Patent Description:
Bone anchors can be used in orthopedic surgery to fix bone during healing, fusion, or other processes. In spinal surgery, for example, bone anchors can be used to secure a spinal fixation element to one or more vertebrae to rigidly or dynamically stabilize the spine.

In a conventional procedure for coupling a bone anchor to bone, access to the bone is obtained, for example by forming a skin incision and resecting soft tissue disposed over the bone or by using a minimally-invasive technique. A bone anchor assembly is coupled to a bone inserter instrument having a stylet protruding therefrom. The stylet can be docked into bone by tapping or urging the instrument distally towards bone. Once the stylet is advanced to the desired depth, the bone anchor assembly is driven along the path created by the stylet. When the bone anchor assembly is driven to the desired depth, the instrument can be detached from the bone anchor assembly and removed from the incision.

During use, as the bone anchor assembly is being driven into bone, the stylet can continue to advance ahead of the screw. Any further advancement of the stylet can lead to further accidental advancement of the bone anchor assembly into bone. In the event that the bone anchor assembly is driven too deep into the bone, undesired damage to the bone and/or underlying tissue or nerves can result, and consequently, additional unnecessary trauma to the patient.

Accordingly, despite existing technologies, there remains a need for improved instrumentation and methods associated with driving bone anchors into bone. <CIT> provides surgical instruments and methods for delivering bone anchor assemblies into bone. Use of these anchors or instruments can eliminate one or more of the steps in a conventional bone anchor installation procedure, improving surgical efficiency and safety. In general, a surgical instrument can include a handle assembly having an elongate shaft extending distally therefrom. The handle assembly can be configured to axially translate a stylet extending therethrough relative to a bone anchor assembly coupled to the elongate shaft, and it can be configured to move the stylet proximally in response to distal advancement of a bone anchor assembly into bone. The surgical instruments can include various mechanisms for adjusting the position of the stylet. <CIT> provides a tool for installing a bone screw in a bone. The tool has a guide wire having an inner end adapted to be seated at the bone at a site where the screw, which is tubular and can fit around and slide along the wire, is to be installed, a tubular tool body fittable over and around the wire and having a tip fittable with the bone screw when same is traversed by the wire to rotate and drive the bone screw, a stabilizer axially and rotationally fixable to the wire offset from the tool body so that the screw can be screwed axially into the bone at the site while the wire is prevented from moving axially by the stabilizer.

Various surgical instruments and methods are disclosed herein for implanting a bone anchor into bone. The methods disclosed herein are not explicitly claimed; however, it is intended that the surgical instrument of the invention may be used to perform these methods.

The invention provides an instrument for driving a bone anchor assembly into bone according to claim <NUM>. Associated methods are described herein to aid understanding the invention; these methods are not explicitly claimed, although it is intended that the surgical instrument of the invention may be used to perform these methods. In one aspect, the instrument can be biased to the disengaged position.

The first handle can also have a variety of configurations. The first handle is configured to be decoupled from the elongate shaft when the instrument is in the disengaged position such that the first handle is freely rotatable relative to the elongate shaft, and the first handle is configured to be coupled to the elongate shaft when the instrument is in the engaged position such that rotation of the first handle rotates the elongate shaft.

The stylet can have a variety of configurations. The stylet may be configured to move proximally in response to the bone anchor assembly being driven into bone when the first handle is rotated and the instrument is in the engaged position. The stylet may be configured to axially translate relative to the elongate shaft in response to rotation of the second handle while the first handle is held stationary and the instrument is in the engaged position. In an embodiment, the stylet assembly can include a carrier coupled to the stylet and disposed within the anchor drive assembly and threadably coupled to the second handle.

The second handle includes an outer sleeve and inner sleeve, and the instrument can be moved from the disengaged position into the engaged position in response to axial movement of the outer sleeve relative to the inner sleeve. The instrument may include a clutch mechanism having a first position and a second position. When the clutch mechanism is in the second position, the clutch mechanism can be configured to couple the first handle to the elongate shaft such that rotation of the first handle rotates the elongate shaft.

In A first locking mechanism may lock the outer sleeve to the inner sleeve in a first position, and movement of the stylet to a proximal-most position relative to the elongate shaft may disengage the first locking mechanism to decouple the outer sleeve from the inner sleeve such that the inner sleeve can rotate independently of the outer sleeve. A second locking mechanism may lock the outer sleeve to the inner sleeve in a second position when the first locking mechanism is disengaged, and distal movement of the stylet from the proximal-most position may disengage the second locking mechanism and reengage the first locking mechanism such that the outer sleeve is recoupled to the inner sleeve. The stylet assembly may include a ratchet mechanism that can be configured to lock the outer sleeve to the inner sleeve such that the outer and inner sleeves can rotate simultaneously in one direction to distally move the stylet relative to the elongate shaft.

In another embodiment, a bone anchor inserter instrument is provided and can include an elongate shaft having a distal tip configured to couple to a bone anchor assembly, a stylet extending through the elongate shaft, and a handle assembly coupled to a proximal end of the elongate shaft. The handle assembly can include a first handle, a second handle, and a carrier movably disposed within the handle assembly and coupled to the stylet. The handle assembly can have a first configuration in which the first handle can rotate freely relative to the elongate shaft, and a second configuration in which rotation of the first handle relative to the second handle can cause corresponding rotation of the elongate shaft, and rotation of the second handle relative to the first handle can cause axial translation of the carrier and the stylet coupled thereto.

The stylet may be configured to move proximally in response to rotation of the first handle when the handle assembly is in the second configuration. Rotation of the first handle can be effective to drive the bone anchor assembly into bone only when the handle assembly is in the second configuration.

The second handle can have a variety of configurations. The second handle includes an outer and an inner sleeve. The inner sleeve can be configured to rotate freely relative to the outer sleeve when the handle assembly is in the second configuration and the carrier is in a most-proximal position. The second handle includes an
outer sleeve and an inner sleeve and the outer sleeve is configured to axially move relative to the inner sleeve to move the handle assembly from the disengaged position into the engaged position. The, the instrument may include a clutch mechanism having a first position and a second position. When the clutch mechanism is in the second position, the clutch mechanism may be configured to couple the first handle to the elongate shaft such that rotation of the first handle rotates the elongate shaft.

In some embodiments, when the handle assembly is in the second configuration, the carrier can be non-rotatably translatable through the handle assembly in response to rotation of the second handle while the first handle is held stationary. In such embodiments, when the handle assembly is in the second configuration, the carrier can be rotatably translatable through the handle assembly in response to rotation of the first handle while the second handle is held stationary.

Methods for implanting a bone anchor assembly are also provided. These methods are not explicitly claimed; however, it is intended that the surgical instrument of the invention may be used to perform these methods. The method may include moving a handle assembly on an inserter tool from a first configuration to a second configuration to axially translate a stylet extending through an elongate shaft of the inserter tool, and rotating a first handle of the handle assembly, while maintaining the handle assembly in the second configuration, to thereby adjust a position of a distal tip of the stylet relative to a bone anchor coupled to a distal end of the elongate shaft. The method can also include manipulating the inserter tool to position the distal tip of the stylet in bone, and rotating a second handle of the handle assembly to rotate the elongate shaft and thereby distally advance the bone anchor coupled to the distal end of the elongate shaft along the stylet and into bone. In one aspect, the first handle can be rotated while the handle assembly is maintained in the second configuration. In another aspect, the first handle can include an inner sleeve and an outer sleeve, and moving the handle assembly from the first configuration to the second configuration can include moving the outer sleeve relative to the inner sleeve in an axial direction. In another aspect, rotating the second handle can be effective to cause axial translation of the stylet in a proximal direction relative to the elongate shaft.

Moving the handle assembly from the first configuration to the second configuration may cause a clutch mechanism to move from a disengaged position to an engaged position. Moving the handle assembly from the first configuration to the second configuration may cause the second handle to mate to the elongate shaft such that rotation of the second handle rotates the elongate shaft.

The methods disclosed herein are not explicitly claimed; however, it is intended that the surgical instrument of the invention may be used to perform these methods.

It will be appreciated that the terms "proximal" and "distal" are used herein with reference to a user, such as a clinician, gripping a handle of an instrument. Other spatial terms such as "front" and "rear" similarly correspond respectively to distal and proximal. It will be further appreciated that for convenience and clarity, spatial terms such as "vertical" and "horizontal" are used herein with respect to the drawings. However, surgical instruments are used in many orientations and positions, and these spatial terms are not intended to be limiting and absolute.

Surgical instruments and methods are provided for driving a bone anchor assembly into bone. These methods are not explicitly claimed; however, it is intended that the surgical instrument of the invention may be used to perform these methods. In general, a bone screw inserter instrument is provided having a disengaged position and an engaged position. As discussed in greater detail below, the instrument can be configured such that the instrument can only drive a bone anchor assembly into bone when the instrument is in the engaged position. The instrument includes an anchor drive assembly having a first handle and an elongate shaft with a distal tip that is configured to couple to a bone anchor assembly. When the instrument is in the disengaged position, the first handle can be decoupled from the elongate shaft such that the first handle can freely rotate relative to the elongate shaft. When the instrument is in the engaged position, however, the first handle can be coupled to the elongate shaft such that rotation of the first handle can be effective to drive the bone anchor assembly into bone. As such, unless the instrument is in the engaged position, rotation of the first handle will not effect rotation of the elongate shaft, and consequently, drive the bone anchor assembly into bone. The instrument can also include a stylet assembly that includes a second handle and a stylet that extends through the elongate shaft. Rotation of the second handle can be effective to cause axial translation of the stylet relative to the elongate shaft when either the instrument is in the engaged position or when the elongate shaft is held stationary. Further, the second handle can be movable from a first position to a second position to cause the instrument to move from the disengaged position to the engaged position. As a result, the instrument can only be moved into and maintained in its engaged position when the second handle is held in the second position. Thus, the bone anchor inserter instrument can allow the bone anchor assembly to be driven into bone while also preventing the stylet from advancing ahead of the bone anchor assembly. That is, unlike conventional bone inserter instruments, the bone anchor inserter instrument can be configured to control the advancement of the stylet such that the stylet is unable to further advance into bone as the bone anchor assembly is being implanted.

A bone anchor inserter instrument can include a variety of features to facilitate implantation of a bone anchor assembly, as described herein and illustrated in the drawings. However, a person skilled in the art will appreciate that the bone anchor inserter instruments can include only some of these features and/or it can include a variety of other features known in the art. The bone anchor inserter instruments described herein are merely intended to represent certain embodiments.

<FIG> illustrate an exemplary embodiment of a surgical instrument <NUM> that is configured to prevent advancement of a stylet when driving a bone anchor assembly into bone. As described in more detail below, the bone anchor assembly cannot advance into bone without retraction of the stylet. The illustrated surgical instrument <NUM> generally includes an anchor drive assembly for driving a bone anchor into bone, and a stylet assembly extending therethrough for controlling positioning of a style relative to the bone anchor.

In general, the anchor drive assembly includes an elongate shaft <NUM> having a distal tip <NUM> configured to couple to a bone anchor assembly (not shown). The anchor drive assembly can also include a proximal driving tube <NUM> and a distal driving tube <NUM>. A proximal end 102p of the elongate shaft <NUM> can be coupled to a distal end 136d of the distal driving tube <NUM>, and the proximal driving tube <NUM> can be coupled to a proximal end 136p of the distal driving tube <NUM> via a clutch assembly <NUM>, which will be discussed in more detail below. A first handle, also referred to as a proximal handle <NUM>, e.g., 110a or 110b as shown in <FIG>, can be mated to a proximal end 134p of the proximal driving tube <NUM>, as shown in FIGS. 1E-1F and <FIG>. The clutch assembly <NUM> can have a disengaged position in which the first handle <NUM> is decoupled from and rotates independent of the elongate shaft <NUM>, and an engaged position in which the first handle <NUM> is coupled to and rotates with the elongate shaft <NUM>. In the engaged positioned, rotation of the first handle <NUM> can thus cause corresponding rotation of the proximal driving tube <NUM>.

The stylet assembly can generally include a stylet <NUM> having a proximal end 112p that removably couples to a depth adjuster <NUM>. The depth adjuster <NUM> can mate to a carrier <NUM>, which can be disposed within the distal drive tube <NUM>. The carrier <NUM> can extend through the distal drive tube <NUM> to threadably engage with a portion of a second handle, also referred to as a distal handle, <NUM>, and in particular with an inner sleeve <NUM> of the second handle <NUM>. The second handle <NUM> can also include an outer sleeve <NUM> disposed around the inner sleeve <NUM>. A locking mechanism, discussed in more detail below, can couple between the inner and outer sleeves <NUM>, <NUM>. When the locking mechanism is in the locked position, rotation of the outer sleeve <NUM> can cause corresponding rotation of the inner sleeve <NUM>, which in turn will cause axial translation of the carrier <NUM> through the distal drive tube <NUM>. Such movement of the carrier <NUM> will thereby adjust the position of the stylet <NUM>. When the carrier <NUM> is moved to its proximal-most position, as shown in <FIG> and <FIG>, it can be configured to cause the locking mechanism to move to an unlocked configuration, thereby decoupling the outer sleeve <NUM> from the inner sleeve <NUM>, thus allowing continued rotation of the outer sleeve <NUM> without causing further movement of the carrier <NUM> and stylet <NUM>. The outer sleeve <NUM> can also be configured to control the clutch mechanism. As will be explained in detail below, the outer sleeve <NUM> can be biased distally, and it can be configured to move proximally to move the clutch mechanism from the disengaged position to the engaged position. Thus, when the outer sleeve <NUM> is moved and held in a proximal position to maintain the clutch mechanism in the engaged position, rotation of the first handle <NUM> relative to the second handle <NUM> will cause the elongate shaft <NUM> to rotate for driving a bone anchor into bone while also causing retraction of the stylet <NUM>.

As indicated above, the stylet assembly can have a variety of configurations. With reference to FIGS. 1D-1F and <FIG>, the proximal and distal driving tubes <NUM>, <NUM> can each be in the form of an elongated tubular member having an inner lumen extending therethrough. As shown in <FIG>, the distal driving tube <NUM> can have two legs <NUM> that are separated by opposed through slots <NUM> that extend through a wall of the distal driving tube <NUM>. In certain embodiments, a washer <NUM> can be provided for coupling the proximal and distal driving tubes <NUM>, <NUM>. In particular, the washer <NUM> can be configured to be affixed or threaded to the distal driving tube <NUM> and it can engage a flange <NUM> of the proximal driving tube <NUM> to prevent the tubes <NUM>, <NUM> from axially translating relative to each other. While the washer <NUM> prevents translational movement of the proximal and distal driving tubes <NUM>, <NUM>, the tubes <NUM>, <NUM> can rotate relative to each other. The clutch mechanism, discussed in more detail below, can be configured to rotatably couple and decouple the proximal and distal drive tubes <NUM>, <NUM>.

The carrier <NUM> of the stylet assembly can be disposed within the distal driving tube <NUM>, and it can facilitate positioning of the stylet <NUM> relative to a bone anchor assembly coupled to the elongate shaft <NUM>. The carrier <NUM> can have a variety of configurations. In the illustrated embodiment, the carrier <NUM> has a generally cylindrical configuration and is cannulated with an inner lumen extending therethrough. As shown in FIG. 1E-1F and <FIG>, the carrier <NUM> can be slidably disposed within the distal driving tube <NUM>. The carrier <NUM> can thus have an outer diameter that is less than an inner diameter of the inner lumen of the distal driving tube <NUM> to allow the carrier <NUM> to be disposed therein. The carrier <NUM> can include one or more thread features <NUM> formed on an outer surface of the carrier <NUM>. As shown in <FIG>, the one or more thread features <NUM> are formed on opposed sides of the carrier <NUM> and do not extend fully circumferentially around the carrier <NUM>. The opposed thread features <NUM> can extend through opposed slots <NUM> formed in the distal driving tube <NUM>. The opposed thread features <NUM> can engage corresponding internal threads <NUM> of the inner sleeve <NUM> of the second handle <NUM>, as will be discussed in more detail below. Such a configuration will allow the opposed thread features <NUM>, and thus the carrier <NUM>, to translate axially along the distal driving tube <NUM> in response to rotation of the second handle <NUM>, yet it will prevent rotation of the carrier <NUM> relative to the distal driving tube <NUM>, and thus the elongate shaft <NUM>.

For example, when the surgical instrument <NUM> is in the engaged position and the first handle <NUM> is held stationary, rotation of the second handle <NUM> can cause the internal threads <NUM> to interact with the opposed thread features <NUM> on the carrier <NUM>. This interaction can cause the carrier <NUM> to non-rotatably translate axially along the distal driving tube <NUM> and relative to the elongate shaft <NUM>. That is, when the surgical instrument <NUM> is in the engaged position, the carrier <NUM> is non-rotatably translatable through the distal driving tube <NUM> in response to rotation of the second handle <NUM> while the first handle <NUM> is held stationary. Alternatively, the elongate shaft <NUM> can be held stationary while the second handle <NUM> is being rotated independent of the surgical instrument <NUM> being in the disengaged or engaged position.

Further, when the surgical instrument <NUM> is in the engaged position and the second handle <NUM> is held stationary, the rotation of the first handle <NUM> can cause corresponding rotation of the distal driving tube <NUM> which will force the carrier <NUM> to rotate and thus move in a proximal direction, thereby retracting the stylet <NUM>. The interaction between the internal threads <NUM> of the second handle <NUM> and the opposed thread features <NUM> on the carrier <NUM> will thus cause the carrier <NUM> to rotatably translate axially along the distal driving tube <NUM> and thus relative to the elongate shaft <NUM>. That is, when the surgical instrument <NUM> is in the engaged position, the carrier <NUM> is rotatably translatable through the distal driving tube <NUM> in response to rotation of the first handle <NUM> while the second handle <NUM> is held stationary.

The depth adjuster <NUM> can be mated to the carrier <NUM> for moving with the carrier <NUM>, and the stylet <NUM> can be mated to the depth adjuster <NUM>. Various configurations for the stylet <NUM> and depth adjuster <NUM>, as well as techniques for mating the depth adjuster <NUM> to the carrier <NUM>, are disclosed in more detail in <CIT> entitled "Spinal Screw Insertion Device and Methods". In certain embodiments, the stylet <NUM> can have an elongate configuration with a pointed distal tip to facilitate insertion into bone. A person skilled in the art will appreciate that in other embodiments the stylet <NUM> can mate directly to the carrier <NUM>.

The positioning of the stylet <NUM> relative to the elongate shaft <NUM>, such as to allow a length of stylet <NUM> to extend from the distal end 102d of the elongate shaft <NUM>, can be effected by the rotation of the second handle <NUM>. The second handle <NUM> has an inner sleeve <NUM> and an outer sleeve <NUM>, and may have a biasing element <NUM>. In this embodiment, the inner sleeve <NUM> includes internal threads <NUM> and the outer sleeve <NUM> is disposed about and is designed to axially translate relative to the inner sleeve <NUM>. As shown, the biasing element <NUM> is in the form of helical spring that is housed within the second handle <NUM> between the outer sleeve <NUM> and the inner sleeve <NUM>. The biasing element <NUM> can bias the outer sleeve <NUM> distally, thereby biasing the second handle <NUM> to a first position (home position).

As the bone anchor assembly is being driven into bone, the stylet <NUM> retracts until it reaches its proximal-most position relative to the elongate shaft <NUM>. That way, the stylet <NUM> can be prevented from advancing with or ahead of the bone anchor assembly as the bone anchor assembly is being implanted. As such, in one embodiment, retraction of the stylet <NUM> can be effected by the rotation of the first handle <NUM>. For example, when the instrument <NUM> is in the engaged position and the second handle <NUM> is being held stationary, the stylet <NUM> can proximally retract relative to the elongate shaft <NUM> in response to rotation of the first handle <NUM>.

Further, independent of the instrument being in the disengaged or engaged position, the outer sleeve <NUM> can be locked to the inner sleeve <NUM> by way of a locking assembly <NUM>. While the locking assembly <NUM> can have a variety of configurations, in this embodiment, the locking assembly <NUM> includes a first locking mechanism that includes a spring pin <NUM> and a tumbler pin <NUM> that are positioned within a channel <NUM> that extends through the second handle <NUM> (e.g., extends through the outer and inner sleeves <NUM>, <NUM>) to lock the inner sleeve <NUM> and the outer sleeve <NUM> in a first position. As shown in <FIG>, a first surface 174a of the spring pin <NUM> is flush with a first surface 168a of the outer sleeve <NUM>, and a second surface 174b of the spring pin <NUM> abuts the tumbler pin <NUM>. When the second handle <NUM> is rotated to cause the carrier <NUM> to translate proximally within the distal drive tube <NUM>, the carrier <NUM> will eventually reach a proximal-most position relative to the distal drive tube <NUM>. As the carrier <NUM> reaches its proximal-most position, at least one of the one or more thread features <NUM> of the carrier <NUM> comes in contact with the tumbler pin <NUM> and pushes the tumbler pin <NUM>, and thus the spring pin <NUM>, radially outward relative to the second handle <NUM>. This causes the tumbler pin <NUM> to align with an outer surface 166a of the inner sleeve <NUM>, as shown in <FIG>, and consequently disengages the first locking mechanism. This disengagement causes decoupling of the outer sleeve <NUM> from the inner sleeve <NUM>. In the proximal-most position, the stylet <NUM> is fully retracted relative to the bone anchor assembly, and thus there is no risk of advancing the stylet <NUM> into bone beyond the bone anchor assembly. When the outer sleeve <NUM> is decoupled from the inner sleeve <NUM>, the inner sleeve <NUM> can rotate independently of the outer sleeve <NUM>. In this way, the user can hold the outer sleeve <NUM> with the carrier <NUM> at its proximal-most position while also rotating the first handle <NUM> to continue to drive a bone anchor assembly into bone, as will be discussed in more detail below. Otherwise, once the stylet <NUM> reaches its proximal-most position, the surgical instrument <NUM> would jam and the user would not be able to continue to rotate the first handle <NUM> to distally drive the bone anchor assembly into bone.

In some embodiments, the locking assembly <NUM> can include a second locking mechanism to lock the inner sleeve <NUM> and the outer sleeve <NUM> in a second position independent of the instrument being in the disengaged or engaged position. For example, as shown in <FIG> and <FIG>, the inner sleeve <NUM> can have an engagement element <NUM> that is formed on its outer surface 166a when the spring and tumbler pins <NUM>, <NUM> are pushed radially outward relative to the elongated shaft <NUM>. This engagement element <NUM> allows the inner sleeve <NUM> to rotate relative to the outer sleeve <NUM> only in a first direction. This first direction corresponds to the first direction in which the first handle <NUM> rotates to drive the bone anchor assembly into bone. When the first handle <NUM> is rotated in the opposite direction, e.g., a second direction, the spring pin <NUM> engages the engagement element <NUM> and prevents the inner sleeve <NUM> from rotating in the second direction without causing the outer sleeve <NUM> to rotate in the same direction in tandem. That is, once the spring pin <NUM> engages the engagement element <NUM>, the inner and outer sleeves <NUM>, <NUM> will recouple to move simultaneously in the second direction. As the inner and outer sleeves <NUM>, <NUM> begin to the move in the second direction in tandem, the stylet <NUM> will begin to distally advance relative to the elongate shaft <NUM>, thereby disengaging the second locking mechanism while reengaging the first locking mechanism, and consequently, relocking the outer sleeve <NUM> and inner sleeve <NUM> in the first position.

While the second handle is used to control the stylet assembly, as indicated above the first handle can control the bone anchor drive assembly. With reference to <FIG>, 1D-1F and <FIG>, the elongate shaft <NUM> of the anchor drive assembly has a generally elongate configuration with a distal tip <NUM> configured to engage a bone anchor, and a proximal end 102p that can couple to the distal end 136d of the distal drive tube <NUM>, which in turn can be coupled to the proximal drive tube <NUM> by a clutch assembly. The distal drive tube <NUM> can be in the form of a generally elongate hollow tube having opposed slots <NUM> extending along a length thereof for receiving the opposed thread features <NUM> on the carrier <NUM> therethrough. The proximal drive tube <NUM> can also be in the form of a generally elongate tube. A proximal end 134p of the proximal drive tube <NUM> can include an engagement feature formed thereon, such as a hex feature, for mating with a corresponding feature formed within the first handle <NUM>.

As indicated above, and as shown in FIGS. 1B-1F and <FIG>, and in further detail in <FIG>, the clutch mechanism can be coupled between the proximal and distal driving tubes <NUM>, <NUM> in a manner that allows the tubes <NUM>, <NUM> to selectively rotate together. When the clutch mechanism is in a disengaged position (e.g., a first position), the first handle <NUM> rotates freely relative to the elongate shaft <NUM>, and vice versa, resulting in the inability to distally advance the bone anchor assembly into bone by rotation of the first handle <NUM>. When the clutch mechanism is in an engaged position (e.g., a second position) and the driving tubes <NUM>, <NUM> are coupled, the first handle <NUM> will couple to the elongate shaft <NUM> such that the rotation of the first handle <NUM> can cause the elongate shaft <NUM> to rotate for driving a bone anchor assembly into bone, and consequently, proximal retraction of the stylet <NUM>.

As shown, the clutch mechanism can include a clutch assembly <NUM> having a flange <NUM> with one or more recessed channels <NUM>. The flange <NUM> extends radially outward from the distal end 134d of the proximal driving tube <NUM>. The clutch assembly <NUM> can further include an annular ring <NUM> that is positioned about a proximal portion of the distal driving tube <NUM>. In the illustrated embodiment, the annular ring <NUM> has a base portion <NUM> that extends radially outward from the distal driving tube <NUM> to thereby create an annular channel <NUM> that extends fully circumferentially around the distal driving tube <NUM>. As shown, the flange <NUM> rests within this annular channel <NUM>, and is maintained within this annular channel <NUM> via the washer <NUM>. That is, the washer <NUM>, which is affixed about the top portion of the annular ring <NUM>, maintains the flange <NUM> within the annular channel <NUM> to prevent axial translation of the proximal and distal driving tubes <NUM>, <NUM> relative to each other. The washer <NUM>, however, by being nonaffixed to the flange <NUM>, allows for rotational movement of the proximal and distal driving tubes <NUM>, <NUM> relative to each other.

Further, the annular ring <NUM> can also include one or more through holes <NUM> to receive a corresponding engagement feature <NUM>. Each of the one or more through holes <NUM> can allow a corresponding engagement feature <NUM> to extend therethrough and engage the recessed channels <NUM> of the flange <NUM> when the second handle <NUM> is moved from a first position to a second position (e.g., its proximal-most position). The washer <NUM> can also function as a retention feature that is configured to prevent the engagement features <NUM> from moving radially outward once the engagement features are positioned partially within the annular ring <NUM>. The one or more through holes <NUM> and corresponding engagement features <NUM> can be of various shapes and sizes so long as the corresponding engagement features <NUM> can extend through the through hole <NUM>. In this embodiment, the engagement features <NUM> are spherically shaped.

In use, the surgical instrument <NUM> can be moved from a disengaged position (<FIG>) to an engaged position (<FIG>). When in the disengaged position (<FIG>), the first handle <NUM> and the elongate shaft <NUM> are decoupled, and therefore the first handle <NUM> can freely rotate relative to the elongate shaft <NUM>. When in the engaged position (<FIG>), however, the first handle <NUM> is coupled to the elongate shaft <NUM> such that rotation of the first handle <NUM> rotates the elongate shaft <NUM>, and in turn, drives a bone anchor assembly that is coupled to the elongate shaft <NUM> into bone while also retracting the stylet <NUM> to its proximal-most position. It should be noted that although the surgical instrument <NUM> is illustrated in <FIG> with the carrier <NUM> in its proximal-most position and the first locking mechanism disengaged, this is not required for the surgical instrument <NUM> to be in the engaged position. That is, the surgical instrument can be in the engaged position independent of the position of the carrier and the disengagement/engagement of the first locking mechanism.

The surgical instrument <NUM> can be moved from the disengaged position (<FIG>) to the engaged position (<FIG>) by moving (e.g. pulling) the second handle <NUM> in a proximal direction (e.g., towards the first handle <NUM>). In particular, the axial translation of the outer sleeve <NUM> from its first position (home position) to a second position can cause the biasing element <NUM> to move from a first position to a second position to thereby allow engagement of the clutch assembly <NUM>, and consequently moving the instrument <NUM> from its disengaged position to its engaged position. In this way, the pulling force applied by a user can overcome the biasing force of the biasing element <NUM> to allow the outer sleeve <NUM> to move in a proximal direction. As such, the clutch assembly <NUM> becomes engaged when the outer sleeve <NUM> is moved from its first position to its second position causing the engagement features <NUM> to slide into engagement with the recessed channels <NUM> of the flange <NUM>.

For example, as the outer sleeve <NUM> is being moved in a proximal direction, the engagement features <NUM> slide along a tapered portion <NUM> of the inner surface of the outer sleeve <NUM>. As the outer sleeve <NUM>, and thus the second handle <NUM>, reaches its proximal-most position (<FIG>), the engagement features <NUM> come in contact with a non-tapered portion <NUM> of the inner surface of the outer sleeve <NUM> that pushes the engagement features <NUM> radially inward, causing the engagement features <NUM> to engage the recessed channels <NUM> of the flange <NUM>. Once the engagement features <NUM> are at least partially positioned within the recessed channels <NUM>, the proximal driving tube <NUM> becomes rotatably engaged with the distal driving tube <NUM>. Consequently, the first handle <NUM> is therefore coupled to the elongate shaft <NUM>, and as a result, the first handle <NUM> can rotate the elongate shaft <NUM> to drive a bone anchor assembly into bone.

Once the surgical instrument <NUM> is in the engaged position (<FIG>), distal movement of the outer sleeve <NUM> allows the outer sleeve <NUM> to return to its first position, and consequently the biasing element <NUM>. This movement of the outer sleeve <NUM> disengages the clutch assembly <NUM> and allows the surgical instrument <NUM> to move from its engaged position back to its disengaged position. In particular, when the outer sleeve <NUM> is moved back to its first position, the engagement features <NUM> move radially outward and disengage the recessed channels <NUM> of the flange <NUM>, thereby disengaging the clutch assembly <NUM>.

For example, in use, when the outer sleeve <NUM> is in its second position (<FIG>), a user can release the outer sleeve <NUM> (e.g., stop applying a pulling force to the outer sleeve <NUM> towards the first handle <NUM>). This causes the biasing element <NUM> to distally advance, and thus the outer sleeve <NUM>, back towards its first position. In this way, by moving the outer sleeve <NUM> in a distal direction, e.g., by the user releasing the outer sleeve <NUM>, the biasing element <NUM> returns to its first position, and consequently, the instrument <NUM> returns to its disengaged position.

As mentioned above, the surgical instrument <NUM> includes a clutch mechanism that can be configured to couple the proximal and distal driving tubes <NUM>, <NUM> when the instrument is in the engaged position. As shown in detail in <FIG>, the clutch mechanism can include a clutch assembly <NUM> having a bearing configuration. In other embodiments, the clutch assembly can have a gear pin configuration (<FIG>) or a dowel pin configuration (<FIG>). It is also contemplated that the clutch assembly <NUM> can include configurations other than those described below.

<FIG> illustrates an exemplary embodiment of a clutch assembly <NUM> having a gear pin configuration. The clutch assembly <NUM> is similar to clutch assembly <NUM> except for the flange, the through holes, and the engagement features. In this embodiment, the engagement features <NUM> are gear pins that are configured to extend through rectangular shaped through holes <NUM> and mesh with teeth <NUM> of the flange <NUM>. The engagement and disengagement of the engagement features <NUM> are similar to engagement and disengagement of engagement features <NUM> (FIGS. 1D-1F and <FIG>) and are therefore not described in detail herein. Further, the engagement features <NUM> each include a flange <NUM> that is configured to retain the engagement features <NUM> within the holes <NUM> and prevent the engagements features <NUM> from moving radially outward once they are positioned within the holes <NUM>. Thus, in this embodiment, while the washer <NUM> can be provided for axial securement of the proximal drive tube with the distal driving tube, the flange <NUM> is provided for the retention of the engagement features <NUM>.

<FIG> illustrate an exemplary embodiment of a clutch assembly <NUM> having a dowel pin configuration. In this illustrated embodiment, the clutch assembly <NUM> can include a first annular ring 352a having one or more recessed channels <NUM> about the distal end 334d of the proximal driving tube <NUM>. The clutch assembly <NUM> can further include a second annular ring 352b that is positioned about the distal driving tube <NUM>. The second annular ring 352b can have a base portion <NUM> that extends radially outward from the distal driving tube <NUM> to thereby create an annular channel <NUM> that extends fully circumferentially around the distal driving tube <NUM>. As shown, the first annular ring 352a rests within this annular channel <NUM>.

The second annular ring 352b can also include one or more through holes <NUM> to receive one or more first engagement features 358a and one or more second engagement features 358b. In this exemplary embodiment, the one or more first engagement features 358a is a set screw that can be configured to couple the proximal driving tube <NUM> to the distal driving tube <NUM> by engaging the second annular ring 352b of the distal driving tube <NUM>. In particular, each set screw extends through the corresponding through hole <NUM> and engages with a flange <NUM> extending radially outward from the distal end 364p of the proximal driving tube <NUM>. This engagement functions as an axial retention mechanism to prevent separation of the proximal and distal driving tubes <NUM>, <NUM>. The one or more first engagement features 358a are set in place by an annular collar <NUM> that is positioned about the outer surface of the second annular ring 352b. The annular collar <NUM> can include one or more through holes <NUM> configured to receive the one or more second engagement features 358b. As shown, the one or more second engagement features 358b are elliptically shaped. The engagement and disengagement of the one or more second engagement features 358b are similar to engagement and disengagement of engagement features <NUM> (FIGS. 1D-1F and <FIG>) and is therefore not described in detail herein.

<FIG> illustrate another embodiment of a surgical instrument. Aside from the differences described in detail below, the surgical instrument <NUM> can be similar to the surgical instrument <NUM> (<FIG>) and is therefore not described in detail herein. Further, for purposes of simplicity, certain components of the surgical instrument <NUM> are not illustrated in <FIG>.

As shown, the surgical instrument <NUM> includes a locking assembly <NUM> having a locking mechanism, and a ratchet mechanism having a ratchet assembly <NUM>. The locking mechanism can be similar to the first locking mechanism as shown in FIGS. 1D-1F and <FIG>, and is therefore not described in detail herein.

While the ratchet mechanism can have a variety of configurations, in this embodiment, the ratchet mechanism includes a ratchet assembly <NUM>. The ratchet assembly <NUM> can include a pawl-like element <NUM> that extends through a through hole <NUM> of the outer sleeve <NUM> of the second handle <NUM> and abuts a tapered portion <NUM> of the inner sleeve <NUM>. The tapered portion <NUM> includes a proximal end 486p and a distal end 486d in which the proximal end 486p forms teeth <NUM> extending radially outward from the inner sleeve <NUM>. When the surgical instrument <NUM> is in the disengaged position, the pawl-like element <NUM> abuts the distal end 486d of the tapered portion <NUM>, and therefore is not engaged. When the surgical instrument <NUM> is moved to its engaged position, however, the pawl-like element <NUM> slides along the tapered portion <NUM> in a proximal direction (e.g., a direction towards the proximal end 486p) and engages the teeth <NUM>. As such, the inner sleeve <NUM> can only freely rotate relative to the outer sleeve <NUM> in a first direction that corresponds to the direction in which the first handle (not shown) rotates to bone anchor assembly into bone. When the first handle is rotated in the opposite direction, e.g., a second direction, the engagement of the pawl-like element <NUM> against the teeth <NUM> causes the inner and outer sleeves <NUM>, <NUM> to rotate together. As the inner and outer sleeves <NUM>, <NUM> begin to the rotate in tandem, the stylet (not shown) will begin to distally advance, thereby disengaging the ratchet assembly <NUM> while reengaging the first locking mechanism.

<FIG> illustrate another exemplary embodiment of a surgical instrument for driving a bone anchor assembly into bone. Aside from the differences described in detail below, the surgical instrument <NUM> can be similar to surgical instrument <NUM> (<FIG>) and is therefore not described in detail herein. Further, for purposes of simplicity, certain components of the surgical instrument <NUM> are not illustrated in <FIG>.

As shown, the surgical instrument <NUM> includes a drive tube assembly having a proximal driving tube <NUM> and a distal driving tube <NUM>. While the proximal and distal driving tubes <NUM>, <NUM> are prevented from axial decoupling via a locking mechanism, e.g., like the locking mechanism shown in FIGS. 8A-8C, the proximal and distal driving tubes <NUM>, <NUM> rotate independently of each other when the surgical instrument <NUM> is in the disengaged position (i.e., the home position). <FIG> shows the surgical instrument <NUM> in its disengaged position. As a result, the first handle (not shown) is decoupled from the elongate shaft (not shown), and therefore any rotation of the first handle, when the surgical instrument <NUM> is in the disengaged position, is ineffective to drive a bone anchor assembly (not shown) that is attached to the elongate shaft into bone. When the surgical instrument <NUM> is in the engaged position (<FIG>), however, a clutch mechanism is engaged that couples the proximal and distal driving tubes <NUM>, <NUM> together in a manner that allows the tubes <NUM>, <NUM>, and thus the first handle and elongate shaft, to rotate together.

The clutch mechanism, as shown in <FIG>, includes a clutch assembly <NUM> that is engaged when the second handle, also referred to as a distal handle, <NUM> is moved in a distal direction relative to the elongate shaft. In this exemplary embodiment, a lever <NUM> and a spring <NUM> are used to axially bias the second handle <NUM> in a first position (home position), when the surgical instrument <NUM> is in the disengaged position (<FIG>). In particular, the lever <NUM> engages with an engagement feature <NUM> of the inner sleeve <NUM> to prevent distal movement of the second handle <NUM>. In this exemplary embodiment, the engagement feature <NUM> is a flange. A portion 518p of the inner sleeve <NUM> is removed to form the flange at the distal end 518d thereof, and the lever <NUM> is coupled to the outer sleeve <NUM> via a pin <NUM>. The lever <NUM> is pivotable between a first position (<FIG>) and a second position (<FIG>).

As shown in <FIG>, when the lever <NUM> is in its first position, a distal end 512d of the lever <NUM> engages with the flange of the inner sleeve <NUM>, this maintains the second handle <NUM> in its first position. To move the second handle <NUM> from its first position to a second position, and consequently, the surgical instrument <NUM> from its disengaged position to its engaged position, (e.g., a grasping force) a force is applied to the lever <NUM>. The applied force causes the lever <NUM> to pivot about pin <NUM>, which defines the lever pivot axis (LA), and move from its first position to its second position. When the lever <NUM> pivots from its first position to its second position, the lever <NUM> disengages from the inner sleeve <NUM> and moves into a substantially longitudinal position within a housing <NUM> in the outer sleeve <NUM>. When the lever <NUM> moves into its second position, the second handle <NUM> can then be advanced in a distal direction such that the surgical instrument <NUM> can move from its disengaged position to its engaged position.

In this exemplary embodiment, the clutch assembly <NUM> includes a male engagement feature 508a and a female engagement feature 508b. As shown in <FIG>, the male engagement feature 508a is formed in the proximal driving tube <NUM> and the female engagement feature 508b is formed in the distal driving tube <NUM>. When the second handle <NUM> is moved from its first position (<FIG>) to its second position (<FIG>), the male engagement feature 508a engages with the female engagement feature 508b, thereby coupling the proximal driving tube <NUM> to the distal driving tube <NUM>. Once the male and female engagement features 508a, 508b are engaged, the surgical instrument <NUM> is in its engaged position. When in the engaged position, the surgical instrument <NUM> operates similarly to surgical instrument <NUM> and therefore is not described in detail herein.

8A-8C illustrate another exemplary embodiment of a surgical instrument for driving a bone anchor assembly into bone. Aside from the differences described in detail below, the surgical instrument <NUM> can be similar to surgical instrument <NUM> (<FIG>) and is therefore not described in detail herein. Further, for purposes of simplicity, certain components of the surgical instrument <NUM> are not illustrated in FIG.

In this exemplary embodiment, the surgical instrument <NUM> includes a second handle <NUM> having an inner and outer sleeve <NUM>, <NUM>, and a drive tube assembly having a proximal driving tube <NUM> and a distal driving tube <NUM>. The proximal and distal driving tubes <NUM>, <NUM> are prevented from axial decoupling via a locking mechanism that includes male and female engagement features 611a, 611b. While the locking mechanism prevents axial decoupling of the proximal and distal driving tubes <NUM>, <NUM>, the tubes <NUM>, <NUM> rotate independently of each other when the surgical instrument <NUM> is in the disengaged position (i.e., the home position). As a result, the first handle (not shown) is decoupled from the elongate shaft (not shown). <FIG> shows the surgical instrument <NUM> in its disengaged position. When the surgical instrument <NUM> is in the engaged position (<FIG>), however, a clutch mechanism is engaged that rotatably couples the proximal and distal driving tubes <NUM>, <NUM> together in a manner that allows the tubes <NUM>, <NUM>, and thus the first handle and elongate shaft, to rotate together to facilitate driving a bone anchor assembly that is attached to the elongate shaft into bone.

As shown, the clutch mechanism includes a clutch assembly <NUM> having male and female engagement features <NUM>, <NUM>. The male engagement feature <NUM> includes a first portion 614a and a second portion 614b with an inner lumen <NUM> extending therethrough. While the first and second portions 614a, 614b can have a variety of configurations, in this exemplary embodiment, the first portion 614a has an annular outer surface <NUM>, whereas the second portion 614b has a hexagonal outer surface <NUM>. The annular outer surface <NUM> includes a recessed channel <NUM> that is configured to receive spring pins <NUM> to thereby couple the male engagement feature <NUM> to the outer sleeve <NUM> of the second handle <NUM>. While the inner lumen <NUM> can have a variety of shapes, in this exemplary embodiment, the inner lumen <NUM> is hexagonally shaped. It is also contemplated that the inner lumen <NUM> and the outer surfaces <NUM>, <NUM> can have other suitable shapes such as a circle or other polygonal shapes, for example, but not limited to, a square, a triangle, a rectangle, an octagon, or a dodecagon.

The female engagement feature <NUM>, as shown in FIGS. 8A-8C, is positioned about the distal driving tube <NUM> and includes an internal cavity <NUM>. When the surgical instrument <NUM> is in the disengaged position (<FIG>), the female engagement feature <NUM> engages with flange <NUM> that extends from the inner surface of the outer sleeve <NUM>. While the internal cavity <NUM> can have a variety of shapes, in this exemplary embodiment, the internal cavity <NUM> is hexagonally shaped. It is also contemplated that the internal cavity <NUM> can have other suitable shapes such as a circle or other polygonal shapes, for example, but not limited to, a square, a triangle, a rectangle, an octagon, or a dodecagon.

Further, the proximal driving tube <NUM> includes a casing <NUM> about a proximal end 608p thereof. While the casing <NUM> can have any suitable configuration, in this exemplary embodiment, the casing <NUM> is hexagonally shaped. As shown, the hexagonal casing <NUM> is configured to engage the inner lumen <NUM> of the male engagement feature <NUM> to thereby couple the proximal driving tube <NUM> to the male engagement feature <NUM>. It is this engagement, the engagement of the female engagement feature <NUM> and the flange <NUM>, and the spring pins <NUM> that couple the outer sleeve <NUM> to the male engagement feature <NUM> that form the locking mechanism and thereby effect axial coupling of the proximal and distal driving tubes <NUM>, <NUM> when the surgical instrument <NUM> is in the disengaged position.

In use, the second handle <NUM> is moved in a distal direction from a first position (FIG. 9A) to a second position (<FIG>), which in turn moves the surgical instrument <NUM> from its disengaged position to its engaged position. When the second handle <NUM> is moved in a distal direction, the second portion 614b of the male engagement feature <NUM> engages the internal cavity <NUM> of the female engagement feature <NUM>, thereby rotatably coupling the proximal and distal driving tubes <NUM>, <NUM>. Once the male and female engagement features <NUM>, <NUM> are engaged, the surgical instrument <NUM> is its engaged position. When the surgical instrument <NUM> is in its engaged position, the surgical instrument <NUM> operates similarly to surgical instrument <NUM> and therefore is not described in detail herein.

As previously mentioned, the surgical instruments can be used implant a bone anchor assembly into bone. Any suitable method can be used for operating any surgical instrument described herein. Such methods are not explicitly claimed, although it is intended that the surgical instrument of the invention may be used to perform these methods. For example, when operating the surgical instrument <NUM> (<FIG>), a handle assembly that includes the proximal handle <NUM> and the distal handle <NUM> can be moved from a first configuration to a second configuration to axially translate the stylet <NUM>. In particular, the distal handle <NUM> can be moved in a proximal direction relative to the proximal handle <NUM>. Moving the handle assembly from the first configuration to the second configuration can cause the clutch mechanism to move from an disengaged position to an engaged position, and consequently, mate the proximal handle <NUM> to the elongate shaft <NUM> such that rotation of the proximal handle <NUM> can rotate the elongate shaft <NUM>. In some embodiments, the handle assembly can be moved by a user manipulating the distal handle <NUM> (e.g., moving the distal handle in a proximal direction, or alternatively, in a distal direction). In other embodiments, the movement of the handle assembly can be automated and triggered by a specific event. The distal handle <NUM> can also be rotated to adjust the position of the distal tip <NUM> of the stylet <NUM> relative to the bone anchor assembly that is coupled to the distal end 102d of the elongate shaft <NUM>. In one embodiment, the distal handle <NUM> can be rotated while the handle assembly is maintained in the second configuration. In another embodiment, the distal handle <NUM> can be rotated when the elongated shaft <NUM> is held stationary. Once the distal tip <NUM> has been adjusted to a desirable position, the surgical instrument <NUM> can be manipulated to insert the distal tip <NUM> into bone. While maintaining the handle assembly in the second configuration, once the distal tip <NUM> is inserted into bone, the proximal handle <NUM> can be rotated to rotate the elongate shaft <NUM> thereby distally advancing the bone anchor assembly along the stylet <NUM> and into bone. The rotation of the proximal handle <NUM> can also cause axial translation of the stylet <NUM> in a proximal direction relative to the elongate shaft <NUM>. That is, rotation of the proximal handle <NUM>, when the handle assembly is maintained in the second configuration, can effect distal advancement of the bone anchor assembly while also retracting the stylet <NUM>.

The instruments disclosed herein can be designed to be disposed of after a single use, or they can be designed to be used multiple times. In either case, however, the instrument can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the instrument, followed by cleaning or replacement of particular pieces and subsequent reassembly. In particular, the instrument can be disassembled, and any number of the particular pieces or parts of the instrument can be selectively replaced or removed in any combination. Upon cleaning and/or replacement of particular parts, the instrument can be reassembled for subsequent use either at a reconditioning facility, or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that reconditioning of an instrument can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned instrument, are all within the scope of the present application.

Claim 1:
An instrument (<NUM>) for driving a bone anchor assembly into bone, comprising:
an anchor drive assembly including a first handle (<NUM>) and an elongate shaft (<NUM>) having a distal tip (<NUM>) configured to couple to a bone anchor assembly; and
a stylet assembly including a second handle (<NUM>) and a stylet (<NUM>) extending through the elongate shaft;
wherein the instrument has a disengaged position and an engaged position, wherein in the disengaged position the first handle is configured to be decoupled from the elongate shaft such that the first handle is freely rotatable relative to the elongate shaft, and wherein in the engaged position the first handle is configured to be coupled to the elongate shaft such that rotation of the first handle rotates the elongate shaft, and wherein rotation of the first handle is effective to drive the bone anchor assembly into bone only when the instrument is in the engaged position, and rotation of the second handle is effective to cause axial translation of the stylet relative to the elongate shaft, and
wherein the second handle includes an outer sleeve (<NUM>) and inner sleeve (<NUM>), and wherein the instrument is moved from the disengaged position into the engaged position in response to axial movement of the outer sleeve relative to the inner sleeve.