Patent Description:
Surgical procedures are commonly performed to correct problems with displaced, damaged, or degenerated intervertebral discs in the spine. A wide spectrum of spinal procedures involve the insertion of bone anchors. The accurate and efficient insertion of such bone anchors may be facilitated by the use of a stylet that extends beyond the distal tip of the bone anchor. Stylets may assist in avoiding screw skiving, and in planning insertion trajectory. However, existing stylets have demonstrated limitations with respect to ease of manipulation and retraction by the surgeon, and interference with screw insertion. Examples of instruments for use during insertion of a bone anchor can be found in <CIT>, <CIT> and <CIT>.

The present invention provides a ratchet retracting handle for use in an assembly for inserting a bone anchor into a bone as set out in claim <NUM>.

As described below, a ratchet retracting handle is provided for automatically retracting a stylet during insertion of a bone anchor. In embodiments according to this aspect, the ratchet retracting handle comprises: a cap assembly translationally fixed to the stylet; a retractor assembly engaged with the cap assembly and disposed distally thereof, wherein engagement of the retractor assembly with the cap assembly produces translational movement of the retractor assembly in a distal direction; a lead screw rotatably coupled with the retractor assembly; a ratchet assembly comprising a ratchet knob and a ratchet body, the ratchet body being coupled to a distal end of the lead screw and to a proximal end of the screw driver; and a cover disposed over and rotationally fixed to the retractor assembly. In such embodiments, due to the ratcheting relationship between ratchet body and ratchet knob, rotation of the cover in a first direction is configured to advance the stylet and the bone anchor distally, while rotation of the cover in a second direction, opposite the first direction, is configured to retract the retractor assembly and the stylet proximally relative to the bone anchor, while the bone anchor is restrained from rotating.

As also described below, an insertion and retraction assembly is provided for inserting a bone anchor and retracting a stylet. In embodiments according to this aspect, the insertion and retraction assembly comprises: a ratchet retracting handle comprising: a cap assembly translationally fixed to the stylet; a retractor assembly engaged with the cap assembly and disposed distally thereof, wherein engagement of the retractor assembly with the cap assembly produces translational movement of the retractor assembly in a distal direction; a lead screw coupled with the retractor assembly; a ratchet assembly comprising a ratchet knob and a ratchet body, the ratchet body being coupled to a distal end of the lead screw; a screw driver coupled at a proximal end thereof to the ratchet body; and a cover disposed over and rotationally fixed to the retractor assembly. Due to the ratcheting relationship between the ratchet body and the ratchet knob, rotation of the cover in a first direction is configured to advance the stylet and the bone anchor distally, while rotation of the cover in a second direction, opposite the first direction, is configured to retract the retractor assembly and the stylet proximally relative to the bone anchor, while the bone anchor and the screw driver are restrained from rotating.

As further described below, a method is provided for inserting a bone anchor (this method do not form part of the claimed invention) and automatically retracting a stylet associated with the bone anchor, the method comprising: providing a ratchet retracting handle, wherein the ratchet retracting handle comprises: a cap assembly translationally fixed to the stylet; a retractor assembly engaged with the cap assembly and disposed distally thereof, wherein engagement of the retractor assembly with the cap assembly produces translational movement of the retractor assembly in a distal direction; a lead screw rotatably coupled with the retractor assembly; a ratchet assembly comprising a ratchet knob and a ratchet body, wherein the ratchet body is coupled to a distal end of the lead screw; and a cover disposed over and rotationally fixed to the retractor assembly. The ratchet retracting handle may then be coupled to a driver of the bone anchor. The method further comprises rotating the cover in a first direction to advance the stylet and the bone anchor in the distal direction; and rotating the cover in a second direction, opposite the first direction, to restrain the bone anchor from rotating and simultaneously retract the retractor assembly and the stylet proximally relative to the bone anchor.

The invention will become apparent from the following detailed description, which, when taken in conjunction with the annexed drawings, where like parts are designated by like reference characters throughout the drawings, disclose embodiments of the invention.

As indicated above and as illustrated in <FIG>, aspects of the invention provide a ratchet retracting handle <NUM> for use in an insertion and retracting assembly <NUM> for the insertion of a bone anchor <NUM> into a bone. Ratchet retracting handle <NUM> may include integrated mechanisms as described further herein to manage the retention, deployment, and retraction of a stylet <NUM>, and allow the user to fix the protrusion of the stylet <NUM> from the tip of the screw <NUM>, and mallet or push on the proximal end of ratchet retracting handle <NUM> to extend the stylet <NUM> in a distal direction. During or after the insertion of screw <NUM>, the ratcheting mechanism of the handle <NUM> may be used to automatically retract the stylet <NUM>.

Embodiments of the ratchet retracting handle <NUM> disclosed herein advantageously facilitate automatic retraction of stylet <NUM>, which can be conveniently and efficiently achieved using only one hand, e.g., by rotating handle <NUM>. The distance of retraction can be pre-determined, e.g., stylet <NUM> may be retracted a predetermined distance sufficient to withdraw the tip of the stylet from within a patient during a procedure. Further, ratchet retracting handle <NUM> may provide a surgeon with improved flexibility by facilitating retraction of stylet <NUM> in both a docking mode and an extended mode.

As disclosed herein, the term bone anchor is used interchangeably with, and is considered equivalent to and synonymous with the terms: bone fastener, fastener, fixation screw, spinal fixation screw, bone screw, and pedicle screw. The term driver is used interchangeably with, and is considered equivalent to and synonymous with a screw driver, or any device that drives insertion of a bone anchor as would be understood by one skilled in the art. The term stylet is used interchangeably with, and is considered equivalent to the terms, k-wire, guide wire, and wire. Use of the term proximal refers to the direction away from attachment of an element to the subject, shown in <FIG> as direction P, while use of the term distal refers to the direction opposite the proximal direction and toward attachment of an element to the subject, shown in <FIG> as direction D.

With reference to <FIG>, an insertion and retraction assembly <NUM> is provided, including a ratchet retracting handle <NUM> as discussed above. Assembly <NUM> is provided for use in the insertion and fixation of bone anchors <NUM> into a bony structure such as, e.g., a vertebra, and for automatically retracting stylet <NUM> during or after such insertion of a bone anchor <NUM>.

Handle <NUM> may be movable between a first mode and a second mode of operation, e.g., a docking mode and a deployed or extended mode. In the docking mode, stylet <NUM> may be retained at a fixed protrusion amount from the tip of bone screw <NUM> (see, e.g., <FIG>). The fixed protrusion amount may be, e.g., about <NUM> to about <NUM>, and more particularly may be about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. When in the docking mode, stylet <NUM> remains at this fixed protrusion amount relative to the tip of bone anchor <NUM> even when malleting or pushing is applied to cap <NUM> (<FIG>) at the proximal end of handle <NUM>. The fixed protrusion of stylet <NUM> from screw <NUM> may advantageously allow the surgeon to dock the screw <NUM> and stylet <NUM> on the bone without the screw <NUM> skiving off the bony surface. When the handle <NUM> is in the extended mode, handle <NUM> may allow translation of the stylet relative to the screw <NUM> to facilitate extension of stylet <NUM> past not only a distal tip of bone screw <NUM> but also past the fixed point in the docking mode. The transition from docking mode to extended mode unlocks the translation of stylet <NUM> relative to bone screw <NUM>. Malleting or pushing on cap <NUM> of handle <NUM> in the extended mode extends stylet <NUM> distally for a predetermined distance, e.g., an additional <NUM>. In one example, stylet <NUM> may extend beyond the tip of bone anchor <NUM> by about <NUM>, and may extend an additional <NUM> in the extended mode, for a total distance of <NUM> in the extended mode. In other embodiments, however, the total extension of the tip of stylet <NUM> in the extended mode may be about <NUM> to about <NUM> beyond the tip of bone screw <NUM>, or more particularly, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> beyond the tip of bone screw <NUM>.

The practice of extending stylet <NUM> past the distal tip of bone screw <NUM> can advantageously allow the surgeon to confirm the trajectory of screw <NUM>, e.g., under fluoroscopy, before deploying the screw <NUM> into bone. In the extended mode, as the screw <NUM> is deployed into bone, the backwards ratchet mechanism of the handle <NUM> may advantageously pull stylet <NUM> back to a retracted position. Thus, screw <NUM> is inserted and stylet <NUM> is retracted in simultaneous actions.

If desired, the user can mallet or push again on cap <NUM> of handle <NUM> to redeploy stylet <NUM>, and when inserting screw <NUM>, stylet <NUM> may retract again using the ratchet mechanism. Methods of advancing stylet <NUM> distally other than malleting may also be used, including threaded and spring loading mechanisms. Methods of facilitating forward advancement of stylet <NUM> besides the overrunning thread can be used, including a threaded, ball-detent "quick-release.

Referring again to <FIG>, ratchet retracting handle <NUM> may have an elongated body extending axially along a longitudinal axis (not shown), and in a proximal to distal direction, and may be configured to be coupled to a proximal portion of screw driver <NUM> for inserting bone anchor <NUM> into bone during a surgical procedure. Stylet <NUM> may be coupled at a proximal end thereof to handle <NUM> (<FIG>), and may extend longitudinally within and through screw driver <NUM> and through a central, longitudinal cavity of bone anchor <NUM>. Driver <NUM>, bone anchor <NUM>, stylet <NUM>, and handle <NUM> may all be substantially coaxial. A distal tip of stylet <NUM> may be adjustably extended beyond the distal tip of bone anchor <NUM>.

With reference to <FIG> and <FIG>, ratchet retracting handle <NUM> is illustrated in greater detail. Ratchet retracting handle <NUM> may include a cap assembly <NUM> comprising a cap <NUM>, a knob <NUM>, and a cap body <NUM>. Cap body <NUM> may include a distal portion that may be substantially annularly shaped, and a proximal portion that couples to knob <NUM>. Knob <NUM> may be disposed proximally relative to cap body <NUM> and coupled thereto, and may be configured to rotatably control or initiate transitions of the ratchet retracting handle <NUM> between a docking mode and an extended mode, as discussed further herein. Cap <NUM> may be disposed at a proximal end of cap assembly <NUM>, and may be matingly engaged with a proximal end of knob <NUM>, as discussed further herein. Knob <NUM> may further include a retention button <NUM> disposed thereon, that controls operation of retention element <NUM> (<FIG>) disposed within knob <NUM>. Retention element <NUM> is configured to releasably retain stylet <NUM> within knob <NUM>, and maintain stylet <NUM> fixed in its translational position with respect to knob <NUM>, described further below.

As shown in <FIG>, cap <NUM> may further include two or more pushing posts <NUM>, each of which extends distally from cap <NUM>. Some particular embodiments may include, e.g., two pushing posts <NUM> as shown in <FIG>, or three pushing posts <NUM>, or four pushing posts <NUM>, or more. Cap body <NUM> may further include one or more legs <NUM>, disposed distally of knob <NUM>. Each leg <NUM> may extend a distance in a direction radially outward relative to the longitudinal axis of the device, and substantially perpendicular to a longitudinal axis of cap body <NUM> and handle <NUM>. The distance extended radially outwardly by each leg <NUM> is such that each leg <NUM> may be securely received in a complementary-shaped extension channel <NUM> in a cover <NUM>, as discussed further herein. Each leg <NUM> may further have a height that substantially corresponds to the depth of the corresponding extension channel <NUM>. As shown in, e.g., <FIG>, pushing posts <NUM> may extend distally from cap <NUM> through legs <NUM>. Cap assembly <NUM> may further include a cap assembly spring <NUM> disposed on the distal portion of cap body <NUM>. In particular, spring <NUM> may be coiled around an outer surface, e.g. an outer circumferential surface, of the distal portion of cap body <NUM>. Cap assembly spring <NUM> may be configured to bias or move stylet <NUM> in a distal direction relative to cap assembly <NUM>, and participates in the advancement of stylet <NUM>. The advantages and functions of pushing posts <NUM>, leg <NUM>, and spring <NUM> are discussed further below.

With further reference to <FIG>, ratchet retracting handle <NUM> may also include a retractor assembly <NUM> coupled to cap body <NUM> at a distal end thereof. Retractor assembly <NUM> may include a retractor body <NUM>, which may be substantially annular in shape. Retractor body <NUM> may include one or more retractor posts <NUM> extending proximally from a proximal end of retractor body <NUM>. In some embodiments, the number of retractor posts <NUM> may be two, as illustrated in, e.g., <FIG>, however other embodiments may include other numbers of retractor posts <NUM> extending proximally from retractor body <NUM>, e.g., retractor assembly <NUM> may include one, two, three, or more retractor posts <NUM>. In embodiments having two or more retractor posts <NUM>, the retractor posts <NUM> may be evenly spaced around a circumference of the proximal end of retractor body <NUM>. For example, in embodiments having two retractor posts <NUM>, the retractor posts may be disposed approximately <NUM> degrees apart along the circumference of the proximal end of retractor body <NUM>, such that the two retractor posts <NUM> are on approximately opposite sides of the longitudinal axis from one other, as shown in <FIG>. In embodiments having three retractor posts <NUM>, the retractor posts may be disposed approximately <NUM> degrees apart along the circumference of the proximal end of retractor body <NUM>, such that the three retractor posts <NUM> are approximately equally spaced around an outer circumference of the proximal end of retractor body <NUM>. A retractor spring <NUM> may be disposed over retractor body <NUM> such that retractor spring <NUM> may be coiled around an outer surface of the retractor body <NUM> (<FIG>), e.g., around an outer circumferential surface of retractor body <NUM>. Retractor spring <NUM> may be biased such that it functions to retract stylet <NUM> in a proximal direction, thereby participating in the retraction of stylet <NUM> as described further herein. Certain embodiments, as illustrated in <FIG>, may further include a bushing or washer <NUM>. Bushing or washer <NUM> is a substantially rigid annular member that reduces the area for retractor spring <NUM>, and thereby acts to prevent retractor spring <NUM> from being canted within handle <NUM>. Thus, bushing or washer <NUM> may contribute to the avoidance of undesired binding of the assembly during operation of certain embodiments.

Referring back to <FIG> and <FIG>, ratchet retracting handle <NUM> may further include a ratchet assembly <NUM> that includes a ratchet knob <NUM> and a ratchet body <NUM>. Ratchet knob is movable, e.g., rotatable, relative to ratchet body <NUM>. As shown in <FIG>, ratchet body <NUM> is coupled to and rotationally fixed to lead screw <NUM>. In some embodiments, ratchet body <NUM> may be coupled to lead screw <NUM> via lead screw attachment <NUM>, as shown in, e.g., <FIG>. In other embodiments, ratchet body <NUM> may be coupled to lead screw <NUM> via an integrally formed ratchet body attachment <NUM>, which may be integrally formed with lead screw <NUM>, as shown in <FIG>. This configuration provides an alternative to the use of lead screw attachment <NUM> as discussed herein. In either case, lead nut <NUM> may be coupled on lead screw <NUM>, and sleeve <NUM> may be disposed over at least part of lead nut <NUM> (<FIG>). Lead nut <NUM> and sleeve <NUM> may be rotationally fixed to retractor assembly <NUM>. As shown in <FIG>, retractor assembly <NUM> may rotate and translate together with lead nut <NUM> and sleeve <NUM>, all relative to screw driver <NUM>, ratchet assembly <NUM>, and lead screw <NUM>. As shown in <FIG>, screw driver <NUM> may be coupled at a proximal end thereof to ratchet body <NUM>, and at a distal end thereof to bone anchor <NUM> with associated stylet <NUM> prior to insertion.

As further shown in <FIG>, a cover <NUM> may be disposed over and may enclose portions of ratchet retracting handle <NUM>. Cover <NUM> may cover and/or enclose retractor assembly <NUM>, portions of ratchet assembly <NUM>, and a portion of cap assembly <NUM>, e.g., at least a portion of cap body <NUM>. In some embodiments, cover <NUM> may include a see-through window <NUM> (<FIG>) as discussed further herein, as well as one or more axially extending slots <NUM> (<FIG>). Each axially extending slot <NUM> may terminate in an opening at the proximal edge of cover <NUM>, and each slot <NUM> may be shaped, dimensioned, and positioned to facilitate mating engagement with a retractor post <NUM> and with a pushing post <NUM> as discussed further herein. Each retractor post <NUM> is configured to travel axially within a corresponding slot <NUM> of the cover <NUM>. The number slots <NUM> and position of each slot <NUM>, e.g., its circumferential position relative to the proximal end of cover <NUM>, may be determined based on the corresponding number and position of retractor posts <NUM> and/or pushing posts <NUM>. For example, various embodiments may include two, three, four, or more slots <NUM> disposed about cover <NUM>. In further embodiments, a ball detent <NUM> is provided, which travels within axially-extending groove <NUM> within cap body <NUM>. Ball detent <NUM> is spring loaded, the force of which can be overcome to allow translation of pins (not shown in <FIG>) into fixed positions, thereby providing rotational resistance and tactile feedback. An additional configuration for ball detent <NUM> is described further herein with respect to <FIG>.

Cover <NUM> may be rotationally fixed to retractor assembly <NUM>, although cover <NUM> and retractor assembly <NUM> may translate axially relative to one another. As a result, rotation of cover <NUM> may cause rotation of retractor assembly <NUM>, lead nut <NUM>, and sleeve <NUM>. Rotation of cover <NUM> in a first direction (e.g., clockwise) may cause rotation of ratchet knob <NUM> and ratchet body <NUM> along with cover <NUM> in the first direction, thereby causing rotation of screw driver <NUM> and advancement of stylet <NUM> and bone anchor <NUM> in a distal direction, e.g., for insertion. Rotation of cover <NUM> in a second direction opposite the first direction, e.g., a counter clockwise direction, may cause ratchet knob <NUM> to rotate along with cover <NUM>, while ratchet body <NUM> does not rotate. The relative rotation in the second direction of ratchet knob <NUM> relative to ratchet body <NUM> results in bone anchor <NUM> and screw driver <NUM>, along with lead screw attachment <NUM> and lead screw <NUM> remaining translationally fixed in position, while retractor assembly <NUM>, lead nut <NUM>, sleeve <NUM>, stylet <NUM>, and cap assembly <NUM> may translate proximally, thereby retracting stylet <NUM>. The gripping force on bone anchor <NUM> also holds screw driver <NUM> and bone anchor <NUM> and prevents these features from rotating at the same time.

In <FIG>, handle <NUM> is shown in the docking mode. As illustrated, cap assembly <NUM> may further include biasing element <NUM> (<FIG>) disposed between cap <NUM> and knob <NUM>. Biasing element <NUM> may be, for example, a coil spring. Biasing element <NUM> biases cap <NUM> in a proximal direction relative to knob <NUM>, such that cap <NUM> is separated from knob <NUM> by gap <NUM> when biasing element <NUM> is in its resting state. As long as gap <NUM> is maintained by biasing element <NUM>, pushing posts <NUM>, which extend distally from cap <NUM>, are prevented from engaging with retractor posts <NUM> and slots <NUM>.

In the docking mode, one or more legs <NUM> (<FIG>) of cap assembly <NUM> may abut the distal edge of cover <NUM>, so that knob <NUM> is translationally fixed at least in a distal direction relative to the cover <NUM>, i.e., knob <NUM> cannot move further in a distal direction toward cover <NUM>. When a mallet or pushing force <NUM> is applied on cap <NUM>, cap <NUM> moves or translates distally relative to knob <NUM> against the force of biasing element <NUM> until it is stopped by knob <NUM>, which remains translationally fixed relative to cover <NUM>. During this process, each pushing post <NUM> may translate to a limited extent into a corresponding slot <NUM> in cover <NUM>, insufficient to materially engage with retractor posts <NUM>. Stylet <NUM>, which is retained by retention elements <NUM> in knob <NUM>, may remain translationally fixed to knob <NUM>. Thus, stylet <NUM> does not move distally even when cap <NUM> moves distally and abuts knob <NUM>, as shown in <FIG>.

<FIG> and <FIG> illustrate the transition from the docking mode to the deployed or extended mode. <FIG> and <FIG> illustrate ratchet retracting handle <NUM> in the docking mode prior to beginning the transition to the extended mode. As described above, when mallet force <NUM> is applied to cap <NUM> in the docking mode, cap <NUM> moves distally until a distal edge of leg(s) <NUM> abuts a proximal edge of cover <NUM> (<FIG>). From this position in <FIG>, knob <NUM> may be turned, e.g., a clockwise or a counterclockwise direction relative to cover <NUM>. This turn brings leg(s) <NUM> into alignment with extension channel(s) <NUM> in cover <NUM>. When leg(s) <NUM> reaches alignment with a corresponding extension channel(s) <NUM> in cover <NUM>, as shown in <FIG>, knob <NUM> can move further in a distal direction until it abuts the distal edge of cover <NUM>. At this point, a distal surface of knob <NUM> may make substantially uninterrupted contact, e.g., circumferential contact, with a proximal edge of cover <NUM>. Leg(s) <NUM> move progressively distally into the corresponding and complementary-shaped extension channel(s) <NUM> as shown in <FIG>. The stylet <NUM> that is translationally locked to knob <NUM> via retention elements <NUM> (<FIG>) thus also moves distally. Cap <NUM> can also be pushed distally until it contacts knob <NUM> in a fashion similar to that in the docking mode during or after stylet <NUM> extension.

As knob <NUM> approaches cover <NUM> as it moves out of the docking mode of <FIG> and <FIG>, through the progressive transitional phases depicted in <FIG> and <FIG>, and <FIG> and <FIG>, and into the extended mode of <FIG> and <FIG>, pushing posts <NUM> may translate distally in corresponding slots <NUM> as shown in <FIG> and <FIG>, achieve contact at their distal ends with the proximal ends of retracting posts <NUM>, and push the retracting posts <NUM> distally, traveling within the same slots <NUM>. As a result, the distal movement of cap <NUM> and pushing posts <NUM> pushes retractor assembly <NUM> distally as well, as shown in <FIG>, and extends stylet <NUM> in a distal direction beyond bone screw <NUM> as shown in <FIG>. The distance by which stylet <NUM> extends beyond the distal tip of bone screw <NUM> in the extended mode may be predetermined for a particular application. In particular, retention elements <NUM> retain stylet <NUM> within cap assembly <NUM>, such that the predetermined distance is governed by the distance traveled by cap assembly <NUM> when malleted.

In some exemplary embodiments, this distance may be, e.g., about <NUM> to about <NUM>, or more particularly, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>, or other distances.

<FIG> illustrates in greater detail the balance of forces in the extended mode. In this particular embodiment, advancing force 218a in a distal direction of cap assembly spring <NUM> is smaller than biasing force 242a in a proximal direction of retractor spring <NUM>. However, the additional gripping force from the bone holding stylet <NUM> extended may be cumulative with the advancing force 218a. This can balance out or even exceed the retracting force 242a, thereby causing stylet <NUM> to remain extended.

In some embodiments, the biasing forces are pre-adjusted, taking into consideration the gripping force from the bone that holds stylet <NUM> extended. For example, the biasing force 218a of cap assembly spring <NUM> may be smaller than the biasing force 242a of retractor spring <NUM>. In another example, the biasing forces may be adjusted so that the sum of the gripping force and the biasing force 218a of cap assembly spring <NUM> is equivalent to or slightly larger than the biasing force 242a of retractor spring <NUM> by about <NUM>% to about <NUM>% of the force of retractor spring <NUM>, so as to keep stylet <NUM> extended. In some embodiments, the biasing forces may be customized for specific applications of stylet <NUM>, different medical procedures, or different patients. For example, the stiffness of the spring may vary with the hardness of the bone into which bone anchor <NUM> is inserted, such that a harder bone demands a harder or more firm spring, while softer bone does not demand such a firm spring.

Turning back to <FIG>, as previously noted, after insertion of bone screw <NUM> initiated by rotation of cover <NUM> in the first direction, cover <NUM> may then be rotated in a second direction that is opposite the first direction. For example, where the first direction for bone anchor insertion is clockwise, the second direction may be counter clockwise. When cover <NUM> is rotated in the second direction, ratchet knob <NUM> (<FIG>) may rotate along with cover <NUM>, but ratchet body <NUM> may not rotate. The gripping force on bone anchor <NUM> may hold screw driver <NUM> and bone anchor <NUM> from rotating or translating distally, but upon rotation of ratchet knob <NUM> relative to ratchet body <NUM>, retractor assembly <NUM> and therefore stylet <NUM> may automatically retract proximally relative to the bone anchor <NUM>. As a result, lead nut <NUM>, sleeve <NUM>, retractor assembly <NUM>, and cap assembly <NUM> may all rotate and translate proximally together until retractor assembly <NUM> is stopped, e.g., by a proximal edge of the window <NUM>, or a stopping element <NUM> (<FIG>), e.g., a stopping ledge on cover <NUM>. Thus, cover <NUM> may rotate but does not translate proximally. Rather, lead nut <NUM>, sleeve <NUM>, retractor assembly <NUM>, and cap assembly <NUM> rotate and translate proximally together. In some embodiments, the automatic retraction of stylet <NUM> can be performed using only one hand, providing increased convenience and efficiency for the user.

<FIG> shows, in a particular embodiment, that retractor assembly <NUM>, cap assembly <NUM>, lead nut <NUM>, and sleeve <NUM> all translate proximally relative to cover <NUM> and ratchet assembly <NUM>. <FIG> shows at the end of the retraction process, progress in the proximal direction of retractor assembly <NUM> is stopped, and retractor assembly <NUM> abuts a stop element <NUM> on cover <NUM>, in this case, the distal edge of window <NUM> on cover <NUM>. <FIG> is an enlarged view showing sleeve <NUM> and lead nut <NUM>, which are free to rotate after they retract along with stylet <NUM>, and move away from groove <NUM> at a distal end of retractor body <NUM>. Rotation of lead nut <NUM> and sleeve <NUM> within the cavity of retractor body <NUM> as shown in <FIG> may allow uninterrupted screw <NUM> insertion after stylet retraction.

The proximal translation of lead nut <NUM>, retractor assembly <NUM>, and cap assembly <NUM> may cause retraction of stylet <NUM> for a predetermined or customized distance. For example, it can be within a predetermined range or a fixed value. As a non-limiting example, the retractable distance may be large enough so that the tip of stylet <NUM> is retracted out of the patient. In various embodiments, the retractable distance is in a range of about <NUM> to about <NUM>, a range of about <NUM> to about <NUM>, or a range of about <NUM> to about <NUM>. The foregoing ranges are merely illustrative and are intended to be combinable, e.g., to include about <NUM> to about <NUM>, about <NUM> to about <NUM>, and to include all distances within the foregoing ranges including, e.g., about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>.

As discussed above, cover <NUM> may include a see-through window <NUM> thereon (<FIG>), which may provide a visual indication and/or visual confirmation of retraction of stylet <NUM>. In some cases, at least a part of retractor body <NUM> may be visible in see-through window <NUM>. In further embodiments, at least a part of retractor body <NUM> may extend radially outwardly into see-through window <NUM>, thereby constraining or eliminating rotational movement of retractor assembly <NUM> relative to cover <NUM>. As described herein, cover <NUM> may be rotationally fixed relative to retractor assembly <NUM>, rotatable relative to ratchet assembly <NUM>, translationally fixed relative to ratchet assembly <NUM>, and translatable relative to retractor assembly <NUM>.

Turning to <FIG>, embodiments are depicted in which ratchet retracting handle <NUM> may be reset to extend again subsequent to the retraction of stylet <NUM>. After retraction of stylet <NUM>, cap <NUM> and knob <NUM> can be re-aligned so that leg(s) <NUM> (<FIG>) can again move into extension channel(s) <NUM> (<FIG>). A pushing force in a distal direction (<FIG>) may be applied to the proximal end of cap <NUM>, causing pushing posts <NUM> on cap <NUM> to engage first with posts <NUM> of retractor assembly <NUM>, before cap assembly <NUM> pushes on lead nut <NUM>. This can be ensured by gap <NUM> between cap <NUM> and knob <NUM>, which ensures that pushing post(s) <NUM> and retractor post(s) <NUM> contact first. When pushing posts <NUM> of cap <NUM> contact retractor posts <NUM> of retractor assembly <NUM>, retractor assembly <NUM> can be pushed distally. As cap assembly <NUM> moves distally, force is applied in a distal direction by cap assembly <NUM> on lead nut <NUM>, which may cause lead nut <NUM> to rotate and advance distally on the threads of lead screw <NUM>. Lead nut <NUM> may rotate and advance until it falls back into grooves <NUM> of retractor body <NUM>. Ratchet retracting handle <NUM> is then reset and ready for a new screw <NUM> insertion and/or stylet <NUM> retraction.

As described herein, ratchet retracting handle <NUM> herein may extend and/or automatically retract a stylet <NUM> associated with a bone anchor <NUM> to be inserted. In the docking mode, stylet <NUM> may extend beyond the distal tip of bone screw <NUM> for a first distance. The first distance may be, e.g., about <NUM>, or any value in the range of about <NUM> to about <NUM>. In the extended mode, distal movement of cap <NUM> and knob <NUM> may cause stylet <NUM> to be extended further beyond a distal tip of bone screw <NUM> for a pre-determined second distance into a bone. For example, the pre-determined second distance is about <NUM> to about <NUM>. Thus, if the first distance, between the tip of stylet <NUM> in the docking mode to the tip of the bone screw <NUM>, is <NUM>, and the second distance it can be further extended by a second distance of another <NUM> in the extended mode, the tip of stylet <NUM> may be extended a cumulative <NUM> beyond the distal tip of bone screw <NUM>. Ratchet retracting handle <NUM> advantageously allows stylet <NUM> to be retracted either in the docking mode or in the extended mode.

Referring to <FIG>, ratchet retracting handle <NUM> is illustrated in a number of positions discussed herein. <FIG> illustrate ratchet retracting handle <NUM> in the extended mode with stylet <NUM> extended and retracted, respectively, while <FIG> illustrate ratchet retracting handle <NUM> in the docking mode with stylet <NUM> extended and retracted, respectively.

As shown in <FIG>, further embodiments may additionally include housing element <NUM> (<FIG>). Housing element <NUM> may be rotationally and translationally fixed to the cover <NUM>, and it may be rotationally fixed to retractor assembly <NUM> and translatable relative to retractor assembly <NUM>. In some embodiments, housing element <NUM> may be a rigid element that contains the components therein including, e.g., retractor assembly <NUM>, retractor spring <NUM>, a portion of cap body <NUM>, cap assembly spring <NUM>, etc. In embodiments in which housing element <NUM> provides structure and rigidity to support and retain these components, cover <NUM> may be made of a softer, less rigid material such as, e.g., a silicon over mold. In embodiments in which housing element <NUM> is not present, the rigidity may instead be provided by cover <NUM> itself. Thus, embodiments with and without housing element <NUM> may function similarly.

Still further, additional features of cap assembly <NUM>, present in certain embodiments, are illustrated in <FIG>, and in greater detail in <FIG>. In such embodiments, cap body <NUM> may include a first groove <NUM> which runs axially along an outer surface of cap body <NUM>. First groove <NUM> further includes a first horizontal portion <NUM> and a second horizontal portion <NUM>. A pin <NUM> is provided, which translates along first groove <NUM>, and may be fixed in position within first horizontal portion <NUM> or second horizontal portion <NUM>. Cap body <NUM> may also include a second groove <NUM>, which runs axially along an outer surface of cap body <NUM>, which may be radially spaced from first groove <NUM>. A ball detent or ball plunger <NUM> may be provided, which may movable in and out of second groove <NUM>, and may travel axially within second groove <NUM> within cap body <NUM>. Ball detent <NUM> may be spring loaded, the force of which may be overcome to allow translation of pin <NUM> into fixed positions, e.g., within first horizontal slot <NUM> or second horizontal slot <NUM>. Ball detent <NUM> provides rotational resistance and tactile feedback, and pops in and out of second groove <NUM> channel as cap body <NUM> is rotated.

Also disclosed herein are methods (these methods do not form part of the claimed invention) for automatically retracting a stylet associated with a bone anchor during insertion of the bone anchor. Methods according to such embodiments may include one or more operations as disclosed herein. For example, such methods may include providing a ratchet retracting handle as disclosed herein to a user. The ratchet retracting handle can be coupled to a driver for inserting the bone anchor. The method may include, when in the docking mode or extended mode, retracting the stylet proximally by rotating the cover relative to the ratchet assembly using only one hand, while holding the driver and the bone screw rotationally and translationally fixed relative to the ratchet assembly. The method may further include causing the retractor assembly, the cap assembly, and the lead nut to translate proximally by rotating the cover, thereby retracting the stylet that is locked to the cap body.

Claim 1:
A ratchet retracting handle (<NUM>) for use in an assembly (<NUM>) for inserting a bone anchor (<NUM>) into a bone,
wherein, prior to insertion, a stylet (<NUM>) extends longitudinally through the bone anchor (<NUM>), and the bone anchor (<NUM>) is configured to couple with a distal end of a screw driver (<NUM>), and
wherein the ratchet retracting handle (<NUM>) is adapted to transition between a docking mode, in which the stylet (<NUM>) is retained at a fixed axial position extending beyond a distal tip of the bone anchor (<NUM>), and an extended mode, in which the stylet (<NUM>) is distally translatable beyond the fixed axial position, and to automatically retract the stylet (<NUM>) during insertion of the bone anchor (<NUM>),
the ratchet retracting handle (<NUM>) being characterized by comprising:
a cap assembly (<NUM>) comprising: a cap body (<NUM>); a knob (<NUM>) configured to releasably retain the stylet (<NUM>), wherein the knob is coupled to and disposed proximally relative to the cap body (<NUM>); and a cap (<NUM>) matingly engaged with a proximal end of the knob (<NUM>);
a retractor assembly (<NUM>) engaged with the cap assembly (<NUM>) and disposed distally thereof, wherein the retractor assembly (<NUM>) comprises a retractor body (<NUM>) and two or more retractor posts (<NUM>) extending proximally therefrom; a ratchet assembly (<NUM>) rotatably engaged with the retractor assembly (<NUM>) and including a ratchet body (<NUM>) and a ratchet knob (<NUM>) rotatable relative thereto, wherein the ratchet body (<NUM>) is rotationally fixed to a lead screw (<NUM>), and coupled to a proximal end of the screw driver (<NUM>); and a cover (<NUM>) disposed over at least part of each of the ratchet assembly (<NUM>), the retractor assembly (<NUM>), and the cap assembly (<NUM>), wherein the cover (<NUM>) is rotationally fixed to the retractor assembly (<NUM>).