Multi-point Angled Fixation Implant for Multiple Screws

Abstract

Disclosed herein is a bone anchor assembly and related method that can provide improved fixation of a main bone anchor. The bone anchor assembly can include wings having a distal portion that can define a plurality of auxiliary bone anchor openings. Each auxiliary bone anchor opening can receive an auxiliary bone anchor that can enhance fixation of the main bone anchor of the bone anchor assembly. The plurality of auxiliary bone anchor openings can be oriented such that when the wings are coupled to the main bone anchor assembly of a vertebral level in a first configuration, at least one auxiliary bone anchor can be driven to extend across a facet of the vertebral level, and when coupled in a second configuration, each auxiliary bone anchor received within the wing can be driven to coincide with the vertebral level.

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Orthopaedic implants and related methods are disclosed herein. For example, a bone anchor assembly having multiple bone engagement points is disclosed. [Background technology]

[0002] Bone anchor assemblies can be used in orthopedic surgery to fix bones during healing, fusion, or other procedures. For example, in spinal surgery, bone anchor assemblies can be used to attach spinal fixation elements to one or more vertebrae to rigidly or dynamically fixate the spine. Bone anchor assemblies can also be used as engagement points to align bones (e.g., to deflect, compress, or rotate one vertebra relative to another, reduce fractures in long bones, etc.).

[0003] The integrity with which the bone anchor assembly engages the bone can affect the transmission of corrective biomechanical forces. Although great care is taken when placing the bone anchor assemblies, the bone anchor assemblies are commonly inserted in a compromised state. For example, the bone opening into which the assembly is placed may be stripped (e.g., by driving the bone anchor assembly past its optimal holding position), the bone anchor assembly may be placed incorrectly (e.g., by using imprecise instrumentation such as a pilot hole that is larger than necessary), the bone anchor assembly may be placed outside of its intended trajectory (e.g., within the facet capsule or through the pedicle wall), or the bone anchor assembly may be inserted into a compromised bone (e.g., a fractured, osteoporotic, diseased, or other bone lacking structural integrity).

[0004] When the bone anchor assembly is in a compromised state, there is less than optimal bite between the bone anchor assembly and the bone. The bone anchor assembly may cause the surgeon to feel unstable, and the bone anchor assembly may back out or loosen over time. When faced with these types of situations, the surgeon has limited options. For example, in spinal surgery, the surgeon can remove the bone anchor assembly and skip that vertebral level, which may undesirably require extending the surgical site to additional vertebral levels. The surgeon can remove the bone anchor and reinsert a larger anchor, which may not be an option if there is limited space to attach the anchor to the bone. The surgeon may leave the compromised bone anchor assembly in place, which may be the safest alternative since if the bone anchor assembly is in a safe position and the attachment to the plate, rod, or other implant construct is solid, further compromised fixation may be better than removal.

[0005] Even when the bone anchor assembly is deployed in an uncompromised state, the geometry of conventional bone anchor assemblies can limit the flexibility with which bone attachment points can be positioned relative to a plate, rod, or other implant construct coupled to the bone anchor assembly. Summary of the Invention [Problem to be solved by the invention]

[0006] There remains a need for improved bone anchor assemblies and related methods. [Means for solving the problem]

[0007] Disclosed herein is a bone anchor assembly that can provide improved fixation compared to conventional bone anchor assemblies. One embodiment of the assembly can include a bracket or wing that extends downwardly from a receiver member and accommodates a number of auxiliary bone anchors that enhance fixation of the primary bone anchor of the assembly. Also disclosed is a surgical method for using the bone anchor assembly described herein.

[0008] In one aspect, the bone anchor assembly may include a bone anchor, a receiver member coupled to a proximal end of the bone anchor and defining a recess configured to receive a rod, a closure mechanism mated to the receiver member, wings having a proximal portion disposed proximally of the receiver member, a distal portion defining a plurality of auxiliary screw openings, each of the auxiliary screw openings configured to receive an auxiliary bone anchor screw, and a spanning portion connecting the proximal and distal portions. The plurality of auxiliary screw openings extend in an angled trajectory relative to a proximal-distal axis of the spanning portion such that in a first configuration, each auxiliary screw received in each of the plurality of screw openings can be matched to a vertebral level in which the bone anchor is inserted, and in a second configuration, at least one of the plurality of auxiliary bone anchor screws received in at least one of the screw openings can extend across a facet of a vertebral level in which the bone anchor is inserted. The bone anchor assembly further includes a nut configured to engage the closure mechanism to secure the proximal portion of the wings to the proximal end of the receiver member.

[0009] The devices and methods described herein can have many additional features and / or variations, all of which are within the scope of this disclosure. In some embodiments, for example, the distal portion of the wing can extend generally perpendicular to the proximal-distal axis of the spanning portion. The distal portion of the wing can be configured such that when the wing is secured to the receiver member, a gap exists between the distal portion of the wing and a proximally-facing surface of the bone into which the bone anchor is inserted.

[0010] In some embodiments, a central axis of each of the plurality of screw openings can extend in one of a caudal direction or a cranial direction. In some such embodiments, a central axis of each of the plurality of screw openings can extend in a medial direction. A central axis of each of the plurality of screw openings can extend at an angle of about 0 to about 60 degrees relative to a proximal-distal axis of the spanning portion.

[0011] Each of the plurality of screw openings can include at least one threaded portion such that the screw can be received at a variable angle. In some such embodiments, the at least one threaded portion can be a conical threaded portion. In some embodiments, each of the plurality of screw openings can define an interlocking interface.

[0012] In another aspect, a method of securing a main bone anchor assembly to bone is provided that includes driving a main bone anchor having a receiver member coupled to a proximal end of the bone anchor into a vertebral level of a patient's spine, positioning a rod in the receiver member, attaching a closure mechanism to the receiver member to retain the rod within the receiver member, and coupling a proximal portion of a wing to at least one of the closure mechanism and the receiver member. The wing can have a distal portion defining first and second auxiliary bone anchor openings and a spanning portion connecting the proximal and distal portions, each of the first and second auxiliary bone anchor openings extending at an oblique angle relative to a proximal-distal axis of the spanning portion. The method can include positioning the wing in one of a first position where a first auxiliary bone anchor and a second auxiliary bone anchor received in the wing correspond to a vertebral level at which the bone anchors are to be driven and a second position where at least one of the first auxiliary bone anchor and the second auxiliary bone anchor received in the wing extends across a facet of the vertebral level at which the bone anchors are to be driven; inserting the first auxiliary bone anchor through the first bone anchor opening in the first trajectory; inserting the second auxiliary bone anchor through the second bone anchor opening in the second trajectory; and driving the first auxiliary bone anchor into the vertebral level in the first trajectory and the second auxiliary bone anchor into the bone in the second trajectory such that the first auxiliary bone anchor and the second auxiliary bone anchor enhance fixation of the main bone anchor.

[0013] The method may further include positioning the wing relative to the receiver member such that the first and second auxiliary bone anchor openings are biased in a cephalad direction, driving the first auxiliary bone anchor at a first trajectory such that the first auxiliary bone anchor extends entirely within the vertebral level at which the main bone anchor is driven, and driving the second auxiliary bone anchor at a second trajectory such that the second auxiliary bone anchor extends entirely within the vertebral level at which the main bone anchor is driven. In some such embodiments, the driving at the vertebral level at which the main bone anchor is driven may be a vertebral level of the cervical spine.

[0014] The method can further include positioning a wing relative to the receiver member such that the first and second auxiliary bone anchor openings are biased in a caudal direction, and impacting at least one of the first and second auxiliary bone anchors to penetrate the facet joint surface of the vertebral level into which the primary bone anchor is driven. In some embodiments, positioning the wing can further include positioning the wing such that a gap exists between a distal portion of the wing and a proximally-facing surface of the vertebral level into which the primary bone anchor is driven.

[0015] Coupling the proximal portion of the wing to at least one of the closure mechanism and the proximal surface of the receiver member can include attaching the wing via an expansion set screw and locking the wing in place with a nut. In some such embodiments, the method can further include rotating the wing relative to the receiver member about an axis of the expansion screw to achieve the desired first auxiliary bone anchor opening trajectory and the desired second auxiliary bone anchor opening trajectory.

[0016] In some embodiments, driving the main bone anchor into a vertebral level of the spine can include driving the main bone anchor into a fused vertebral level of the spine. In some embodiments, driving the first secondary bone anchor in a first trajectory and driving the second secondary bone anchor in a second trajectory can distract at least one of the first secondary bone anchor and the second secondary bone anchor from the main bone anchor.

[0017] In some embodiments, a central axis of the first auxiliary bone anchor opening and a central axis of the second auxiliary bone anchor opening can each be biased from about 0 to about 60 degrees from a proximal-distal axis of the spanning portion. In some embodiments, the first trajectory can extend at an oblique angle relative to the central axis of the first auxiliary bone anchor opening.

[0018] Inserting the first auxiliary bone anchor and inserting the second auxiliary bone anchor may further include engaging a threaded surface of the first auxiliary bone anchor with an interlocking interface of the first auxiliary bone anchor opening and engaging a threaded surface of the second auxiliary bone anchor with an interlocking interface of the second auxiliary bone anchor opening.

[0019] In any of the methods of the above embodiments, the closure mechanism can include a threaded post having a radially extending shoulder portion. Coupling the proximal portion of the wing to at least one of the closure mechanism and the proximal end of the receiver member can include disposing at least a portion of the threaded post through an opening formed in the proximal portion of the wing and receiving a radially extending shoulder portion, the shoulder portion extending at least partially above the proximal end of the receiver member, within a counterbore formed about the opening in a distal-facing surface of the proximal portion of the wing.

[0020] Any of the above-described features or variations may be applied to any particular aspect or embodiment of the present disclosure in many different combinations, and no explicit description of any particular combination is provided, simply to avoid redundancy in this summary. [Brief description of the drawings]

[0021] [Figure 1A] FIG. 1 is an exploded perspective view of a prior art bone anchor assembly. [Figure 1B] FIG. 1B is a cross-sectional view of the bone anchor assembly of FIG. [Figure 1C] FIG. 1B is a perspective view of the bone anchor assembly of FIG. 1A shown with an extension tab. [Figure 2A] FIG. 2 is a perspective view of a bone anchor assembly and a spinal rod. [Figure 2B] FIG. 2B is a perspective exploded view of the bone anchor assembly and spinal rod of FIG. 2A. [Figure 2C] FIG. 2B is a perspective view of the bone anchor assembly and spinal rod of FIG. 2A. [Figure 2D] FIG. 2B is a top view of the bone anchor assembly and spinal rod of FIG. 2A. [Figure 2E] FIG. 2B is a perspective view of a wing of the bone anchor assembly of FIG. 2A. [Figure 2F] FIG. 2B is another perspective view of the wing of the bone anchor assembly of FIG. 2A. [Figure 2G] FIG. 2B is another perspective view of the wing of the bone anchor assembly of FIG. 2A. [Figure 2H] FIG. 2B is another perspective view of the wing of the bone anchor assembly of FIG. 2A. [Figure 2I] FIG. 2B is a perspective view of the bone anchor assembly and spinal rod of FIG. 2A shown with adjustable height wings. [Figure 2J] FIG. 2J is a perspective view of a wing of the bone anchor assembly of FIG. 2I. [Figure 2K] FIG. 2I is another perspective view of the wing of the bone anchor assembly of FIG. 2I. [Figure 2L] FIG. 2I is another perspective view of the wing of the bone anchor assembly of FIG. 2I. [Figure 2M] FIG. 2I is another perspective view of the wing of the bone anchor assembly of FIG. 2I. [Figure 3A] FIG. 2 is a perspective view of a bone anchor assembly and spinal rod attached to a spine. [Figure 3B]FIG. 3B is a perspective view of a wing of the bone anchor assembly of FIG. 3A. [Figure 3C] FIG. 3B is another perspective view of the wing of the bone anchor assembly of FIG. 3A. [Figure 3D] FIG. 3B is another perspective view of the wing of the bone anchor assembly of FIG. 3A. [Figure 3E] FIG. 3B is a side view of a wing of the bone anchor assembly of FIG. 3A. [Figure 3F] FIG. 3B is another perspective view of the wing of the bone anchor assembly of FIG. 3A. [Figure 3G] FIG. 3B is another perspective view of the wing of the bone anchor assembly of FIG. 3A. [Figure 3H] FIG. 3B is a top view of the wing of the bone anchor assembly of FIG. 3A with the angled distal portion facing in the caudal direction. [Figure 3I] FIG. 3B is a top view of the wing of the bone anchor assembly of FIG. 3A, with the angled distal portion facing in a cranial direction. [Figure 4A] 3B is a cross-sectional view of a wing of the bone anchor assembly of FIG. 3A prior to being secured to a closure mechanism. [Figure 4B] FIG. 4B is a cross-sectional view of the wing of FIG. 4A secured to a closure mechanism. [Figure 4C] FIG. 4B is another cross-sectional view of the wing of FIG. 4A secured to a closure mechanism. [Figure 5A] FIG. 2 is a perspective view of a bone anchor assembly and spinal rod attached to a spine. [Figure 5B] FIG. 5B is a perspective view of a wing of the bone anchor assembly of FIG. 5A. [Figure 5C] FIG. 5B is another perspective view of the wing of the bone anchor assembly of FIG. 5A. [Figure 5D] FIG. 5B is a side view of a wing of the bone anchor assembly of FIG. 5A. [Figure 5E] FIG. 5B is a top view of the wing of the bone anchor assembly of FIG. 5A, with the angled distal portion facing in a cranial direction. [Figure 5F] FIG. 5B is a top view of the wing of the bone anchor assembly of FIG. 5A with the angled distal portion facing in the caudal direction. [Figure 6A]FIG. 2 is a perspective view of a wing of the bone anchor assembly. [Figure 6B] FIG. 6B is a side view of the wing of FIG. 6A. [Figure 6C] FIG. 6B is another side view of the wing of FIG. 6A. [Figure 6D] FIG. 6B is a side cross-sectional view of the wing of FIG. 6A. [Figure 6E] FIG. 6B is another cross-sectional side view of the wing of FIG. 6A. [Figure 7] FIG. 2 is a perspective view of a bone anchor assembly and spinal rod attached to a spine. [Figure 8] 8 is a perspective view of one embodiment of a wing of the bone anchor assembly of FIG. 7. [Figure 9] 8 is a side cross-sectional view of a wing of the bone anchor assembly of FIG. 7. [Figure 10] FIG. 10 is a detailed cross-sectional view of the wing of FIG. [Figure 11] FIG. 8 is a perspective view of a wing of the bone anchor assembly of FIG. 7. [Figure 12] 8 is another perspective view of the wing of the bone anchor assembly of FIG. 7. [Figure 13] FIG. 8 is a side view of a wing of the bone anchor assembly of FIG. 7. [Figure 14] 12 is a cross-sectional view of the wing of the bone anchor assembly of FIG. 7 taken along line AA of FIG. 11. [Figure 15] 12 is a cross-sectional view of the wing of the bone anchor assembly of FIG. 7 taken along line BB of FIG. 11. [Figure 16] FIG. 8 is a top view of a wing of the bone anchor assembly of FIG. 7, with the auxiliary bone anchor opening extending in a cranial direction. [Figure 17] FIG. 8 is a top view of a wing of the bone anchor assembly of FIG. 7, with the auxiliary bone anchor opening extending in the caudal direction. [Figure 18] FIG. 2 is a perspective view of a bone anchor assembly and spinal rod attached to a spine. [Figure 19] FIG. 20 is a perspective view of a wing of the bone anchor assembly of FIG. 18. [Figure 20] FIG. 20 is a perspective view of a wing of the bone anchor assembly of FIG. 18. [Figure 21] 21 is a cross-sectional view of the wing of the bone anchor assembly of FIG. 18 taken along line CC of FIG. 20. [Figure 22] FIG. 19 is a top view of a wing of the bone anchor assembly of FIG. 18, with the auxiliary bone anchor opening extending in the caudal direction. [Diagram 23] 19 is a top view of a wing of the bone anchor assembly of FIG. 18, with the auxiliary bone anchor opening extending in a cranial direction. [Figure 24] 1 illustrates one embodiment of a method for enhancing fixation of a bone anchor assembly using an auxiliary fixation member of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Disclosed herein are bone anchor assemblies that can provide improved fixation compared to conventional bone anchor assemblies. An exemplary assembly can include a bracket or wing that extends downward from a receiver member and houses one or more auxiliary bone anchors that enhance fixation of the primary bone anchor of the assembly. Another exemplary assembly can include a plate that seats between the receiver member and a rod and houses one or more auxiliary bone anchors that enhance fixation of the primary bone anchor of the assembly. Another exemplary assembly can include a hook that extends from the receiver member and hooks onto an anatomical structure or other implant to enhance fixation of the primary bone anchor of the assembly. Surgical methods for using the bone anchor assemblies described herein are also disclosed.

[0023] Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the systems and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will appreciate that the systems and methods described in detail herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments.

[0024] Prior Art Bone Anchor Assemblies 1A-1C show a prior art bone anchor assembly 100 having various features that may be included in the bone anchor assemblies described below. It will be understood that the illustrated bone anchor assembly 100 is exemplary and that the bone anchor assemblies described herein may include additional or alternative features.

[0025] The illustrated bone anchor assembly 100 includes a bone anchor 102, a receiver member 104 for receiving a spinal fixation element, such as a spinal rod 106 coupled to the bone anchor 102, and a closure mechanism 108 for capturing the spinal fixation element within the receiver member and locking the spinal fixation element relative to the receiver member. The bone anchor 102 includes a proximal head 110 and a distal shaft 112 configured to engage bone. The receiver member 104 has a proximal end having a pair of spaced apart arms 114A, 114B with a recess 116 defined therebetween, and a distal end having a distal end face defining an opening through which at least a portion of the bone anchor 102 extends. A closure mechanism 108 is positionable between the arms 114A, 114B and can engage the arms 114A, 114B to capture a spinal fixation element (e.g., spinal rod 106) within the receiving member 104 and secure the spinal fixation element relative to the receiving member.

[0026] The proximal head 110 of the bone anchor 102 is generally in the shape of a truncated sphere with a planar proximal surface and a generally spherical distal surface. The illustrated bone anchor assembly 100 is a polyaxial bone screw designed for posterior implantation into the pedicle or lateral mass of a vertebra. The proximal head 110 of the bone anchor 102 engages the distal end of the receiver member 104 in a ball and socket-like arrangement that allows the proximal head and distal shaft 112 to pivot relative to the receiver member. The distal surface of the proximal head 110 of the bone anchor 102 and the mating surface within the distal end of the receiver member 104 can have any shape that facilitates this arrangement, including, for example, spherical (as shown), annular, conical, frusto-conical, and any combination of these shapes.

[0027] The distal shaft 112 of the bone anchor 102 can be configured to engage bone and in the illustrated embodiment includes external threads for engaging bone. The thread form of the distal shaft 112, including the number of threads, pitch, major and minor diameters, and thread shape, can be selected to facilitate connection with bone. Exemplary thread forms are disclosed in U.S. Patent Application Publication No. 2011 / 0288599, filed May 18, 2011, and U.S. Patent Application Publication No. 2013 / 0053901, filed August 22, 2012, the disclosures of both of which are incorporated herein by reference. The distal shaft 112 can also include other structures for engaging bone, such as hooks. For example, to facilitate delivery of the bone anchor over a guidewire in a minimally invasive procedure, the distal shaft 112 of the bone anchor 102 can be cannulated and have a central passage or cannula extending the length of the bone anchor. For example, other components of the bone anchor assembly 100, including the closure mechanism 108, the receiver member 104, and the compression member or cap 118 (discussed below), can be cannulated or have openings to allow delivery over a guidewire. The distal shaft 112 can further include one or more sidewall openings or fenestrations in communication with a cannula to allow bone ingrowth or to allow bone cement or other materials to be dispensed through the bone anchor 102. The sidewall openings can extend radially from the cannula through the sidewall of the distal shaft 112. Exemplary systems for delivering bone cement to the bone anchor assembly 100, as well as alternative bone anchor configurations for facilitating cement delivery, are described in U.S. Patent Application Publication No. 2010 / 0114174, filed October 29, 2009, the disclosure of which is incorporated herein by reference. The distal shaft 112 of the bone anchor 102 may further be coated with a substance that allows for bone ingrowth, such as, for example, hydroxyapatite, and the bone anchor assembly 100 may be partially or completely coated with an anti-infective substance, such as, for example, triclosan.

[0028] The proximal end of the receiver member 104 includes a pair of spaced apart arms 114A, 114B defining a U-shaped recess 116 therebetween for receiving a spinal fixation element (e.g., spinal rod 106). Each of the arms 114A, 114B can extend from the distal end to a free end of the receiver member 104. The outer surface of each of the arms 114A, 114B can include features, such as, for example, recesses, indentations, notches, protrusions, etc., to facilitate connection of the receiver member 104 to an instrument. For example, the outer surface of each arm 114A, 114B can include an arcuate groove at the respective free end of the arm. Such grooves are described in more detail in U.S. Patent No. 7,179,261, issued Feb. 20, 2007, the disclosure of which is incorporated herein by reference.

[0029] The distal end of the receiving member 104 includes a generally annular shaped distal end surface that defines a circular opening through which at least a portion of the bone anchor 102 extends. For example, the distal shaft 112 of the bone anchor 102 may extend through the opening.

[0030] The bone anchor 102 may be selectively secured to the receiver member 104. Prior to securing, the bone anchor 102 is movable relative to the receiver member 104 within a cone of angulation generally defined by the geometry of the distal end of the receiver member and the proximal head 110 of the bone anchor 102. The bone anchor assembly 100 may be a favored angle screw, for example, as disclosed in U.S. Patent No. 6,974,460, issued December 13, 2005, and U.S. Patent No. 6,736,820, issued May 18, 2004, both of which are incorporated herein by reference. Alternatively, the bone anchor assembly 100 may be a conventional (non-biased) polyaxial screw in which the bone anchor 102 pivots the same amount in all directions.

[0031] A spinal fixation element, such as a spinal rod 106, may directly contact the proximal head 110 of the bone anchor 102 or may contact an intermediate element, such as a compression member 118. The compression member 118 may be positioned within the receiving member 104 interposed between the spinal rod 106 and the proximal head 110 of the bone anchor 102 to compress a distal outer surface of the proximal head into direct fixed engagement with a distal inner surface of the receiving member 104. The compression member 118 may include a pair of spaced apart arms 120A and 120B that define a U-shaped seat 122 for receiving the spinal rod 106 and a distal surface for engaging the proximal head 110 of the bone anchor 102.

[0032] The proximal end of the receiver member 104 can be configured to receive a closure mechanism 108 positionable between and engaging the arms 114A, 114B of the receiver member. The closure mechanism 108 can be configured to capture a spinal fixation element (e.g., spinal rod 106) within the receiver member 104 to secure the spinal rod relative to the receiver member and to secure the bone anchor 102 relative to the receiver member. The closure mechanism 108 can be a single set screw externally threaded for engaging with internal threads on the arms 114A, 114B of the receiver member 104. However, in the illustrated embodiment, the closure mechanism 108 includes an external set screw 124 operable to act on the compression member 118 and an internal set screw 126 operable to act on the rod 106. The receiver member 104 may include, be integrally formed with, or be coupled to, one or more extension tabs 128 (shown in FIG. 1C ) that extend proximally from the receiver member 104 to operatively extend the length of the arms 114A, 114B. The extension tabs 128 may facilitate placement and assembly of an anchoring or stabilizing structure and may be removed prior to completing a surgical procedure.

[0033] The bone anchor assembly 100 may be used in conjunction with a spinal fixation element, such as a rigid spinal rod 106. Alternatively, the spinal fixation element may be a dynamic stabilizing member that allows controlled mobility between the vertebrae in which the device is implanted.

[0034] In use, the bone anchor assembly 100 can be assembled such that the distal shaft 112 extends through an opening in the distal end of the receiver member 104 and the proximal head 110 of the bone anchor 102 is received in the distal end of the receiver member 104. A driver instrument can be provided with the bone anchor to drive the bone anchor 102 into bone. The compression member 118 can be positioned within the receiver member 104 such that the arms 120A, 120B of the compression member are aligned with the arms 114A, 114B of the receiver member 104 and an underside of the compression member 118 contacts the proximal head 110 of the bone anchor 102. A spinal fixation element (e.g., spinal rod 106) can be positioned in the recess 116 of the receiver member 104. The closure mechanism 108 can be engaged with female threads provided on the arms 114A, 114B of the receiver member 104. A torsional force can be applied to the external set screw 124 to move the external set screw within the recess 116 to force the compression member 118 against the proximal head 110 of the bone anchor 102, thereby locking the angular position of the bone anchor 102 relative to the receiver member 104. A torsional force can be applied to the internal set screw 126 to force the spinal rod 106 into engagement with the compression member 118, thereby fixing the spinal rod 106 relative to the receiver member 104.

[0035] The bone anchor assemblies described below may be configured to operate with or include any of the features of the types of bone anchor assemblies described above (i.e., bone anchor assembly 100), or other types of bone anchor assemblies known in the art. Exemplary bone anchor assemblies include monoaxial screws, polyaxial screws, uniplanar screws, favored angle screws, and / or any of a variety of other bone anchors known in the art. More information on favored angle screws can be found in U.S. Patent Application No. 2013 / 0096618, filed October 9, 2012, the disclosure of which is incorporated herein by reference.

[0036] Multi-point fixation implant 2A-2M show an exemplary embodiment of a bone anchor assembly 200 shown in conjunction with a spinal rod 206. As discussed above, bone anchors can often be inserted in a compromised state. This can be undesirable, especially in the cervical region of the spine where there is limited bone area to place additional bone anchors. The illustrated bone anchor assembly 200 allows for secondary fixation of a primary bone anchor in a compact footprint without necessarily requiring removal or reinsertion of the primary bone anchor. As shown, the bone anchor assembly 200 can include a bone anchor 202, a receiving member 204, a closure mechanism 208, a bracket or wing 230, a nut 232, and one or more secondary bone anchors 234. In use, the wings 230 can be secured to the receiving member 204, for example, with the closure mechanism 208 and the nut 232, thereby providing the ability to enhance fixation of the bone anchor 202 to the one or more secondary bone anchors 234.

[0037] Except as described below and as would be readily understood by one of ordinary skill in the art, the bone anchor 202 and the receiving member 204 are substantially similar to the bone anchor 102 and the receiving member 104 described above. Accordingly, a detailed description of their structure and function is omitted herein for the sake of brevity. The bone anchor assembly 200 can include any one or more of the features of the bone anchor assembly 100 described above.

[0038] The closure mechanism 208 can be selectively secured to the receiver member 204 to capture a spinal fixation element, such as a spinal rod 206, within the receiver member. Tightening or locking of the closure mechanism 208 can be effective to secure the spinal rod 206 relative to the receiver member 204 and fix the angular position of the bone anchor 202 relative to the receiver member 204. The illustrated closure mechanism 208 is in the form of a threaded post having an enlarged diameter distal portion 208d and a reduced diameter proximal portion 208p. In other embodiments, the proximal portion 208p and the distal portion 208d can have the same diameter or the proximal portion can have a diameter larger than that of the distal portion. The distal portion 208d of the closure mechanism 208 can be threaded into the receiver member 204 to engage the spinal rod 206 disposed therein. As described further below, a proximal portion 208p of the closure mechanism 208 can protrude above the receiving member 204, for example, above a proximally facing end face of the receiving member, through an opening 230 formed in a wing 236.

[0039] In the illustrated embodiment, the closure mechanism 208 directly abuts the spinal rod 206, which in turn abuts directly against the head of the bone anchor 202. However, it will be appreciated that one or more intermediate elements may also be included in the bone anchor assembly 200. For example, the bone anchor assembly 200 may include a compression member of the type described above disposed between the spinal rod 206 and the head of the bone anchor 202. The closure mechanism 208 may be a single set screw as shown, or may include an external set screw operable to act on the compression member and an internal set screw operable to act on the rod 206. The closure mechanism 208 may include a driver interface (e.g., torx, flathead, Phillips head, square, or other) to facilitate rotational advancement or retraction of the closure mechanism relative to the receiver member 204 using a driver instrument.

[0040] The nut 232 can include a central opening 238 dimensioned to receive at least a portion of the proximal end 208p of the closure mechanism 208 therein. The central opening 238 can include female threads that correspond to the male threads of the closure mechanism 208 such that the nut 232 is threaded and tightened onto the closure mechanism such that the wings 230 are securely secured to the closure mechanism and the receiving member 204 in which the closure mechanism is disposed. The outer surface of the nut 232 can be faceted or configured to facilitate application of torque to the nut. In some embodiments, the nut 232 can have a hexagonal or square cross-section.

[0041] As shown in Figures 2E-2H, the bracket or wing 230 can include a proximal portion 230p that can contact the receiving member 204, a distal portion 230d that can contact or be positioned adjacent to a bone surface, and a spanning portion 230s that connects the proximal and distal portions.

[0042] The proximal portion 230p of the wing 230 can include a central opening 236 that is dimensioned to receive at least a portion of the closure mechanism 208 therein. For example, the central opening 236 can be dimensioned to receive the proximal portion 208p of the closure mechanism 208 therein. The central opening 236 can include a smooth, non-threaded inner surface such that the wings 230 and the closure mechanism 208 can freely rotate relative to one another. The proximal-facing surface 240 of the proximal portion 230p of the wing 230 can be domed or rounded to provide an atraumatic surface to reduce the risk of tissue irritation after implantation. The distal-facing surface 242 of the proximal portion 230p of the wing 230 can be configured to engage a proximal-facing surface of the receiver member 204. The distally facing surface 242 may form a convex or substantially convex inverse of the proximal facing surface of the receiver member 204. For example, the proximal facing surfaces of the arms 214A, 214B of the receiver member 204 may be radially convex, and the distally facing surfaces 242 of the wings 230 may define radially concave channels that receive the convex ends of the arms. In some embodiments, the central opening 236 or another feature of the wings 230 may be sized and configured to snap-fit ​​or capture a portion of the closure mechanism 208 or the proximal surface of the receiver member 204.

[0043] The distal portion 230d of the wing 230 can include one or more openings 244 configured to receive the bone anchor 234 therein. Although two bone anchor openings 244 are shown in the illustrated embodiment, it will be understood that the wing 230 can include any number of bone anchor openings (e.g., one, two, three, four, five, etc.). The bone anchor openings 244 can include any of a number of features for receiving the bone anchor 234 at different angles and / or for increasing the security and stability with which the bone anchor can be secured to the wing 230. Exemplary features that may be included are disclosed in U.S. Patent No. 7,637,928 issued December 29, 2009, U.S. Patent No. 8,343,196 issued January 1, 2013, U.S. Patent No. 8,574,268 issued November 5, 2013, U.S. Patent No. 8,845,697 issued September 30, 2014, and U.S. Patent No. 8,758,346 issued June 24, 2014, each of which is incorporated by reference herein. For example, the bone anchor opening 244 may be at least partially threaded to receive a variable angle locking screw having a threaded proximal head. As shown, the opening 244 may have multiple rows of threads spaced apart to define a plurality of non-threaded recesses. In the illustrated embodiment, each of the openings 244 has four rows of threads. A row of threads may be provided around the inner surface of each of the openings 244 for engaging threads on the head of the locking and / or variable angle locking secondary bone anchor, such that the secondary bone anchor 234 may be locked to the wing 230 either coaxially with the central axis of the opening 244 or at a selected angle within a selectable range of angles relative to the central axis of the opening. The secondary bone anchor 234 may include features to facilitate this variable angle locking, such as an at least partially spherical proximal head having threads with a profile that follows the arcuate radius of curvature of the spherical portion of the head.The variable angle nature of the screw / aperture interface allows the user to place the locking auxiliary bone anchor in the bone at any angle within the predefined angulation limits, thus improving placement versatility and eliminating or reducing the need to conform the distal portion of the wing to the bone surface to achieve the desired insertion angle. The auxiliary bone anchors 234 can be driven into the bone in divergent or converging directions (relative to each other and / or to the main bone anchor 202) along the longitudinal axis, which can provide improved pull-out resistance. In some embodiments, the interior surface of the aperture 244 can be smooth or spherical without threads or locking features.

[0044] The central axis of each of the openings 244 can be orthogonal or substantially orthogonal to the distally facing surface 246 of the wing 230. Alternatively, one or more of the openings can have a central axis that extends at an oblique angle relative to the distally facing surface 246. In the illustrated embodiment, the central axis of each opening 244 extends at an angle of about 7 degrees relative to the distally facing surface 246. In some embodiments, the central axis of each opening 244 can extend at an angle of about 0 degrees to about 15 degrees relative to the distally facing surface 246 (e.g., embodiments used for bony attachment locations that allow for direct proximal to distal screw insertion). In some embodiments, the central axis of each opening 244 can extend at an angle of about 15 degrees to about 45 degrees relative to the distally facing surface 246 (e.g., embodiments used for bony attachment locations where an angled trajectory may avoid or target certain anatomical structures). An angled or bifurcated central axis can advantageously increase the pull-out resistance of the construct.

[0045] The distal portion 230d of the wing 230 can have a distally facing surface 246 configured to contact or be placed proximate to a bone. The distally facing surface 246 can include teeth, texturing, or other surface features to enhance grip with adjacent bone. The distal portion 230d of the wing 230 can have an outer surface 248 that abuts the sidewall of the receiver member 204. The outer surface 248 can form an inverted concave-convex shape with the sidewall of the receiver member 204 such that the distal portion 230d of the wing 230 hugs the receiver member with minimal or no clearance. For example, the outer surface 248 can be concave with a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 204.

[0046] The spanning portion 230s of the wing 230 can extend perpendicularly in a proximal to distal direction to join the proximal portion 230p of the wing to the distal portion 230d of the wing. The spanning portion 230s of the wing 230 can have an outer surface 250 that engages the sidewall of the receiver member 204. The outer surface 250 can form an inverted concave-convex shape with the sidewall of the receiver member 204 such that the spanning portion 230s of the wing 230 hugs the receiver member with minimal or no clearance. For example, the outer surface 250 can be a recess having a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 204. The outer surface 250 can also include one or more recesses 252 for engaging a corresponding recess 254 formed in the sidewall of the receiver member 204 or for engaging one or more recesses in which a protrusion of the receiver member is received. The interaction between the one or more protrusions 252 and the one or more recesses 254 may be effective to limit or prevent rotation of the wing 230 relative to the receiver member 204. This interaction may also be effective to limit or prevent movement of the wing 230 along a proximal-distal axis relative to the receiver member 204. The spanning portion 230s may include webbing or ribs 256 to increase the structural rigidity of the wing 230. The ribs 256 may be formed on an outer surface of the spanning portion 230s opposite the outer surface 250 that engages the receiver member 204.

[0047] Proximal portion 230p, distal portion 230d, and spanning portion 230s may be integrally formed as a one-piece unit as shown, or one or more of the components may be separate and selectively attachable to the other components. In some embodiments, a kit of modular components may be provided to allow for the selection of the components best suited for a given application. For example, the appropriate height of spanning portion 230s may be selected based on the distance between the proximal end of receiver member 204 and the bone surface in a given application.

[0048] One or more portions of the wings 230 may be flexible or deformable to allow customization of the wings to a particular situation. For example, the distal portion 230d of the wings 230 may be flexible or deformable to allow the distal portion to be contoured to a bone surface. The distal portion 230d may be contoured pre-implant or in vivo. The distal portion 230d may be contoured using a separate bending tool or may be formed by tightening the bone anchor 234 to deform the distal portion to fit the bone surface. The distal portion 230d of the wings 230 may be pre-shaped or pre-contoured, for example, during manufacture, to match the bone surface on which the bone anchor assembly 200 is to be used.

[0049] As a further example, the spanning portion 230s of the wing 230 may be flexible or deformable to allow the positioning of the bone anchor opening 244 to be adjusted relative to the receiver member 204. The spanning portion 230s may be bent or curved inwardly or outwardly (e.g., in a medial-lateral direction) to move the bone anchor opening 244 inwardly toward the receiver member 204 or outwardly away from the receiver member. Such bending may increase or decrease the effective height of the wing 230 to accommodate the variable distance that may occur between the proximal end of the receiver member 204 and the bone surface. The spanning portion 230s may be bent or curved upwardly or downwardly (e.g., in a superior to inferior direction) to move the bone anchor opening 244 relative to the receiver member 204. The spanning portion 230s may be contoured pre-implantation or in vivo. The spanning portion 230s can be contoured using a separate bending tool, or can be contoured by tightening the bone anchors 234 to deform the spanning portion into the desired shape. The spanning portion 230s of the wing 230 can be pre-shaped or pre-contoured for a given application, for example, during manufacture.

[0050] As yet another example, proximal portion 230p of wing 230 can be flexible or deformable and / or the joints or locations at which proximal portion 230p, distal portion 230d, and spanning portion 230s are joined can also be flexible or deformable. Proximal portion 230p, distal portion 230d, and spanning portion 230s can be joined by living hinges or other joints that allow adjustment of their relative positions.

[0051] The spanning portion 230s can have an adjustable height. For example, as shown in FIGS. 2I-2M, the spanning portion 230s can include first and second flexible or deformable legs 258. The legs 258 can be bent inwardly toward one another to increase the height of the spanning portion 230s. The legs 258 can be bent outwardly toward one another to decrease the height of the spanning portion 230s. Each leg 258 can include an upper portion and a lower portion joined by a flexible joint (e.g., a living hinge, a pivot pin, etc.). To reduce material stress when bending the legs, rounded or semicircular surfaces can be formed at the joints between the legs 258 and the proximal and distal portions 230p, 230d of the wings 230. Similarly, rounded or semicircular cutout surfaces can be formed so that the upper portion of each leg 258 meets the lower portion. The cut-out surfaces can reduce pressure and can also provide an engagement surface for gripping the legs 258 with a tool configured to apply a squeezing force thereto.

[0052] The bone anchor assembly 200 can provide significant flexibility to the surgeon. The wings 230 can be easily rotated 180 degrees to be positioned on either side of the rod 206 (e.g., on the inside or outside of the rod). As shown in FIG. 2D, the wings 230 can be freely rotated about the closure mechanism 208 before final locking of the wings to the receiver member 204 so that the auxiliary bone anchor holes 244 can be positioned in various positions relative to the spinal rod 206. As described in detail above, the wings 230 can be deformable or flexible or can include deformable or flexible portions to allow the wings to fit snugly against the receiver member 204, to conform to the contours of the bone surface, to reposition the auxiliary bone anchor holes 244 relative to the receiver member, and / or to adjust the height of the wings to accommodate situations where receiver members of different heights or the main bone anchor 202 are inserted higher or lower within the bone.

[0053] 2A , the proximal-most segment of each auxiliary bone anchor 234 can be distal to the spinal rod 206. In other embodiments, the proximal-most segment of each auxiliary bone anchor 234 can be distal to the distal-most segment of the receiver member 204. These configurations can advantageously reduce the overall profile of the assembly 200. The wings 200 can be Z-shaped or substantially Z-shaped.

[0054] The wings 230 can extend radially outward from the receiver member 204 (e.g., a distance equal to the width of the distal portion 230d of the wings). The extent to which the wings 230 extend outward from the receiver member 204 can vary among different embodiments. In the illustrated embodiment, the ratio of the wing extension to the rod diameter (or the ratio of the wing extension to the width of the rod-receiving recess in the receiver member) is about 2:1. In some embodiments, this ratio can be less than about 10:1, less than about 5:1, less than about 3:1, less than about 2:1, less than about 1:1, and / or less than about 0.5:1. In some embodiments, this ratio can be about 10:1, about 5:1, about 3:1, about 2:1, about 1:1, or about 0.5:1.

[0055] The center of the auxiliary bone anchor hole 244 (and thus at least a portion of the auxiliary bone anchor 234 disposed therein) may be radially spaced from the center of the opening of the receiver member 204 in which the primary bone anchor 202 is disposed. In some embodiments, this spacing may be less than about 2.5 times the diameter of the receiver member 204. In some embodiments, this spacing may be less than about 2 times the diameter of the receiver member 204. In some embodiments, this spacing may be less than the diameter of the receiver member 204. In some embodiments, this spacing may be between about 5 mm and about 10 mm. In some embodiments, this spacing may be about 7.5 mm. In some embodiments, the auxiliary bone anchor 234 may be contained within an envelope of no more than 2.5 times the diameter of the receiver member 204. In some embodiments, the auxiliary bone anchor 234 may be contained within an envelope of no more than 2 times the diameter of the receiver member 204.

[0056] The auxiliary bone anchor 234 may include any of the features of the bone anchor 202 described above, and may be used in place of or in addition to any of a variety of other bone screws or other anchors. As described above, the auxiliary bone anchor 234 may have a threaded proximal head to facilitate variable angle locking with the wings 230. In some embodiments, the auxiliary bone anchor 234 may have a length of about 6 mm to about 20 mm (e.g., in embodiments used in cervical applications). In some embodiments, the auxiliary bone anchor 234 may have a length of about 6 mm to about 100 mm (e.g., in embodiments used in lumbar or sacral applications). The length of the auxiliary bone anchor 234 may be selected based on a variety of factors, including the safe bone available at any given attachment location. The auxiliary bone anchor 234 may have a length equal to the length of the main bone anchor 202. The auxiliary bone anchor 234 may have a length less than the length of the main bone anchor 202. The auxiliary bone anchor 234 may have a length that is about 60% to about 80% of the length of the main bone anchor 202. The auxiliary bone anchor 234 can have a length that is about 70% of the length of the main bone anchor 202. The auxiliary bone anchor 234 can have a length of about 10 mm. The auxiliary bone anchor 234 can have a length of about 14 mm. In some embodiments, two 10 mm auxiliary bone anchors can be used with one 14 mm main bone anchor. In some embodiments, one 14 mm auxiliary bone anchor can be used with one 14 mm main bone anchor. The auxiliary bone anchor 234 can have a shank diameter equal to the shank diameter of the main bone anchor 202. The auxiliary bone anchor 234 can have a shank diameter smaller than the shank diameter of the main bone anchor 202. The auxiliary bone anchor 234 can have a shank diameter that is about 50% to about 70% of the shank diameter of the main bone anchor 202. The auxiliary bone anchor 234 can have a shank diameter that is about 60% of the shank diameter of the main bone anchor 202.

[0057] As described above in the embodiments of Figures 2A-2M, secondary fixation of the primary bone anchor in the bone anchor assembly can be accomplished using wings or brackets having one or more bone anchor openings through which one or more secondary bone anchors can be driven into the bone. However, in some cases, surgeons may experience difficulty in placing a particular bone anchor having an angular trajectory. Variations in the bone anatomy of the spine may make it difficult to position the distal portion of the wing in close proximity to the bone to facilitate proper engagement or purchase of the anchor. The driver instrument used to drive the secondary anchor into the bone may require more clearance to access the bone anchor opening in the wing.

[0058] To address such potential difficulties in the supplemental fixation of the auxiliary bone anchor, various embodiments of bone anchor assemblies are disclosed herein that include wings or brackets with angled distal portions. In some embodiments, the distal portion of the wing may be angled to the right or left of the spanning portion of the wing to facilitate placement of bone anchors having a cephalad trajectory (i.e., toward the patient's head) and / or a caudal trajectory (i.e., toward the patient's foot). In some embodiments, the distal portion of the wing or bracket may alternatively or additionally be angled inwardly or outwardly to facilitate placement of bone anchors having a medial trajectory (i.e., toward the patient's middle) or a lateral trajectory (i.e., toward the patient's side). Such angling may improve engagement or fixation of the auxiliary anchor to the bone and / or facilitate access by a driver instrument to the bone anchor opening in the wing.

[0059] 3A-3I show an exemplary embodiment of a bone anchor assembly 500 including a bracket or wing 530 having an angled distal portion 530d. When viewed from the perspective of FIG. 3A, the distal portion 530d is angled toward the right side of the wing 530. The bone anchor assembly 500 can include a bone anchor 502, a receiver member 504, a closure mechanism 508, a bracket or wing 530, a nut 532, and a secondary bone anchor 534. The wing 530 can be secured to the receiver member 504, for example, with the closure mechanism 508 and the nut 532, thereby providing the ability to enhance fixation between the bone anchor 502 and the secondary bone anchor 534 having an angled trajectory. The closure mechanism 508 can be secured to the receiver member 504 to capture a spinal fixation element, for example, a spinal rod 506, within the receiver member. Tightening or locking of the closure mechanism 508 can be effective to fix the spinal rod 506 relative to the receiver member 504 and fix the angular position of the bone anchor 502 relative to the receiver member 504.

[0060] Except as described below or as would be readily understood by one of ordinary skill in the art, the bone anchor 502, the receiving member 504, the closure mechanism 508, the nut 532, and the auxiliary bone anchor 534 are substantially similar to the bone anchor 202, the receiving member 204, the closure mechanism 208, the nut 232, and the auxiliary bone anchor 234 described above with respect to Figures 2A-2M. Accordingly, a detailed description of their structure and function is omitted here for the sake of brevity. The bone anchor assembly 500 can include any one or more of the features of the bone anchor assembly 200 and / or the bone anchor assembly 100 described above.

[0061] In the illustrated embodiment, the bracket or wing 530 may include a proximal portion 530p, an angled distal portion 530d, and a spanning portion 530s connecting the proximal portion of the wing to the distal portion. The proximal portion 530p of the wing 530 may extend horizontally from the proximal end of the spanning portion 530s of the wing 530. The proximal portion 530p may include a proximal-facing surface 540 and a distal-facing surface 542. The proximal-facing surface 540 of the proximal portion 530p of the wing 530 may be domed or rounded to provide an atraumatic surface to reduce the risk of tissue irritation after implantation. The distal-facing surface 542 of the proximal portion 530p of the wing 530 may be configured to abut the proximal end or surface of the receiver member 504. The distally facing surface 542 may form a convex or substantially convex inverse of the proximal end or surface of the receiver member 504. For example, the proximal facing surfaces of the arms of the receiver member 504 may be radially convex and the distally facing surfaces 542 of the wings 530 may define radially concave channels (not shown) that receive the convex ends of the arms.

[0062] The proximal portion 530p of the wing 530 can define a central opening 536 extending through the proximal-facing surface 540 and the distal-facing surface 542. The central opening 536 can be oriented such that a central axis of the opening A3 is perpendicular or substantially perpendicular to the distal-facing surface 542 of the proximal portion 530p of the wing 530. The central opening 536 can be sized such that the closure mechanism 508 is inserted through the opening and extends at least partially above the proximal-facing surface 540 of the proximal portion 530p of the wing 530. The central opening 536 can include a smooth, non-threaded interior surface such that the wings 530 and the closure mechanism 508 are freely rotatable relative to one another. The central opening 536 or another feature of the wing 530 can be sized and configured to snap-fit ​​or capture a portion of the closure mechanism 508 or a proximal surface of the receiving member 504. In the illustrated exemplary embodiment, a counterbore 560 may be formed about central opening 536 in distally facing surface 542 of proximal portion 530p of wing 530 to accommodate a radially extending shoulder portion of closure mechanism 508, which may extend above the proximal end of receiver member 504. The structure and function of counterbore 560 will be discussed in more detail with respect to Figures 4A-4C.

[0063] The spanning portion 530s of the wing 530 can extend vertically in a proximal to distal direction to join the proximal portion 530p of the wing to the distal portion 530d of the wing. The spanning portion 530s of the wing 530 can be an elongated arm that extends distally from the sidewall of the proximal portion 530p of the wing in a vertical or substantially vertical plane. The spanning portion 530s of the wing 530 can have an outer surface 550 that engages or faces the sidewall of the receiver member 504. The outer surface 550 can form an inverted concave-convex shape with the sidewall of the receiver member 504 such that the spanning portion 530s of the wing 530 can embrace the receiver member with minimal or no clearance between the outer surface 550 and the sidewall of the receiver member 504. For example, the outer surface 550 can be a concave shape having a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 504. Proximal portion 530p, distal portion 530d, and spanning portion 530s may be integrally formed as a one-piece unit as shown, or one or more of the components may be separate and selectively attachable to the other components. In some embodiments, a kit of modular components may be provided to allow for selection of the components best suited for a given application. For example, an appropriate height of spanning portion 530s may be selected based on the distance between the proximal end of receiver member 504 and the bone surface in a given application.

[0064] In some embodiments, the wing 530 may include one-sided locking interfaces of various mechanisms, such as, but not limited to, one or more grooves 570a, 570b, and surface protrusions 570c. The one-sided locking interfaces allow a surgical instrument including a one-sided locking mechanism (not shown) to securely attach to one side of the wing 530. Exemplary one-sided locking interfaces that may be included on the wing 530 are disclosed in U.S. Patent Application No. 15 / 843,618, entitled "Unilateral Implant Holders and Related Methods," filed December 15, 2017, the entire contents of which are incorporated herein by reference.

[0065] Angled distal portion 530d of wing 530 can extend outwardly from a distal end of spanning portion 530s away from receiver member 504. The extent to which wings 530 extend outwardly from receiver member 504 can vary among different embodiments. In the illustrated embodiment, the ratio of the wing extension to the rod diameter (or the ratio of the wing extension to the width of the rod-receiving recess in the receiver member) is about 2:1. In some embodiments, this ratio can be less than about 10:1, less than about 5:1, less than about 3:1, less than about 2:1, less than about 1:1, and / or less than about 0.5:1. In some embodiments, this ratio can be about 10:1, about 5:1, about 3:1, about 2:1, about 1:1, or about 0.5:1.

[0066] When viewed from the perspective of FIG. 3E, the angled distal portion 530d is angled to the right of the vertically disposed spanning portion 530s of the wing 530. As shown, the angled distal portion 530d includes a distal surface 546 and a proximal surface 548. The distal surface 546 and the proximal surface 548 may be oriented in a parallel or substantially parallel orientation. The distally facing surface 546 may include teeth, texturing, or other surface features to enhance grip with adjacent bone. The distal portion 530d of the wing 530 may have an outer surface 552 that abuts or faces the sidewall of the receiver member 504. The outer surface 552 may form an inverted contour with the sidewall of the receiver member 504 such that the distal portion 530d of the wing 530 can hug the receiver member with minimal or no clearance between the outer surface 552 and the sidewall of the receiver member 504. For example, the outer surface 552 can be a recess having a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 504 .

[0067] The distal portion 530d of the wing 530 can define an opening 544 extending through the proximal face 548 and the distal face 546 for receiving the auxiliary bone anchor 534. The bone anchor opening 544 can be sized to allow the distal shaft of the auxiliary bone anchor 534 to be inserted therethrough and abut the proximal head of the auxiliary bone anchor when the auxiliary bone anchor is positioned therein. As shown in the illustrated embodiment, the bone anchor opening 544 can be oriented perpendicular or substantially perpendicular to the distal face 546 of the wing 530. In other configurations, the nominal or central axis of the bone anchor opening can be angled obliquely relative to the distal face 546 and / or the proximal face 548 of the wing 530. The distal face 546 of the wing 530 and / or the proximal face 548 of the wing can be angled obliquely relative to the superior-inferior axis or the proximal-distal axis of the wing. For example, as shown, the distal face 546 is angled to face toward the right of the vertically disposed spanning portion 530s. In such an embodiment, the central axis A2 of the bone anchor opening 544 may extend downward and to the right at an oblique angle relative to the proximal-distal axis A1 of the wing spanning portion 530s. This configuration can facilitate a variety of bone anchor arrangements in which the distal end of the auxiliary bone anchor is to the right of the wing spanning portion 530s when viewed from the perspective of FIG. 3A.

[0068] For example, as shown in FIG. 3A, such bone anchor placement can include an arrangement in which the wings 530 are positioned on the outside of the spinal rod 506 and the auxiliary bone anchor 534 is driven through the bone anchor opening 544 in a cephalad trajectory (i.e., toward the patient's head). This orientation can allow the auxiliary bone anchor 534 to remain entirely at the same vertebral level as the main bone anchor 502, for example, within the lateral mass of the vertebra. It will be appreciated that the wings 530 can be rotated 180 degrees to be positioned on the opposite side of the illustrated rod 506 (e.g., medial side of the rod) or to be positioned on the outside of the contralateral spinal rod (not shown). In these cases, this positioning of the wings 530 can facilitate bone anchor placement in which the auxiliary bone anchor 534 can be driven through the bone anchor opening 544 in a caudal trajectory (i.e., toward the patient's foot). 5A, the caudal trajectory can allow for anchoring of multiple (e.g., at least two, at least three, or more) auxiliary bone screws 534 into the cortical bone layer. The angled distal portion 530d can allow for bone anchor placement as described above while maintaining the distal faces 546 of the wings 530 in contact with or in close proximity to the bone surface (e.g., within 0-3 mm).

[0069] In some embodiments, the distal surface 546 of the wing 530 can be angled obliquely to fix the central axis A2 of the bone anchor opening 544 at any oblique angle to the right of the spanning portion 530s of the wing 530, depending on the requirements of a particular application. For example, as shown in FIG. 3E, the distal surface 546 of the distal portion 530d of the wing 530 can be angled obliquely so that the central axis A2 of the bone anchor opening 544 extends at an angle of 35 degrees to the right of the proximal-distal axis A1 of the spanning portion 530s of the wing 530. Thus, the auxiliary bone anchor 534 can be easily positioned within the bone anchor opening 544 with the distal shaft of the anchor having an angular trajectory coaxial with the central axis A2 of the bone anchor opening 544 toward the right of the spanning portion 530s, or within a predefined conical angle relative to the central axis A2 of the bone anchor opening 544. In some embodiments, the distal surface 546 of the wing 530 can be angled obliquely such that the central axis A2 of the bone anchor opening 544 can extend at an angle of 15 to 45 degrees (inclusive) to the right of the proximal-distal axis A1 of the spanning portion 530s.

[0070] In some embodiments, the distal surface 546 of the wing 530 can be further angled inwardly or outwardly relative to the perpendicularly disposed spanning portion 530s of the wing 530. By angling the distal surface 546 inwardly or outwardly, the distal portion 530d can facilitate a supplemental bone anchor placement through the bone anchor opening 544 having a medial or lateral trajectory component in addition to or instead of a cranial or caudal trajectory component. In some embodiments, angling the distal surface 546 inwardly or outwardly can facilitate a bone anchor placement in which the supplemental bone anchor 534 is secured within the lateral mass of the vertebra. In some embodiments, angling the distal surface 546 of the wing 530 inwardly or outwardly can provide clearance for a driver instrument to access the bone anchor opening 544 on the proximal surface 548 of the distal portion 530d of the wing 530. In some embodiments, the distal surface 546 of the wing 530 can be angled obliquely inwardly or outwardly to fix the central axis A2 of the bone anchor opening 544 at any medial or lateral angle relative to the proximal-distal axis A1 of the spanning portion 530s of the wing 530 based on the requirements of a particular application. For example, as shown in FIG. 3F, the distal surface 546 of the distal portion 530d of the wing 530 can be angled inwardly toward the spanning portion 530s of the wing 530 such that the central axis A2 of the bone anchor opening 544 extends inwardly at a 15 degree medial angle relative to the proximal-distal axis A1 of the spanning portion 530s. Thus, the auxiliary bone anchor 534 can be easily positioned within the bone anchor opening 544 with the distal shaft of the anchor having an inner trajectory that is coaxial with the central axis A2 of the bone anchor opening 544 or within a predefined conical angle relative to the central axis A2 of the bone anchor opening 544. In some embodiments, the distal surface 546 of the distal portion 530d of the wing 530 can be angled obliquely such that the central axis A2 of the bone anchor opening 544 can extend at an inner angle of 5 to 20 degrees, inclusive.

[0071] Alternatively, as shown in FIG. 3G, the distal surface 546 of the distal portion 530d of the wing 530 can be angled outwardly away from the spanning portion 530s such that the central axis A2 of the bone anchor opening 544 extends outward at an outer angle of 15 degrees relative to the proximal-distal axis A1 of the spanning portion 530s of the wing 530. Thus, the auxiliary bone anchor 534 can be easily placed in the bone anchor opening 544 with the distal shaft of the anchor having an outer trajectory that is coaxial with the central axis A2 of the bone anchor opening 544 or within a predefined cone-shaped angle relative to the central axis A2 of the bone anchor opening 544. In some embodiments, the distal surface 546 of the distal portion 530d of the wing 530 can be angled obliquely such that the central axis A2 of the bone anchor opening 544 can extend at an outer angle of 5 to 20 degrees inclusive. Such embodiments can be useful to accommodate the bony anatomy of the lumbar spine.

[0072] FIG. 3H is a top view of the wing 530 of the bone anchor assembly of FIG. 3A with the angled distal portion 530d facing in a caudal direction. As shown in FIG. 3H, from a posterior perspective, the wing 530 can be positioned with the angled distal portion 530d extending laterally to the left of the spinal midline and thus facing in a caudal direction. In this exemplary caudal configuration, the angled distal portion 530d of the wing 530 has an upper end 580, a lower end 582, a free outer end 584 extending between the upper and lower ends, and a medial end 586 extending between the upper and lower ends. With the angled distal portion 530d facing caudally, the upper end 580 of the distal portion 530d is distal (or lower) than the lower end 582, such that the distal surface 546 faces in a caudal direction. In some embodiments, when distal portion 530d is also angled medially (e.g., as described above in FIG. 3F), the upper end 580 of distal portion 530d is distal to the lower end 582 and the free lateral end 584 is distal to the medial end, such that distal surface 546 faces in both the caudal and medial directions. In some embodiments, when distal portion 530d is also angled laterally (e.g., as described above in FIG. 3G), the upper end 580 of distal portion 530d is distal to the lower end 582 and the medial end 586 is distal to the free lateral end 584, such that distal surface 546 faces in both the caudal and lateral directions.

[0073] FIGURE 3I is a top view of the wing 530 of the bone anchor assembly of FIGURE 3A with the angled distal portion 530d facing in a cranial direction. As shown in FIGURE 3I, from a posterior perspective, the wing 530 can be positioned with the distal portion 530d extending laterally to the right of the spinal midline and thus facing in a cranial direction. In this exemplary cranial configuration, the angled distal portion 530d of the wing 530 has an upper end 590, a lower end 592, a free outer end 594 extending between the upper and lower ends, and a medial end 596 extending between the upper and lower ends. With the distal portion 530d facing cranially, the lower end 592 of the distal portion 530d is distal (or lower) than the upper end 590, such that the distal surface 546 faces in a cranial direction. In some embodiments, when distal portion 530d is also angled medially (e.g., as described above in FIG. 3F), the lower end 592 of distal portion 530d is distal (or inferior) to the upper end 590 and the free outer end 594 is distal to the inner end 596, such that distal surface 546 faces in both the cranial and medial directions. In some embodiments, when distal portion 530d is also angled laterally (e.g., as described above in FIG. 3G), the lower end 592 of distal portion 530d is distal (or inferior) to the upper end 590 and the inner end 596 is distal to the free outer end 594, such that distal surface 546 faces in both the cranial and medial directions.

[0074] In some embodiments, the bone anchor opening 544 can include any of a number of features for receiving the bone anchor 534 at various angles. For example, as described above with respect to FIGS. 2A-2M, the bone anchor opening 544 can be at least partially threaded to receive a variable angle locking screw having a threaded proximal head. As shown, the opening 544 can have multiple rows of threads spaced apart to define multiple non-threaded recesses. In the illustrated embodiment, the opening 544 has four rows of threads. The rows of threads can be provided around an inner surface of the opening 544 to engage threads on the head of the locking auxiliary bone anchor and / or the variable angle locking auxiliary bone anchor. This allows the auxiliary bone anchor 534 to lock into the wing 530 coaxially with the central axis A2 of the opening 544 or at a selected angle within a selectable range of angles relative to the central axis A2 of the opening 544. The auxiliary bone anchor 534 can include features to facilitate this variable angle locking, such as a proximal head that is at least partially spherical with threads having a profile that follows the arcuate radius of curvature of the spherical portion of the head. The variable angle capability of the screw / aperture interface can allow the user to place the locking auxiliary bone anchor into the bone at any angle within defined angle limits. In some embodiments, the interior surface of the aperture 544 can be smooth or spherical without threads or locking features.

[0075] In some embodiments, the proximal-most segment of each auxiliary bone anchor 534 can be distal to the spinal rod 506. In other embodiments, the proximal-most segment of each auxiliary bone anchor 534 can be distal to the distal-most segment of the receiver member 504. These configurations can advantageously reduce the overall profile of the assembly 500. The wings 500 can be Z-shaped or substantially Z-shaped. Although one bone anchor opening 544 is shown in the illustrated embodiment, it will be understood that the wings 530 can include any number of bone anchor openings (e.g., 1, 2, 3, 4, 5, etc.).

[0076] 4A-4C are cross-sectional views of a wing or bracket 530 secured to the bone anchor assembly 500 of FIGS. 3A-3H. As mentioned above, the proximal portion 530p of the wing can include a distally facing surface 542 configured to abut a proximal end or surface of the receiver member when the wing 530 is secured to the receiver member 504. For example, in some embodiments, the closure mechanism 508 can be in the form of a threaded post having an enlarged distal portion 508d and a reduced proximal portion 508p. The distal portion 508d of the closure mechanism 508 can thread into the receiver member 504 and engage a spinal rod 506 disposed therein. The proximal portion 508p of the closure mechanism 508 can protrude above the receiver member 504, e.g., above a proximal opposing end surface of the receiver member, through an opening 536 formed in the wing.

[0077] However, the distal portion 508d of the closure mechanism 508 may not be fully threaded into the receiver member 504, which may cause the radially extending shoulder portion 508s of the closure mechanism 508 to protrude above the proximal end of the receiver member 504. In such a case, the shoulder portion 508s of the closure mechanism 508 may abut the proximal portion 530p of the distally facing surface 542 of the wing 530, thereby preventing the proximal portion 530p from bearing weight on the receiver member 504. This may result in unreliable and / or inconsistent tightening of the wing 530 to the bone anchor assembly 500.

[0078] As shown in the illustrated embodiment of FIGS. 4A and 4B, a counterbore 560 may be formed around the opening 536 in the distally facing surface 542 of the proximal portion 530p to more consistently secure the wing 530 to the bone anchor assembly 500. The counterbore 560 may be an annular ring or channel formed around the opening 536. The counterbore 560 may be sized to correspond to the width of the shoulder portion 508s. The depth or height of the counterbore 560 may be configured to at least partially receive the shoulder portion 508s that protrudes above the receiver member 504 to maintain contact between the proximal portion 530p of the wing 530 and the proximally facing surface of the receiver member 504. The depth or height of the counterbore 560 may be configured not to exceed a threshold depth or height at which the closure mechanism may disengage from the spinal rod and thus compromise the fixation of the rod 506 within the receiver member 504. Embodiments including countersunk holes can provide more reliable and / or consistent fastening regardless of the vertical position of the closure mechanism by ensuring that the wings are always fastened to the receiving member.

[0079] Alternatively or additionally, as shown in the illustrated embodiment of FIG. 4C, the closure mechanism 508 can be sized such that the radially extending shoulder portion 508s is configured to always extend above the receiver member 504. In such an embodiment, the distally facing surface 542 of the proximal portion 530d of the wing 530 abuts the radially extending shoulder portion 508s of the closure mechanism 508 instead of the receiver member 504. For example, as shown in FIG. 4C, the enlarged distal portion 508d of the closure mechanism 508 can be configured with an extension height H that allows the shoulder portion 508s of the closure mechanism 508 to protrude above the receiver member 504 when contacted with the spinal rod 506. Such an embodiment can provide more reliable and / or consistent tightening of the wing 530 regardless of the vertical position of the closure mechanism by ensuring that the wing is always tightened against the closure mechanism.

[0080] As mentioned above, some embodiments of the bone anchor assembly can include wings having a distal portion angled to the left of the vertically disposed wings. In such embodiments, the auxiliary bone anchor can be placed through an opening in the distal portion in a caudal or cranial trajectory similar to that facilitated by the wing 530 of the bone anchor assembly 500 when implanted on the opposite side of the patient's spine (i.e., on the patient's left hand side).

[0081] 5A-5F show an exemplary embodiment of a bone anchor assembly 700 including a bracket or wing 730 having an angled distal portion 730d. As shown, the bone anchor assembly 700 includes a bone anchor 702, a receiving member 704, a closure mechanism 708, a bracket or wing 730, a nut 732, and a supplementary bone anchor 734. Except as described below or as would be readily understood by one of ordinary skill in the art, the bone anchor 702, the receiving member 704, the closure mechanism 708, the nut 732, and the supplementary bone anchor 734 are substantially similar to the bone anchor 202, the receiving member 204, the closure mechanism 208, the nut 232, and the supplementary bone anchor 234 described above with respect to FIGS. 2A-2M. Thus, a detailed description of their structure and function is omitted here for the sake of brevity. The bone anchor assembly 700 may include any one or more of the features of one or more of the bone anchor assemblies described above.

[0082] As shown in Figures 5A-5F, bracket or wing 730 may include a proximal portion 730p, an angled distal portion 730d, and a spanning portion 730s connecting the proximal portion of the wing to the distal portion. Except as described below or as would be readily understood by one of ordinary skill in the art, the proximal portion 730p and the spanning portion 730s of wing 730 are substantially similar to the proximal portion 530p and the spanning portion 530s of wing 530 described above in connection with Figures 3A-3I and 4A-4C. Thus, a detailed description of their structure and function will be omitted here for the sake of brevity. Wing 730 may include any one or more of the features of wing 500 described above.

[0083] In the illustrated embodiment, the distal portion 730d of the wing 730 is substantially similar to the distal portion 530d of the wing 500, except that the distal portion 730d is angled to the left of the perpendicularly disposed spanning portion 730s (as viewed from the perspective of FIG. 5D). As shown, the angled distal portion 730d can include a distal face 746 and a proximal face 748 that can be oriented in a parallel or substantially parallel orientation. The distal portion 730d of the wing 730 can define an opening 744 extending through the proximal face 748 and the distal face 746 for receiving the auxiliary bone anchor 534. As shown in the illustrated embodiment, the bone anchor opening 744 can be oriented perpendicular or substantially perpendicular to the distal face 746 of the wing 730. In other configurations, a nominal or central axis of the bone anchor opening can be angled obliquely relative to the distal face 746 and / or the proximal face 748. The distal surface 746 of the wing 730 and / or the proximal surface 748 of the wing can be angled obliquely relative to the superior-subordinate or proximal-distal axis of the wing. For example, as shown, the distal surface 546 is angled to face to the left of the vertically disposed spanning portion 730s. In such an embodiment, the central axis A2 of the bone anchor opening 744 can extend downward and to the left at an oblique angle relative to the proximal-distal axis A1 of the wing spanning portion 730s. This configuration can facilitate a variety of bone anchor arrangements in which the distal end of the auxiliary bone anchor is to the left of the wing spanning portion 530s when viewed from the perspective of FIG. 5A.

[0084] For example, as shown in FIG. 5A, such bone anchor placement can include an arrangement in which the wings 730 are positioned on the outside of the spinal rod 506 and the auxiliary bone anchor 534 is driven through the bone anchor opening 744 in a caudal trajectory (i.e., toward the patient's foot). This orientation can allow the auxiliary bone anchor 534 to span one or more adjacent vertebral levels, for example, across a facet joint. A caudal trajectory can allow the auxiliary bone screw 534 to be secured in multiple (e.g., at least two, at least three, or more) cortical bone layers. For example, as shown in FIG. 5A, with the main bone anchor 502 positioned at a superior vertebral level, the bone anchor assembly 700 can provide a tricortical fixation in which the auxiliary bone anchor 534 crosses the facet joint between the superior vertebral level and the adjacent inferior vertebral level. It will be appreciated that the wings 730 may be rotated 180 degrees to be positioned on the opposite side of the illustrated rod 506 (e.g., on the inside of the rod) or to be positioned on the outside of the contralateral spinal rod (not shown). In these cases, this positioning of the wings 530 may facilitate bone anchor placement in which the secondary bone anchor 534 may be driven in a cephalad trajectory (i.e., toward the patient's head) through the bone anchor opening 744. As discussed above with respect to FIG. 3A, a cephalad trajectory may allow the secondary bone anchor 534 to remain entirely at the same vertebral level as the primary bone anchor 502, for example, within the lateral mass of the vertebra. The angled distal portion 730d may allow for such bone anchor placement while the distal face 746 of the wings 730 remains in contact with or in close proximity to the bone surface (e.g., within 0-3 mm).

[0085] In some embodiments, the distal surface 746 of the wing 730 can be angled obliquely to fix the central axis A2 of the bone anchor opening 744 at any oblique angle to the left of the spanning portion 730s of the wing 730, depending on the requirements of a particular application. For example, as shown in FIG. 5D, the distal surface 746 of the distal portion 730d of the wing 730 can be angled obliquely so that the central axis A2 of the bone anchor opening 744 extends at an angle of 35 degrees to the left of the proximal-distal axis A1 of the spanning portion 730s of the wing 730. Thus, the auxiliary bone anchor 534 can be easily positioned within the bone anchor opening 744 with the distal shaft of the anchor having an angular trajectory coaxial with the central axis A2 of the bone anchor opening 744 toward the left of the spanning portion 730s or within a predefined conical angle with respect to the central axis A2 of the bone anchor opening 744. In some embodiments, the distal surface 746 of the wing 730 can be angled obliquely such that the central axis A2 of the bone anchor opening 744 can extend at an angle of 15 to 45 degrees (inclusive) to the left of the proximal-distal axis A1 of the spanning portion 730s.

[0086] As discussed above with respect to Figures 3F and 3G, in some embodiments, the distal surface 746 of the wing 730 can be further angled inwardly or outwardly relative to the perpendicularly disposed spanning portion 730s of the wing 730. In some embodiments, the distal surface 746 of the wing 730 can be angled obliquely inwardly or outwardly to fix the central axis A2 of the bone anchor opening 744 at any medial or lateral angle between 5 and 20 degrees, inclusive, relative to the proximal-distal axis A1 of the spanning portion 730s of the wing 730, based on the requirements of a particular application. Thus, by angling the distal surface 746 inwardly or outwardly, the distal portion 730d can facilitate placement through the bone anchor opening 744 of a supplemental bone anchor 534 having a medial or lateral trajectory component in addition to or instead of a cranial or caudal trajectory component. In some embodiments, the distal surface 746 can be angled inwardly or outwardly to facilitate bone anchor deployment where the auxiliary bone anchor 534 is secured within the lateral mass of the vertebra. In some embodiments, the distal surface 746 of the wing 730 can be angled inwardly or outwardly to provide clearance for a driver instrument to access the bone anchor opening 744 on the proximal surface 748 of the distal portion 730d of the wing 730.

[0087] FIG 5E is a top view of the wing 730 of the bone anchor assembly of FIG 5A with the angled distal portion 730d facing in a cranial direction. As shown in FIG 5E, from a posterior perspective, the wing 730 can be positioned with the distal portion 730d extending laterally to the left of the spinal midline and thus facing in a cranial direction. In this exemplary cranial configuration, the angled distal portion 730d of the wing 730 has an upper end 780, a lower end 782, a free outer end 784 extending between the upper and lower ends, and a medial end 786 extending between the upper and lower ends. With the distal portion 730d facing cranially, the lower end 782 of the distal portion 730d is distal (or lower) than the upper end 780, such that the distal surface 746 faces in a cranial direction. In some embodiments, when distal portion 730d is also angled medially (e.g., as described above in FIG. 3G), the lower end 782 of distal portion 730d is distal (or inferior) to the upper end 780 and the free outer end 784 is distal to the inner end 786, such that the distal surface 746 faces in both the cranial and medial directions. In some embodiments, when distal portion 730d is also angled laterally (e.g., as described above in FIG. 3H), the lower end 782 of distal portion 730d is distal (or inferior) to the upper end 780 and the inner end 786 is distal to the free outer end 784, such that the distal surface 746 faces in both the cranial and medial directions.

[0088] FIG. 5F is a top view of the wing 730 of the bone anchor assembly of FIG. 5A with the angled distal portion 730d facing in a caudal direction. As shown in FIG. 5F, from a posterior perspective, the wing 730 can be positioned with the angled distal portion 730d extending laterally to the right of the spinal midline and thus facing in a caudal direction. In this exemplary caudal configuration, the angled distal portion 730d of the wing 730 has an upper end 790, a lower end 792, a free outer end 794 extending between the upper and lower ends, and a medial end 796 extending between the upper and lower ends. With the angled distal portion 730d facing caudally, the upper end 790 of the distal portion 730d is distal (or lower) than the lower end 792, such that the distal surface 746 faces in a caudal direction. In some embodiments, when distal portion 730d is also angled medially (e.g., as described above in FIG. 3G), the upper end 790 of distal portion 730d is distal to the lower end 792 and the free outer end 794 is distal to the inner end 796, such that the distal surface 746 faces in both the caudal and medial directions. In some embodiments, when distal portion 730d is also angled laterally (e.g., as described above in FIG. 3H), the upper end 790 of distal portion 730d is distal to the lower end 792 and the inner end 796 is distal to the free outer end 794, such that the distal surface 746 faces in both the caudal and lateral directions.

[0089] As mentioned above, some embodiments of the bone anchor assembly can include wings having distal portions that are angled inwardly or outwardly relative to the perpendicularly disposed spanning portion, but not angled to the right or left. In such embodiments, the auxiliary bone anchors can be easily placed through bone anchor openings in the distal portions having an inner or outer track.

[0090] 6A-6E show an exemplary embodiment of a bracket or wing 830 of a bone anchor assembly having an angled distal portion 830d. ​​As shown, the bracket or wing 830 can include a proximal portion 830p, an angled distal portion 830d, and a spanning portion 830s connecting the proximal portion to the distal portion. The angled distal portion 830d has a free outer end 850 and an inner end 852. Except as described below or as would be readily understood by one of ordinary skill in the art, the proximal portion 830p and the spanning portion 830s of the wing 830 are substantially similar to the proximal and spanning portions of the wings 230, 530, and / or 730 described above in connection with FIGS. 2A-2M, 3A-3I, and 5A-5F. Accordingly, a detailed description of their structure and function is omitted herein for the sake of brevity. Wing 830 may include any one or more of the features of wings 230, 530 and / or 730 described above.

[0091] In the illustrated embodiment, the distal portion 830d of the wing 830 is substantially similar to the angled distal portions 530d, 730d disclosed in connection with FIGS. 3A-3I and 5A-5F, except that the distal portion 830d is angled inwardly toward the perpendicularly disposed spanning portion 830s, and is not angled toward the right or left of the wing 830s. The angled distal portion 830d of the wing 830 includes a distal face 846 and a proximal face 848. The distal face 846 and the proximal face 848 may be parallel or substantially parallel and downwardly sloping. When the distal portion 830d is angled inwardly (or inwardly as viewed from the perspective of FIG. 6B), the free outer end 850 is distal to the inner end 852, which results in the distal face 846 facing inwardly.

[0092] The distal portion 830d of the wing 830 can define one or more openings 844 extending through the proximal and distal faces 848, 846 for receiving the auxiliary bone anchor 534. As shown in the illustrated embodiment, the bone anchor opening 844 can be oriented perpendicular or substantially perpendicular to the distal face 846 of the wing 830. The distal face 846 of the wing 830 can be angled obliquely inwardly toward the perpendicularly disposed spanning portion 830s of the wing 830 to fix a central axis A2 of the bone anchor opening 844 at an inner angle relative to the proximal-distal axis A1 of the spanning portion 830s. Thus, the auxiliary bone anchor 534 can be easily positioned within the bone anchor opening 844 with the distal shaft of the auxiliary bone anchor 534 having an inner trajectory that is coaxial with the central axis A2 of the bone anchor opening or within a predefined conical angle relative to the central axis A2 of the bone anchor opening.

[0093] For example, in the illustrated embodiment of FIG. 6D, the distal surface 846 of the distal portion 830d of the wing 830 can be angled inwardly toward the spanning portion 830s such that the central axis A2 of the bone anchor opening 844 extends inwardly at a 15 degree angle relative to the proximal-distal axis A1. Thus, the auxiliary bone anchor 534 can be easily positioned within the bone anchor opening 844 with the distal shaft of the anchor having a 15 degree medial trajectory relative to the proximal-distal axis A1. In some embodiments, the distal surface 846 of the distal portion 830d of the wing 830 can be angled obliquely to fix the central axis A2 of the bone anchor opening 844 at an inward angle of 5 to 20 degrees, inclusive, relative to the proximal-distal axis A1 of the spanning portion 830s of the wing 830. In such an embodiment, angling the distal surface 846 inwardly can facilitate bone anchor placement in which the auxiliary bone anchor 534 is fixed within the lateral mass of the vertebra. In some embodiments, the distal surface 846 of the wing 830 can be angled inwardly to provide clearance on the proximal surface 848 of the distal portion 830d of the wing 830 for a driver instrument to access the bone anchor opening 544.

[0094] In an alternative embodiment shown in FIG. 6E, the distal portion 830d may be angled outward (or outward when viewed from the perspective of FIG. 6E) such that the inner end 852 of the distal portion is more distal than the free outer end 850. In this outward configuration, the distal face 846 faces outwardly away from the spanning portion 830s and the central axis A2 of the bone anchor opening 844 extends outwardly at an outward angle relative to the proximal-distal axis A1 of the spanning portion 830s of the wing 830. Thus, the auxiliary bone anchor 534 may be easily placed in the bone anchor opening 844 with the distal shaft of the anchor having an outer trajectory that is coaxial with the central axis A2 of the bone anchor opening 844 or within a predefined conical angle relative to the central axis A2 of the bone anchor opening 844. In some embodiments, the distal surface 846 of the distal portion 830d of the wing 830 can be angled obliquely such that the central axis A2 of the bone anchor opening 844 can extend at an outward angle of 5 to 20 degrees inclusive (e.g., 15 degrees). In such embodiments, angling the distal surface 846 outwardly can facilitate bone anchor placement in which the auxiliary bone anchor 534 is secured in a lateral position. Such embodiments can be useful to accommodate the bony anatomy of the lumbar spine.

[0095] As described above in the embodiments of Figures 2A-2M, auxiliary fixation of the main bone anchor in the bone anchor assembly can be achieved using wings or brackets having one or more bone anchor openings through which one or more auxiliary bone anchors can be driven into the bone. However, in some cases, surgeons may experience difficulty in placing a particular bone anchor having an angled trajectory. Variations in the bone anatomy of the spine may make it difficult to position the distal portion of the wing in close proximity to the bone to facilitate proper engagement or purchase of the anchor. Furthermore, for optimal additional fixation strength, it may be desirable to insert the auxiliary bone anchor such that it extends through multiple bone surfaces. With respect to the embodiments of Figures 3A-6E, in some applications, the angled distal portion of the wing may interfere with the spine's bone anatomy or limit optimal placement of the auxiliary bone anchor screw. Furthermore, in certain applications, it may be advantageous to use multiple auxiliary bone anchors to further secure or enhance the fixation of the main bone anchor inserted into the vertebral mass. Therefore, it may be desirable to insert one or more auxiliary bone anchor screws in an angled trajectory to accommodate a particular spinal anatomy and / or surgical application while optimally enhancing the bite and fixation strength of the main bone anchor.

[0096] In some embodiments of the present disclosure, the wings can have a distal portion defining a plurality of auxiliary bone anchor openings, each of which can be biased or angled relative to the distal portion and relative to the proximal-distal axis of the wings so that the auxiliary bone anchor can be driven into the bony mass in an angular trajectory. In some embodiments, each of the auxiliary bone anchor openings can be angled so that the auxiliary bone anchor can be driven into the bony mass in a caudal or cranial direction in an angular trajectory with the wings secured to the receiver member. As a non-limiting example, the auxiliary bone anchor openings can extend at an angle relative to the distal portion and relative to the proximal-distal axis of the wings so that the auxiliary bone anchor driven in a caudal trajectory can be closer to the center of the bony mass (e.g., a vertebra or its facet joint) and can prevent undesired interaction with the edge of the bony mass. Furthermore, for auxiliary bone anchors driven in a cranial trajectory, the angular trajectory can keep the anchor within the bony mass, e.g., the narrow outer mass of a vertebra. In some embodiments, the wings can be configured to allow each of the auxiliary bone anchors to be inserted to extend entirely within the vertebral level in which the main bone anchor is inserted. In other words, the bone anchor assembly can include wings that can allow insertion of multiple auxiliary bone anchors at an angled trajectory so that the auxiliary bone anchors match the vertebral level of the bone anchor assembly without penetrating or crossing the facet joint plane. In other embodiments, the wings of the present disclosure can be configured to allow at least one of the multiple auxiliary bone anchors to be inserted at an angled trajectory to penetrate the facet joint plane of the vertebral level in which the main bone anchor is inserted. In some embodiments, the auxiliary bone anchors can extend through multiple cortical levels into the adjacent vertebrae.

[0097] 7-17 show an exemplary embodiment of a bone anchor assembly 900 including a bracket or wing 930 having a distal portion 930d defining a plurality of auxiliary bone anchor openings 944 that can extend in a biased or angled trajectory relative to the distal portion and the proximal-distal axis of the wing. As discussed in more detail below, the wings of this embodiment can facilitate the insertion of a plurality of auxiliary bone anchor screws into a vertebral level of the bone assembly. In some embodiments, each of the auxiliary bone anchors can match a vertebral level of the bone anchor assembly. Alternatively, the wings can be configured such that at least one auxiliary bone anchor screw can penetrate the facet joint plane of a vertebral level of the bone anchor assembly and extend into an adjacent vertebral level. Thus, a bone anchor assembly including wings of the present disclosure can increase the pullout strength of the primary bone anchor by providing multiple auxiliary fixation points and distributing bone stresses. The wings can facilitate the insertion of multiple auxiliary bone anchors in a desired trajectory to account for the anatomy of a particular spinal region and a particular surgical application. Thus, the wings of the present disclosure can provide surgeons with more flexibility regarding secondary bone anchor placement to achieve optimal fixation strength and greater bite of the main bone anchor.

[0098] 7 and 8, a bone anchor assembly 900 can be implanted into a vertebral level 901. The vertebral level 901 can have a first facet joint plane 905 and a second facet joint plane 907. The bone anchor assembly 900 can include a bone anchor (labeled 902 and visible in the vertebra 901 and adjacent vertebra 903), a receiver member 904, a closure mechanism 908, a bracket or wing 930, a nut 932, and one or more auxiliary bone anchors 934. The wing 930 can be secured to the receiver member 904 using, for example, the closure mechanism 908 and the nut 932. As discussed above, the wing 930 can be rotatable relative to the closure mechanism 908. Prior to securing the wing 930, the wing can be disposed in a desired position or configuration relative to the receiver member. The desired position or configuration of the wings can establish a target insertion trajectory for each of the one or more auxiliary bone anchors 934 received by the auxiliary bone anchor openings 944. The closure mechanism 908 can be secured to the receiver member 904 to capture a spinal fixation element, such as a spinal rod 906, within the receiver member. In some embodiments, tightening or locking of the closure mechanism 908 can be effective to secure the spinal rod 906 relative to the receiver member 904 and fix the angular position of the bone anchor 902 relative to the receiver member 904.

[0099] Except as described below or as would be readily understood by one of ordinary skill in the art, the bone anchor 902, the receiving member 904, the closure mechanism 908, the nut 932, and the auxiliary bone anchor 934 are substantially similar to the bone anchor 202, the receiving member 204, the closure mechanism 208, the nut 232, and the auxiliary bone anchor 234 described above with respect to Figures 2A-2M. Accordingly, a detailed description of their structure and function is omitted here for the sake of brevity. The bone anchor assembly 900 may include any one or more of the features of the bone anchor assemblies 200, 500, 700, or 800 and / or the bone anchor assembly 100 described above.

[0100] As described in more detail below, the wing 930 of this exemplary embodiment may include a plurality of auxiliary bone anchor openings biased to the left side of the wing, for example, when viewed from the perspective of Figures 8-10. An exemplary embodiment of the wing 930 will now be described with reference to Figures 8-17. In the illustrated embodiment, the bracket or wing 930 may include a proximal portion 930p, a distal portion 930d, and a spanning portion 930s connecting the proximal portion to the distal portion of the wing. In one embodiment, the distal portion 930d may extend perpendicular or substantially perpendicular to a proximal-distal axis of the spanning portion 930s. The proximal portion 930p of the wing 930 may extend horizontally from a proximal end of the spanning portion 930s. The wing 930 may be Z-shaped or substantially Z-shaped.

[0101] The proximal portion 930p can include a proximal-facing surface 940 and a distal-facing surface 942. The proximal-facing surface 940 can be domed or rounded to provide an atraumatic surface to reduce the risk of tissue irritation after implantation. The distal-facing surface 942 of the proximal portion 930p can be configured to abut a proximal end or surface of the receiver member 904. The distal-facing surface 942 can form a convex or substantially convex inverse of the proximal end or surface of the receiver member 904. For example, the proximal-facing surfaces of the arms of the receiver member 904 can be radially convex and the distal-facing surfaces 942 of the wings 930 can define radially concave channels (not shown) that receive the convex ends of the arms.

[0102] The proximal portion 930p of the wing can define a central opening 936 extending through a proximal-facing surface 940 and a distal-facing surface 942. The central opening 936 can be oriented such that a central axis of the opening B1 is perpendicular or substantially perpendicular to the distal-facing surface 942 of the proximal portion 930p. In some embodiments, the central opening 936 can be dimensioned such that the closure mechanism 908 can be inserted through the opening and extend at least partially above the proximal-facing surface 940 of the proximal portion 930p. The central opening 936 can include a smooth, non-threaded inner surface such that the wings 930 and the closure mechanism 908 can freely rotate relative to one another. The central opening 936 or another feature of the wings 930 can be dimensioned and configured to snap-fit ​​or capture a portion of the closure mechanism 908 or a proximal surface of the receiving member 904. 4A-4C, a counterbore may be formed about central opening 936 in distally facing surface 942 of proximal portion 930p to accommodate a radially extending shoulder portion of closure mechanism 908, which may extend above the proximal end of receiver member 904. Proximal portion 930p of wing 930 may include any of the features described herein with reference to wing portions 230, 530, 730, and / or 830.

[0103] The spanning portion 930s of the wing 930 can extend perpendicularly in a proximal-distal direction to join the proximal portion 930p of the wing to the distal portion 930d of the wing. The spanning portion 930s of the wing 930 can be an elongated arm that extends distally from the sidewall of the proximal portion 930p in a vertical or substantially vertical plane. The spanning portion 930s can have an outer surface 950 that engages or faces the sidewall of the receiver member 904. The outer surface 950 can form an inverted concave-convex shape with the sidewall of the receiver member 904 such that the spanning portion 930s can embrace the receiver member with minimal or no clearance between the outer surface 950 and the sidewall of the receiver member 904. For example, the outer surface 950 can be a concave having a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 904.

[0104] In some embodiments, the wings 930 can include various features of a unilateral locking interface, including, but not limited to, one or more grooves and surface protrusions (not shown). As described and illustrated above with respect to the wings 530, the unilateral locking interface allows a surgical instrument including a unilateral locking mechanism to be held on one side of the wings 930, as shown, for example, in Figures 3C and 3D. Exemplary unilateral locking interfaces that can be included on the wings 930 are disclosed in U.S. Patent Application No. 15 / 843,618, filed December 15, 2017, entitled "Unilateral Implant Holders and Related Methods," the entire contents of which are incorporated herein by reference.

[0105] The proximal portion 930p, the distal portion 930d, and the spanning portion 930s may be integrally formed as a one-piece unit as shown. Alternatively, one or more of the components may be separate and selectively attachable to the other components. In some embodiments, a kit of modular components may be provided to allow for selection of the components best suited for a given application. For example, a spanning portion 930s of appropriate height may be selected based on the distance between the proximal end of the receiver member 904 and the bone surface in a given application. The length of the spanning portion may vary to accommodate different lengths of auxiliary bone anchor screws or desired auxiliary bone anchor screw entry points. As discussed above, in some embodiments, the length of the spanning portion may be adjustable. In other embodiments, the length of the spanning portion may be fixed.

[0106] In one embodiment, the wings 930 can be designed such that there is a gap between the distal surface 946 of the distal portion 930d of the wings 930 and the bone surface of the vertebral level associated with the bone anchor assembly 900. For example, the length of the spanning portion 930s can be selected or manufactured such that the distal surface 946 of the distal portion 930d is disposed in close proximity to the bone surface without contacting the bone surface when the wings are secured to the receiver member of the bone anchor assembly. To achieve this configuration, the length of the spanning portion can depend on various contextual factors, such as the patient's spinal anatomy, the configuration and size of the complementary bone anchor, and / or the constraints of the particular surgical application. The gap between the wings 930 and the bone surface can be advantageous to maintain a tight locking connection between the wings and the receiver member. By preventing the distal portion of the wings from contacting the bone surface, the gap eliminates upward or proximal contact forces from the bone that can result in tensioning or loosening of the connection between the wings and the receiver member.

[0107] Distal portions 930d of wings 930 can extend outwardly from the distal end of spanning portion 930s away from receiver member 904. The extent to which wings 930 extend outwardly from receiver member 904 can vary among different embodiments. In the illustrated embodiment, the ratio of the wing extension to the rod diameter (or the ratio of the wing extension to the width of the rod-receiving recess in the receiver member) is about 2:1. In some embodiments, this ratio can be less than about 10:1, less than about 5:1, less than about 3:1, less than about 2:1, less than about 1:1, and / or less than about 0.5:1. In some embodiments, this ratio can be about 10:1, about 5:1, about 3:1, about 2:1, about 1:1, or about 0.5:1.

[0108] 14 and 15, in one embodiment, the distal portion 930d can extend outwardly perpendicular or nearly perpendicular to the proximal-distal axis B2 of the spanning portion 930s. As shown, the distal portion 930d can have a distal surface 946 and a proximal surface 948. The distal surface 946 can be perpendicular or substantially perpendicular to the proximal-distal axis B2 of the spanning portion 930s. The distal portion 930d of the wing can have an outer surface 922 that abuts or faces the sidewall of the receiver member 904 such that the distal portion 930d of the wing 930 can embrace the receiver member with minimal or no clearance. For example, the outer surface 922 can be a recess having a radius of curvature equal or substantially equal to the radius of curvature of the outer sidewall of the receiver member 904.

[0109] The distally facing surface 946 can be configured to contact or be placed adjacent to a bone. In some embodiments, the distally facing surface 946 can include teeth, texturing, or other surface features to enhance grip with the adjacent bone. In other embodiments, the wings 930 can be configured such that there is a gap between the distally facing surface 946 of the distal portion 930d and the proximally facing surface of the bone into which the main bone anchor is inserted. As discussed above, such a configuration can maintain the integrity of the connection between the wings 930 and the receiver member 904.

[0110] The distal portion 930d of the wing 930 can define a plurality of auxiliary bone anchor openings 944, each extending through a proximal-facing surface 948 and a distal-facing surface 946 of the distal portion. Each of the plurality of auxiliary bone anchor openings 944 can be configured to receive an auxiliary bone anchor 934. As seen, for example, in FIGS. 8-10, each auxiliary bone anchor opening 944 can be sized to allow a distal shaft of the auxiliary bone anchor 934 to be inserted through the opening and abut a proximal head of the auxiliary bone anchor when the auxiliary bone anchor is positioned therein. Each bone anchor opening 944 can extend at an oblique angle relative to a proximal-distal axis B2 of the spanning portion 930s. With reference to FIG. 14, a central axis B3 of the auxiliary bone anchor opening 944 can be angled obliquely relative to the proximal-distal axis B2 of the wing, with the proximal-distal axis B3 extending perpendicular or substantially perpendicular to the distal surface 946 of the wing 930. For example, as shown, the bone anchor opening 944 can be angled to extend to the left of the vertically disposed spanning portion 930s. In such an embodiment, the central axis B3 of the bone anchor opening 944 can extend downward and to the left at an oblique angle α1 relative to the proximal-distal axis B2 of the spanning portion 930s.

[0111] In some embodiments, depending on the requirements of a particular application, the auxiliary bone anchor opening can extend at an oblique angle to the left of the proximal-distal axis B2 of the spanning portion 930s. For example, with reference to FIGURE 14, the central axis B3 of the auxiliary bone anchor opening 944 can extend down and to the left at an oblique angle α1 relative to the proximal-distal axis B2 of the spanning portion 930s of the wing 930. This configuration can facilitate placement of a variety of bone anchors where the distal end of the auxiliary bone anchor extends toward the left of the wing 930 when viewed from the perspective of FIGS. 8-10.

[0112] For example, the central axis B3 of each opening 944 can extend to the left of axis B2 at an angle α1 of about 35 degrees. In some embodiments, the central axis B3 of each opening 944 can extend at an angle α1 of about 0 degrees to about 60 degrees from the proximal-distal axis B2 of the spanning portion. Biasing the central axis B3 of the auxiliary bone anchor opening by the angle α1 can establish an insertion trajectory of the auxiliary bone anchor into the bone that is angled along the cranial-caudal axis of the patient. For example, the angle α1 can be selected to drive the auxiliary bone anchor closer to the center of the vertebra or facet joint when the auxiliary bone anchor is inserted in a caudal direction to avoid placement too close to the edge of the vertebra or facet joint, and to keep the auxiliary bone anchor within the narrow outer mass of the vertebra or facet joint when the auxiliary bone anchor is inserted in a cranial direction. In some embodiments, the angle α1 can be about 46 degrees to about 60 degrees from the proximal-distal axis B2 of the spanning portion. In some embodiments, angling the openings 944 at this angle can enable the functions described above (i.e., keeping a caudally directed anchor away from the edge of a vertebra or facet joint, or keeping a cranially directed anchor within the narrow lateral mass of a vertebra or facet joint). This configuration can facilitate placement of a variety of bone anchors with the distal end of the auxiliary bone anchor extending to the left of the wing 930 when viewed from the perspective of FIG.

[0113] For example, as shown in FIG. 7, placement of such a bone anchor can include placement where the wings 930 are positioned on the outside of the spinal rod 906 and the auxiliary bone anchor 934 is driven in a cephalad trajectory (i.e., toward the patient's head) through the bone anchor opening 944. This orientation can allow the auxiliary bone anchor 934 to remain entirely at the same vertebral level 901 as the main bone anchor 902 associated with the bone anchor assembly 900, for example, within the lateral mass of the vertebra. It will be appreciated that the wings 930 can be rotated 180 degrees to be positioned on the opposite side of the illustrated rod 906 (e.g., on the medial side of the rod) or to be positioned on the lateral side of the contralateral spinal rod (not shown). In these cases, this positioning of the wings 930 can facilitate placement of the bone anchor where the auxiliary bone anchor 934 can be driven in a caudal trajectory (i.e., toward the patient's foot) through the bone anchor opening 944. In some embodiments, as described further below with respect to FIGURE 18, the caudal trajectory can allow for anchoring of multiple (e.g., at least two, at least three, or more) supplemental bone screws 934 into the cortical bone layer. The angled supplemental bone anchor openings 944 can allow for placement of the bone anchors described above while accommodating a particular spinal anatomy or surgical application.

[0114] In some embodiments, each of the bone anchor openings 944 can include any of a number of features for receiving the bone anchor 934 at different angles. For example, as described above with respect to FIGS. 2A-2M, the bone anchor openings 944 can be at least partially threaded to receive a variable angle locking screw having a threaded proximal head. As shown, the openings 944 can have multiple rows of threads 945 spaced apart to define multiple non-threaded recesses 947. In this manner, the threads of the openings 944 can form an interlocking interface and mate with the threads of the auxiliary bone anchor to lock the auxiliary bone anchor therein. For example, FIGS. 8-10 show an embodiment of a wing 930 with two auxiliary bone anchors 934 engaged within the auxiliary bone anchor receiving recesses 944. In one embodiment, the threads of the openings 944 can be conical threads. The rows of threads can be provided around an inner surface of the openings 944 to engage threads on the heads of the locking auxiliary bone anchors and / or the variable angle locking auxiliary bone anchors. Thus, the auxiliary bone anchor 934 can lock into the wing 930 coaxially with the central axis B3 of the opening 944 or at a selected angle within a selectable range of angles relative to the central axis B3 of the opening 944. Although the illustrated embodiment has four rows of threads in the auxiliary bone anchor opening, it will be understood that the auxiliary bone anchor opening can have any number of rows of threads (e.g., two, three, four, five, etc.) to facilitate variable angles of locking by the auxiliary bone anchor.

[0115] The auxiliary bone anchor 934 can include features to facilitate this variable angle locking, such as a proximal head that is at least partially spherical with threads having a profile that follows the arcuate radius of curvature of the spherical portion of the head. The ability of the variable angle interlocking interface (i.e., the screw / aperture interface) can allow the user to dispose the locking auxiliary bone anchor in the bone at any angle within the defined angle limits. The locking interface between the auxiliary bone anchor aperture and the auxiliary bone anchor received therein can increase stability and prevent the auxiliary bone anchor from backing out of the aperture. Additionally, the interlocking interface can be biased to create an angled insertion trajectory for the auxiliary bone anchor screw. In other embodiments, the interior surface of the aperture 944 can be smooth or spherical without threads or locking features.

[0116] In some embodiments, the proximal-most segment of each auxiliary bone anchor 934 can be distal to the spinal rod 906. In other embodiments, the proximal-most segment of each auxiliary bone anchor 934 can be distal to the distal-most segment of the receiver member 904. These configurations may advantageously reduce the overall profile of the assembly 900. Although two bone anchor openings 944 are shown in the illustrated embodiment, it will be understood that the wing 930 may include any number of auxiliary bone anchor openings.

[0117] In some embodiments, the central axis B3 of each of the plurality of auxiliary bone anchor openings can additionally or alternatively be biased along a medial-lateral axis. As best seen in FIG. 15, the central axis B3 of the auxiliary bone anchor opening 944 can extend inwardly or outwardly from the proximal-distal axis B2 of the wing at an angle α2. The angle α2 can extend inwardly or inwardly toward the central axis B1 of the wing. The angle α2 can bias the trajectory of the central axis B3 of the auxiliary bone anchor opening inwardly or inwardly to compensate for the outward extension of the distal portion 930d of the wing and to direct the auxiliary bone anchor 934 into the bone toward the centerline of the patient's spine. In some embodiments, α2 can be between about 0 degrees and about 30 degrees. In some embodiments, α2 can be between about 0 degrees and about 25 degrees. In yet other embodiments, α2 can be between about 5 degrees and about 10 degrees.

[0118] 16 is a top view of the wing 930 of the bone anchor assembly of FIGS. 8-14, i.e., a wing including a plurality of auxiliary bone anchor openings 944 extending downward and to the left of the wing, with the central axis B3 of the auxiliary bone anchor openings 944 extending to the left of the wing. As shown in FIG. 16, from a rear perspective, the wing 930 can be positioned with the distal portion 930d extending outward from the left side of the bone anchor assembly (i.e., extending outward from a bone anchor assembly disposed to the left of the spinal midline, or extending inward from a bone anchor assembly disposed to the right of the spinal midline). With such an orientation, the central axis B3 of the auxiliary bone anchor openings can extend in a cranial direction (or toward the patient's head). In this exemplary cranial configuration, each angled auxiliary bone anchor opening 944 has an upper surface 980 and a lower surface 982. With the auxiliary bone anchor opening extending in a cranial direction, the upper surface 980 is more proximal (or higher) than the lower surface 982 such that the opening of the auxiliary bone anchor opening 944 faces in a caudal direction, while the central axis B3 of the auxiliary bone anchor opening extends in a cranial insertion trajectory such that the auxiliary bone anchor received therein extends toward the patient's head. The distal portion 930 can extend substantially perpendicular to the wings such that the distally facing surface 946 is perpendicular or substantially perpendicular to the proximal-distal axis B2 of the wings 930. In some embodiments, when the bone anchor opening is also angled inwardly (e.g., as described above in FIG. 15), the surface of the bone anchor opening 944 closest to the spanning portion 930s can be more proximal (or higher) than the opposing surface of the bone anchor opening, i.e., the surface further away from the spanning portion. In some embodiments, if the auxiliary bone anchor opening is also angled outward, the surface of the bone anchor opening 944 closest to the spanning portion 930s can be distal (or lower) than the opposing surface of the bone anchor opening.

[0119] 17 is a top view of the wing 930 of the bone anchor assembly of FIGS. 8-14, i.e., a wing including multiple auxiliary bone anchor openings extending down and to the left of the wing, with the central axis B3 of each of the auxiliary bone anchor openings 944 extending in a caudal direction. As shown in FIG. 17, from a posterior perspective, the wing 930 can be positioned with the distal portion 930d extending outward from the right side of the bone anchor assembly (i.e., extending medially from a bone anchor assembly disposed to the left of the spinal midline, or extending laterally from a bone anchor assembly disposed to the right of the spinal midline), thus facing in a caudal direction. In this exemplary caudal configuration, each angled auxiliary bone anchor opening 944 has an upper end 990 and a lower end 992. With the auxiliary bone anchor opening extending in a caudal direction, the upper end 990 is more distal (or lower) than the lower end 982 such that the opening of the auxiliary bone anchor opening 944 faces in a cranial direction, while the central axis B3 of the auxiliary bone anchor opening extends in a caudal insertion trajectory such that the auxiliary bone anchor received therein extends toward the patient's foot. The distal portion 930 can extend substantially perpendicular to the wings such that the distally facing surface 946 is perpendicular or substantially perpendicular to the proximal-distal axis B2 of the wings 930. In some embodiments, when the bone anchor opening is angled inward (e.g., as described above in FIG. 15), the surface of the bone anchor opening 944 closest to the spanning portion 930s can be more proximal (or higher) than the opposing surface of the bone anchor opening, i.e., the surface further away from the spanning portion. In some embodiments, if the bone anchor opening is angled outward, the surface of the bone anchor opening 944 closest to the spanning portion 930s can be distal (or lower) than the opposing surface of the bone anchor opening.

[0120] Some embodiments of the bone anchor assembly can include a wing having a distal portion that defines a plurality of auxiliary bone anchor openings, each of which is angled to the right of the vertically disposed spanning portion of the wing. In such embodiments, the auxiliary bone anchors can be placed through the openings in a caudal or cranial trajectory similar to that facilitated by the wing 930 of the bone anchor assembly 900 when implanted on the opposite side of the patient's spine (i.e., the patient's left hand side).

[0121] 18-23 show an exemplary embodiment of a bone anchor assembly 1000 including a bracket or wing 1030 having a distal portion 1030d defining a plurality of auxiliary bone anchor openings 1044 that may extend on a biased or angled trajectory toward the right of a vertically disposed spanning portion 1030s of the wing 1030. As shown, the bone anchor assembly 1000 may be implanted at a vertebral level 1001. The bone anchor assembly 1000 can include a bone anchor (labeled 1002 and visible in the vertebra 1001 associated with the bone anchor assembly 1000 and the adjacent vertebra 1003), a receiver member 1004, a closure mechanism 1008, a bracket or wing 1030, a nut 1032, and one or more auxiliary bone anchors 1034 inserted into the auxiliary bone anchor opening 1044 and traversing a first layer of the cortical bone 1009 of the vertebra 1001, as seen, for example, in FIG. 18. Also shown in FIG. 18 are a first facet 1005 and a second facet 1007 of the vertebrae. As described herein, in some embodiments, the auxiliary bone anchor 1034 can be driven across a facet (e.g., the facet 1005) such that the bone anchor extends through multiple vertebrae and / or the cortical bone layer of one or more vertebrae. Except as described below, or as would be readily understood by one of ordinary skill in the art, the bone anchor 1002, the receiving member 1004, the closure mechanism 1008, the nut 1032, and the auxiliary bone anchor 1034 are substantially similar to the bone anchor 202, the receiving member 204, the closure mechanism 208, the nut 232, and the auxiliary bone anchor 234 described above with respect to Figures 2A-2M. Accordingly, a detailed description of their structure and function is omitted here for the sake of brevity. The bone anchor assembly 1000 may include any one or more of the features of one or more of the bone anchor assemblies described above.

[0122] As shown in Figures 18-23, the bracket or wing 1030 can include a proximal portion 1030p, a distal portion 1030d, and a spanning portion 1030s connecting the proximal portion of the wing to the distal portion. Except as described below or as would be readily understood by one of ordinary skill in the art, the proximal portion 1030p and the spanning portion 1030s of the wing 1030 are substantially similar to the proximal portion 930p and the spanning portion 930s of the wing 930 described above in connection with Figures 7-17. Accordingly, a detailed description of their structure and function will be omitted here for the sake of brevity. The wing 1030 can include any one or more of the features of the wing 930 described above.

[0123] In the illustrated embodiment, the distal portion 1030d of the wing 1030 and the auxiliary bone anchor openings 1044 are substantially similar to the distal portion 930d of the wing 930 and the auxiliary bone anchor openings 1044, except that each of the auxiliary bone anchor openings 1044 is angled or extends toward the right of the perpendicularly disposed spanning portion 1030s (e.g., when viewed from the perspective of FIG. 21). As shown, the distal portion 1030d can extend outwardly from the distal end of the spanning portion 1030s perpendicular or substantially perpendicular to the proximal-distal axis B2 of the spanning portion. The distal portion 1030d can have a distally facing surface 1046 and a proximally facing surface 1048. The distal surface 1046 can be perpendicular or substantially perpendicular to the proximal-distal axis B2 of the spanning portion 1030s. The distal portion 1030d can define a plurality of auxiliary bone anchor openings 1044, each extending through the proximal facing surface 1048 and the distal facing surface 1046, and each configured to receive an auxiliary bone anchor 1034. As shown in the illustrated embodiment, the bone anchor openings 1044 can be angled or biased to the right of the vertically extending axis B2 of the spanning portion 1030s, while the distal surface 1046 and the distal portion 1030d remain perpendicular or nearly perpendicular to the axis B2. In such an embodiment, the central axis B3 of the bone anchor opening 1044 can extend downward and to the right at an oblique angle α1 to the proximal-distal axis B2 of the wing spanning portion 1030s. This configuration can facilitate the placement of a variety of bone anchors with the distal ends of the auxiliary bone anchors extending toward the right of the wing 1030 when viewed from the perspective of FIG. 21. Although two bone anchor openings 1044 are shown in the illustrated embodiment, it will be understood that the wing 1030 may include any number of bone anchor openings (e.g., one, two, three, four, five, etc.). In some embodiments, multiple auxiliary bone anchor openings may be preferred to provide multiple additional fixation points to increase the pull-out strength of the bone anchor.

[0124] For example, as shown in FIG. 18, such bone anchor arrangements can include an arrangement in which the wings 1030 are positioned on the outside of the spinal rod 1006 and the auxiliary bone anchor 1034 is driven through the bone anchor opening 1044 in a caudal trajectory (i.e., toward the patient's foot). This orientation can allow the auxiliary bone anchor 1034 to span one or more adjacent vertebral levels, for example, across a facet joint or facet of one or more adjacent vertebral levels. The caudal trajectory can allow at least one auxiliary bone anchor screw 1034 to be secured in multiple (e.g., at least two, at least three, or more) cortical bone layers. For example, continuing with reference to FIG. 18, with the primary bone anchor (not shown) of the bone anchor assembly 1000 positioned at the upper vertebral level 1001, the bone anchor assembly can provide a tricortical fixation in which the auxiliary bone anchor 1034 crosses the facet joint between the upper vertebral level and the adjacent lower vertebral level 1003. It will be appreciated that the wings 1030 may be rotated 180 degrees to be positioned on the opposite side of the illustrated rod 1006 (e.g., on the inside of the rod) or on the outside of the contralateral spinal rod (not shown). In these cases, this positioning of the wings 1030 may facilitate placement of the bone anchor in which the auxiliary bone anchor 1034 may be driven in a cephalad trajectory (i.e., toward the patient's head) through the bone anchor opening 1044. As discussed above with respect to FIG. 7, a cephalad trajectory may allow at least one auxiliary bone anchor 1034 to remain entirely at the same vertebral level as the main bone anchor 1002 of the main bone anchor 1000, for example, within the lateral mass of the vertebra. The angled auxiliary bone anchor opening 1044 may allow placement of the bone anchors described above while accommodating a particular spinal anatomical structure or surgical procedure.

[0125] Returning to FIG. 21, in some embodiments, depending on the requirements of a particular application, the central axis B3 of the auxiliary bone anchor opening 1044 can be angled obliquely at any angle α1 to the right of the axis B2 of the spanning portion 1030s. The axis B2 can be perpendicular or substantially perpendicular to the distally facing surface 1046 of the distal portion 1030d of the wing. For example, as shown in FIG. 21, the bone anchor opening 1044 can be angled obliquely such that the central axis B3 of the bone anchor opening 1044 extends at an angle α1 of 35 degrees to the right of the proximal-distal axis B2 of the spanning portion 1030s. In some embodiments, the bone anchor opening 1044 can be angled obliquely such that the central axis B3 of the bone anchor opening 1044 can extend at an angle α1 of about 0 degrees to about 60 degrees to the right of the proximal-distal axis B2 of the spanning portion 1030s. For example, the angle α1 can be selected to drive the auxiliary bone anchor closer to the center of the vertebra or facet joint to avoid placement too close to the edge of the vertebra or facet joint when the auxiliary bone anchor is inserted in a caudal direction, and to keep the auxiliary bone anchor within the narrow lateral mass of the vertebra or facet joint when the auxiliary bone anchor is inserted in a cranial direction. In some embodiments, the angle α1 can be about 46 degrees to about 60 degrees from the proximal-distal axis B2 of the spanning portion. In some embodiments, angling the opening 1044 at this angle can enable the functions described above (i.e., keeping a caudally directed anchor away from the edge of the vertebra or facet joint, or keeping a cranially directed anchor within the narrow lateral mass of the vertebra or facet joint). As described above, the auxiliary bone anchor 1044 can include one or more rows of threads 1045 to establish an interlocking interface in which the auxiliary bone anchor is received. In some embodiments, the interlocking interface can be a variable angle interlocking interface. Thus, the auxiliary bone anchor 1034 can be easily positioned within the bone anchor opening 1044 with the anchor's distal shaft having an angular trajectory coaxial with the central axis B3 of the bone anchor opening 1044 or within a predefined conical angle relative to the central axis B3 of the bone anchor opening 1044.

[0126] As discussed above with respect to FIG. 15, in some embodiments, the bone anchor opening 1044 can be further angled to face inwardly or outwardly (i.e., medially or externally) relative to the perpendicularly disposed spanning portion 1030s. Thus, in some embodiments, the bone anchor opening 1044 can be angled obliquely inwardly or outwardly to fix the central axis B3 of the bone anchor opening 1044 at any medial or lateral angle α2 between about 0 and about 30 degrees relative to the proximal-distal axis B2 of the spanning portion 1030s based on the requirements of a particular application. In some embodiments, the bone anchor opening 1044 can be angled such that the central axis B3 extends at an angle α2 between about 5 and about 10 degrees inclusive. Thus, by angling the bone anchor opening 1044 inwardly or externally, the distal portion 1030d can facilitate placement therethrough of a supplemental bone anchor 1034 having a medial or lateral track component in addition to or instead of a cranial or caudal track component. In some embodiments, the bone anchor opening 1044 can be angled inwardly or outwardly to facilitate bone anchor placement where the auxiliary bone anchor 1034 is secured within the lateral mass of the vertebra. In some embodiments, the bone anchor opening 1044 can be angled inwardly or outwardly to provide clearance for a driver instrument to access the bone anchor opening 1044.

[0127] 22 is a top view of the wing 1030 of the bone anchor assembly of FIG. 18, i.e., a wing including a plurality of auxiliary bone anchor openings 1044 extending downward and to the right of the wing, with the central axis B3 of the auxiliary bone anchor opening 944 extending to the right of the wing. As shown in FIG. 22, from a rear perspective, the wing 1030 can be positioned with the distal portion 1030d extending outward from the left side of the bone anchor assembly (i.e., extending outward from a bone anchor assembly disposed to the left of the spinal midline, or extending inward from a bone anchor assembly disposed to the right of the spinal midline). With such an orientation, the central axis B3 of the auxiliary bone anchor opening can extend in a caudal direction (or toward the patient's foot). In this exemplary caudal configuration, each angled auxiliary bone anchor opening has an upper end 1080 and a lower end 1082. With the auxiliary bone anchor opening extending in a caudal direction, the upper end 1080 is more distal (or lower) than the lower end 1082 such that the opening of the auxiliary bone anchor opening 1044 faces in a cranial direction, while the central axis B3 of the auxiliary bone anchor opening extends in a caudal insertion trajectory such that the auxiliary bone anchor received therein extends toward the patient's foot. The distal portion 1030 can extend substantially perpendicular to the wings such that the distally facing surface 1046 is perpendicular or substantially perpendicular to the proximal-distal axis B2 of the wings 1030. In some embodiments, when the bone anchor opening is also angled inwardly (e.g., as described above with reference to FIG. 15), the surface of the bone anchor opening 1044 closest to the spanning portion 1030s can be more proximal (or higher) than the opposing surface of the bone anchor opening, i.e., the surface further away from the spanning portion. In some embodiments, if the bone anchor opening is angled outward, the surface of the bone anchor opening 1044 closest to the spanning portion 1030s can be distal (or lower) than the opposing surface of the bone anchor opening.

[0128] 23 is a top view of the wing 1030 of the bone anchor assembly of FIG. 18, i.e., a wing including a plurality of auxiliary bone anchor openings 1044 extending down and to the right of the wing, with the central axis B3 of the auxiliary bone anchor opening 944 extending to the right of the wing. As shown in FIG. 23, from a rear perspective, the wing 1030 can be positioned with the distal portion 1030d extending outward from the right side of the bone anchor assembly (i.e., extending medially from a bone anchor assembly disposed to the left of the spinal midline, or extending laterally from a bone anchor assembly disposed to the right of the spinal midline). With the distal portion 1030d extending outward to the right of the spinal midline, the central axis B3 of the auxiliary bone anchor opening can extend in a cranial direction (or toward the patient's head). In this exemplary cephalad configuration, each angled auxiliary bone anchor opening 1044 has an upper end 1090 and a lower end 1092, with the upper end 1090 being more proximal (or higher) than the lower end 1092 such that the opening of the auxiliary bone anchor opening 1044 faces in a caudal direction, while the central axis B3 of the auxiliary bone anchor opening extends in a cephalad insertion trajectory such that the auxiliary bone anchor received therein extends toward the patient's head. The distal portion 1030 can extend substantially perpendicular to the spanning portion such that the distally facing surface 1046 is perpendicular or substantially perpendicular to the proximal-distal axis B2 of the wing 1030. In some embodiments, when the bone anchor opening is also angled inwardly (e.g., as described above in FIG. 15), the surface of the bone anchor opening 1044 closest to the spanning portion 1030s can be more proximal (or higher) than the opposing surface of the bone anchor opening, i.e., the surface further away from the spanning portion. In some embodiments, if the auxiliary bone anchor opening is angled outward, the surface of the bone anchor opening 1044 closest to the spanning portion 1030s can be distal (or lower) than the opposing surface of the bone anchor opening.

[0129] With reference to FIG. 24, an exemplary method of using the bone anchor assemblies disclosed herein is described below.

[0130] The surgical procedure may begin at step 1110. For example, the procedure may begin by making an open or percutaneous incision in the patient to access the bone into which the bone anchor assembly is to be implanted. The bone may be prepared to receive the bone anchor assembly as known in the art. For example, the pedicle of the spine may be prepared using standard awl, probe, and tap steps.

[0131] Next, the bone anchor may then be advanced into the bone at step 1120. After advancing the primary bone anchor into the bone, i.e., into the patient's vertebrae at step 1130, the user may evaluate the fixation of the bone anchor, taking into account the patient's anatomy and the particular circumstances of the surgical application. At step 1140, if the user feels that the bite of the bone anchor is insufficient or that supplemental fixation is otherwise desirable, a supplemental fixation member may be selected based on the particular application added to the bone anchor assembly. The selected fixation member may then be disposed at a desired location (1150) and secured relative to the bone anchor assembly (1160). With the fixation member secured, at least one supplemental bone anchor screw may be driven into the bone to provide supplemental fixation of the bone anchor (1170).

[0132] For example, referring to the embodiment of Figures 2A-2M, a spinal rod 206 can be seated in the receiver member 204 and a closure mechanism 208 can be screwed onto the rod. Wings 230 can then be positioned over the closure mechanism 208 and locked into place with nuts 232. One or more secondary bone anchors 234 can be inserted through the wings 230 to attach the construct to a second location (or more than one location) on the bone. This method can include bending or curving the wings 230 to better fit the receiver member 204 or bone surface, for example, by squeezing the legs 258 of the wings together to increase the height of the wings.

[0133] As another example, referring to the embodiment of Figures 3A-3I, a spinal rod 506 can be seated in a receiver member 504 and a closure mechanism 508 can be screwed onto the rod. A wing 530 can be positioned over the closure mechanism 508 and secured in place with a nut 532. As described above, the wing 530 can include a distal portion 530d that is angled toward the right side of the wing 530. Thus, if the wing is positioned outside of a bone anchor positioned to the left of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 544 and driven into the bone in a caudal trajectory. If the wing is positioned outside of a bone anchor positioned to the right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 544 and driven into the bone in a cranial trajectory.

[0134] As another example, referring to the embodiment of Figures 5A-5F, a spinal rod 506 can be seated in the receiving member 504 and a closure mechanism 508 can be screwed onto the rod. A wing 730 can be positioned over the closure mechanism 508 and secured in place by a nut 532. As described above, the wing 730 can include a distal portion 730d that is angled toward the left side of the wing 730. Thus, if the wing is positioned outside of a bone anchor positioned to the left of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 744 and driven into the bone in a cranial trajectory. If the wing is positioned outside of a bone anchor positioned to the right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 744 and driven into the bone in a caudal trajectory.

[0135] As another example, referring to the embodiment of Figures 6A-6D, the spinal rod 506 can be seated in the receiving member 504 and the closure mechanism 508 can be screwed onto the rod. The wings 830 can be positioned over the closure mechanism 508 and secured in place by a nut 532. As described above in some embodiments, the wings 830 can include a distal portion 830d that is angled inwardly toward the spanning portion 830s of the wings 830. Thus, when the wings are positioned on the outside of a bone anchor that is positioned to the left or right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 844 and driven into the bone on a medial trajectory. In some embodiments, the wings 830 can include a distal portion 830d that is angled outwardly away from the spanning portion 830s of the wings 830. Thus, when the wings are positioned on the outside of a bone anchor placed to the left or right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 534 can be inserted through the bone anchor opening 844 and driven into the bone on an outer trajectory.

[0136] In yet another example, referring to the embodiment of Figures 7-23, a spinal rod can be seated in the receiving member of the bone anchor assembly and a closure mechanism can be screwed onto the rod. After assessing the need to enhance fixation of the bone anchor assembly with an auxiliary fixation member, the user can determine the optimal placement and trajectory of one or more auxiliary bone anchor screws received in the auxiliary fixation member. For example, the user can evaluate the patient's spinal anatomy, the goal of the particular surgical procedure, and the conditions surrounding the vertebrae to determine whether the desired auxiliary fixation should include one or more auxiliary bone anchor screws that penetrate the facet joint surface of the bone into which the bone anchor assembly is inserted. This may be appropriate in applications that do not require preservation of movement between adjacent vertebrae. For example, in a surgical procedure in which the bone anchor assembly is inserted into a vertebral level that is fused with an adjacent vertebral level, the fixation strength of the bone anchor assembly can be increased by driving at least one auxiliary bone anchor screw through multiple layers of cortical bone. In other embodiments, the desired auxiliary fixation may include one or more auxiliary bone anchor screws that extend entirely into the bone, i.e., completely into the vertebral level where the bone anchor assembly is inserted, without any auxiliary bone anchor screws extending beyond the bone. For example, such an approach may be optimal for surgical applications where it is desired to preserve movement between adjacent vertebrae. In some embodiments, it may be desirable to use multiple auxiliary bone anchor screws to enhance fixation of the bone anchor assembly.

[0137] The user can then select the appropriate auxiliary fixation member to achieve the desired auxiliary fixation, also taking into account the patient's anatomy and the requirements of the particular surgical application. By way of non-limiting example, when selecting the appropriate auxiliary fixation member, the user can consider factors such as the location of the bone anchor assembly relative to the patient's spinal midline, the spinal anatomy, and the bone quality within the surgical area. For example, in a surgical procedure performed on the cervical spine, the user may want to angle the auxiliary bone anchor screws so that each matches the orientation of the vertebral facets so as not to encroach on the non-fusion level.

[0138] In some embodiments, the wing 930 can be positioned on the closure mechanism 908 of the bone anchor assembly 900 and secured in place by the nut 932. As described above, the wing 930 can include a distal portion 930d having a number of auxiliary bone anchor openings 944 that extend in a biased trajectory toward the left side of the wing 930. Thus, when the wing is positioned on the outside of a bone anchor positioned to the left of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 934 can be inserted through the bone anchor opening 944 and driven into the bone in a caudal trajectory. When the wing is positioned on the outside of a bone anchor positioned to the right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 934 can be inserted through the bone anchor opening 944 and driven into the bone in a cranial trajectory.

[0139] For example, as shown in FIG. 7, the main bone anchor can be embedded in a vertebra 901 with a bone anchor assembly 900. The vertebra 901 can be defined by a superior facet 905 and an inferior facet 907. The wings 930 can be positioned and secured in a desired location using fasteners 932 as described above so that the bone anchor 934 can be inserted and driven in a trajectory that matches the vertebra 901 without penetrating either of the facets 905, 907. A driver tool 909 can be used to insert the bone anchor 934 into the auxiliary bone anchor opening 944 in the distal portion 930 of the wings. In the embodiment shown in FIG. 7, the wings 930 are positioned outwardly to the left of the receiver 904. The central axis of the bone anchor opening 944 in the wings 930 extends in a cephalad direction such that the auxiliary bone anchor received therein extends toward the patient's head.

[0140] In other embodiments, the wing 1030 can be positioned on the closure mechanism 1008 of the bone anchor assembly 1000 and secured in place with a nut 1032. As described above, the wing 1030 can include a distal portion 1030d having a plurality of auxiliary bone anchor openings 1044 that extend in a biased trajectory toward the right side of the wing 1030. Thus, when the wing is positioned on the outside of a bone anchor positioned to the left of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 1034 can be inserted through the bone anchor opening 1044 and driven into the bone in a cranial trajectory. When the wing is positioned on the outside of a bone anchor positioned to the right of the spinal midline when viewed from a posterior vantage point, the auxiliary bone anchor 1034 can be inserted through the bone anchor opening 1044 and driven into the bone in a caudal trajectory.

[0141] As discussed above, some embodiments of the wings can include one or more auxiliary bone anchor openings with interlocking interfaces that can facilitate variable angle locking connections with the auxiliary bone anchor screws. Thus, in these embodiments, a user can insert and drive an auxiliary bone anchor through an auxiliary bone anchor opening that is coaxial with the central axis of the auxiliary bone anchor opening or at an oblique angle to the central axis of the auxiliary bone anchor opening. In this manner, the wings can provide an extended angular range or trajectory through which the auxiliary bone anchor can be inserted into the bone to enhance fixation of the primary bone anchor.

[0142] The above steps can be repeated to place additional bone anchor assemblies at the same or different vertebral levels, with or without ancillary fixation members. Final tightening or other adjustments of the construct can be performed using known techniques, the procedure can be completed, and the incisions closed.

[0143] In any of the above embodiments or methods, the primary bone anchor can be omitted and the user can rely only on one or more secondary fixation features to secure the bone anchor assembly, which can advantageously allow the fixation location to be completely offset from the receiver member, for example, if the initially placed bone anchor needs to be removed due to incorrect positioning or insufficient bite, or if the receiver member needs to be positioned over a location where the bone anchor cannot be inserted.

[0144] Although the methods shown and described herein involve bone anchor assemblies disposed in the pedicle or lateral mass of a vertebra, it will be understood that the systems and methods herein may be used in any bone, non-bone tissue, or in non-living or non-cellular subjects.

[0145] The auxiliary fixation members disclosed herein may be implanted in the same surgical procedure as the bone anchors, receiver members, and spinal rods, or, in the case of revision surgery, during a post-surgical procedure.

[0146] It should be noted that any order of method steps depicted or suggested in the above description or the accompanying drawings should not be construed as limiting the disclosed methods to performing the steps in that order. Rather, the various steps of each of the methods disclosed herein can be performed in any of a variety of orders. Additionally, the methods described are merely exemplary embodiments, and various other methods including additional or fewer steps are within the scope of the present disclosure.

[0147] As is clear from the above, in at least some embodiments, the systems and methods disclosed herein can provide enhanced fixation for a given surgical site, providing greater bone fixation strength at a given location without having to transfer the fixation to additional vertebrae or skip / increase an associated vertebral level.

[0148] The bone anchor assemblies disclosed herein and their various components can be constructed from any of a variety of known materials. Exemplary materials include materials suitable for use in surgical applications, including, for example, metals such as stainless steel, titanium, or alloys thereof, polymers such as PEEK, ceramics, and carbon fiber. The various components of the devices disclosed herein can be rigid or flexible. One or more components or portions of the device can be formed from a radiopaque material to facilitate visualization under fluoroscopy and other imaging techniques, or can be formed from a radiolucent material so as not to interfere with visualization of other structures. Exemplary radiolucent materials include carbon fiber and high strength polymers.

[0149] The systems and methods disclosed herein can be used in minimally invasive and / or open surgery. Although the systems and methods disclosed herein are generally described in the context of spinal surgery, it will be understood that the systems and methods disclosed herein can be used in any of a variety of surgeries performed on humans or animals, and / or in fields unrelated to implants or surgery, with either human or animal implants.

[0150] Although particular embodiments have been described above, it should be understood that many changes may be made within the spirit and scope of the described concepts. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but rather have its full scope defined by the language of the following claims.

[0151] The above exemplary embodiment describes a spinal surgical application. While this is one contemplated use, the methods and devices disclosed herein may be equally adapted for use in other areas of a patient's body. Thus, the devices described herein may be formed in a variety of sizes and materials suitable for use in various areas of a patient's body.

[0152] Those skilled in the art will appreciate further features and advantages based on the above-described embodiments. Therefore, the present disclosure is not limited by what has been particularly shown and described. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

[0153] [Embodiment] (1) A method for fastening a bone anchor assembly to a bone, comprising: driving a main bone anchor into a vertebral level of the patient's spine, the bone anchor having a receiving member coupled to a proximal end thereof; Positioning a rod within the receiving member; attaching a closure mechanism to the receiving member to retain the rod within the receiving member; coupling a proximal portion of a wing to at least one of the closure mechanism and the receiving member, the wing having a distal portion defining first and second auxiliary bone anchor openings and a spanning portion connecting the proximal and distal portions, each of the first and second auxiliary bone anchor openings extending at an oblique angle relative to a proximal-distal axis of the spanning portion; positioning the wing in one of a first position in which a first auxiliary bone anchor and a second auxiliary bone anchor received within the wing correspond to the vertebral level in which the bone anchors are driven, and a second position in which at least one of the first auxiliary bone anchor and the second auxiliary bone anchor received within the wing extends across a facet of the vertebral level in which the bone anchor is driven; inserting a first supplemental bone anchor through the first bone anchor opening at a first track; inserting a second supplemental bone anchor through the second bone anchor opening at a second trajectory; driving the first auxiliary bone anchor into the vertebral level at the first trajectory and the second auxiliary bone anchor into the vertebral level at the second trajectory, such that the first auxiliary bone anchor and the second auxiliary bone anchor enhance fixation of the main bone anchor. (2) positioning the wing relative to the receiving member such that the first and second auxiliary bone anchor openings are biased in a cranial direction; driving the first secondary bone anchor at the first trajectory such that the first secondary bone anchor extends completely into the vertebral level into which the main bone anchor is driven; 2. The method of claim 1, further comprising driving the second auxiliary bone anchor at the second trajectory such that the second auxiliary bone anchor extends completely into the vertebral level at which the main bone anchor is driven. (3) The method of claim 2, wherein the vertebral level at which the main bone anchor is driven is a cervical vertebral level. (4) positioning the wing relative to the receiving member such that the first auxiliary bone anchor opening and the second auxiliary bone anchor opening are biased in a caudal direction; 2. The method of claim 1, further comprising driving at least one of the first auxiliary bone anchor and the second auxiliary bone anchor to penetrate the facet of the bone anchor at the vertebral level. (5) The method of embodiment 1, wherein coupling the proximal portion of the wing to at least one of the closure mechanism and the proximal surface of the receiving member includes attaching the wing via an expansion set screw and locking the wing in place with a nut.

[0154] (6) The method of claim 5, further comprising rotating the wing relative to the receiver member about an axis of the expansion set screw to achieve a desired first auxiliary bone anchor opening trajectory and a desired second auxiliary bone anchor opening trajectory. (7) The method of embodiment 1, wherein driving the main bone anchor into the vertebral level of the spine comprises driving the main bone anchor into a fused vertebral level of the spine. (8) The method of embodiment 1, wherein driving the first auxiliary bone anchor at the first trajectory and driving the second auxiliary bone anchor at the second trajectory distracts at least one of the first auxiliary bone anchor and the second auxiliary bone anchor from the main bone anchor. (9) The method of embodiment 1, wherein the central axis of the first auxiliary bone anchor opening and the central axis of the second auxiliary bone anchor opening are each biased from about 0 to about 60 degrees from the proximal-distal axis of the spanning portion. (10) The method of embodiment 1, wherein the first track extends at an oblique angle relative to a central axis of the first auxiliary bone anchor opening.

[0155] (11) The method of embodiment 1, wherein inserting the first auxiliary bone anchor and inserting the second auxiliary bone anchor further comprises engaging a threaded surface of the first auxiliary bone anchor with an interlocking interface of the first auxiliary bone anchor opening and engaging a threaded surface of the second auxiliary bone anchor with an interlocking interface of the second auxiliary bone anchor opening. (12) The method of claim 1, further comprising positioning the wing such that there is a gap between the distal portion of the wing and a proximally-facing surface of the vertebral level into which the main bone anchor is driven. (13) A bone anchor assembly, comprising: A bone anchor; a receiving member coupled to a proximal end of the bone anchor and defining a recess configured to receive a rod; a closing mechanism that is fitted to the receiving member; a wing having a proximal portion disposed proximally of the receiver member, a distal portion defining a plurality of auxiliary screw openings, each of the plurality of auxiliary screw openings configured to receive a auxiliary bone anchor screw therein, and a spanning portion connecting the proximal portion and the distal portion; a nut configured to engage the closure mechanism to secure the proximal portion of the wing to the proximal end of the receiver member; a plurality of auxiliary screw openings extending at an angled trajectory relative to a proximal-distal axis of the spanning portion such that in a first configuration, each auxiliary screw received in each of the plurality of screw openings can be matched to a vertebral level at which the bone anchor is inserted, and in a second configuration, at least one of the plurality of auxiliary bone anchor screws received in at least one of the screw openings can extend across a facet of the vertebral level at which the bone anchor is inserted. (14) The assembly of embodiment 13, wherein the distal portion extends approximately perpendicular to the proximal-distal axis of the spanning portion. (15) The assembly of embodiment 13, wherein a central axis of each of the plurality of screw openings extends in one of a caudal direction or a cranial direction.

[0156] (16) The assembly of claim 14, wherein the central axis of each of the plurality of threaded openings extends in an inward direction. (17) The assembly of claim 13, wherein each of the plurality of threaded openings defines an interlocking interface. (18) The assembly of claim 13, wherein each of the plurality of screw openings includes at least one threaded portion so as to be capable of receiving a screw at varying angles. (19) The assembly of embodiment 17, wherein the at least one threaded portion is a conical threaded portion. (20) The assembly of embodiment 13, wherein a central axis of each of the plurality of threaded openings extends at an angle of about 0 to about 60 degrees relative to the proximal-distal axis of the spanning portion.

[0157] (21) The assembly of claim 13, wherein the distal portion of the wing is separated from a proximally-facing surface of the bone into which the bone anchor is inserted.

Claims

1. 1. A bone anchor assembly comprising: A bone anchor; a receiving member coupled to a proximal end of the bone anchor, the receiving member defining a recess configured to receive a rod; a closing mechanism that is fitted to the receiving member; a wing having a proximal portion disposed proximally of the receiving member, a distal portion defining a plurality of auxiliary screw openings, each of the plurality of auxiliary screw openings defining a respective central axis, each of the plurality of auxiliary screw openings configured to receive a auxiliary bone anchor screw therein, and a spanning portion connecting the proximal portion and the distal portion, the spanning portion defining a proximal-distal axis; a nut configured to engage the closure mechanism to secure the proximal portion of the wing to the proximal end of the receiver member; a distal surface of the distal portion of the wings is angled obliquely inwardly to fix the central axis of each of the plurality of auxiliary screw openings between 5 degrees and 20 degrees relative to the proximal-distal axis of the spanning portion of the wings.

2. The bone anchor assembly of claim 1 , wherein each of the plurality of auxiliary screw openings defines an interlocking interface.

3. The bone anchor assembly of claim 1 , wherein each of the plurality of auxiliary screw openings includes at least one threaded portion for receiving a screw at variable angles.

4. The bone anchor assembly of claim 3 , wherein the at least one threaded portion is a conical threaded portion.

5. The bone anchor assembly of claim 1 , wherein the central axis of each of the plurality of auxiliary screw openings extends at an angle of 15 degrees relative to the proximal-distal axis of the spanning portion.

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