as a shoulder relative to the first portion212asuch that a proximal end of the second portion212bmay engage a distal end of the cover214to limit a proximal withdrawal or retraction of the shield212. Other suitable configurations, of the inner diameter of the cover214, the outer diameter of the first portion212aof the shield212, and the outer diameter of the second portion212bof the shield212are contemplated.

The third portion212cof the shield212may form a distal end of the shield212and terminate at a terminal tip224. Though not required, the third portion212cmay have a tapering portion226that terminates at or prior to the terminal tip224, where the tapering portion226may facilitate inserting the drill bit assembly206to a target bone at a surgical site by guiding obstructions contacting the tapering portion226away from the drill bit assembly206. In some cases, the terminal tip224of the shield212may be flat (e.g., is in a plane that is perpendicular or is otherwise transverse to a longitudinal access of the drill bit assembly206), as depicted inFIG.2, curved, a rigid terminal tip, a soft or pliable terminal tip for engaging the target bone, a serrated or toothed terminal tip for engaging the target bone, one or more other configurations, or combinations thereof. Further, in some cases, the third portion212cmay be separable from or releasably engageable with one or more other portions of the shield212.

FIG.3depicts a schematic perspective view of an illustrative configuration of a distal end component328for the shield212, where the distal end component328may have a terminal tip324with a serrated or toothed configuration. In some cases, the distal end component328may form, or at least form part of, the third portion212cof the shield212, which was discussed above with respect toFIG.2.

As depicted inFIG.3, the distal end component328may include a tapering portion326that extends distally to an extension (e.g., a portion of the distal end component328extending from a distal end of the taper portion326to the terminal tip324) forming a serrated or toothed terminal tip324. Although the extension forming the serrated or toothed terminal tip324is depicted as relatively short compared to an entire length between a proximal terminal end of the distal end component328and the terminal tip324, the extension may be further elongated (e.g., longer) or may be shorter than an entire length of the extension depicted inFIG.3. Further, although the extension forming the terminal tip324is depicted as being a reduced diameter relative to a proximal portion of the distal end component328extending proximally of the taper portion326, the extension may have a same diameter as or a larger diameter than the proximal portion of the distal end component328.

The serrated or toothed terminal tip324may take on any suitable configuration that facilitates stabilizing the drill bit assembly206as the assembly is brought into contact with a target bone or other tissue and as a drill bit of the drill bit assembly206drills into the target bone or other tissue. As depicted inFIG.3, the terminal tip324may include a plurality of teeth325(for clarity purposes, not all teeth are labeled) circumferentially spaced around the terminal tip324such that the teeth are configured to engage bone or other tissue, but other serrated or toothed configurations are contemplated.

Although the distal end component328for the shield212may be monolithically or integrally formed with other portions or components (e.g., the first portion212a, the second portion212b, etc.) of the shield212, the distal end component328may be configured to be releasably engaged with a portion of the shield212without destroying the shield212or otherwise preventing the shield212from being used. In some cases, the distal end component328may include a connector portion330configured to engage a portion (e.g., a distal end of the second portion212bor other suitable portion) of the shield212to form at least part of the third portion212cand facilitate removal from the engaged portion of the shield212. Although the connector portion330is depicted as a threaded male connector, the connector portion330may be configured to connect with another portion of the shield212in one or more other manners including, but not limited to, through female-male connection, a snap connection, a friction fit connection, a ball detent connection, a luer lock connection, or other suitable connections. Further, in some cases, the distal end component328may be configured to be permanently connected (e.g., connected through an adhesive connection or other suitable fixed connection) to a portion of the shield212, such that the distal end component328cannot be removed or separated from the portion of the shield212without causing destruction of the shield212.

FIG.4depicts a schematic cross-sectional view of the drill bit assembly206, taken along line4-4inFIG.2. As depicted inFIG.4, the surgical bone drill bit223may extend along a length of the drill bit assembly206and may be covered by one or more components of the drill bit assembly206. Further, the drill bit assembly206may include a locking system444in communication with the shield212, where the locking system444may extend at least partially through the drill bit223.

The drill bit223may have a distal end portion223aand a proximal end portion223b. A cutting portion432(e.g., a fluted portion or other cutting portion) of the drill bit223may be located at the distal end portion223aand the drill bit shank222may be located at the proximal end portion223b.

The drill bit223may be formed from any suitable number of components. For example, the drill bit223may be monolithically formed from a single component or formed from two or more components. When formed from two or more components, the components may be connected to each other with one or more connection techniques configured to withstand high rotational speeds typical of surgical bone drills including, but not limited to, welded connections, adhesive connections, threaded connection, other suitable connections, or combinations of connections. As depicted inFIG.4, the drill bit223may be formed from a solid first component434defining the cutting portion432, a second component436being hollow or having a lumen448extending at least partially therethrough that may be welded to the first component434, and a third component438forming the drill bit shank222and connected to the second component436via a threaded connection.

As depicted inFIG.4, one or more components of the drill bit assembly206may extend over or cover the drill bit223. In some cases, the one or more components of the drill bit assembly206extending over or covering the drill bit223may be configured to electrically insulate the drill bit223or prevent unintended exposure of the cutting portion432of the drill bit223to bone or tissue of a subject on which the drill bit assembly is to be or is being used. In one example, the shield212and the sleeve213(e.g., the cover214, the spacer215, and the contoured portion216) may be configured to electrically insulate a conductive path extending through the drill bit223(e.g., a conductive path extending from the neuromonitoring connection portion218to the distal end or tip of the drill bit223or other suitable conductive path).

The shield212and the sleeve213may be configured from any suitable material configured to electrically insulate a conductive path through the drill bit223. In some cases, the shield212may be made out of one or more same materials as or one or more different materials than one or more materials of the components of the sleeve213. In one example, the shield212may be formed from a rigid electrically insulating material that facilitates contacting a subject's bone or tissue and the contoured portion216of the sleeve213may be formed from a resilient electrically insulating material that facilitates a user gripping the contoured portion. Other configurations are contemplated.

Any suitable rigid, flexible, or resilient biocompatible, electrically insulating material may be utilized for the components of the shield212and the sleeve213. Example electrically insulating materials may include, but are not limited to, ceramics, natural polymers, synthetic polymers, cellulose, silk, shellac, gelatin, silicone, polyphenylsulfone (PPSU), homopolymer polypropylene (PP), polyvinyl alcohol (PVA), polydimethylsiloxane (PDMS), polylactide (PLA), polycaprolactone (PCL), polycaprolactone (PCL), polyglycerol-co-sebacate (PGS), polylactic-co-glycolic acid (PLGA), acrylics, or other suitable insulating materials.

As depicted inFIG.4, the drill bit assembly206may include a first spring440that may be configured to bias the shield212toward the distal end portion223aof the drill bit223. In some cases, the shield212may be biased to cover the cutting portion432of the drill bit223or other portions of the drill bit223. In one example configuration, the first spring440may be configured to engage an interior ledge442of the cover214and a proximal end of the shield212(e.g., a proximal cap443or other suitable portion of the shield212), as depicted inFIG.4. However, other suitable configurations of the first spring440relative to the shield212are contemplated. Further, biasing mechanisms in addition to or as alternatives to the first spring440may be utilized.

The locking system444may be in communication with the shield212and may be configured to adjust between a shield lock position at which the shield212is prevented from withdrawing or retracting with respect to the distal end portion223aof the drill bit223and a shield unlock position at which the shield212is able to withdraw or retract with respect to the distal end portion223aof the drill bit223. Among other components, the locking system444may include an elongated member446extending along the drill bit223(e.g., the elongated member446may extend through the lumen448of the drill bit223) and the lock actuator220may be configured to engage the elongated member446and slide along the surgical drill bit223to adjust the locking system444between the shield lock position and the shield unlock position. In some cases, the locking system444may be biased to the shield lock position by a second spring450or other suitable biasing mechanism.

An illustrative configuration of the locking system444is more fully described with respect toFIGS.5and6.FIG.5is an enlargement of the drill bit assembly206within circle-5inFIG.4.FIG.6is an enlargement of the drill bit assembly206within circle-6inFIG.4.

In addition to the lock actuator220and the elongated member446, the locking system444may include one or more balls552(e.g., the locking system444may include two balls, as depicted inFIG.5, but one, three, or other suitable number of balls552may be utilized) or other suitable adjustable components configured to engage the shield212and prevent the shield212from retracting or withdrawing along the drill bit223when the elongated member446is distally positioned. In some cases, the one or more balls552may be configured to be positioned in or received by one or more openings554in the drill bit223, the lumen448in the drill bit223, or both.

The one or more openings554may extend outward (e.g., radially outward or otherwise extend outward) from one or more axial locations along a central axis of the drill bit223. Further, the one or more openings554may extend from the lumen448through an exterior surface of the drill bit223, but other configurations of the openings554are contemplated. Although the openings554are depicted as extending radially outward from the lumen448in a central plane that is perpendicular to a central axis of the lumen448, the openings554may be in one or more planes intersecting the central axis of the lumen448at one or more other angles.

In operation, when the locking system444is in the shield lock position, as depicted inFIG.5, the elongated member446may extend through the lumen448and may be biased in a distal direction D such that the elongated member446may extend distally to or beyond the openings554in or through the drill bit223. In some cases, as the elongated member446reaches or passes through an axial location of the balls552, a tapered portion556of the elongated member446may engage the one or more balls552and urge the one or more balls552into the openings554. Further, the elongated member446may maintain the balls552in or extending through the openings554while the locking system444is in the shield lock position. When the balls552are maintained within the openings554of the drill bit223, the balls552may extend at least partially through an outer perimeter of the openings554and engage the shield212as it attempts to retract or withdraw along the drill bit assembly206. Even if a bias force of the first spring440is overcome by a force acting on the shield212in a proximal direction P, the locking system444prevents proximal movement of the shield212when the locking system444is in the shield lock position.

As described in further detail below, when the locking system444is in the shield unlock position, the elongated member446may withdraw in the proximal direction P, which may allow the one or more balls552to move freely (e.g., without obstruction from the elongated member446) within the openings554, the lumen448, or both. As such, when a force acting on the shield212in the proximal direction P overcomes the bias force of the first spring440in the distal direction D, the shield212may engage the one or more balls552to the extent the balls552are extending beyond an outer perimeter of the drill bit223, direct the one or more balls552into the openings554, and withdraw or retract with respect to the distal end portion223aof the drill bit223. In some cases, an interior circumference of the shield may have a tapered portion558that is configured to engage the one or more balls552and direct the one or more balls552into the openings554and the lumen448.

Although the elongated member446is depicted in the Figures as being configured to withdraw in the proximal direction P when the locking system444is adjusted from the shield lock position to the shield unlock position, this is not required. In some cases, the locking system444may be configured such that the elongated member446or other components of the locking system444may move in the distal direction D in response to the locking system444being adjusted from the shield lock position to the shield unlock position. That is, the elongated member446or other suitable components of the locking system444may be configured to translate axially (e.g., in a proximal or a distal direction) to facilitate adjusting the locking system44from the shield lock position to the shield unlock position.

In the locking system444described with respect toFIG.5, a sum of the diameters of the two balls552and the diameter of the elongated member446may be a value that is greater than an outer diameter of the drill bit223at the axial location of the openings554such that the balls552extend through the openings554and engage the shield212to prevent movement of the shield212in the proximal direction P when the locking system444is in the shield lock position. Further, a sum of the diameter of the two balls552may be a value that is less than the outer diameter of the drill bit223at the axial location of the openings554such that the balls552may slide into the openings554, the lumen448, or both as the shield moves in the proximal direction P when the locking system444is in the shield unlock position. In some cases, a diameter of one of the one or more balls552may be greater than the diameter of the lumen448so as to prevent the ball552from traveling longitudinally through the lumen448. However, other configurations are contemplated and diameters may be dependent on a number of balls552used, openings554used, or other suitable factors.

As discussed, the locking system444may be adjustable between the shield lock position and the shield unlock position by manipulating the lock actuator220.FIG.6depicts a schematic cross-sectional view of the lock actuator220and a connection between the lock actuator220and the elongated member446.

The lock actuator220and the elongated member446may be connected in any suitable manner. In some cases, the lock actuator220and the elongated member446may be directly connected to one another through one or more connection techniques. For example, the elongated member446can cooperate with the lock actuator220such that a user can manipulate the elongated member446(e.g., via proximal or distal movement) to switch the locking system444between the shield lock position and the shield unlock position. In other cases, the lock actuator220and the elongated member446may be connected to one another indirectly via a connector component658, as depicted inFIG.6, and one or more coupling or connection techniques.

When included, the connector component658may be located within or about the drill bit223. The connector component658may be configured to slide or otherwise move in the distal direction D and the proximal direction P with the elongated member446and the lock actuator220and relative to the drill bit223, as the lock actuator220is adjusted to switch the locking system444between the shield lock position and the shield unlock position.

The one or more connection techniques for connecting the elongated member446, the connector component658(when included), and the lock actuator220may include any suitable techniques for connecting rotational components of a medical or surgical device to one another. Example suitable connection types include, but are not limited to, adhesive connections, weld connections, screw or bolt connections, threaded connections, luer lock connections, friction fit connections, crim connections, swag connections, brazed connections, other types of connections, or combinations thereof. In the example depicted inFIG.6, the connector component658may receive a portion of the elongated member446and may be connected to the elongated member446via a weld connection or an adhesive connection. Further, in the example, the connector component658may be connected to the lock actuator220via a screw connection or other suitable connection in which a connector660(e.g., a pin, a screw, or other suitable connector) may engage the lock actuator220(e.g., threads of the lock actuator220or other features of the lock actuator220) and extend through an opening of the drill bit223and an opening of the connector component658.

To facilitate the movement of the lock actuator220, the drill bit223may include one or more openings662extending from an exterior circumference of the drill bit223to the lumen448and may be configured to receive the connector660securing the lock actuator220to the drill bit223and the connector component658. The openings662in the drill bit223may take on any suitable configuration. In some cases, the openings662may be configured to facilitate receiving the connector660or other feature securing the lock actuator220to the other components of the drill bit assembly206and facilitating adjustment of the lock actuator220between a shield lock position and an unlock position.

In some cases, the openings662may include an axial portion662a(e.g., an elongated axial portion that extends at least partially in an axial direction) and a circumferential portion662b(e.g., a circumferential portion that extends at least partially in a circumferential direction) in communication with the axial portion662a. The circumferential portion662bmay extend from the axial portion662aat any suitable location along the axial portion662a. In one example, the circumferential portion662bmay extend from a proximal end of the axial portion662a, as depicted inFIG.6, to facilitate securing the locking system444in the shield unlock position relative to the drill bit223.

The axial portion662amay extend in an axial direction any suitable distance required to adjust the locking system444between the shield lock position and the shield unlock position. The circumferential portion662bmay extend circumferentially any suitable distance around the drill bit223to facilitate securing the locking system444in the shield unlock position or providing feedback to a user indicating the locking system444is in the shield unlock position.

The axial portion662aand the circumferential portion662bof the openings662are further depicted inFIG.7, which is a schematic cross-sectional view taken long line7-7inFIG.6. As depicted inFIG.7, the connector660may be located in the axial portion662aof the openings662while the lock actuator220is in the lock position. To secure the lock actuator220in the unlock position, the lock actuator may be manually adjusted against a bias force of the second spring450in a proximal direction (e.g., out of the page, toward a reader ofFIG.7) relative to the drill bit223until the connector660reaches an axial location of the circumferential portion662bof the openings662. Once the connector660has reached the axial location of the circumferential portion662b, the lock actuator220may be rotated in a rotational direction R1relative to the drill bit223such that the connector660is within the circumferential portion662bof the openings662and the bias force of the second spring450seats the connector660in the circumferential portion662b.

Although not depicted, the circumferential portion662bof the openings662may include an indent or further slot circumferentially spaced from the axial portion662a. Such an indent or further slot may be configured to receive the connector660so as to secure the connector660in the unlocked configuration.

Returning toFIG.6, an operation of the locking system444is discussed. The depicted locking system444is in a shield lock position with the lock actuator220in a lock position, such that the elongated member446may extend through the lumen448of the drill bit223and position the balls552within and at least partially through the openings554to prevent the shield212from withdrawing in the proximal direction relative to the distal end portion223aof the drill bit223(e.g., as shown inFIG.5). The second spring450(e.g., extending in the lumen448of the drill bit223and acting on the connector component658and the third component438of the drill bit223or otherwise acting on the lock actuator220) or other bias mechanism may bias the lock actuator220to the lock position and the locking system444to the shield lock position.

To adjust the lock actuator220to the unlock position and thus, the locking system444to the shield unlock position, the lock actuator220may be adjusted against the force of the second spring450in the proximal direction P relative to the drill bit223, such that the connector660may slide or otherwise move in the proximal direction P relative to the drill bit223within the axial portion662aof the openings662. As the lock actuator220is adjusted in the proximal direction P relative to the drill bit223, the elongated member446may move in the proximal direction P relative to the drill bit223such that balls may enter the openings554and the lumen448to allow the shield212to withdraw proximally relative to the drill bit223in response to forces acting on the shield212in the proximal direction P.

Once the lock actuator220is in the unlock position and thus, the locking system444is in the shield unlock position, the locking system444may be secured in the shield unlock position. For example, once the lock actuator220is in the unlock position, the lock actuator220may be rotated in the rotational direction R1relative to the drill bit223such that the connector660may slide in the circumferential portion662bof the openings662to secure the lock actuator220in the unlock position and secure the locking system444in the shield unlock position, as discussed above. When the connector660is positioned in the circumferential portion662bof the openings662, the bias force of the second spring450may be prevented from causing the lock actuator220to return to its lock position without additional forces acting on the lock actuator220that facilitate returning to the lock position.

The lock actuator220may be manually or automatically adjusted from the secured unlock position to the lock position. To return the lock actuator220to the lock position from the secured unlock position, the lock actuator220may be manually rotated in a rotational direction R2relative to the drill bit223, which may be opposite or substantially opposite the rotational direction R1. Such rotation of the lock actuator220may cause the connector660to move within the circumferential portion662bof the openings662to the axial portion662a, where the lock actuator220may be released from a secured position and the bias force of the second spring450may cause the connector660to move within the axial portion662aof the openings662. As a result, the lock actuator220may return to the lock position and thus, the locking system444may return to the shield lock position.

Alternatively or additionally to manually returning the lock actuator220to the lock position, the lock actuator220may be configured to automatically adjust from the secured unlock position to the lock position in response to an adjustment in inertia in, rotation of, or torque on the drill bit223. For example, if the drill bit223stops rotating in a first direction (e.g., the rotational direction R1) or if the drill bit223starts rotating in a second direction (e.g., the rotational direction R2) opposite or substantially opposite the first direction, an inertia of the drill bit223or an associated change in torque of the drill bit assembly206may cause the lock actuator220to rotate in the rotational direction R2relative to the drill bit223and with the bias force of the second spring450, automatically return to the lock position. Other configurations for manually or automatically switching the locking system444from the shield unlock position to the shield lock position are contemplated.

Further, the lock actuator220may include one or more first guide components664configured to engage or couple with one or more second guide components666on the drill bit223, where the engagement or coupling is configured to facilitate longitudinally, rotationally, or longitudinally and rotationally translating the lock actuator220relative to the drill bit223. In one example configuration depicted inFIG.6, the lock actuator220may include one or more first guide components664which may have a protrusion668configured to engage or couple with an indentation of the second guide component66in the drill bit223. In another example, the first guide components664of the lock actuator220may include an indentation and the second guide components666of the drill bit223may include a protrusion configured to engage the indentation of the first guide components664. Other designs and configurations of the first guide component664and the second guide component666are contemplated.

Although the first spring440, the second spring450, force directions applied by the first spring440and the second spring450, and directions of movement of components of the locking system444are discussed with respect to the configuration of components of the locking system444depicted inFIGS.4-7, it is contemplated that the locking system444may take on one or more other suitable configurations. For example, there may be additional or alternative biasing mechanisms configured to apply forces to components of the locking system444and the drill bit assembly206in one or more other suitable manners.

The drill bit assembly206described herein may include components configured to rotate with the drill bit223and components not configured to rotate with the drill bit223(e.g., the drill bit223may be configured to rotate relative to these components). In some cases, the neuromonitoring connection218and the locking system444(e.g. the lock actuator220, the first spring440, the elongated member446, the second spring450, the balls552, the connector component658, the connector660, or other components of the locking system444), or other suitable components of the drill bit assembly206may be configured to rotate with the drill bit223. Further, the shield212, the sleeve213(e.g., cover214, the spacer215, the contoured portion216, or other suitable components of the sleeve), or other suitable components of the drill bit assembly206may be configured such that the drill bit223rotates relative to these components. Such a configuration may result in the components of the drill bit assembly206that are exposed to a subject's tissue at a surgical site, other than the drill bit223, not rotating with the drill bit223so as to mitigate an injury risk to the patient at the surgical site.

FIGS.8and9depict the drill bit assembly206with the lock actuator220in an unlock position (e.g., the locking system444is in the shield unlock position) and the shield212has been withdrawn such that the drill bit223and the cutting portion432thereof is exposed. As depicted inFIG.8, the lock actuator220has been withdrawn and secured in the lock position, in a manner discussed herein or otherwise, such that the locking system444is in the shield unlock position. With the locking system444in the shield unlock position, the shield is able to withdraw in the proximal direction P and has withdrawn in the proximal direction P relative to the distal end portion223aof the drill bit223in response to a force F acting on the shield212in the proximal direction P, where the force F is greater than a bias force of the first spring440acting on the shield212in the distal direction D.

FIG.9depicts a schematic partial cross-sectional view of the configuration of the drill bit assembly206depicted inFIG.8, taken along line9-9. As discussed, the locking system444has been adjusted to the shield unlock position in response to the lock actuator220being secured in the unlock position. As such, the lock actuator220, the connector660, the connector component658, and the elongated member446have been moved in the proximal direction P and rotated in the rotational direction R1. The proximal positioning of the lock actuator220may result in the second spring450being compressed between the connector component658and the drill bit223(e.g., the third component438) or between other suitable components of the drill bit assembly206. Further, in response to withdrawing the elongated member446, the balls552may be able to move freely within the openings554and the lumen448at the axial locations of the openings554.

When the locking system444is in the shield unlock position and the bias force of the first spring440has been overcome, the shield212may withdraw with respect to the distal end portion223aof the drill bit223. As depicted inFIG.9, when the shield212withdraws, the shield212may engage the balls552and force the balls552into the openings554and the lumen448, and compress the first spring440between the shield212(e.g., the cap443of or on the shield212) and the interior ledge442. When the force F is removed or lessened to a level below the bias force of the first spring440, the bias force of the first spring440may cause the shield212to move or extend in the distal direction D relative to the drill bit223to cover distal end portion223athereof.

FIG.10is a schematic view of a surgical setup using the drill bit assembly206. As depicted inFIG.10, the drill bit assembly206has been inserted into and engaged with a drill1004and a navigational sleeve1070, while the locking system444is in the shield lock position. The drill1004may be configured to engage the drill bit assembly206and rotate the drill bit (not shown) after the drill bit assembly206has been inserted into a subject1072. Although not shown, a neuromonitoring clip may be connected to the neuromonitoring connection location218of the drill bit assembly206to facilitate using the drill bit assembly206to monitor target tissue and tissue around the target.

The navigational sleeve1070may include a sleeve component1074defining a lumen configured to receive drill bit223and the drill bit assembly206(e.g., the shield212and other components of the drill bit assembly206) and one or more sense elements1076in a known position and configuration relative to the received drill bit assembly206such that a navigation system in a procedure room may sense the sense elements1076. For example, the sense elements1076may be infrared emitters or retroreflective spheres detectable by the navigation system. Based on sensing the sense elements and the known position and configuration of the sensed elements relative to the drill bit assembly206, the navigation system may determine a position of the drill bit assembly206or components thereof, and facilitate navigating the drill bit assembly206to and at a target location (e.g., a location in the subject1072at which to drill a hole or implant an implant).

Once the drill bit assembly206has been inserted into the navigational sleeve1070, the drill bit assembly206in the navigational sleeve1070and connected to the drill1004may be inserted in the direction of arrow A into a surgical access tube1077to a surgical site (e.g., at the subject's vertebra1078or other target location). The surgical access tube1077may be held by a robotic arm, but this is not required. In some cases, a user (e.g., a surgeon or other suitable medical professional) may grip the drill1004with one hand and grasp the contoured portion216of the drill bit assembly206with two digits of a second hand, but this is not required, as the user inserts the drill bit assembly206into the surgical access tube1077. Once at the surgical site, the user may engage the terminal tip224of the drill bit assembly206with a target bone, adjust the lock actuator220to the unlock position, secure the lock actuator220in the unlock position, and begin drilling a hole in the target bone, optionally using assistance from the surgical navigation system, the neuromonitoring system, or both. The surgical access tube1077may constrain a positioning of the drill bit223and the drill bit assembly206while the drill bit223is advanced into the target bone.

FIG.11is a schematic diagram depicting illustrative steps of using the drill bit assembly206to drill a hole (e.g., a pilot hole for a pedicle screw or other suitable hole) into a vertebra1178of a subject. At step A, the shield212(e.g., the terminal tip224) of the drill bit assembly206may be brought into contact with the vertebra1178(e.g., a target bone of the subject). As discussed herein, the shield212may provide electrical insulation and act as a cutting guard for the drill bit223.

At step B, a drill connected to the drill bit assembly206may initiate rotation of the drill bit223and the cutting portion432of the drill bit223may drill into the vertebra1178, which may allow electrical stimulation from a conductive path through the drill bit223to be applied to the vertebra1178and surrounding tissue for neuromonitoring or other purposes. As the drill bit223drills into the vertebra1178, the shield212may remain in contact with the vertebra1178and retract or withdraw relative to the distal end portion223aof the drill bit, as shown in step B ofFIG.11.

At step C, the drill may cause the drill bit223to stop rotating or reverse rotation to facilitate withdrawal of the drill bit223from a hole1180in the vertebra1178formed by the drill bit223. As the drill bit223withdraws or retracts from the hole1180, the shield212may extend distally over the cutting portion432of the drill bit223and maintain contact with the vertebra1178to shield surrounding tissue from the drill bit223. Once the drill bit223has been fully retracted from the vertebra1178, the shield212may extend over an entirety of the drill bit223to cover the cutting portion432of the drill bit223and electrically insulate a conducive path through the drill bit223as the drill bit assembly206is withdrawn from the subject.

FIG.12depicts an illustrative method1200of using the drill bit assembly206to drill a hole (e.g., a pilot hole for a pedicle screw or other hole) into a bone (e.g., vertebra or other bone tissue) of a subject. The method may include coupling1202a drill104to a neuromonitoring bone drill bit223or other suitable surgical bone drill bit. In some cases, the neuromonitoring bone drill bit223may include an electrically insulating shield212and a cover214extending over the neuromonitoring bone drill bit, which may be part of the drill bit assembly206, as discussed herein. The drill104may be coupled to the neuromonitoring bone drill bit223in any suitable manner for coupling drills and drill bits. In some cases, the drill may grasp or engage the drill bit shank222of the neuromonitoring bone drill bit223.

Further, the method1200may include coupling1204a neuromonitoring clip to the bone drill bit. In some cases, the neuromonitoring clip may be applied to the neuromonitoring connection portion218of the drill bit assembly206, where the neuromonitoring connection portion218is in electrical communication with the neuromonitoring bone drill bit223.

The neuromonitoring clip may be connected to the drill bit assembly206in any suitable manner. In one example, the neuromonitoring clip (e.g., a spring-loaded metallic clip or other suitable neuromonitoring clip) may be electrically and mechanically coupled to the neuromonitoring connection portion218such that the neuromonitoring bone drill bit223may rotate relative to the neuromonitoring clip, but this is not required and the neuromonitoring clip may be electrically coupled to the neuromonitoring bone drill bit223in one or more other suitable manners. In other examples, the neuromonitoring clip may be mechanically coupled directly to the neuromonitoring bone drill bit223or to the drill (e.g., the drill104) to create an electrical coupling between the neuromonitoring clip and the drill bit223.

Once the neuromonitoring bone drill bit223is connected to the drill104and the neuromonitoring clip is coupled to the neuromonitoring bone drill bit223, the neuromonitoring bone drill bit223may be inserted into a surgical site at a bone (e.g., a target bone) of the subject. The neuromonitoring bone drill bit223any be inserted into the surgical site in any suitable manner. In one example, as discussed herein, the neuromonitoring bone drill bit223may be inserted into the surgical site with a locking system444of the drill bit assembly206in a locked position in which an electrically insulating shield212is not able to retract or withdraw from a position at which the electrically insulating shield212is covering the distal end portion223aof the neuromonitoring bone drill bit223to insulate a conductive path through the neuromonitoring bone drill bit223. Further, in some cases, the neuromonitoring bone drill bit223may be inserted into the surgical site by disposing the neuromonitoring bone drill bit223in a surgical access tube1077(e.g., a guide tube) held by a robotic arm or other secure support. The surgical access tube1077may constrain positioning of the neuromonitoring bone drill bit223while the neuromonitoring bone drill bit223is advanced into the bone of the subject.

The method1200may further include securing1206a locking system444of the drill bit assembly206including the neuromonitoring bone drill bit223in an unlocked position (e.g., the shield unlock position), for example, after the neuromonitoring bone drill bit223has been inserted to a surgical site. In one example when utilizing the drill bit assembly206, the locking system444may be adjusted to and secured in the unlocked position by moving (e.g., proximally withdrawing or otherwise moving) the lock actuator220to an unlock position and rotating the lock actuator220to secure the lock actuator220in the unlock position. The locking system444may be secured in the unlocked position in one or more other suitable manners. Securing the locking system444in the unlocked position may allow the electrically insulating shield212to withdraw proximally in response to engagement of the electrically insulating shield212with tissue of the subject.

Once the locking system444has been secured in the unlocked position, the neuromonitoring bone drill bit223may be advanced1208into the bone of the subject. The neuromonitoring bone drill bit223may be advanced into the bone by a user causing the drill104to rotate the neuromonitoring bone drill bit223and the user applying a force to the drill104. Advancing the neuromonitoring bone drill bit223into tissue of the subject may cause the electrically insulating shield212to engage the tissue and result in the electrically insulating shield212withdrawing proximally relative to the distal end portion223aas the neuromonitoring bone drill bit223advances into the tissue of the subject. Although other configurations are contemplated, the electrically insulating shield212may be configured to retract or withdraw in the manners discussed herein.

In some cases, as the neuromonitoring bone drill bit223is advanced into the bone of the subject, an electrical stimulation may be applied to the bone by electrically stimulating the neuromonitoring bone drill bit223with the neuromonitoring clip coupled thereto. Further, a neuromonitoring system may monitor the electrical stimulation or the subject's response to the electrical stimulation for responses to the electrically stimulation that are indicative of a pedicle breach. Further, the electrical stimulations may be monitored for one or more other suitable purposes.

After advancing the neuromonitoring bone drill bit223into tissue of the subject, the neuromonitoring bone drill bit223may be withdrawn1210from the tissue of the subject. In some cases, as the neuromonitoring bone drill bit223is withdrawn from the tissue of the subject, the electrically insulating shield212may automatically advance distally over the distal end portion223aof the neuromonitoring bone drill bit223in the manners discussed herein or in other manners. The electrically insulating shield212covering the distal end portion223aof the neuromonitoring bone drill bit223during and after withdrawal of the neuromonitoring bone drill bit223from the subject's tissue may facilitate electrically insulating the neuromonitoring bone drill bit223as the neuromonitoring bone drill bit223is withdrawn from the subject.

For the following defined terms, these definitions shall be applied, unless a different definition is given in the claims or elsewhere in this specification.

All numeric values are herein assumed to be modified by the term “about”, whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (e.g., having the same function or result). In many instances, the terms “about” may include numbers that are rounded to the nearest significant figure.

The recitation of numerical ranges by endpoints includes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

It is noted that references in the specification to “an embodiment”, “some embodiments”, “other embodiments”, etc., indicate that the embodiment described may include one or more particular features, structures, or characteristics. However, such recitations do not necessarily mean that all embodiments include the particular features, structures, or characteristics. Additionally, when particular features, structures, or characteristics are described in connection with one embodiment, it should be understood that such features, structures, or characteristics may also be used connection with other embodiments whether or not explicitly described unless clearly stated to the contrary.

The above detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the invention.

It should be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size, and arrangement of steps without exceeding the scope of the disclosure. This may include, to the extent that it is appropriate, the use of any of the features of one example embodiment being used in other embodiments. The invention's scope is, of course, defined in the language in which the appended claims are expressed.