Screw inserter instrument and method

Abstract

This disclosure relates to a screw inserter instrument and method for implanting bone screws. In one exemplary embodiment, the screw inserter instrument can include a screw drive assembly having a first handle and a drive shaft coupled to the first handle, and a stylet assembly having a second handle and a stylet extending through the drive shaft. The first handle can have a locked configuration and an unlocked configuration. In the locked configuration, the first handle and the drive shaft are coupled such that when the second handle is rotated relative to the first handle, the first handle can hold the drive shaft in a fixed position. In the unlocked configuration, the first handle and the drive shaft can be rotated simultaneously in a first direction, and the first handle can be rotated independently of the drive shaft in an opposite second direction.

Description

Technical Field

[0001] This disclosure relates to screw inserter instruments and methods. Background Art

[0002] Bone screws, such as pedicle screws, can be used in orthopedic surgery to fixate bone during healing, fusion, or other processes. In spinal surgery, for example, bone screws can be used to fixate spinal fixation elements to one or more vertebrae to rigidly or dynamically stabilize the spine.

[0003] Conventional posterior pedicle screw fixation requires the pedicle screw to be prepared by tapering, probing, and threading prior to insertion. Although progress has been made to allow for the insertion of pre-assembled pedicle screws, these systems are not ideal for placing all screws in a construct prior to transforaminal lumbar interbody fusion (TLIF). This is because the pre-assembled head of the pedicle screw obstructs the view.

[0004] When inserting most pedicle screws, the screw must be held in a certain manner relative to the screw inserter instrument. This is typically achieved by screwing a cannula into the multi-axis head of the screw, or in the case of a modular screw, by screwing a cannula into a chuck coupled thereto. In use, the user holds the cannula stationary, and thus, the action of driving the screw into the bone also causes the cannula to become disengaged from the screw before the screw is fully inserted into the bone. Clinically, this can result in delays as the surgeon then has to re-engage the screw to complete the implantation. This re-engagement can be challenging, particularly when the direct visualization of the screw is affected.

[0005] During minimally invasive surgery, it can be difficult for the surgeon to directly visually observe the screw as it is being driven into the bone. Therefore, determining the depth of insertion of the screw can be visually challenging, which can result in incomplete implantation of the screw, or alternatively, over-insertion of the screw. For example, when using a modular screw, the screw may be driven too deeply into the bone such that the length of the screw extending outward from the bone is insufficient to properly attach the multi-axis head to the screw.

[0006] Screw inserter instruments are available that have a stylet protruding therefrom. The stylet can be docked into the bone by tapping or pushing the instrument distally towards the bone. Once the stylet has been advanced to the desired depth, the coupled bone screw is driven along the path formed by the stylet while the stylet retracts from the path. To prevent the coupled bone screw from being inserted into or removed from the bone during advancement and retraction of the stylet, the user must hold the screw driver handle of the instrument in a stationary position. However, this can be difficult and can interfere with the advancement and retraction of the stylet.

[0007] Accordingly, despite the existing art, there remains a need for improved instruments and methods associated with driving bone screws into bone. SUMMARY OF THE INVENTION

[0008] The present invention discloses various screw inserter instruments and methods for implanting bone screws or bone screw assemblies into bone.

[0009] In one embodiment, a screw inserter instrument is provided, and the screw inserter instrument includes a screw drive assembly having a first handle and a drive shaft coupled to the first handle, and a stylet assembly having a second handle and a stylet extending through the drive shaft. The drive shaft may have a distal end configured to be coupled to a bone screw for driving the bone screw into bone. The first handle may have a locked configuration and an unlocked configuration. In the locked configuration, the first handle and the drive shaft are coupled such that when the second handle is rotated relative to the first handle, the first handle can hold the drive shaft in a fixed position. In the unlocked configuration, the first handle and the drive shaft can be rotated simultaneously in a first direction, and the first handle can be rotated independently of the drive shaft in an opposite second direction. In one embodiment, the first handle may be biased to the locked configuration.

[0010] In some embodiments, the screw inserter instrument may include a control mechanism disposed within the first handle and in communication with the drive shaft. The control mechanism may have various configurations. For example, in some embodiments, the control mechanism may include at least one trigger element fixedly coupled to a locking ring such that movement of the at least one trigger element can move the locking ring to move the first handle between the locked configuration and the unlocked configuration. In one embodiment, when the first handle is in the locked configuration, the locking ring can be operably coupled to the drive shaft such that the first handle and the drive shaft are locked together. In another embodiment, when the first handle is in the unlocked configuration, the locking ring can be operably disengaged from the drive shaft such that the first handle and the drive shaft can rotate independently of each other.

[0011] In other embodiments, the screw inserter instrument may include a ratchet mechanism disposed within the first handle. The ratchet mechanism may have various configurations. In one embodiment, the ratchet mechanism may allow bidirectional rotation of the first handle to unidirectionally drive the drive shaft when the first handle is in the unlocked configuration to drive the bone screw into bone.

[0012] In some embodiments, the screw inserter instrument may include a retaining sleeve disposed around the drive shaft. The retaining sleeve may have a distal end configured to threadedly engage a bone screw. In one embodiment, when the first handle is in the locked configuration, the first handle can hold the drive shaft in a stationary position while the retaining sleeve can be rotated to threadedly disengage from the bone screw, and when the first handle is in the unlocked configuration, the second handle can remain stationary while the first handle can be rotated in a first direction to rotate the drive shaft and the retaining sleeve together to drive the bone screw into bone.

[0013] In another exemplary embodiment, a screw inserter instrument is provided that has: a screw drive assembly including a handle and a drive shaft operably coupled to the handle; a locking assembly located within the handle and in communication with the drive shaft; and a clutch assembly in communication with the handle and the drive shaft. The drive shaft may have a distal end configured to be coupled to a bone screw for driving the bone screw into bone. The locking assembly may have a locked configuration and an unlocked configuration, in which the handle and the drive shaft are locked to each other such that they rotate as a unit, and in which the handle and the drive shaft rotate independently of each other. When the locking assembly is in the unlocked configuration, the clutch assembly may be configured to allow the handle to rotate in a first direction and in an opposite second direction to drive the drive shaft in only the first direction. In one embodiment, the locking assembly may be biased to the locked configuration.

[0014] The locking assembly may have a variety of configurations. For example, in some embodiments, the locking assembly may include at least one trigger element that is fixedly coupled to a locking ring such that movement of the at least one trigger element is capable of moving the locking ring to move the locking assembly between the locked configuration and the unlocked configuration. In one embodiment, when the locking assembly is in the locked configuration, the locking ring is operably coupled to the drive shaft such that the handle and the drive shaft are locked together. In another embodiment, when the locking assembly is in the unlocked configuration, the locking ring is operably disengaged from the drive shaft such that the handle and the drive shaft rotate independently of each other.

[0015] The clutch assembly may have a variety of configurations. For example, in some embodiments, the clutch assembly may include an inner ring and an outer ring that are selectively engageable with each other such that rotation of the handle in the first direction effectively causes rotation of the drive shaft only when the first inner and outer rings and the second inner and outer rings are engaged.

[0016] In some embodiments, the screw inserter instrument may include a retaining sleeve disposed about the drive shaft. The retaining sleeve may have a distal end configured to threadedly engage a bone screw. In one embodiment, when the locking assembly is in the locked configuration, the drive shaft may remain stationary while the retaining sleeve rotates to threadedly disengage from the bone screw, and when the locking assembly is in the unlocked configuration, the locking sleeve may remain stationary while the handle rotates in the first direction to rotate the drive shaft and the retaining sleeve together to drive the bone screw into bone.

[0017] A method for implanting a bone screw is also provided. The method can employ any of the screw inserter instruments disclosed in this document. In one exemplary embodiment, the method can include moving an actuator on a first handle of the screw inserter instrument to switch the first handle from a locked configuration to an unlocked configuration, thereby decoupling the first handle from a drive shaft on the screw inserter instrument. The drive shaft can have a distal end coupled to the bone screw. The method can also include rotating the first handle in a first direction and a second direction while keeping a second handle on the screw inserter instrument stationary, so as to drive the drive shaft in only the first direction by the first handle, thereby driving the bone screw into the bone.

[0018] In some embodiments, rotating the first handle in the first direction can cause a clutch assembly to couple the first handle to the drive shaft. When the first handle rotates in the second direction, the clutch assembly can prevent the drive shaft from rotating in the second direction. In other embodiments, moving the actuator to switch the first handle from a locked configuration to an unlocked configuration can cause a locking ring in the first handle to move from a first position to a second position. In the first position, the locking ring is operatively coupled to the first handle and the drive shaft. In the second position, the locking ring is operatively decoupled from the drive shaft.

[0019] In other embodiments, the method can include rotating the second handle before moving the actuator on the first handle, while keeping the first handle stationary to axially translate a trocar that is coupled to the second handle and extends through the bone screw, thereby adjusting the axial position of the trocar relative to the bone screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0021] Figure 1A A perspective view of one embodiment of a screw inserter instrument, the screw inserter instrument including a drive shaft, a retaining sleeve, and a locking sleeve, the figure showing the locking sleeve in a first position or disengaged position;

[0022] Figure 1B For Figure 1A A partial exploded view of the screw inserter instrument;

[0023] Figure 2 For Figure 1A A perspective view of the screw inserter instrument, where the locking sleeve is removed;

[0024] Figure 3 For a cross-sectional view of the screw inserter instrument taken at 3-3 of Figure 1A the screw inserter instrument;

[0025] Figure 4 For a cross-sectional view of the screw inserter instrument taken at 4 of Figure 3An enlarged cross-sectional view of a portion of a screw inserter instrument, showing a retention sleeve coupled to an exemplary bone screw;

[0026] Figure 5 Taken at 5 Figure 3 An enlarged cross-sectional view of a portion of a screw inserter instrument;

[0027] Figure 6A Taken at 6-6 Figure 1A A cross-sectional view of a screw inserter instrument, rotated 90 degrees relative to Figure 3 the cross-sectional view;

[0028] Figure 6B Taken at 6B Figure 6A An enlarged cross-sectional view of a portion of a screw inserter instrument;

[0029] Figure 7A For Figure 6A a cross-sectional view of a screw inserter instrument, showing the locking sleeve in a second or engaged position;

[0030] Figure 7B Taken at 7B Figure 7A An enlarged cross-sectional view of a portion of a screw inserter instrument;

[0031] Figure 8A A perspective view of another embodiment of a screw inserter instrument, the screw inserter instrument including a drive shaft, a retention sleeve, a locking sleeve, and a stop sleeve, showing the instrument coupled to a bone screw;

[0032] Figure 8B Taken at 8B-8B Figure 8A An enlarged cross-sectional view of a portion of a screw inserter instrument;

[0033] Figure 9A A perspective view of another embodiment of a screw inserter instrument, the screw inserter instrument including a drive shaft, a retention sleeve, a locking sleeve, and a stop sleeve, showing the instrument coupled to a bone screw;

[0034] Figure 9B Taken at 9B-9B Figure 9A A cross-sectional view of a portion of a screw inserter instrument;

[0035] Figure 10A A side view of an embodiment of a screw inserter instrument, the screw inserter instrument including a first handle, a drive shaft, a stylet assembly, a retention sleeve, a locking sleeve, and a stop sleeve;

[0036] Figure 10B Taken at 10-10 Figure 10A A cross-sectional view of a screw inserter instrument;

[0037] Figure 11A Perspective view of the first handle portion of Figure 10A ;

[0038] Figure 11B Side view of the first handle portion of Figure 11A ;

[0039] Figure 11C Partial exploded view of the first handle portion of Figure 11A ;

[0040] Figure 11D Perspective view of the first handle portion of Figure 11A , showing only the base member;

[0041] Figure 11E Cross-sectional view of the first handle portion of Figure 11A taken at 11-11, showing only the base member and the coupling member;

[0042] Figure 11F Cross-sectional view of the first handle portion of Figure 11A taken at 11-11;

[0043] Figure 11G Bottom view of the first handle portion of Figure 11A , showing the locking assembly located within the first handle portion; and

[0044] Figure 11H Cross-sectional view of the first handle portion of Figure 11B taken at 11H-11H. DETAILED DESCRIPTION

[0045] Certain exemplary embodiments will now be described to provide a thorough understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are shown in the drawings. Those skilled in the art will understand that the devices, systems, and methods specifically described herein and shown in the drawings are non-limiting exemplary embodiments, and the scope of the present invention is defined only by the claims. Features shown or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

[0046] The present invention provides various surgical instruments and methods for driving a bone screw or bone screw assembly into bone. In some embodiments, these instruments and methods allow maintaining the connection between the bone screw and the instrument while the bone screw is being driven into the bone. This connection can help control the alignment of the bone screw, thereby reducing back-and-forth switching during insertion. Accordingly, the bone screw can be inserted more accurately into the bone along the desired path. Alternatively or in addition, these instruments and methods can be designed to provide haptic feedback once the screw has reached the desired insertion depth within the bone (e.g., the insertion depth associated with the sufficient length of the screw required for a multi-axis head assembly). This haptic feedback can allow for controlled screw insertion such that, for example, the user can avoid driving the screw too deeply into the bone. Further, in other embodiments, these instruments and methods can be designed to allow a surgeon to drive the screw into the bone using a ratchet mechanism, thereby allowing the surgeon to keep his / her hand engaged with the instrument. Thus, the surgeon has more limited control during screw insertion.

[0047] Exemplary screw inserter instruments can include a plurality of features to facilitate the implantation of a bone screw, as described herein and shown in the figures. However, those skilled in the art will understand that a screw inserter instrument can include only some of these features and / or can include a plurality of other features known in the art. The screw inserter instruments described herein are merely intended to represent certain exemplary embodiments.

[0048] Figures 1A through 7B An exemplary embodiment of a screw inserter instrument 100 is shown that is configured to prevent a retention sleeve from becoming decoupled from a bone screw when driving the bone screw into bone. The shown screw inserter instrument 100 generally includes a drive shaft 102, a retention sleeve 104 disposed about the drive shaft 102, and a locking sleeve 118. The retention sleeve 104 and the locking sleeve 118 are collectively referred to herein as the sleeve assembly. For simplicity, certain components of the screw inserter instrument 100 are not shown in Figures 1A through 7B the figures.

[0049] Although the drive shaft 102 can have a variety of configurations, the drive shaft 102, as Figures 1A through 3 , Figure 6A and Figure 7A shown in the embodiments, has a generally elongated configuration having a distal end 102a configured to be coupled to a bone screw (such as the bone screw 103 in Figure 4 ). Further, a proximal end 102b of the drive shaft 102 can be coupled to a first handle (not shown), also referred to herein as the proximal handle, such that rotation of the first handle in a first direction (e.g., clockwise) can effectively drive the coupled bone screw into the bone while rotating the drive shaft 102. The first handle and the drive shaft 102 are collectively referred to herein as the screw drive assembly.

[0050] The bone screw may include a proximal head portion having a proximal cavity and a distal cavity defined therein. The proximal cavity may be generally cylindrical, with internal threads formed therein for engaging corresponding threaded portions of the retention sleeve 104, as described below. The distal cavity may be shaped to non-rotatably engage the distal end 102a of the drive shaft 102. Thus, the distal end 102a of the drive shaft 102 may have a variety of shapes and sizes, at least partially depending on the shape and size of the distal cavity of the bone screw. As Figures 1A through 3 shown, in this exemplary embodiment, the distal end 102a of the drive shaft 102 has a hexagonal configuration. In other embodiments, the distal end 102a may have any other suitable shape. As will be understood by those skilled in the art, any bone screw configured to engage bone may be used in conjunction with a screw inserter instrument (including any of the screw inserter instruments described herein). Exemplary embodiments of bone screws are described in greater detail in U.S. Patent Publication Nos. 2018 / 0014858 and 2018 / 0014862, each of which is hereby incorporated by reference in its entirety.

[0051] As Figures 1A through 3 、 Figure 6A and Figure 7A shown, the retention sleeve 104 extends from a proximal end 104a to a distal end 104b. The distal end 104b of the retention sleeve 104 is configured to couple with a bone screw (such as the bone screw 103 in Figure 4 ). Although the distal end 104b of the retention sleeve 104 may have a variety of configurations, as shown, the distal end 104b includes threads 106 that are configured to threadedly engage corresponding internal threads of the proximal cavity of a bone screw (not shown). In this exemplary embodiment, the retention sleeve 104 is disposed around a portion of the drive shaft 102 such that the retention sleeve 104 extends between the proximal end 102b and the distal end 102a of the drive shaft 102. Thus, the distal end 102a of the drive shaft 102 is exposed such that it may ultimately engage a bone screw (such as the bone screw 103 in Figure 4 ), as described below. Thus, a bone screw may be coupled to the screw inserter instrument 100, for example, by inserting the distal end 102a into the distal cavity of the bone screw and threadedly engaging the distal end 104b of the retention sleeve 104 to the proximal cavity of the bone screw.

[0052] Figure 4An exemplary bone screw 103 coupled to a screw inserter instrument 100 is shown. The bone screw 103 is tubular and includes a head portion 103a and a threaded shaft 103b extending distally from the head portion. The head portion 103a includes a threaded proximal cavity 109 and an unthreaded distal cavity 111, each of which is defined in the head portion. As shown, the distal end 102a of the drive shaft 102 is positioned within the distal cavity 111 and is non-rotatably engaged with the distal cavity, and a portion of the threads 106 of the retaining sleeve 104 is threadedly engaged with the corresponding internal threads 109a of the proximal cavity 109. In this illustrated embodiment, the diameter (D1) of the proximal cavity 109 is greater than the diameter (D2) of the distal cavity 111, thereby forming a shoulder 113 within the head portion 103a of the bone screw 103. Accordingly, the distal end 104b of the retaining sleeve 104 is screwed into the proximal cavity 109 until the most distal end 104d of the retaining sleeve 104 contacts the shoulder 113.

[0053] The proximal end 104a of the retaining sleeve 104 is selectively couplable to the drive shaft 102 by a coupling mechanism 108. The coupling mechanism 108 can have a variety of configurations. For example, as Figure 3 shown and more particularly as Figure 5 shown, the coupling mechanism 108 includes a release button 110 that engages a groove 112 of the drive shaft 102 adjacent the proximal end 102b of the drive shaft 102. Specifically, the release button 110 includes a first portion 110a and a second portion 110b, the first portion being configured to engage the groove 112 and the second portion being configured to be spaced from the groove 112 by a distance (D). As described in more detail below, this distance can allow the second portion 110b to be selectively depressed toward the groove 112 so as to move the first portion 110a away from the groove 112, thereby decoupling the retaining sleeve 104 and the drive shaft 102. As Figure 3 and Figure 5 shown, the release button 110 is engaged to the drive shaft 102 in an extended configuration via a biasing element 114. Although the biasing element 114 can have a variety of configurations, as Figure 3 and Figure 5 shown the biasing element 114 is in the form of a helical spring that biases the first portion 110a of the release button 110 toward the groove 112 and biases the second portion 110b of the release button 110 away from the groove 112 by a distance (D).

[0054] In use, the drive shaft 102 is inserted into the retaining sleeve 104 until the first portion 110a of the release button 110 slides into contact with and engages the groove 112 of the drive shaft 102. To remove the drive shaft 102 from the retaining sleeve 104, the release button 110 can be actuated to move the first portion 110a of the release button 110 away from the groove 112 and thus disengage from the engaging groove. For example, the user can actuate the release button by applying sufficient force to the second portion 110b of the release button 110 such that the second portion 110b moves toward the groove 112. This displaces the first portion 110a of the release button 110 away from the groove 112 and moves the biasing element 114 into a compressed configuration. Accordingly, the first portion 110a of the release button 110 disengages from the groove 112 of the drive shaft 102, allowing the drive shaft 102 to be slidably removed. In other embodiments, other coupling mechanisms can be used.

[0055] Additionally, the groove 112 of the drive shaft 102 can include additional features configured to engage the retaining sleeve 104. For example, as Figure 5 shown, the distal portion 112d of the groove 112 includes an angled interface 116 that can be used to bias the drive shaft 102 in the distal direction. The angled interface 116 can extend at various angles relative to the intermediate portion 112a of the groove 112. In the illustrated embodiment, the angled interface extends at a lateral angle greater than 0 degrees and less than 90 degrees relative to the intermediate portion 112a of the groove 112 extends. In other embodiments, the angle can be from about 35° to 45°. In one embodiment, the angle can be about 45°.

[0056] In use, once the retention sleeve 104 is coupled to the bone screw, the distal end 110d of the release button 110 engages the angled interface 116 such that the distal end 110d of the release button 110 is in direct contact with the groove 112. This direct contact biases the drive shaft 102 in the distal direction. Additionally, this engagement removes any clearance between the distal end 110d of the release button 110 and the angled interface 116 of the groove 112. Thus, as described above, this engagement, along with bottoming of the distal most end of the retention sleeve 104 on the shoulder within the bone screw, can inhibit switching of the bone screw relative to the drive shaft 102 during screw insertion. Further, by directly engaging only a portion of the release button 110 with the angled interface 116, the release button 110 can be easily actuated without the retention sleeve 104 being disengaged (e.g., loosened) from the bone screw, which is attributable to the engagement of the retention sleeve 104 with the shoulder of the bone screw and the clearance remaining between other portions of the release button 110 and the groove 112. Thus, the retention sleeve 104 can remain threadably engaged with the bone screw while the drive shaft 102 is disengaged via the release button 110 and thus removed therefrom. Once the drive shaft 102 is removed from the bone screw, other components can be inserted through the retention sleeve 104 and into the coupled bone screw to perform additional procedures, such as those described in U.S. Patent No. 9,265,548 and U.S. Patent Application No. 16 / 439,977, filed June 13, 2019, entitled "Instruments and Methods for Delivering Bone Cement to a Bone Screw", each of which is incorporated herein by reference in its entirety.

[0057] As Figure 1A , Figure 3 and Figures 6A through 7B further shown, a locking sleeve 118 is disposed about a portion of the retention sleeve 104. The locking sleeve 118 is configured (e.g., by user activation) to be in a first position or disengaged position ( Figure 1A and Figures 6A through 6B ) and a second position or engaged position ( Figure 7A and Figure 7B) translate between them. As discussed in more detail below, when the locking sleeve 118 is in its first or disengaged position, the drive shaft 102 and the retaining sleeve 104 are rotatable while the locking sleeve 118 remains stationary. Thus, the drive shaft 102 and the retaining sleeve 104 can rotate together as a unit in a first direction (e.g., clockwise) to drive the bone screw into the bone while rotating the retaining sleeve 104 such that it remains engaged with the bone screw. When the locking sleeve 118 is in the second or engaged position, the retaining sleeve 104 and the locking sleeve 118 are rotatable while the drive shaft 102 remains stationary. Thus, the retaining sleeve 104 and the locking sleeve 118 can rotate together as a unit in a second direction opposite the first direction (e.g., counterclockwise) to allow the retaining sleeve 104 to disengage from the implanted bone screw while the drive shaft 102 remains stationary such that it does not cause the implanted bone screw to translate relative to the bone. Thus, the locking sleeve 118 allows the retaining sleeve 104 to remain coupled to the bone screw during implantation and allows the retaining sleeve 104 to disengage from the bone screw after implantation.

[0058] The locking sleeve 118 is coupled to the retaining sleeve 104 by a coupling element 120, as Figures 2 through 3 and Figures 6A through 7B shown. The coupling element 120 (which is shown in more detail in Figure 1B and Figure 2 ) is disposed between the retaining sleeve 104 and the locking sleeve 118. Although the coupling element 120 can have a variety of configurations, as Figures 2 through 3 and Figures 6A through 7B shown, the coupling element 120 is in the form of a first cylindrical snap ring that has a first set of teeth 122 at a first end 120a. As shown, the first set of teeth 122 engages a second set of teeth 123 at a first end 124a of a second cylindrical snap ring 124 disposed around the retaining sleeve 104.

[0059] Although the first set of teeth 122 and the second set of teeth 123 can have a variety of configurations, as Figure 1B and Figure 2 shown, the first set of teeth 122 extends at a first angular orientation and the second set of teeth 123 extends at a complementary second angular orientation. Once the drive shaft 102 and the retaining sleeve 104 are coupled to the bone screw and are thus rotatably coupled to each other, the engagement of the first set of teeth 122 and the second set of teeth 123 allows the drive shaft 102 and the retaining sleeve 104 to rotate together in a first direction (e.g., clockwise) to drive the bone screw into the bone while the locking sleeve 118 remains stationary. In this way, during screw insertion, the retaining sleeve 104 will not remain stationary relative to the bone screw, which would cause the retaining sleeve 104 to become disengaged from the bone screw. Instead, when the bone screw is driven into the bone, the retaining sleeve 104 rotates with the bone screw and thus remains coupled to the bone screw.

[0060] As Figure 3 、 Figure 6A and Figure 7A further shown, the biasing element 126 is located within the locking sleeve 118. Although the biasing element 126 can have various configurations, in the illustrated embodiment, the biasing element 126 is a helical spring. The biasing element 126 can continuously bias the first set of teeth 122 toward the second set of teeth 123. Thus, the first set of teeth 122 and the second set of teeth 123 remain engaged regardless of the position of the locking sleeve 118. Additionally, as described below, the biasing element 126 can bias the locking sleeve 118 distally, thereby biasing the locking sleeve 118 to its first position or disengaged position.

[0061] In addition, as Figure 1B 、 Figure 2 、 Figure 6B and Figure 7B shown, the coupling element 120 includes a first cutout portion 128a and a second cutout portion 128b that are defined in the coupling element and are positioned adjacent the first end 120a of the coupling element. Although the first cutout portion 128a and the second cutout portion 128b can have various shapes and sizes, each cutout portion 128a, 128b (as Figure 1B and Figure 2 shown) is generally rectangular in shape. The dimensions and shape of the first cutout portion 128a and the second cutout portion 128b are configured to allow a first locking pin 130a and a second locking pin 130b that extend radially inward from the locking sleeve 118 to extend therethrough for selective engagement with the threaded portion 105 of the retaining sleeve 104, as discussed in more detail below. Additionally, the dimensions of the first cutout portion 128a and the second cutout portion 128b can be designed to allow relative movement between the locking sleeve 118 and the retaining sleeve 104 and to allow the locking sleeve 118 to return to the first position. Thus, the first cutout portion 128a and the second cutout portion 128b can allow a certain amount of sliding between the locking sleeve 118 and the retaining sleeve 104.

[0062] When implanting a bone screw, the retention sleeve 104 can be disengaged from the implanted bone screw. This disengagement can be achieved by moving the locking sleeve 118 from its first or disengaged position to its second or engaged position. As will be described in more detail below, the locking sleeve 118 can be configured to move proximally and rotate in a second direction (e.g., counterclockwise) while the drive shaft 102 remains stationary, thereby allowing the retention sleeve 104 to be disengaged from the implanted bone screw. Thus, when the drive shaft 102 remains stationary and the locking sleeve 118 is moved to its second or engaged position, further rotation of the locking sleeve 118 in the second direction will cause simultaneous rotation of the retention sleeve 104. This will thus disengage the retention sleeve 104 from the implanted bone screw.

[0063] For example, in use, by moving (pulling) the locking sleeve 118 in a proximal direction (e.g., toward a first handle coupled to the proximal end 102b of the drive shaft 102), the locking sleeve 118 can transition from the first position / disengaged position ( Figure 1A 、 Figure 3 and Figures 6A through 6B ) to the second position / engaged position ( Figure 7A and Figure 7B ). In this way, the pulling force applied by the user can overcome the biasing force of the biasing element 126, and thus cause the biasing element 126 to move from its expanded configuration to its compressed configuration. This allows the locking sleeve 118 to move proximally relative to the retention sleeve 104. The axial translation of the locking sleeve 118 in the proximal direction causes axial translation of the locking pins 130a, 130b that extend radially inward from the locking sleeve 118. This axial translation causes the locking pins 130a, 130b to abut the ends 105a of the threaded portion 105 of the retention sleeve 104. In the case where the locking sleeve 118 is pulled proximally, the locking sleeve 118 can rotate relative to the retention sleeve 104 in a second direction (e.g., counterclockwise) to threadedly engage the locking pins 130a, 130b and translate proximally and rotatably through a portion of the threaded portion 105 of the retention sleeve 104 (e.g., toward the first handle). As Figures 7A through 7B shown, the locking sleeve 118 has rotated 35 degrees counterclockwise. In other embodiments, the locking sleeve 118 can rotate relative to the retention sleeve 104 in the second direction by about 0° to 180°. Those skilled in the art will understand that the amount of rotation of the locking sleeve depends at least on the pitch and the clearance space between the locking sleeve and other components of the instrument 100.

[0064] As the locking sleeve 118 rotates, the locking pins 130a, 130b eventually reach a proximal position within the cutout portions 128a, 128b where a flange 119 extending from the inner surface 118a of the locking sleeve 118 contacts the proximal end 104a of the retention sleeve 104, as Figure 7A andFigure 7B As shown. This causes the locking sleeve 118 to move into its second position / engagement position. Specifically, the proximal end 104a prevents further proximal translation of the locking sleeve 118 relative to the retaining sleeve 104. This causes the locking sleeve 118 to drop to its lowest point, and the locking pins 130a, 130b are retained within the threaded portion 105 of the retaining sleeve 104, thereby preventing it from moving distally through the threaded portion of the retaining sleeve. Thus, when the locking sleeve 118 is in the second position / engagement position, further rotation of the locking sleeve 118 in the second direction (counterclockwise) causes the retaining sleeve 104 to simultaneously rotate in the same direction relative to the drive shaft 102, which remains stationary to hold the implanted bone screw in a fixed position. This rotation of the locking sleeve 118 and the retaining sleeve 104 in the second direction causes the distal end 104b of the retaining sleeve 104 to become disengaged from the threads of the implanted bone screw.

[0065] Once the retaining sleeve 104 and the drive shaft 102 are removed from the implanted bone screw, the locking sleeve 118 can return to its first position. For example, in use, when the locking sleeve 118 is in its second position, the user can release the locking sleeve 118. This causes the biasing element 126 to expand from its compressed configuration back to its expanded configuration, thereby moving the locking sleeve 118 towards its first position / engagement position. In this way, as the biasing element 126 pushes the locking sleeve 118 in the distal direction, the locking pins 130a, 130b translate distally past the end 105a of the threaded portion 105 of the retaining sleeve 104.

[0066] As previously described, the screw inserter instrument can be used to implant the bone screw assembly into bone. Any suitable method can be used to operate any of the screw inserter instruments having a sleeve assembly as described herein. For example, when operating the screw inserter instrument 100( Figures 1A through 7B) When, the retaining sleeve 104 is kept rotatable relative to the drive shaft 102, wherein the drive shaft 102 remains stationary, so that the retaining sleeve 104 is threadedly engaged with the bone screw coupled to the distal end 102a of the drive shaft 102. Once coupled to the bone screw, the handle on the drive shaft 102 can be rotated in a first direction while the locking sleeve 118 remains stationary to drive the bone screw into the bone. This rotation can also cause the retaining sleeve 104 to rotate together with the drive shaft 102, as described above. Once the bone screw is implanted into the bone, the locking sleeve 118 can be moved from a first position to a second position relative to the retaining sleeve 104. This can be achieved by pulling the locking sleeve 118 proximally and by rotating the locking sleeve 118 counterclockwise relative to the retaining sleeve 104. When the locking sleeve 118 is rotated into the locked position, the drive shaft 102 can remain stationary. When in the second position, rotating the locking sleeve 118 counterclockwise while keeping the drive shaft 102 stationary can cause the retaining sleeve 104 to rotate, so that the retaining sleeve is threadedly disengaged from the bone screw, as described above.

[0067] Thus, the locking sleeve described herein provides a position for the user to grasp the screw inserter instrument such that the drive shaft can be rotated to drive the bone screw coupled thereto into the bone. This grasping position also allows the retaining sleeve to rotate in the same direction as the drive shaft and thus prevents the retaining sleeve from separating from the coupled bone screw during bone screw insertion. In addition, the locking sleeve provides a position for the user to grasp the screw inserter instrument and rotate the locking sleeve while keeping the drive shaft stationary to allow the retaining sleeve to separate from the implanted bone screw.

[0068] In some embodiments, the screw inserter instrument may further include a stop sleeve configured to limit the insertion depth of the bone screw driven into the bone. The stop sleeve may be partially disposed around the retaining sleeve such that a portion of the stop sleeve can surround at least a portion of the bone screw coupled to the retaining sleeve. The overlapping length may be associated with the length of the bone screw required for the multi-axis head assembly. Thus, the stop sleeve may be configured to limit the insertion of a portion of the bone screw into the bone. For example, when the bone screw has reached the desired insertion depth, the stop sleeve can provide tactile and visual feedback to the user. Additionally, in certain embodiments, the stop sleeve may be coupled to the retaining sleeve to allow the retaining sleeve and the stop sleeve to rotate together, while in other embodiments, the stop sleeve may be rotatable freely relative to the retaining sleeve.

[0069] Figures 8A through 8B An embodiment of a screw inserter instrument 200 having a stop sleeve 232 is shown. Except for the differences described in detail below, the screw inserter instrument 200 may be similar to the screw inserter instrument 100 ( Figures 1A through 7B ) and thus is not described in detail herein. Additionally, for simplicity, certain components of the screw inserter instrument 200 are not shown in Figures 8A through 8Bis shown. Additionally, for illustrative purposes only, bone screw 234 is coupled to screw inserter instrument 200.

[0070] The stop sleeve 232 can have a variety of configurations. For example, Figures 8A through 8B the stop sleeve 232 shown includes an elongated cylindrical body 236 that is disposed around a portion of the retention sleeve 204 and has a head 238 that extends distally therefrom by a length (L H ). The elongated cylindrical body 236 and the head 238 include windows 239a, 239b defined therein on their opposite sides. The windows 239a, 239b can, for example, allow a user to observe the bone screw as the bone screw 234 is being coupled to the retention sleeve 204. Additionally, the proximal end 232p of the stop sleeve 232 can be fixedly coupled to the distal end 218d of the locking sleeve 218. Thus, movement of the locking sleeve 218 effects simultaneous movement of the stop sleeve 232. Those skilled in the art will understand that in other embodiments, the proximal end 232p of the stop sleeve 232 can be coupled to the distal end 218d of the locking sleeve 218 in a manner that allows the stop sleeve 232 to rotate freely relative to the locking sleeve 218 and thus relative to the retention sleeve 204 and the drive shaft 202.

[0071] As further shown, when the bone screw 234 is fully engaged with the retention sleeve 204, a portion 238a of the head 238 overlaps a portion of the bone screw 234. Thus, during use, as the bone screw 234 is driven into bone, the distal end 238d of the head 238 will eventually contact the surface of the bone. This contact will indicate to the user (e.g., via tactile and visual feedback) that the bone screw 234 has reached a predetermined insertion depth. As described above, the length of the overlap can be predetermined to provide a clearance amount that effectively allows a multi-axis head assembly (not shown) to be attached to the bone screw 234.

[0072] Although the head 238 can have a variety of configurations, Figures 8A through 8B the head 238 in can have a generally conical configuration. In this illustrated embodiment, the head 238 has a first outer diameter that increases distally along a first portion 240a, a second outer diameter that is substantially constant along a second portion 240b, and a third outer diameter that decreases distally along a third portion 240c. Those skilled in the art will understand that in other embodiments, the head 238 can have an outer diameter that increases or decreases or remains constant distally along the entire length L H of the head 238. Additionally, in other embodiments, the head 238 can have other suitable shapes and dimensions.

[0073] Figures 9A through 9BShows another embodiment of a stop sleeve 332 coupled to a screw inserter instrument 300. Except for the differences described in detail below, the screw inserter instrument 300 may be similar to the screw inserter instrument 100( Figures 1A through 7B ) and is therefore not described in detail herein. In addition, for simplicity, certain components of the screw inserter instrument 300 are not shown in Figures 9A through 9B . Additionally, for illustrative purposes only, a bone screw 334 is coupled to the screw inserter instrument 300.

[0074] Figures 9A through 9B The stop sleeve 332 shown includes an elongated body 336 that is disposed around a portion of the retaining sleeve 304 and has a head 338 that extends distally therefrom by a length (L H ). As shown, a portion 338a of the head 338 overlaps a portion of the bone screw 234. In this illustrated embodiment, the head 338 has a generally U-shaped configuration having a base 343a and two opposing legs 343b, 343c extending from the base. Additionally, the head includes windows 340a, 340b, and 340c positioned therearound.

[0075] As Figures 9A through 9B further shown, the proximal end 332p of the stop sleeve 332 is coupled to the distal end 318d of the locking sleeve 318 by a coupling element 339. Although the coupling element 339 may have a variety of configurations, in this illustrated embodiment, the coupling element 339 is in the form of a generally cylindrical body extending from a first end 339a to a second end 339b. The coupling element 339 includes an annular ring 337 that extends radially outward therefrom. As shown, the annular ring 337 engages an internal groove 319 defined within the locking sleeve 318 such that the first end 339a of the coupling element 339 is located within the locking sleeve 318. As shown, the second end 339b of the coupling element 339 is positioned within a cavity 341 defined within the proximal end 332p of the stop sleeve 332. Additionally, a first set of threads 342a at the second end 339b of the coupling element 339 engages a second set of threads 342b in the cavity 341 in the stop sleeve 332. Thus, the stop sleeve 332 can be fitted to the locking sleeve 318 in a manner that allows the stop sleeve 332 to rotate freely relative to the locking sleeve 318 and thus relative to the retaining sleeve 304 and the drive shaft 302.

[0076] In certain embodiments, the stop sleeve may be formed of or coated with an insulating material that is configured to electrically insulate the retaining sleeve and / or drive shaft during neuromonitoring. For example, the stop sleeve may be formed of one or more plastics that act as a barrier so that electrical current applied to the retaining sleeve and / or drive shaft will be isolated from surrounding tissue at the surgical site. Additionally or alternatively, a radiopaque material may be inserted into the distal end of the stop sleeve to allow a user to visualize the interface between the stop sleeve and the bone screw prior to application of electrical current.

[0077] In some embodiments, the screw inserter instrument may include a stylet assembly, such as Figures 10A through 10B The stylet assembly 450 is used to control the positioning of the stylet relative to a bone screw coupled to the distal end of the instrument, such as Figures 1A through 7B Generally speaking, the stylet assembly may include a second handle, such as Figures 10A through 10B The second handle 450a in the embodiment is also referred to herein as the distal handle; and the stylet, such as Figures 10A through 10B The stylet 450b in the apparatus extends through the drive shaft of the apparatus, such as Figures 10A through 10B The drive shaft 402 in the instrument. The axial position of the stylet can be adjusted by the rotation of the second handle. In order to prevent the connected bone screw from being inserted into or removed from the bone during the advancement and retraction of the stylet, the user can apply a counter torque to the first handle of the instrument during the rotation of the second handle. Therefore, as discussed in more detail below, the user can rotate the second handle while keeping the first handle stationary to be able to cause axial translation of the stylet. Conversely, during use, once the stylet is positioned relative to the bone, the second handle remains stationary while the first handle is rotated to drive the bone screw into the bone. During the advancement of the screw, it may be desirable to allow the user to continuously rotate the drive shaft of the instrument without removing his / her hand from the first handle. Therefore, a clutch mechanism with a ratchet feature and a switch mechanism can be provided. The switch can allow the user to switch the first handle between a first mode (e.g., a locked configuration) and a second mode (e.g., an unlocked configuration), in which the first handle can remain stationary to apply a counter torque during the rotation of the second handle, and in which the ratchet feature is activated in the unlocked configuration. The ratchet feature allows the first handle to continuously drive the drive shaft in only one direction while preventing movement in the opposite direction, thereby driving the bone screw into the bone. This configuration allows the user to maintain contact with the first handle and advance the screw into the bone more quickly.

[0078] Figures 10A through 10B An exemplary screw inserter instrument 400 is shown. The screw inserter instrument 400 may be similar to the screw inserter instrument 100 ( Figures 1A through 7B)and are not described in detail herein. For simplicity, certain components of the screw inserter instrument 400 are not shown in Figures 10A through 10B . The screw inserter instrument 400 generally includes a first handle 446, a drive shaft 402, a drive tube 448, and a stylet assembly 450. The first handle 446 and the drive shaft 402 are collectively referred to herein as the screw drive assembly. Although the screw inserter instrument 400 also includes a retaining cannula 404, a locking cannula 418, and a stop cannula 432 similar to those described above, one of ordinary skill in the art will understand that in certain embodiments, the retaining cannula 404 and / or the locking cannula 418 and / or the stop cannula 432 may be omitted.

[0079] As Figure 10B shown, the proximal end 402p of the drive shaft 402 is coupled to the distal end 448d of the drive tube 448, and the proximal end 448p of the drive tube 448 mates with the first or proximal handle 446. The drive tube 448 may be in the form of a generally elongated hollow tube having a proximal portion 448a and a distal portion 448b. Although the first handle 446 may be selectively mated to the drive tube 448 using a variety of mechanisms, the proximal end 448p of the drive tube 448 includes mating features 449 formed thereon for mating with the inner surface 463b of the distal portion 463 of a coupling member 452 disposed within the first handle 446. In this illustrative embodiment, the mating features 449 on the drive tube 448 are convex hexagonal features, and as Figures 11E through 11G shown, the inner surface 463b of the distal portion 463 is in the form of a concave hexagonal feature. In other embodiments, the mating features may have any other configuration suitable for selectively mating the first handle 446 to the drive tube 448.

[0080] The stylet assembly 450 includes a second handle 450a and a stylet 450b, as Figures 10A through 10BAs shown. The second handle portion 450a is rotatably positioned above the distal portion 448b of the drive tube 448, and the stylet 450b extends through the drive shaft 402. In use, the first handle portion 446 remains stationary while the second handle portion 450a rotates to advance or retract the stylet 450b distally or proximally relative to the drive shaft 402. Additionally, to drive a bone screw coupled to the screw drive assembly into bone, the second handle portion 450a remains stationary while the first handle portion 446 and the drive shaft 402 rotate. The stylet assembly 450 may include a carrier 450c that is coupled to the stylet 450b and is movably disposed within the drive tube 448. Further details regarding the stylet assembly 450 and other exemplary stylet assemblies can be found in U.S. Patent Publication 2018 / 0368893 and U.S. Patent Application 15 / 801,917, filed November 2, 2017, entitled "Bone Anchor Insertion Instruments and Methods", each of which is incorporated herein by reference in its entirety.

[0081] To prevent the drive shaft 402 from rotating during stylet advancement and retraction, the drive shaft 402 may be locked to the first handle portion 446 via a locking assembly 466 (also referred to herein as a control mechanism) located within the first handle portion 446. The locking assembly 466 may be configured to selectively lock the first handle portion 446 and the drive shaft 402 to each other such that they rotate as a unit. Thus, the locking assembly 466 has a locked configuration and an unlocked configuration. When the locking assembly 466 is in the locked configuration, the user can grasp and hold the first handle portion 446 stationary and, thus, keep the drive shaft 402 stationary while rotating the second handle portion 450a to advance or retract the stylet 450b to a desired length. That is, the locking assembly 466 allows the user to apply a counter torque through the first handle portion 446 while the second handle portion 450a rotates in a clockwise or counterclockwise direction and also prevents the drive shaft 402 from rotating. Thus, during stylet advancement and retraction, axial translation of a bone screw (not shown) coupled to the distal end 402a of the drive shaft 402 can be prevented. When the locking assembly 466 is in its unlocked configuration, the first handle portion 446 may be coupled to the drive shaft 402 via a clutch assembly (such as Figure 11H the clutch assembly 480 in) and rotate with the drive shaft, which will be discussed in more detail below. The clutch assembly functions as a ratchet such that the user can continuously drive the drive shaft 402 in only one direction without removing their hand from the first handle portion 446.

[0082] The first handle portion 446 may have a variety of configurations that allow the user to effectively grasp the first handle portion 446 and operate the screw inserter instrument 400. For example, as Figure 10AAs shown, the first handle portion 446 may be in the form of a T-shaped handle. The first handle portion 446 is shown in more detail in Figures 11A through 11H , and includes a base member 454 and a first arm member 456a and a second arm member 456b that extend outwardly from the base member in opposite directions. The first arm member 456a and the second arm member 456b allow a user to easily grasp the first handle portion 446 to rotate it. Additionally, as shown in Figure 11D and Figure 11E , each of the first arm member 456a and the second arm member 456b includes a passage 457a, 457b that extends therethrough along the longitudinal axis (L H ) of the first handle portion 446.

[0083] Although the base member 454 may have various configurations, as shown in Figures 11A through 11G , the base member 454 includes a passage 454a that extends therethrough. As shown, the passage 454a extends along an axis that is transverse to the longitudinal axis (L H ) of the first handle portion 446. Further as shown in Figure 11D and Figure 11E , a portion of the passage 454a is defined by the inner surface 459a of a first flange 459 that extends radially inwardly from the inner surface 454b of the base member 454. Thus, a first cavity 460 is formed within the base member 454 and a second cavity 461 that communicates with the first cavity 460 via the passage 454a.

[0084] As further shown in Figure 11E and Figure 11F , the coupling member 452 is positioned within the first cavity 460 of the base member 454 and extends from the first cavity into the second cavity 461. The coupling member 452 may have various configurations. In this illustrated embodiment, the coupling member 452 is in the form of a generally elongated hollow tube that has a proximal portion 462, a distal portion 463, and an intermediate portion 464 that extends therebetween. These portions 462, 463, 464 each have an outer surface 462a, 463a, 464a and an inner surface 462b, 463b, 464b, wherein the shape of each outer surface 462a, 463a, 464a is generally circular. As shown, the outer diameter of the coupling member 452 is generally along its length (L C)Decrease distally. In other embodiments, the coupling member 452 may have other suitable shapes and sizes. Additionally, the shape of the inner surface 463b of the distal portion 463 is generally hexagonal. Thus, this inner surface 463b serves as a concave hexagonal feature that is configured to receive a convex hexagonal feature on the drive tube 448 to mate the first handle 446 to the drive tube 448. The coupling member 452 includes additional features that form part of a locking assembly 466 or a clutch assembly 480, which are located within the first handle 446 and will be discussed in more detail below.

[0085] The locking assembly 466 can have a variety of configurations. For example, as Figure 11C , Figure 11F and Figure 11G shown, the locking assembly 466 includes a first trigger element 476 and a second trigger element 478 that are coupled to a locking ring 468, which is positioned within a second cavity 461 of the base member 454. In this illustrated embodiment, when the locking assembly 466 is in the locked configuration, the locking ring 468 is coupled to the drive shaft 402 such that the first handle 446 and the drive shaft 402 are locked together and rotate as a unit. When the locking assembly 466 is in the unlocked configuration, the locking ring 468 is decoupled from the drive shaft 402, thereby allowing the drive shaft 402 to rotate freely relative to the first handle 446. As discussed in more detail below, the locking assembly 466 is biased to its locked configuration, and thus the first handle 446 and the drive shaft 402 are locked together until the locking assembly 466 is moved to its unlocked configuration.

[0086] Although the first trigger element 476 and the second trigger element 478 can have a variety of configurations, as Figure 11F and Figure 11G shown, each trigger element 476, 478 is generally in the form of an elongated cylindrical member having a first end 476a, 478a and a second end 476b, 478b. As shown, a portion of the first trigger element 476 extends through a channel 457a of the first arm member 456a, and a portion of the second trigger element 478 extends through a channel 457b of the second arm member 456b. Thus, the first ends 476a, 478a of each trigger element 476, 478 are positioned outside of the first handle 446, and the second ends 476b, 478b of each trigger element 476, 478 are fixedly coupled to the locking ring 468, as Figure 11F and Figure 11G shown. In other embodiments, the first handle 446 may include trigger elements having other suitable configurations. For example, in one embodiment, at least one trigger element may be in the form of a switch.

[0087] As Figure 11FAs shown, a first biasing element 479a is disposed within a channel 457a of a first arm member 456a, and a second biasing element 479b is disposed within a channel 457b of a second arm member 456b. Although the first biasing element 479a and the second biasing element 479b may have various configurations, in this illustrated embodiment, each biasing element 479a, 479b is a helical spring. When in the expanded configuration, the first biasing element 479a and the second biasing element 479b may bias a first trigger element 476 and a second trigger element 478 to first positions, respectively, as Figure 11F and Figure 11G shown. Thus, the first trigger element 476 and the second trigger element 478 are biased to their first positions, and thus the locking assembly 466 is biased to its locked configuration.

[0088] The locking ring 468 may have various configurations. As Figure 11G shown, the locking ring 468 includes a first set of two adjacent recesses 469 that define a first engagement interface 471a therebetween and a second set of two adjacent recesses 470 that define a second engagement interface 471b therebetween. When the locking assembly 466 is in its locked configuration, the first engagement interface 471a and the second engagement interface 471b frictionally engage with a first engagement feature 472a and a second engagement feature 472b, respectively, as Figure 11G shown. Although the engagement features 472a, 472b may have various configurations, the engagement features 472a, 472b each have a spherical configuration. In other embodiments, the engagement features 472a, 472b may have other suitable shapes and sizes.

[0089] As Figure 11G further shown, a portion of the first engagement feature 472a extends through a hole 473a defined in a first stop member 474a, and a portion of the second engagement feature 472b extends through a hole 473b defined in a second stop member 474b. Although the first stop member 474a and the second stop member 474b may have various configurations, in this illustrated embodiment, the first stop member 474a and the second stop member 474b are in the form of a second flange and a third flange, respectively. The second flange and the third flange each extend outwardly from the first flange 459 in a direction transverse to the longitudinal axis (L H ) of the first handle 446 and thus extend into the second cavity 461. Thus, each stop member 474a, 474b is positioned between the locking ring 468 and the distal portion 463 of the coupling member 452. In other embodiments, each stop member 474a, 474b may have other suitable configurations that allow the engagement features to frictionally engage between the locking ring 468 and the distal portion 463 of the coupling member 452.

[0090] Although not shown, the first engagement feature 472a is partially disposed within a first channel of a set of channels 475, and the second engagement feature 472b is partially disposed within a second channel of the set of channels 475. Each channel of the set of channels 475 is recessed from an outer surface 463a of a distal portion 463 of the coupling member 452, as Figure 11E and Figure 11F shown. Thus, when the first engagement interface 471a and the second engagement interface 471b contact the corresponding first engagement feature 472a and second engagement feature 472b, a frictional engagement is formed between the locking ring 468 and the coupling member 452. This frictional engagement locks the first handle 446 and the drive shaft 402 to each other. This is because an inner surface 463b of the distal portion 463 of the coupling member 452 mates with a proximal end 448p of the drive tube 448, and a distal end 448d of the drive tube 448 is coupled to the drive shaft 402, as described above. Accordingly, rotational movement of the coupling member 452 relative to the first handle 446 is inhibited to lock the first handle 446 to the drive shaft 402 such that they can rotate together as a unit.

[0091] In use, for example, when a user actuates one of the first trigger element 476 and the second trigger element 478, the locking assembly 466 can move from a locked configuration to an unlocked configuration to displace the locking ring 468 out of frictional engagement with the first engagement feature 472a and the second engagement feature 472b. For simplicity, the following discussion is with respect to the first trigger element 476. However, those skilled in the art will understand that the following discussion also applies to the second trigger element 478, which is structurally similar to the first trigger element 476 as Figure 11F and Figure 11G shown.

[0092] In some embodiments, for example, the user may actuate the first trigger element 476 by applying sufficient force to its first end 476a to axially translate the first trigger element 476 in a first direction (D1). Accordingly, the first trigger element 476 moves from its first position to its second position. This causes its second end 476b to further move into the second cavity 461 of the base member 454, thereby shifting the locking ring 468 in the first direction (D1). This movement of the locking ring overcomes the frictional forces between the locking ring 468 and the first engagement feature 472a and the second engagement feature 472b. Specifically, the first engagement feature 472a and the second engagement feature 472b also move in the first direction (D1) and are respectively received partially within the first recess 469a of the first set of adjacent recesses 469 and the first recess 470a of the second set of adjacent recesses 470. Accordingly, each engagement feature 472a, 472b is no longer frictionally engaged to the locking ring 468, and thus, the first handle 446 can rotate freely relative to the drive shaft 402 and vice versa.

[0093] To move the locking assembly 466 back to the locked configuration, the first trigger element 476 is returned to its first position. For example, in use, when the first trigger element 476 is in its second position, the user may release the first trigger element 476, which causes the first biasing element 479a to expand back towards its first position. This forces the first trigger element 476 towards its first position, and thus, the locking ring 468 is shifted back into frictional engagement with the first engagement feature 472a and the second engagement feature 472b.

[0094] As described above, when the locking assembly 466 is in its locked configuration, the first handle 446 and the drive shaft 402 may rotate together as a unit. Although the user may thus rotate the first handle 446 to effect rotation of the drive shaft 402 to drive the bone screw into bone, the user will not be able to continuously rotate the drive shaft 402 without removing his / her hand from the first handle 446. Thus, when the locking assembly 466 is in its unlocked configuration, the first handle 446 can be decoupled from the drive shaft 402 and rotated independently of the drive shaft, and the first handle 446 may include a clutch assembly 480 (also referred to herein as a ratchet mechanism) for allowing the user to continuously drive the drive shaft 402 in only one direction without removing their hand from the first handle 446.

[0095] The clutch assembly 480 can be configured to selectively engage to couple the first handle portion 446 to the drive shaft 402 and rotate therewith. Thus, the clutch assembly 480 has an engaged configuration and a disengaged configuration. Although the clutch assembly 480 can have various configurations, in some embodiments, the clutch assembly 480 can be in the form of a one-way bearing. For example, in one embodiment, as Figure 11H shown, the clutch assembly 480 can include an outer ring 481 and an inner ring 482. In this illustrated embodiment, the inner ring 482 is also the intermediate portion 464 of the coupling member 452.

[0096] As Figure 11E and Figure 11F shown, the outer ring 481 is located within the distal portion 460a of the first cavity 460 of the base member 454, and as Figure 11H shown, is positioned between the inner ring 482 and the inner surface 454c of the base member 454. More specifically, the inner surface 481b of the outer ring 481 abuts the outer surface 482a of the inner ring 482, and the outer surface 481a of the outer ring 481 abuts the inner surface 454c of the base member 454, which inner surface defines the distal portion 460a of the first cavity 460. Additionally, the outer surface 481a of the outer ring 481 and the inner surface 454c of the base member 454 have corresponding hexagonal shapes such that the outer ring 481 is non-rotatably coupled to the base member 454. In other embodiments, the outer surface 481a and the inner surface 454c can have other suitable corresponding shapes.

[0097] As Figure 11E 、 Figure 11F and Figure 11H further shown, the inner ring 482 includes a cutout portion 483 extending from its outer surface 482a toward its inner surface 482b. The cutout portion 483 can have any suitable shape and size. In this illustrated embodiment, each cutout portion 483 is tubular in shape and extends inwardly at an angle to form a ramp interface 483a. Additionally, each cutout portion 483 includes an engagement feature 484 disposed therein. In this illustrated embodiment, each engagement feature 484 is a spherical element that remains in contact with the outer ring 481 via a biasing element 486 located within the corresponding cutout portion 483. Although each biasing element 486 can have various configurations, as Figure 11H shown, each biasing element 486 is a helical spring that biases its corresponding engagement feature 484 outwardly and into contact with the inner surface 481b of the outer ring 481.

[0098] In use, the first handle portion 446 can be rotated in a clockwise direction, which ultimately causes it to frictionally engage with the drive shaft 402 via the clutch assembly 480 such that they can rotate as a unit in the clockwise direction to drive the bone screw into the bone only. More specifically, the clockwise rotation of the first handle portion 446 causes each engagement feature 484 of the clutch assembly 480 to be pulled radially outward via friction against the outer ring 481. That is, the frictional force generated by the clockwise rotation of the first handle portion 446 forces each engagement feature 484 to move radially outward along the ramp interface 483a of its corresponding notch portion 483. As a result, the friction between each engagement feature 484 and the outer ring 481 increases, thereby frictionally locking the outer ring 481 to the drive tube 448 and thus locking the first handle portion 446 to the drive shaft 402. In this way, the first handle portion 446 can be rotated clockwise and counterclockwise without the user having to remove his or her hand therefrom to drive the drive shaft only in the clockwise direction to drive the bone screw into the bone. Additionally, this can be achieved without generating an audible cue that may be confused with any other audible cue of the instrument 400.

[0099] Additionally, the clutch assembly 480 can inhibit withdrawal of an implanted bone screw from the bone. That is, the clutch assembly 480 can disengage when the first handle portion is rotated counterclockwise. This causes the first handle portion 446 to disengage from the drive shaft 402 such that the counterclockwise rotation of the first handle portion does not cause a corresponding counterclockwise rotation of the drive shaft 402. In use, when the first handle portion 446 and thus the outer ring 481 are rotated counterclockwise, the outer ring 481 exerts a frictional reaction force on the engagement features 484. This causes each engagement feature 484 to travel radially inward along the ramp interface 483a of its corresponding notch portion 483, thereby compressing the biasing element 486 with which it is in contact. As a result, this radial movement of each engagement feature 484 reduces its friction with the outer ring 481. Accordingly, the outer ring 481 and thus the first handle portion 446 can thus rotate freely relative to the drive shaft 402 in the counterclockwise direction.

[0100] Accordingly, the clutch assembly described herein allows the first handle portion to be rotated in a first direction (e.g., clockwise) to drive the drive shaft to drive a bone screw coupled thereto into the bone and allows the first handle portion to be rotated in a second direction (e.g., counterclockwise), wherein the first handle portion rotates freely relative to the drive shaft. Accordingly, the user can maintain contact with the first handle portion and repeatedly rotate clockwise and counterclockwise to drive the screw into the bone only in the clockwise direction. Accordingly, the clutch assembly allows the user to drive the bone screw into the bone without having to remove his or her hand from the first handle portion.

[0101] As described above, a screw inserter instrument can be used to implant a bone screw assembly into bone. Any suitable method can be used to operate any of the screw inserter instruments having a first handle as described herein. For example, when operating the screw inserter instrument 400( Figures 10A through 10B ), the retention cannula 404 can be threadedly engaged with the bone screw coupled to the distal end of the drive shaft 402, as described above. Once coupled to the bone screw, the second handle 450a of the stylet assembly 450 can be rotated with the locking assembly 466 in the locked configuration and the first handle 446 held stationary to axially translate the stylet 450b relative to the drive shaft 402. Once the stylet 450b is in the desired position, the stylet 450b can be docked within the bone. The locking assembly 466 can be moved from its locked configuration to its unlocked configuration to decouple the first handle 446 from the drive shaft 402. This can be accomplished by actuating the first trigger element 476 or the second trigger element 478 of the locking assembly 466 to move the locking ring 468 from the first position to the second position and thus operably decouple it from the drive shaft 402. When the locking assembly 466 is in the unlocked configuration, the first handle 446 can be rotated in a first direction with the second handle 450a held stationary to couple the first handle 446 to the drive shaft 402 and rotate therewith to drive the bone screw into the bone. This rotation can cause the outer ring 481 and the inner ring 482 of the clutch assembly 480 to lock to each other. When the locking assembly 466 is in the unlocked configuration, the first handle 446 can be rotated relative to the drive shaft 402 in a second direction. Once the bone screw has been driven into the bone to the desired insertion depth, the retention cannula 404 can be disengaged from the bone screw, as described above.

[0102] The instruments disclosed herein can be designed to be discarded after single use, or they can be designed for multiple use. However, in either case, the instrument can be repaired and reused after at least one use. Repair can include any combination of disassembling the instrument, followed by cleaning or replacing specific parts, and subsequent reassembly steps. Specifically, the instrument is disassemblable, and any number of specific parts or components of the instrument can be selectively replaced or removed in any combination. After cleaning and / or replacing specific components, the instrument can be reassembled for subsequent use at a repair facility or by the surgical team just prior to surgery. Those skilled in the art will understand that repairing the instrument can be accomplished using a variety of techniques for disassembling, cleaning / replacing, and reassembling. The use of such techniques and the resulting repaired instrument are within the scope of this application.

[0103] In addition, in the present disclosure, components with similar names in each implementation generally have similar features. Therefore, in a specific implementation, each feature of each component with a similar name may not be fully described. Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed systems, devices, and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such systems, devices, and methods. Those skilled in the art will recognize that equivalent dimensions for such linear and circular dimensions can be readily determined for any geometry. The size and shape of the systems and devices and their components can depend at least on the anatomy of the subject to be treated in which the systems and devices will be used, the size and shape of the components with which the systems and devices will be used, and the methods and procedures in which the systems and devices will be used.

[0104] It should be understood that the terms "proximal" and "distal" are used herein relative to a user of the grasping instrument handle, such as a clinician. Other spatial terms such as "front" and "back" similarly correspond to distal and proximal, respectively. It should also be understood that, for convenience and clarity, spatial terms such as "vertical" and "horizontal" are used herein with reference to the figures. However, surgical instruments are used in many orientations and positions, and these spatial terms are not restrictive and absolute.

[0105] In this document, a value or range may be expressed as "about" and / or from "about" a particular value to another particular value. When expressing such a value or range, other implementations disclosed include the recited particular value and / or from one particular value to another particular value. Similarly, when a value is expressed as an approximation by use of the antecedent "about", it should be understood that many values are disclosed herein and that the particular value forms another implementation. It should also be understood that where many values are disclosed, each value is also disclosed herein as "about" that particular value in addition to the value itself. In an implementation, "about" can be used to represent, for example, within 10% of the recited value, within 5% of the recited value, or within 2% of the recited value.

[0106] For purposes of describing and defining the present teachings, note that unless otherwise specified, the term "substantially" is used herein to represent the inherent uncertainty that can characterize any quantitative comparison, value, measurement, or other representation. The term "substantially" can also be used herein to represent the degree to which a quantitative representation can vary with respect to the stated reference without causing a change in the basic function of the subject matter of concern.

[0107] Based on the above embodiments, those skilled in the art will recognize additional features and advantages of the present invention. Accordingly, the present invention should not be limited by what has been specifically shown and described herein, unless indicated by the appended claims. All publications and references cited herein are hereby expressly incorporated by reference in their entirety. Any patent, publication, or information incorporated by reference in whole or in part herein is incorporated only to the extent that the incorporated material does not conflict with the existing definitions, statements, or other disclosure material set forth in this document. Similarly, the disclosure set forth expressly in this application supersedes any conflicting material incorporated by citation into this application.

Claims

1. A screw inserter instrument, comprising: A screw driving assembly having a first handle and a drive shaft coupled to the first handle, the drive shaft having a distal end configured to be coupled to a bone screw for driving the bone screw into bone; A locking assembly disposed within the first handle and in communication with the drive shaft, the locking assembly including at least one trigger element fixedly coupled to a locking ring such that movement of the at least one trigger element causes movement of the locking ring; And A trocar assembly having a second handle and a trocar extending through the drive shaft; Wherein the first handle has a locked configuration in which the locking ring is operatively coupled to the drive shaft such that the first handle and the drive shaft are coupled such that when the second handle is rotated relative to the first handle, the first handle is capable of holding the drive shaft in a fixed position, and Wherein the first handle has an unlocked configuration in which the locking ring is operatively decoupled from the drive shaft such that the first handle and the drive shaft are capable of rotating simultaneously in a first direction and the first handle is capable of rotating independently of the drive shaft in an opposite second direction.

2. The screw inserter instrument according to claim 1, wherein, The first handle is biased to the locked configuration.

3. The screw inserter instrument according to claim 1 or 2, wherein, Movement of the at least one trigger element causes movement of the locking ring to move the first handle between the locked configuration and the unlocked configuration.

4. The screw inserter instrument according to claim 1 or 2, wherein, When the first handle is in the locked configuration, the locking ring is operatively coupled to the drive shaft such that the first handle and the drive shaft are locked together.

5. The screw inserter instrument according to claim 3, wherein, When the first handle is in the unlocked configuration, the locking ring is operatively decoupled from the drive shaft such that the first handle and the drive shaft rotate independently of each other.

6. The screw inserter instrument according to claim 1 or 2, further comprising a ratchet mechanism disposed within the first handle, the ratchet mechanism allowing bidirectional rotation of the first handle to unidirectionally drive the drive shaft to drive a bone screw into bone when the first handle is in the unlocked configuration.

7. The screw inserter instrument according to claim 1 or 2, further comprising a retaining sleeve disposed around the drive shaft and having a distal end configured to threadedly engage a bone screw.

8. The screw inserter instrument according to claim 7, wherein, When the first handle is in the locked configuration, the first handle is capable of holding the drive shaft in a stationary position while the retaining sleeve is capable of rotating to threadedly disengage from the bone screw, and when the first handle is in the unlocked configuration, the second handle is capable of remaining stationary while the first handle is capable of rotating in the first direction to rotate the drive shaft and the retaining sleeve together to drive the bone screw into bone.

9. A screw inserter instrument, comprising: A screw driving assembly, the screw driving assembly including a handle portion and a drive shaft operably coupled to the handle portion, the drive shaft having a distal end configured to be coupled to a bone screw for driving the bone screw into bone; A locking assembly located within the handle portion and in communication with the drive shaft, the locking assembly having a locked configuration and an unlocked configuration, in the locked configuration, the handle portion and the drive shaft are locked to each other such that they rotate as a unit, and in the unlocked configuration, the handle portion and the drive shaft rotate independently of each other; and A clutch assembly in communication with the handle portion and the drive shaft, the clutch assembly being configured to allow the handle portion to rotate in a first direction and an opposite second direction to drive the drive shaft only in the first direction when the locking assembly is in the unlocked configuration, wherein the clutch assembly includes an inner ring and an outer ring, the inner ring and the outer ring selectively engaging each other such that rotation of the handle portion in the first direction effectively causes rotation of the drive shaft only when the inner ring and the outer ring are engaged.

10. The screw inserter instrument according to claim 9, wherein, The locking assembly is biased to the locked configuration.

11. The screw inserter instrument according to claim 9 or 10, wherein, The locking assembly includes at least one trigger element fixedly coupled to a locking ring such that movement of the at least one trigger element moves the locking ring to move the locking assembly between the locked configuration and the unlocked configuration.

12. The screw inserter instrument according to claim 11, wherein, When the locking assembly is in the locked configuration, the locking ring is operably coupled to the drive shaft such that the handle portion and the drive shaft are locked together.

13. The screw inserter instrument according to claim 11, wherein, When the locking assembly is in the unlocked configuration, the locking ring is operably disengaged from the drive shaft such that the handle portion and the drive shaft rotate independently of each other.

14. The screw inserter instrument according to claim 9 or 10, further comprising a retaining sleeve disposed around the drive shaft and having a distal end configured to threadedly engage the bone screw.

15. The screw inserter instrument according to claim 14, wherein, When the locking assembly is in the locked configuration, the drive shaft can remain stationary while the retaining sleeve can rotate to threadedly disengage from the bone screw, and when the locking assembly is in the unlocked configuration, the handle portion can rotate in the first direction to rotate the drive shaft and the retaining sleeve together to drive the bone screw into bone.

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