Multifunctional multi-axis screw

Abstract

Disclosed herein is a bone anchor assembly that provides a single bone anchor assembly that can be utilized across a variety of spinal surgical procedures, reducing manufacturing burden and costs, and providing greater flexibility during surgical procedures. The bone anchor assembly disclosed herein includes, among other components, an implantable shank and a receiving member having two spaced arms that form a U-shaped seat for receiving a rod. The bone anchor assembly disclosed herein also provides several features for enhancing performance and utility. Examples include features that facilitate better implantation of the shank, better coupling of instrumentation to the anchor, better performance in reducing a spinal fixation element such as a rod within the receiving member seat, and the like.

Description

Technical Field

[0001] The present disclosure generally relates to an improved multi-axis bone anchor assembly that can include, for example, multiple features for optimizing or improving engagement with surgical instruments, surgical instruments, and / or bone, and is applicable for use at least in thoracolumbar spinal applications.

Background Art

[0002] Bone anchor assemblies can be used in orthopedic surgery to fix bone during healing, fusion, or other processes. For example, in spinal surgery, a bone anchor assembly can be used to fix a rod or other spinal fixation element to one or more vertebrae to rigidly or dynamically stabilize the spine. A bone anchor assembly typically includes a bone screw having a threaded shank adapted to be screwed into a vertebra and a rod receiving element, usually in the form of a U-shaped slot formed in the head. The shank and the rod receiving assembly can be provided as a uniaxial screw in which the rod receiving element is fixed to the shank, or a multi-axis screw in which the rod receiving element has free angular movement with respect to the shank. In use, when the shank portion of each screw is screwed into the vertebra and properly positioned, the fixation rod is seated on the rod receiving element of each screw. Then, the rod is locked in place by tightening a set screw, plug, or similar type of fastening mechanism into the rod receiving element.

[0003] In conventional bone anchor assemblies, there are a wide variety of anchors suitable for specific applications, which can make it difficult for the user to select the appropriate anchor and for the supplier to manufacture and maintain inventory. Further, there are many ways in which conventional anchors can be difficult to use, such as when embedding the anchor, coupling instruments to the anchor, or reducing the spinal fixation element towards the anchor.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, there is a need for improved bone anchor assemblies, particularly those that can be used in a wide variety of situations and provide solutions to various utility challenges. [Means for solving the problem]

[0005] The bone anchor assemblies and related methods disclosed herein provide a single bone anchor assembly that can be used across a variety of spinal surgical procedures, reducing manufacturing burden and cost and providing greater flexibility during surgical procedures. The bone anchor assembly disclosed herein includes, among other components, an implantable shank and a receiving member having two spaced-out arms that form a U-shaped seat for receiving a rod. The bone anchor assembly disclosed herein also provides several features to enhance capability and usefulness. These include, for example, features that facilitate better implantation of the shank, better connection of instruments to the anchor, and better performance in repositioning spinal fixation elements such as rods within the receiving member seat.

[0006] In one embodiment, a bone anchor assembly is disclosed, which includes a bone anchor having a proximal head portion and a distal threaded bone engagement portion. The bone anchor further includes a receiving member having a proximal end defined by a pair of spaced arms forming a U-shaped recess between them, a distal end having a multiaxial seat portion formed internally for multiaxially seating the head portion of the bone anchor, grooves formed on the outer surface of each spaced arm at each proximal end of the spaced arms, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. Furthermore, the first and second recesses are configured to be coupled to surgical instruments.

[0007] Various alternative or additional features may be included and are considered to be within the scope of this disclosure. For example, in some embodiments, at least a portion of the first recess in each arm may extend proximal beyond the groove. In certain embodiments, each of the second recesses may be longitudinally aligned with one of the first recesses. In some embodiments, the first recesses may be configured to be pivotably coupled to a surgical instrument. In certain embodiments, a pair of second recesses may be configured to be pivotably coupled to a surgical instrument.

[0008] In some embodiments, the U-shaped recess can be configured to accommodate spinal fixation elements of various sizes.

[0009] In certain embodiments, each spaced-out arm may have transverse recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the transverse recesses may be configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. In some embodiments, each transverse recess may extend distally from the proximal end of the spaced-out arm. In certain embodiments, each transverse recess may have a concave distal surface. In some embodiments, each transverse recess may have a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them.

[0010] In some embodiments, the proximal ends of the spaced arms can be positioned along a common circular circumferential path.

[0011] In certain embodiments, opposing transverse sides of the receiving member may taper inward toward the proximal end of the receiving member. In some embodiments, the first pair of opposing sides of the receiving member may have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. The second pair of opposing sides of the receiving member may have a second taper with respect to a second plane containing the proximal-distal axis and offset from the first plane. The first plane may be perpendicular to the second plane.

[0012] In some embodiments, the assembly may include a resistance ring, which is disposed within the receiving member and can be configured to exert a frictional force on the head portion of the bone anchor.

[0013] In certain embodiments, the assembly may include a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other, forming a seat for receiving a spinal fixation element. The displaced material in the formation of the second recess may be configured to restrict the movement of the compression member relative to the receiving member. The displaced material may be received within the corresponding recess formed in the compression member.

[0014] In some embodiments, the assembly may include a pair of retractable tabs extending proximal to a pair of spaced-apart arms.

[0015] In certain embodiments, the assembly may include a fixing element having a male screw configured to be received between spaced arms of a receiving member.

[0016] In some embodiments, the bone anchor may include a hole extending proximally from the distal tip of the bone engagement portion. The hole may extend throughout the entire length of the bone anchor. The hole may be a blind hole.

[0017] In some embodiments, the distal bone engagement portion may include a male thread that extends distally along the bone engagement portion to the distal tip of the bone engagement portion.

[0018] In another embodiment, a bone anchor assembly is disclosed, comprising a bone anchor having a proximal head portion and a distal threaded bone engagement portion. The assembly further includes a receiving member having a proximal end defined by a pair of spaced arms forming a U-shaped recess configured to receive a spinal fixation element between them, and a distal end having a multiaxial seat portion formed internally for multiaxial seating of the head portion of the bone anchor. Furthermore, opposing lateral sides of the receiving member are tapered inward toward the proximal end of the receiving member.

[0019] Similar to the assemblies described above, there are various additional or alternative features that are considered to be within the scope of this disclosure. For example, in some embodiments, the first pair of opposing transverse surfaces of the receiving member may have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. The second pair of opposing transverse surfaces of the receiving member may have a second taper with respect to a second plane containing the proximal-distal axis and offset from the first plane. The first plane may be perpendicular to the second plane.

[0020] In some embodiments, the receiving member may include a receiving member having grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm such that at least a portion of the first recess intersects the groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. The first and second recesses may be configured to connect to surgical instruments. At least a portion of the first recess on each arm may extend proximal beyond the groove. Each of the second recesses may be longitudinally aligned with one of the first recesses. The first recesses may be configured to connect pivotably to surgical instruments. A pair of second recesses may be configured to connect pivotably to surgical instruments.

[0021] In some embodiments, the U-shaped recess can be configured to receive spinal fixation elements of various sizes.

[0022] In certain embodiments, each spaced-apart arm can have lateral recessed portions formed on both side edges of the arm, each of the lateral recessed portions facing away from the central proximal-distal axis of the receiving member, and the lateral recessed portions are configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. Each of the lateral recessed portions can extend distally from the proximal end of the spaced-apart arm. Each lateral recessed portion can have a concave distal surface. Each lateral recessed portion can have a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface therebetween.

[0023] In some embodiments, the proximal ends of the spaced-apart arms can be positioned along a common circular circumferential path.

[0024] In certain embodiments, the assembly can include a resistance ring disposed within the receiving member and configured to exert a frictional force on the head portion of the bone anchor.

[0025] In some embodiments, the assembly can include a compression member disposed within the receiving member, the proximal portion of the compression member including opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. The material displaced in forming the second recess can be configured to limit the movement of the compression member relative to the receiving member. The displaced material can be received within a corresponding recess formed in the compression member.

[0026] Certain embodiments can include the assembly including a pair of reduction tabs extending proximally from the pair of spaced-apart arms.

[0027] In some embodiments, the assembly can include a fixing element having a male corner screw configured to be received between spaced-apart arms of a receiving member.

[0028] In certain embodiments, the bone anchor can include a hole extending proximally from the distal tip of the bone-engaging portion. The hole can extend through the entire length of the bone anchor. The hole can be a blind hole.

[0029] In some embodiments, the distal bone-engaging portion can include a male thread extending distally along the bone-engaging portion to the distal tip of the bone-engaging portion.

[0030] In another aspect, a bone anchor assembly including a bone anchor having a proximal head portion and a distal threaded bone-engaging portion is disclosed. The assembly further includes a receiving member having a proximal end defined by a pair of spaced-apart arms forming a U-shaped recess configured to receive a spinal fixation element therebetween, and a distal end having a multi-axial seating portion formed therein for seating the head portion of the bone anchor multi-axially. Further, the proximal ends of the spaced-apart arms are positioned along a common circular circumferential path.

[0031] Any of various alternative or additional features can be included and are considered to be within the scope of the present disclosure. For example, in some embodiments, the receiving member includes grooves formed at the proximal ends of each of the spaced-apart arms on the outer surface of each of the spaced-apart arms, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects the groove, a first recess, and a second recess formed on the outer surface of the receiving member at a distal position of the first recess. The first recess and the second recess can be configured to couple to a surgical instrument. At least a portion of the first recess in each arm can extend proximally beyond the groove. Each of the second recesses can be longitudinally aligned with one of the first recesses. The first recess can be configured to pivotally couple to a surgical instrument. A pair of second recesses can be configured to pivotally couple to a surgical instrument.

[0032] In some embodiments, the U-shaped recess can be configured to accommodate spinal fixation elements of various sizes.

[0033] In certain embodiments, each spaced-out arm may have transverse recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the transverse recesses are configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. Each transverse recess may extend distally from the proximal end of the spaced-out arm. Each transverse recess may have a concave distal surface. Each transverse recess may have a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them.

[0034] In some embodiments, opposing transverse sides of the receiving member can taper inward toward the proximal end of the receiving member. The first pair of opposing sides of the receiving member may have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. The second pair of opposing sides of the receiving member may have a second taper with respect to a second plane containing the proximal-distal axis and offset from the first plane. The first plane may be perpendicular to the second plane.

[0035] In certain embodiments, the assembly may include a resistance ring positioned within the receiving member, configured to exert a frictional force on the head portion of the bone anchor.

[0036] In some embodiments, the assembly may include a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other, forming a seat for receiving a spinal fixation element. The displaced material in the formation of a second recess may be configured to restrict the movement of the compression member relative to the receiving member. The displaced material may be received within the corresponding recess formed in the compression member.

[0037] In certain embodiments, the assembly may include a pair of retractable tabs extending proximal to a pair of spaced-apart arms.

[0038] In some embodiments, the assembly may include a fixing element having a male screw configured to be received between spaced arms of a receiving member.

[0039] In certain embodiments, the bone anchor may include a hole extending proximally from the distal tip of the bone engagement portion. The hole may extend throughout the entire length of the bone anchor. The hole may be a blind hole.

[0040] In some embodiments, the distal bone engagement portion may include a male thread that extends distally along the bone engagement portion to the distal tip of the bone engagement portion.

[0041] In another embodiment, a bone anchor assembly is disclosed, comprising a bone anchor having a proximal head portion, a distal bone engagement portion having a male thread extending to the distal tip of the bone anchor, and a hole located in the center of the distal bone engagement portion extending proximal from the distal tip of the bone anchor. The assembly further includes a receiving member having a proximal end defined by a pair of spaced arms forming a U-shaped recess configured to receive a spinal fixation element between them, and a distal end having a multiaxial seat portion formed internally for multiaxially seating the head portion of the bone anchor.

[0042] Any of the various alternative or additional features may be included and will be considered within the scope of this disclosure. For example, in some embodiments, the receiving member may include a receiving member having grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm such that at least a portion of the first recess intersects the groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. The first and second recesses may be configured to connect to a surgical instrument. At least a portion of the first recess on each arm may extend proximal beyond the groove. Each of the second recesses may be longitudinally aligned with one of the first recesses. The first recesses may be configured to connect pivotably to a surgical instrument. A pair of second recesses may be configured to connect pivotably to a surgical instrument.

[0043] In some embodiments, the U-shaped recess can be configured to accommodate spinal fixation elements of various sizes.

[0044] In certain embodiments, each spaced-out arm may have transverse recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the transverse recesses are configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. Each transverse recess may extend distally from the proximal end of the spaced-out arm. Each transverse recess may have a concave distal surface.

[0045] In some embodiments, the proximal ends of the spaced arms can be positioned along a common circular circumferential path.

[0046] In some embodiments, opposing transverse sides of the receiving member can taper inward toward the proximal end of the receiving member. The first pair of opposing sides of the receiving member may have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. The second pair of opposing sides of the receiving member may have a second taper with respect to a second plane containing the proximal-distal axis and offset from the first plane. The first plane may be perpendicular to the second plane.

[0047] In certain embodiments, the assembly may include a resistance ring positioned within the receiving member, configured to exert a frictional force on the head portion of the bone anchor.

[0048] In some embodiments, the assembly may include a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other, forming a seat for receiving a spinal fixation element. The displaced material in the formation of a second recess may be configured to restrict the movement of the compression member relative to the receiving member. The displaced material may be received within the corresponding recess formed in the compression member.

[0049] In certain embodiments, the assembly may include a pair of retractable tabs extending proximal to a pair of spaced-apart arms.

[0050] In another embodiment, a bone anchor assembly is disclosed, comprising a bone anchor having a proximal head portion, a distal bone engagement portion having a male thread extending to the distal tip of the bone anchor, and a hole at the center of the distal bone engagement portion extending proximal from the distal tip of the bone anchor. The assembly also includes a receiving member having a proximal end defined by a pair of spaced arms forming a U-shaped recess between them, a distal end having a multiaxial seat portion formed internally for multiaxially seating the head portion of the bone anchor, grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects the groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. The assembly further includes a resistance ring disposed within the receiving member, configured to exert a frictional force on the head portion of the bone anchor. The assembly further includes a compression member disposed within a receiving member, the proximal portion of which includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. Furthermore, the first and second recesses of the receiving member are configured to engage with surgical instruments. Furthermore, each spaced arm has lateral recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the lateral recesses are configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. Furthermore, the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member.

[0051] Any of the various alternative or additional features may be included and are considered to be within the scope of this disclosure. For example, in some embodiments, the proximal ends of spaced arms may be positioned along a common circular circumferential path. Also, in some embodiments, a compression member may be locked against disengaging from the inside of a receiving member.

[0052] In another embodiment, a bone anchor assembly is disclosed, comprising a bone anchor having a proximal portion and a distal threaded bone engagement portion, and a locking sphere configured to connect to the proximal portion of the bone anchor. The assembly further includes a receiving member having a proximal end defined by a pair of spaced arms forming a U-shaped recess between them, and a distal end having a multiaxial seat formed internally for multiaxially seating the locking sphere; a resistance ring disposed within the receiving member and configured to exert a frictional force on the locking sphere; and a compression member disposed within the receiving member. Furthermore, the distal-facing surface of the receiving member is angled obliquely with respect to the central proximal-distal axis of the receiving member to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to a second opposite direction.

[0053] Any of the various alternative or additional features may be included and are considered to be within the scope of this disclosure. For example, in some embodiments, the receiving member may include grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm. Furthermore, the receiving member may include a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. Furthermore, the first and second recesses may be configured to be coupled to a surgical instrument. In some embodiments, at least a portion of the first recess in each arm may extend proximal beyond the groove. The second recess may be longitudinally aligned with one of the first recesses. The first recess may be configured to be pivotably coupled to a surgical instrument. The second recess may be configured to be pivotably coupled to a surgical instrument.

[0054] In certain embodiments, the U-shaped recess can be configured to accommodate spinal fixation elements of various sizes.

[0055] In some embodiments, each spaced-out arm may have transverse recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the transverse recesses are configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. Each transverse recess may extend distally from the proximal end of the spaced-out arm. Each transverse recess may have a concave distal surface. Each transverse recess may have a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them.

[0056] In certain embodiments, the proximal ends of spaced-out arms can be positioned along a common circular circumferential path.

[0057] In some embodiments, opposing transverse sides of the receiving member can taper inward toward the proximal end of the receiving member. The first pair of opposing sides of the receiving member may have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. The second pair of opposing sides of the receiving member may have a second taper with respect to a second plane containing the proximal-distal axis and offset from the first plane. The first plane may be perpendicular to the second plane.

[0058] In certain embodiments, the proximal portion of the compression member may include opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. The displaced material in the formation of the second recess may be configured to restrict the movement of the compression member relative to the receiving member. The displaced material may be received in the corresponding recess formed in the compression member.

[0059] In some embodiments, the assembly may include a pair of retractable tabs extending proximal to a pair of spaced-apart arms.

[0060] In certain embodiments, the assembly may include a fixing element having a male screw configured to be received between spaced arms of a receiving member.

[0061] In some embodiments, the bone anchor may include a hole extending proximally from the distal tip of the bone engagement portion. The hole may extend throughout the entire length of the bone anchor. The bone anchor may include at least one exit formed on its lateral surface intersecting the hole. The hole may be a blind hole.

[0062] In certain embodiments, the distal bone engagement portion may include a male thread that extends distally along the bone engagement portion to the distal tip of the bone engagement portion.

[0063] In some embodiments, the compression member can be configured to exert force on the locking sphere when the compression member advances distally relative to the receiving member.

[0064] In certain embodiments, the bone anchor may include a first-pitch thread formed along its first bone engagement portion and a second-pitch thread formed along a second bone engagement portion located proximal to the first bone engagement portion. The first pitch may be greater than the second pitch.

[0065] In some embodiments, the bone anchor may include a thread formed on a first distal portion and a second unthreaded portion positioned between the first and proximal portions of the bone anchor. Furthermore, the length of the second unthreaded portion may be at least about 30% of the length of the first portion having the thread formed thereon. The second portion may also be about 30% to about 90% of the length of the first portion.

[0066] Any of the features or modifications described herein can be applied in several different combinations to any particular aspect or embodiment of the present disclosure. There is no explicit description of any particular combination, simply to avoid unnecessary length or repetition. [Brief explanation of the drawing]

[0067] The aspects and embodiments of this disclosure can be better understood by the following detailed description made in conjunction with the accompanying drawings. [Figure 1] This is a perspective view of a bone anchor assembly according to one embodiment. [Figure 2] Figure 1 is a cross-sectional view of the bone anchor assembly. [Figure 3] Figure 1 is an enlarged cross-sectional view of the proximal portion of the bone anchor assembly. [Figure 4] Figure 1 is an enlarged future view of the proximal portion of the bone anchor assembly. [Figure 5] This is a side view of one embodiment of a bone anchor assembly. [Figure 6] Figure 1 is a partial perspective front view of the proximal portion of the bone anchor assembly. [Figure 7] This is a partial perspective side view of the proximal portion of the bone anchor assembly shown in Figure 1, in an orientation offset by 90 degrees from the orientation shown in Figure 6. [Figure 8] This is a front view of the proximal portion of the bone anchor assembly shown in Figure 1, in the orientation indicated in Figure 6. [Figure 9] This is a side view of the bone anchor assembly shown in Figure 1, in the orientation indicated in Figure 7. [Figure 10] This is a perspective view of a compression cap according to one embodiment. [Figure 11] Figure 10 is a front view of the compression cap. [Figure 12] Figure 11 is a front cross-sectional view of the compression cap. [Figure 13A] Figure 1 is a perspective view of the bone anchor assembly. [Figure 13B] Figure 1 is a perspective view of the proximal end of the shank of the bone anchor assembly. [Figure 13C] Figure 1 is a detailed perspective view of the distal end of the shank of the bone anchor assembly. [Figure 13D] Figure 13C is a partial perspective view. [Figure 14]This is a perspective view of a set screw according to one embodiment. [Figure 15A] This is an example of a reduction device introduced into a bone anchor assembly. [Figure 15B] This is an example of a reduction device that holds a rod in a bone anchor assembly and incorporates a set screw to lock the rod in place. [Figure 16] Figure 1 is a top view of the bone anchor assembly. [Figure 17] Figure 1 is a perspective cross-sectional view that divides the receiving member of the bone anchor assembly into two equal parts. [Figure 18] Figure 1 is a detailed perspective view of the proximal portion of the receiving member of the bone anchor assembly. [Figure 19] Figure 1 is an exploded view of the bone anchor assembly. [Figure 20] This is a perspective view of a bone anchor assembly according to one embodiment. [Figure 21] Figure 20 is another perspective view of the bone anchor assembly. [Figure 22] Figure 20 is an exploded view of the bone anchor assembly. [Figure 23] Figure 20 is a perspective longitudinal cross-sectional view of the bone anchor assembly. [Figure 24] Figure 20 is a magnified perspective view of the proximal portion of the bone anchor assembly. [Figure 25] Figure 20 is a front view of the proximal portion of the bone anchor assembly. [Figure 26] Figure 20 is a frontal cross-sectional view of the proximal portion of the bone anchor assembly. [Figure 27] Figure 20 is a side view of the proximal portion of the bone anchor assembly. [Figure 28] This is a side view of the opposite side of Figure 27. [Figure 29] Figure 20 is a top view of the bone anchor assembly. [Figure 30] Figure 20 is a bottom view of the bone anchor assembly. [Figure 31] Figure 20 is a perspective cross-sectional view showing the receiving member of the bone anchor assembly divided into two equal parts. [Figure 32]Figure 20 is an enlarged perspective view of the proximal portion of the receiving member of the bone anchor assembly. [Figure 33] Figure 20 is a partial perspective side view of the proximal portion of the receiving member of the bone anchor assembly. [Figure 34A] Figure 20 is a perspective view of the bone shank of the bone anchor assembly. [Figure 34B] This is a partial perspective view of Figure 34A. [Figure 35] Figure 20 is a perspective view of the receiving member of the bone anchor assembly. [Figure 36] Figure 35 is a front view of the receiving member. [Figure 37] Figure 35 is a top view of the receiving member. [Figure 38] Figure 35 is a bottom view of the receiving member. [Figure 39] Figure 20 is a perspective view of the locking sphere of the bone anchor assembly. [Figure 40] Figure 39 is a perspective cross-sectional view of the locking sphere. [Figure 41] Figure 20 is a perspective view of the resistance ring of the bone anchor assembly. [Figure 42] Figure 20 is a perspective view of the compression member of the bone anchor assembly. [Figure 43] Figure 42 is another perspective view of the compression member. [Figure 44] Figure 42 is a front view of the compression member. [Figure 45] Figure 42 is a front cross-sectional view of the compression member. [Figure 46] This is a perspective view of a bone anchor assembly according to one embodiment. [Figure 47] Figure 46 is another perspective view of the bone anchor assembly. [Figure 48] Figure 46 is an exploded view of the bone anchor assembly. [Figure 49] Figure 46 is a perspective longitudinal cross-sectional view of the bone anchor assembly. [Figure 50] This is a perspective view of a bone anchor assembly according to one embodiment. [Figure 51] Figure 50 is another perspective view of the bone anchor assembly. [Figure 52] Figure 50 is an exploded view of the bone anchor assembly. [Figure 53] Figure 50 is a perspective longitudinal cross-sectional view of the bone anchor assembly. [Figure 54] Figure 50 is a front view of the bone anchor assembly in an angled position. [Figure 55] This is a front view of a bone anchor assembly according to one embodiment. [Figure 56] This is a front view of a bone anchor assembly according to one embodiment. [Figure 57] This is a perspective view of a bone anchor assembly according to one embodiment. [Figure 58] Figure 57 is another perspective view of the bone anchor assembly. [Figure 59A] Figure 57 is a detailed perspective view of the proximal portion of the bone anchor assembly. [Figure 59B] This is a detailed front view of the proximal portion of bone anchor assembly 57. [Figure 60] Figure 60 is a partial perspective front view of the bone anchor assembly. [Figure 61] Figure 57 is an exploded view of the bone anchor assembly. [Figure 62] Figure 57 is a front cross-sectional view of the bone anchor assembly. [Figure 63] Figure 57 is a perspective view of the compression member of the bone anchor assembly. [Figure 64] Figure 63 is a perspective view of the compression member. [Figure 65] Figure 63 is a front view of the compression member. [Figure 66] Figure 63 is a front cross-sectional view of the compression member. [Modes for carrying out the invention]

[0068] Specific exemplary embodiments are described below so that the structure, function, manufacture, and principles of use of the devices, systems, and methods disclosed herein may be understood comprehensively. One or more examples of these embodiments are illustrated in the accompanying drawings. The devices, systems, and methods described herein and illustrated in the accompanying drawings are non-limiting embodiments. Features illustrated or described in relation to one embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of this disclosure. In addition, to the extent that linear, circular, or other dimensions are used in the description of the devices and methods disclosed, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such devices and methods. Dimensions equivalent to such dimensions may be determined for different geometric shapes, etc. Furthermore, components of the same numbering in an embodiment may generally have similar characteristics. Moreover, the size and shape of a device, and its components, may depend at least on the anatomical form of the subject in which the device is used, the size and shape of the object in which the device is used together, and the method and procedure in which the device is used.

[0069] The bone anchor assemblies and related methods disclosed herein provide a single bone anchor assembly that can be used across a variety of spinal surgical procedures, reducing manufacturing burden and cost and providing greater flexibility during surgical procedures. The bone anchor assembly disclosed herein includes an implantable shank and, among other components, a receiving member having two spaced arms that form a U-shaped seat for receiving a rod. The bone anchor assembly disclosed herein also provides several features to enhance capability and usefulness. These include, for example, features that facilitate better implantation of the shank, better connection of instruments to the anchor, and better performance in repositioning spinal fixation elements such as rods within the receiving member seat.

[0070] Figure 1 illustrates a perspective view of one embodiment of a bone anchor assembly 100 of the present disclosure. The bone anchor assembly may include a receiving member 102 and a bone shank 104 having a proximal head portion 106 and a distal bone engagement portion 108. The receiving member 102 may have a proximal portion 110 defined by a pair of spaced arms 112 and 114 that form a U-shaped recess 119 (also called a rod receiving recess or slot) between them for receiving a spinal fixation element (not shown), such as a spinal rod. A multiaxial seat 608 (see Figure 6) is formed at the distal end 120 of the receiving member 102 to multiaxially seat the head portion 302 (shown in Figures 2 and 3) of the bone shank 104. As will be discussed in detail below, the receiving member 102 may have a plurality of distinct engagement or attachment features to facilitate coupling the receiving member 102 with surgical instruments during use. Figure 2 is a cross-sectional view of the bone anchor assembly 100 of Figure 1, and Figure 3 is an enlarged cross-sectional view of the receiving member 102. As shown in Figure 2, the bone anchor assembly 100 may further include a compression cap 202 and a resistance ring 204 positioned within the distal end 120 of the receiving member 102. The compression cap 202 and the resistance ring 204 can contact the proximal head 302 of the shank 104. Figure 3 illustrates that the proximal head 302 of the shank 104 is seated on the distal end 120 of the receiving member 102.

[0071] Figure 4 is an enlarged partial perspective view of the bone anchor assembly 100 of Figure 1, highlighting specific elements or features of the receiving member 102, which are discussed in detail below. The receiving members of this disclosure may include, individually or in combination with each other, any of the features discussed herein. For example, the receiving member 102 may include one or more features to facilitate engagement of a surgical instrument with the bone anchor assembly 100. A groove or channel 402 may be formed on the outer surface of the proximal ends 112', 114' of the spaced-apart arms 112, 114. The groove or channel 402 may define an “upper notch” feature that can engage with a corresponding part of an instrument, such as a projection, to facilitate the attachment of the instrument to the receiving member 102. Further details relating to such features can be found in U.S. Patents 10,039,578 and 10,299,839, the entire contents of which are incorporated herein by reference.

[0072] Figure 4 also shows a proximal rocker feature (also called a first recess) 404 formed in the proximal portion 110 of the receiving member 102, which can be used to facilitate distal reduction of a rod (not shown) into the U-shaped recess 119 of the receiving member 102. The proximal rocker reduction feature 404 can allow a rocker device to pivotably connect to the receiving member 102 for reduction of a spinal fixation element in the receiving member 102 using lever action or oscillating motion. The proximal rocker feature 404 can be a bilateral circular detail or recess intersecting the upper notch feature 402 described above. In other words, each of the spaced arms 112, 114 may include a proximal rocker feature 404 intersecting a groove or channel 402 formed in the proximal ends 112', 114' of the arms 112, 114. A portion of the proximal rocker feature 404 can extend proximal to the groove 402 and intersect with the spaced-apart material of the arms 112, 114 above the groove 402 (see Figure 9). This provides stronger contact between the receiving member 102 and the surgical instrument and can reduce variations in the manufacturing of the receiving member.

[0073] Additionally or alternatively, the receiving member 102 may include a distal rocker feature (also called a second recess) 406. The distal rocker feature 406 can be formed in the receiving member 102 at a distal position to the proximal rocker feature 404. The second rocker feature 406 can provide an alternative coupling position for rocker devices, such as a reducing rocker fork, relative to the proximal / first rocker feature 404. The second rocker feature 406 may also be a swaging feature used to hold the compression cap 202 within the receiving member 102. During assembly, for example, a swaging process can form the second rocker feature 406 and displace the material of the receiving member 102 into the recess 304 formed in the compression cap (also called a compression member) (see Figure 3), thereby constraining the compression cap 202 within the receiving member 102 and preventing, for example, the compression cap 202 from coming off the proximal end 110 of the receiving member 102. A second rocker feature 406 can be formed on both sides of the receiving member 102, and the material in each arm 112, 114 of the receiving member 102 can be displaced by swaging into recesses 304 formed on both sides of the compression cap 202. This displacement of material into the compression cap 202 helps to hold the bone anchor assembly 100 together and can prevent the compression cap 202, bone anchor shank 104, and receiving member 102 from falling apart.

[0074] As shown in Figure 4, the receiving member 102 may include at least one unilateral mounting feature 408 that allows surgical instruments to be coupled to or engaged with the receiving member 102 in a manner that leaves the rod receiving slot 119 unobstructed, for example by engaging only one arm 112, 114 of the receiving member 102. In one embodiment, the receiving member 102 may include unilateral mounting features 408 on four proximal quadrants of the receiving member 102. For example, the unilateral mounting features may be formed on the opposing lateral edges of each of the spaced-apart arms 112, 114. Surgical instruments may be mounted on two adjacent unilateral features 408 on one side of the receiving member 102, leaving the rod receiving slot 119 open to receive a spinal fixation rod and / or set screw introduced distally from the proximal end 110 of the receiving member 102. This allows for the manipulation of the receiving member 102, the attachment of a reduction device, and / or the insertion of a spinal fixation or locking element into the rod receiving slot 119. As shown in Figures 4 and 17, each lateral recessed portion 408 may have a concave distal surface 409. In some embodiments, such as shown in Figure 59, each unilateral mounting feature 408 may have a planar distal surface 5711 at an angle of approximately 90 degrees to the side wall surface 5713, with the concave surface between them having a smaller radius than the surface 409. Such a configuration can provide an additional planar bracing surface for use when coupled with an instrument. Further details relating to unilateral mounting features can be found in U.S. Patent Application Publication No. 2019 / 0183541, entitled "Unilateral Implant Holders and Related Methods," the entire contents of which are incorporated herein by reference.

[0075] As shown in Figure 4 and discussed in detail below with respect to Figures 10-12, the receiving member 102 can accommodate spinal fixation elements of multiple sizes. For example, a spinal rod having a diameter of approximately 5.5 mm or approximately 6.0 mm can be received in the rod receiving recess 119. The proximal portions of the spaced arms 112, 114 of the receiving member 102 may include threaded inner surfaces 410 that can engage with a set screw or other locking element received between them to lock a spinal rod within the receiving member 102. In some embodiments, the internal threaded portions 410 may have square threads to engage with, for example, the male square thread of one half of a set screw (see Figure 14).

[0076] Figure 5 is a front view of another embodiment of the bone anchor assembly 500 of the present disclosure, having a reduction tab 502 extending proximal to spaced arms 512, 514 of a receiving member 504. The bone anchor assembly 500 of Figure 5 may include any of the features described herein.

[0077] The bone anchor assemblies 100, 500 of the present disclosure may include receiving members 102, 504 having a taper in one or more directions. Figure 6 is a partial perspective view of the bone anchor assembly 100 of Figure 1, in particular showing the taper 602 of the outer surface of the receiving member 102 in a first direction. More specifically, the opposing sides 604, 606 of a first pair, shown in Figure 6 as the outer walls of spaced-apart arms 112, 114, may have a first taper with respect to a first plane containing the proximal-distal axis A1 of the receiving member 102 (i.e., the plane of the page in Figure 6). Alternatively, Figure 60 shows an embodiment of a receiving member 5702 in which the opposing sides 6004, 6006 of the first pair do not have a taper with respect to the first plane containing the proximal-distal axis A1 of the receiving member. In other words, the opposing sides 6004 and 6006 of the outer walls of the spaced-apart arms 5712 and 5714 have a substantially straight cylindrical shape.

[0078] Figure 7 is a partial perspective side view of the bone anchor assembly 100 of Figure 1 in an orientation offset by 90 degrees from the orientation shown in Figure 6. Figure 7 illustrates, in particular, the taper 702 of the outer surface of the receptor member 102 in a second orientation. More specifically, the opposing sides 704, 706 of the second pair shown in Figure 7 as the outer wall of the receptor member 120, offset by 90 degrees from the opposing sides 604, 606 of the first pair, may have a second taper with respect to a second plane (i.e., the plane of the page in Figure 7). The second plane includes the proximal-distal axis A1 of the receptor member and is offset from the first plane described above. The first and second planes may be perpendicular to each other in some embodiments, but other offset angles are also possible. Thus, when implanted in the patient's spine, the receptor member 102 may have walls that taper in both the cranial-caudal and medial-lateral directions, for example. The taper of the receiving member 102 toward two offset planes, i.e., the angled characteristics of the receiving member 102, i.e., the tapering of the outer walls 604, 606, 704, 706 or outer surface of the receiving member 102 in two directions, can assist in instrument attachment to the receiving member 102 because it can guide the surgical instrument to become self-centered during attachment to the receiving member. In some embodiments, such as those shown in Figures 57 to 62, the receiving member may be tapered in only one direction. Such a configuration can still provide self-centering guidance during instrument attachment to the receiving member. Figures 8 and 9 are non-transverse front and side views of the bone anchor assembly 100 of Figure 1 in the orientation shown in Figures 6 and 7, respectively. The inward taper 604, 606, 704, 706 of the receiving member 102 toward the proximal end can be seen similarly in these figures. Figures 8 and 9 illustrate that in some embodiments, tapering in multiple planes can be achieved using different surface shapes. For example, in the front view of Figure 8, surfaces 604 and 606 may have a curved shape that generates a first conical taper. However, surfaces 704 and 706 may be planar surfaces angled toward each other to generate a second taper.As described above, in some embodiments, only one of these tapers may be used. For example, in the embodiments shown in Figures 57 to 62, the cylindrical surfaces 6004 and 6006 are not tapered, while the planar surfaces 7004 and 7006 have a taper similar to that of surfaces 704 and 706 in Figures 7 and 9.

[0079] Returning to Figures 6 and 7, the bone anchor assembly 100 may include a resistance ring 204 positioned in a recess or groove 1702 (see Figure 17) formed in the distal portion 120 of the receiving member 102. The resistance ring 204 can create a friction fit between its inner surface 204' and the outer surface of the shank head 302, thereby allowing the receiving member 102 of the bone anchor assembly 100 to provisionally maintain its position relative to the bone shank 104 before the bone anchor assembly 100 is fully locked, for example, with a set screw or other locking element. In some embodiments, the resistance ring 204 can be positioned in the distal portion 120 of the receiving member 102 before insertion of the shank head 302. Further details regarding the resistance ring can be found in U.S. Patent No. 7,087,057, the entire contents of which are incorporated herein by reference. As described above, the distal end 120 of the receiving member 102 may include a multi-axis seat 608 for multi-axis seating the head 302 of the bone shank 104. This multi-axis connection can enable the full range of motion of the bone shank 104 relative to the receiving member 102. For example, the spherical recess of the distal end 120 of the receiving member 102 (see multi-axis seat 1704 in Figure 17) can receive the spherical portion of the shank head 302.

[0080] Figures 10–12 illustrate one embodiment of the compression cap 202 of the present disclosure. Figure 10 is a perspective view of one embodiment of the compression cap 202, Figure 11 is a front view of the compression cap 202 of Figure 10, and Figure 12 is a cross-sectional view of the compression cap 202 shown in Figure 11. As described above, the outer surface of the compression cap 202 may include a recess or depression 304 that can receive material from a receiving member 102 that is displaced during swaging, which can form a second rocker feature 406. The proximal portion of the compression cap may form a seat for receiving a spinal rod. More specifically, two planar surfaces 1002, 1004 of the compression cap may be angled and offset from each other to form a substantially "V" shaped groove that can seat spinal rods of various diameters. This is in comparison to conventional compression caps, which often include a curved proximal surface having a radius matching the diameter of a single spinal rod.

[0081] Figures 13A to 13D illustrate various aspects of one embodiment of the bone shank 104 of the present disclosure. Figure 13A shows the bone anchor assembly 100 of Figure 1. Figure 13B shows a top perspective view of the separated bone shank 104. Figure 13C shows a magnified view of the distal end of the bone engagement portion 108 of the bone shank 104. Figure 13D shows a partial perspective magnified view of the distal end of the bone engagement portion 108 of the bone shank 104. The male thread 1302 may extend along the bone engagement portion 108 of the shank 104. Various thread configurations, including solid double leads, solid cortical fixation, cannula insertion double leads, cannula insertion cortical fixation, and cannula insertion cortical fixation fenestrated threads, can be used for the shank of the present disclosure. The bone shank 104 may have a quick-start tip 1304 with threads that extend distally to the distal tip 3410 of the bone engagement portion 1310. In this way, the threads 1302 can extend to the contact surface between the bone shank 104 and the bone (not shown), which can provide immediate purchase of the threads into the bone. Many conventional screws often use a rounded tip distal to the threads, which may require the screw to be driven axially into the bone a certain distance before the threads can grip the bone.

[0082] The recess 1306 can be formed centered at the distal tip 1310 of the bone shank 104. This recess 1306, which may be called a centering recess, can be used to center and support the distal bone engagement portion 108 of the shank 104 during the manufacturing process. In some embodiments, the centering recess can be a blind hole extending proximal to the distal tip 1310 of the bone engagement portion 108 (for example, as shown in the partial perspective view of Figure 13D). In other embodiments, the centering recess can be a complete cannula-like recess extending from the proximal end to the distal end of the bone shank 104. Such a recess can, for example, allow for the introduction of the shank 104 on a guidewire, delivery of cement or other fluid material into the bone through the shank 104, etc. The drive feature 1308 can be formed at the proximal head 302 of the bone shank 104 to allow a driver to control the rotation of the anchor during implantation, etc. Various drive feature designs can be used, including square drive, hexagonal drive, and lobed drive. The illustrated embodiment includes the T27 drive feature.

[0083] Figure 14 illustrates one embodiment of the set screw 1400 of the present disclosure. The proximal portions of the inner surface 206 (see Figure 2) of the set screw 1400 and the receiving member 102 may each have complementary angular threads 1402 (or other threaded structures) formed thereon. As described above, the set screw 1400 may have a drive feature 1404 formed therein, such as the T27 drive feature 1404 described above. Figures 15A and 15B illustrate one embodiment of a reduction instrument 1500 in the form of a reduction fork that engages with the distal rocker feature 1502 of the bone anchor assembly 1501. The reduction instrument 1500 can be coupled with the receiving member 1503 when the bone anchor assembly 1501 is embedded in the bone by engaging the distal rocker feature 1502 on either side of the receiving member 1503 with, for example, a halved projection formed on the arm of the reduction instrument 1500. The reduction device 1500 can be pivoted or swung to move the spinal rod 1506 distally into the recess of the receiving member 1503. Furthermore, the offset of the device 1500 from the receiving member 1503 generated by the fork arm shape and pivoting motion allows the proximal end of the receiving member 1503 to remain unobstructed so that a set screw 1400 or other locking element can be inserted using a screwdriver 1504 to lock the spinal rod 1506 into the receiving member 1503.

[0084] Figures 16 to 19 provide additional detail views of the bone anchor assembly 100. For example, Figure 16 shows a top view or proximal end view of the assembly 100. This figure illustrates that the spaced arms 112, 114 of the receiving member 102 are generally positioned along a circle 1602. For example, each of the unilateral mounting features 408 found at the lateral ends of the spaced arms 112, 114 can be positioned at an equal distance from the centerline of the assembly, i.e., at a distance equal to the radius of the circle 1602.

[0085] Figure 17 shows a cross-sectional view that bisects the receiving member 102 through the center of a U-shaped recess 119 formed between the spaced arms 112 and 114 at the proximal end 110 of the receiving member 102. This figure provides a better view of the interior of the receiving member 102, including two single-sided mounting features 408 formed at both ends of the receiving member arm 112, a thread 410 formed at the proximal end of the inner surface of the arm 112 to receive a set screw, an intermediate threadless portion 1701, a groove 1702 for receiving a spring clip or resistance ring 204, and a multi-axis seat 1704 formed at the distal end 120 of the receiving member 104 on which the spherical head 302 of the shank 104 can be seated.

[0086] Figure 18 shows a detail view of the external proximal portion 110 of the receiving member 102, including a notch or groove 402 formed in the outer sidewall of the spaced arms 112, 114 of the receiving member 102, and a first rocker feature 404 intersecting the groove 402. Similar to the groove 402, the first rocker feature 404 is recessed below the outer surface 604 of the arms. Furthermore, the first rocker feature 404 extends proximal above the upper or proximal surface of the groove 402, as indicated by the arc 1802. The arc 1802 provides a larger surface area for force transmission when coupled to a rocker fork retractor, which typically includes a cylindrical pin seated in the recess 404 of the first rocker feature. Without the arc 1802, the cylindrical pin of the rocker fork would be in substantially point or line contact with the substantially planar upper or proximal surface of the groove 402.

[0087] Figure 19 illustrates an exploded view of the bone anchor assembly 100. As shown in the figure, in one embodiment, the bone anchor 100 can be assembled by loading a spring clip or ring 204 from above or advancing it distally relative to the receiving member 102, thereby expanding the spring clip / ring 204 within the groove 1702. The shank 104 can then be loaded from above or advanced distally through the interior of the receiving member 102 such that the distal bone engagement portion 108 of the shank 104 extends from a through hole 101 (shown in Figure 17) formed in the bottom of the receiving member 102, the spherical head 302 of the shank 104 rests on the multi-axis seat portion 1704 of the receiving member 102, and the resistance clip / ring 204 frictionally engages with the spherical head 302. The compression cap 202 can also be loaded into the receiving member 102 from above or advanced distally, and a swaging operation can be performed to lock the compression cap 202 in place against dislodging from the inside of the receiving member 102. Although locked in place against complete dislodging after swaging, the compression cap 202 can still translate through its range of motion relative to the receiving member 102 and the shank 104, and such multiaxial motion of the receiving member 102 relative to the shank 104 can be selectively controlled by varying the distal force applied to the compression cap 202, which drives it to frictional contact with the proximal end of the bone shank spherical head 302.

[0088] Figures 20 to 56 illustrate additional embodiments of the bone anchor assembly according to the present disclosure. These embodiments utilize many of the features described above but can be configured for use with larger diameter screw shanks. In addition, the receiving members shown in these embodiments can be configured to bias shank angle formation to one side or in one direction, using a “preferred angle” distal portion that allows for greater shank angle formation in one direction relative to the opposite direction.

[0089] The bone anchor assemblies of these embodiments may generally include a receiving member or head, a compression member or cap, a locking sphere, and a shank. The bone anchor assembly can be assembled by inserting the proximal portion of the screw shank upward through a distal hole formed in the receiving member. The locking sphere can be dropped into the proximal end of the receiving member and pressed onto the screw shank. The sphere can be locked onto the shank by a rib that fits into a recess on the inside of the locking sphere. The compression component is loaded into the receiving member from the proximal end and can be held in place, for example, by swaging, to hold the assembly together. In certain embodiments, resistance features may also be incorporated, such as including resistance rings, spring clips, etc., positioned within the receiving member and around the locking sphere to provide resistance against the multiaxial motion of the receiving member relative to the screw shank.

[0090] Figures 20 to 34 illustrate different diagrams of one embodiment of the large-diameter, preferred-angle bone anchor assembly 2000 according to this disclosure, and Figures 35 to 45 illustrate detailed diagrams of the components of the assembly. More specifically, Figures 20 and 21 provide opposing perspective views of the bone anchor assembly 2000. Figure 22 provides an exploded view of the bone anchor assembly 2000. Figure 23 provides a cross-sectional view of the bone anchor assembly 2000. Figure 24 provides a partial perspective view of the proximal portion of the bone anchor assembly 2000. Figure 25 provides a front view of the proximal portion of the bone anchor assembly 2000. Figure 26 provides a front cross-sectional view of the proximal portion of the bone anchor assembly 2000. Figures 27 and 28 provide opposing side views of the proximal portion of the bone anchor assembly 2000. Figures 29 and 30 provide a top view and a bottom view of the bone anchor assembly 2000. Figures 31 to 34 illustrate various features of the receiving member 2002 of the bone anchor assembly 2000. Figures 35 to 38 provide perspective views, front views, top views, and bottom views of the receiving member 2002. Figures 39 and 40 provide perspective views and cross-sectional views of the locking sphere 2006 of the bone anchor assembly 2000. Figure 41 provides a perspective view of the resistance ring 2010 of the bone anchor assembly 2000. Finally, Figures 42 to 45 provide perspective views, front views, and cross-sectional views of the compression member 2008 of the bone anchor assembly 2000.

[0091] As shown in Figures 20 to 34, one embodiment of a large-diameter, preferred-angle bone anchor assembly 2000 may include a receiving member 2002 and a bone anchor or shank 2004 having a proximal head portion 2204 and a distal bone engagement portion 2007. The receiving member 2002 may have a proximal end 2009 defined by a pair of spaced arms 2013, 2015 that form a U-shaped recess 2019 (also called a rod receiving recess or slot) between them for receiving a spinal fixation element (not shown), such as a spinal rod. A multiaxial seat portion 2602 (see Figure 26) may be formed at the distal end 2011 of the receiving member 2002 to multiaxially seat a locking sphere 2006 coupled to the proximal portion 2204 of the bone anchor / shank 2004. The bone anchor assembly 2000 may further include a compression member or cap 2008 and a resistance ring 2010 disposed within the receiving member 2002, each of which can contact the locking sphere 2006 and exert a frictional force thereon that can selectively resist and / or prevent any relative movement of the receiving member 2002 with respect to the bone anchor / shank 2004.

[0092] The bone anchor assembly 2000 can be similar in many respects to the bone anchor assembly described above and may include any combination of any of the various features described above. For example, the receiving member 2002 may include any of the various features for facilitating engagement between surgical instruments and the bone anchor assembly. These may include grooves or channels 2012 formed on the outer surface at the proximal ends of each separating arm 2013, 2015 of the receiving member 2002, which may define an "upper notch" feature that engages with a corresponding part of the instrument, such as a projection, to facilitate coupling the instrument to the receiving member.

[0093] In other embodiments, the receiving member 2002 may include a proximal rocker feature (or first recess) 2014 formed in the proximal portion 2009 of the receiving member 2002, which can be used to facilitate distal reduction of the rod into the U-shaped recess 2019 of the receiving member 2002. The proximal rocker reduction feature 2014 may allow the rocker device to pivotably connect to the receiving member 2002 for reduction of the spinal fixation element within the receiving member 2002 using lever action or oscillating motion. The proximal rocker feature 2014 may be a bilateral circular detail or recess intersecting the upper notch feature / groove 2012, as described above. However, in other embodiments, different shapes may be utilized for the proximal rocker feature recess.

[0094] In some embodiments, the receiving member 2002 may additionally or alternatively include a distal rocker feature (also called a second recess) 2016. The distal rocker feature 2016 may be formed in the receiving member 2002 at a distal position to the proximal rocker feature 2014. The second or distal rocker feature 2016 can provide an alternative binding position for a rocker device, such as a reducing rocker fork, relative to the proximal rocker feature 2014. The second rocker feature may also be a swage feature used to hold the compression member 2008 within the receiving member 2002. During assembly, for example, a swaging process can form the second rocker feature 2016 and displace the receiving member material into a recess 4202 (see Figure 42) formed in the compression member 2008, thereby confining it within the receiving member 2002 and preventing it from coming loose, for example, from the proximal end 2009 of the receiving member 2002. A second rocker feature 2016 can be formed on both sides of the receiving member, and the material within each arm 2013, 2015 of the receiving member 2002 can be displaced by swaging into recesses formed on both sides of the compression cap 2008.

[0095] The receiving member 2002 may include at least one unilateral mounting feature 2018 that allows a surgical instrument to be coupled to or engaged with the receiving member 2002 in a manner that does not obstruct the rod receiving slot 2019, for example, by enabling the attachment of an instrument to the receiving member 2002 by engaging only one arm 2013 or 2015 of the receiving member 2002. In one embodiment, the receiving member 2002 may include unilateral mounting features 2018 on four proximal quadrants of the receiving member 2002. For example, the unilateral mounting features 2018 may be formed on the opposing lateral edges of each of the spaced-apart arms 2013, 2015. The surgical instrument may be attached to two adjacent unilateral features 2018 on one side of the receiving member 2002, leaving the rod receiving slot 2019 open to receive a spinal fixation rod and / or set screw introduced distally from the proximal end 2009 of the receiving member 2002, as described above.

[0096] As described above, the receiving member 2002 can receive spinal fixation elements of multiple sizes. For example, a spinal rod having a diameter of about 5.5 mm or about 6.0 mm can be received in the rod receiving recess 2019. The proximal portions of the spaced-apart arms 2013, 2015 of the receiving member 2002 may include threaded inner surfaces 2020 that can engage with a set screw or other locking element received between them to lock a spinal rod within the receiving member 2002. In some embodiments, the internal threaded portion 2020 may have square threads to engage with, for example, the male square thread of one half of a set screw (see, for example, Figure 14).

[0097] The receiving member 2002 may also include a taper in at least one direction. Figure 33 is a partial perspective view of the bone anchor assembly 2000 of Figure 20, showing, among other things, the taper 3302 of the outer surface of the receiving member 2002 in a first direction. More specifically, the opposing sides 3304, 3306 of the first pair shown in Figure 33 as the outer walls of spaced-apart arms 2013, 2015 may have a first taper with respect to a first plane (i.e., the plane of the page in Figure 33) that includes the proximal-distal axis A1 of the receiving member. As described above in Figure 7, a second taper may include a second taper with respect to a second plane that is offset 90 degrees from the orientation shown in Figure 33, i.e., includes the proximal-distal axis A1 of the receiving member and is offset from the first plane. However, this second taper is not essential, and in particular, as shown in Figures 20, 25, and 36, the bone anchor assembly 2000 does not include a second taper. Instead, surfaces 2030, 2031 adjacent to the planar tapered surfaces 3304, 3306 have a straight cylindrical contour. In embodiments involving multiple tapers, the first and second planes can be perpendicular to each other in some embodiments, but other offset angles are also possible. Thus, in some embodiments, when implanted in the patient's spine, the receptacle member 2002 may have walls that taper in both the cranial-caudal and medial-lateral directions, for example. The taper of the receptacle member 2002 relative to one or two offset planes can assist in instrument attachment to the receptacle member, as the angled characteristics of the receptacle member, i.e., tapering of the outer wall or surface of the receptacle member in one or two directions, can guide the surgical instrument to become self-centered during attachment to the receptacle member.

[0098] In addition to the above-described features of the receiving member 2002, the receiving member can be configured to provide a greater degree of angulation in the first direction compared to a second direction opposite to the first direction. For example, the receiving member 2002 may include a distal-facing surface 2022 that is angled obliquely with respect to the central proximal-distal axis A1 of the receiving member. This can effectively angle the hole 2202 (see Figure 22) formed in the distal-facing surface of the receiving member 2002 to one side, thereby allowing a greater degree of angulation of the bone anchor 2004 toward that side compared to the opposite side. This can bias the bone anchor assembly 2000 to favor angulation in one direction. Figure 25 illustrates the angle α generated between the central proximal-distal axis A1 and the plane of the distal-facing surface 2022.

[0099] The bone anchor or shank 2004 may similarly include any of the various features described above. For example, the bone anchor 2004 may include a male thread 2024 extending along the bone engagement portion 2007 of the shank 2004. Various thread profiles, including solid double leads, solid cortical fixation, cannula insertion double leads, cannula insertion cortical fixation, and cannula insertion cortical fixation fenestrated threads, can be utilized for the shanks of this disclosure. The bone shank 2004 may have a quick-start tip 3402 having a thread that extends distally to the distal tip 3410 of the bone engagement portion 2007, as shown in Figure 34. In this way, the thread 2024 may extend to the contact surface between the bone shank 2004 and the bone, which can provide immediate engagement of the thread 2024 into the bone.

[0100] In addition, the recess 3404, also shown in Figure 34, can be formed centered at the distal tip of the bone shank 2004. This recess 3404, which may be called a centering recess, can be used to center and support the distal bone engagement portion 2007 of the shank 2004 during the manufacturing process. In some embodiments, the centering recess 3404 can be a blind hole extending proximal to the distal tip of the bone engagement portion (for example, as shown in the partial perspective view of Figure 34). In other embodiments, the centering recess 3404 can be a complete cannula-like recess extending from the proximal to the distal end of the bone shank 2004. Such a recess can, for example, allow for the introduction of the shank 2004 on a guidewire, delivery of cement or other fluid material into the bone through the shank 2004, and so on. The drive feature 2302 (see Figures 23 and 29) can be formed in the proximal head 2204 of the bone shank 2004 to allow the driver to control the rotation of the anchor during implantation or other operations. Any of the various drive feature designs, including square drive, hexagonal drive, and lobed drive, can be used. The illustrated embodiment includes the T27 drive feature.

[0101] The bone anchor assembly 2000 can be configured for use with larger diameter bone anchors or shanks 2004. For example, in some embodiments, the bone anchor assembly 100 described above may have a bone anchor 104 having a shank diameter of up to approximately 7 mm. Beyond that size, the bone anchor may be too large to load from the bottom through a hole formed on the distal surface of the receiving member, especially when the bone anchor includes a spherical proximal end. The bone anchor assembly 2000 can provide larger size bone anchors by utilizing bone anchors with a relatively uniform diameter or columnar proximal end that can be loaded from the bottom into the receiving member 2002 through a hole 2202 and coupled to a locking sphere 2006 loaded from the top into the receiving member. While this modular configuration can, in some embodiments, allow for the use of bone anchors with diameters ranging from approximately 7 mm to approximately 12 mm, this configuration can also be used for any smaller diameter instead of a single-component bone anchor, such as the embodiment shown in Figure 1.

[0102] As shown in Figure 22, the bone anchor 2004 may include a proximal portion 2204 configured to connect with the locking sphere 2006. The proximal portion 2204 may include ribs, projections, or other features 2206 formed on its outer surface that can interact with recesses or other complementary features 4002 (see Figure 40) formed on the inner surface of the locking sphere 2006. This configuration allows the locking sphere 2006 to be fixed to the bone anchor 2004 so that the bone anchor 2004 can move multiaxially relative to the receiving member 2002 when the locking sphere 2006 is positioned in the multiaxial seat portion 2019 of the receiving member 2002. Furthermore, the movement of the bone anchor 2004 relative to the receiving member 2002 can be controlled using the frictional force exerted on the locking sphere 2006, as will be described in more detail below.

[0103] As shown in Figures 39 and 40, the locking sphere 2006 may have a spherical outer surface and a columnar inner surface configured to receive the proximal end portion 2204 of the bone anchor 2004. The locking sphere 2006 may also include one or more relief slits 3902 formed in the locking sphere 2006 to allow deformation of the locking sphere 2006 when coupled with the bone anchor 2004. In the illustrated embodiment, two relief slits 3902, 3904 of different shapes are provided in an alternating pattern around the circumference of the locking sphere 2006. The inner surface of the locking sphere 2006 may include a recess 4002 that can receive a rib 2206 formed on the outer surface of the proximal end portion 2204 of the bone anchor 2004 to help fix the two components relative to each other when coupled.

[0104] As shown in Figures 22-24, 26, and 41, the bone anchor assembly 2000 may include a resistance ring 2010 positioned in a recess or groove 2208 (see Figures 22, 26, and 35) formed in the distal portion 2011 of the receiving member 2002. The resistance ring 2010 can create a friction fit between its inner surface and the outer surface of the locking sphere 2006, thereby allowing the receiving member 2002 of the bone anchor assembly to provisionally maintain its position relative to the bone shank 2004 before the bone anchor assembly is fully locked, for example, with a set screw or other locking element. The resistance ring 2010 can be positioned above the equator or widest diameter of the locking sphere 2006. This may mean that, in some embodiments, the resistance ring 2010 can be positioned within the distal portion 2011 of the receiving member 2002 after the locking sphere 2006 has been loaded from above into the distal portion of the receiving member.

[0105] Figures 42 to 45 illustrate an embodiment of the compression member or cap 2008 of the present disclosure. Figures 42 and 43 are perspective views of an embodiment of the compression member 2008, Figure 44 is a front view of the compression member 2008, and Figure 45 is a cross-sectional view of the compression member 2008. As described above, the outer surface of the compression cap 2008 may include a recess or indentation 4202 that can receive material from a receiving member 2002 that is displaced during swaging, which can form a second rocker feature. The proximal portion of the compression member 2008 may form a seat 4210 for receiving a spinal rod. More specifically, two planar surfaces 4204, 4206 of the compression member may be angled and offset from each other to form a substantially "V" shaped groove that can seat spinal rods of various diameters. The bottom surface 4208 of the compression member 2008 may include a substantially spherical surface configured to contact the locking sphere 2006 and exert a frictional force on the locking sphere 2006 when the compression member 2008 is advanced distally relative to the receiving member 2002 (for example, by a user tightening a set screw onto threads formed on the proximal portion of the receiving member).

[0106] Figures 46 to 49 illustrate different diagrams of another embodiment of the large-diameter, preferred-angle bone anchor assembly 4600 according to this disclosure. More specifically, Figures 46 and 47 provide opposing perspective views of the bone anchor assembly 4600. Figure 48 provides an exploded view of the bone anchor assembly 4600. Figure 49 provides a cross-sectional view of the bone anchor assembly 4600.

[0107] In the embodiments of Figures 46 to 49, the receiving head 2002, locking sphere 2006, compression member 2008, and resistance ring 2010 may be the same as those described above in relation to the embodiment of Figure 20, but bone anchors or shanks 4602 with different configurations may be provided. The bone anchor 4602 may include a plurality of threaded sections that can be configured to enhance the fixation of the bone anchor assembly 4600 within the bone. For example, the bone anchor 4602 may include a first distal threaded section 4604 having a first pitch and a first number of thread initiations, and a second proximal threaded section 4606 having a second pitch smaller than the first pitch and a second number of thread initiations larger than the first number of thread initiations. Different threaded sections or parts 4604, 4606 may have a certain lead (equal to the thread start multiplied by the thread pitch), that is, the bone anchor 4602 may be translated by an equal distance in a direction parallel to the longitudinal axis of the bone anchor shaft when rotated 360°.

[0108] For example, with respect to a bone anchor assembly designed to be implanted through the pedicle of a vertebra, the threaded distal section 4604 may be configured to engage with cancellous bone in the anterior vertebral body of the vertebra, and the threaded proximal section 4606 may be configured to engage with the cortical bone of the pedicle of the vertebra. The use of threaded sections with a certain lead facilitates the insertion of the anchor 4602 into the vertebra and prevents detachment of the pedicle wall. Further details regarding the bone anchor 4602 and its multiple threaded sections can be found in U.S. Patent No. 9,155,580, entitled "Multi-threaded Cannulated Bone Anchors," the entire contents of which are incorporated herein by reference.

[0109] Figures 50 to 54 illustrate different diagrams of yet another embodiment of the large-diameter, preferred-angle bone anchor assembly 5000 according to the present disclosure. More specifically, Figures 50 and 51 provide opposing perspective views of the bone anchor assembly 5000. Figure 52 provides an exploded view of the bone anchor assembly 5000. Figure 53 provides a cross-sectional view of the bone anchor assembly 4600. Figure 54 provides a front view of the bone anchor assembly 5000 in an angled state.

[0110] In the embodiments of Figures 50 to 54, the receiving head 2002, locking sphere 2006, compression member 2008, and resistance ring 2010 may be the same as those described above in relation to the embodiments of Figures 20 and 46, but bone anchors or shanks 5002 with different configurations may be provided. The bone anchor 5002 may include a first distal threaded portion or section 5004 and a second unthreaded portion or section 5006 positioned between the first portion 5004 and the proximal portion 5007 of the bone anchor 5002. The second portion 5006 may have a smooth outer surface with a diameter smaller than the maximum outer diameter of the threaded portion 5004, i.e., smaller than the outer diameter near the proximal end 5009 of the first portion 5004 before the diameter begins to taper as it approaches the distal end 5011 of the bone anchor 5002. In some embodiments, the diameter of the second portion 5006 may be close to the maximum outer diameter of the threaded portion 5004 in order to maximize the strength of the bone anchor 5002. In some embodiments, the diameter of the second portion 5006 may be between the maximum inner diameter and the maximum outer diameter of the threaded portion 5004.

[0111] The second portion 5006 can have a range of lengths equal to the desired total length of the bone anchor 5002. In some embodiments, the length of the second portion 5006 can be at least about 30% of the length of the first portion 5004, and in some embodiments, the length of the second portion can be about 30% to about 90% of the length of the first portion 5004.

[0112] The bone anchor 5002 can be useful in certain applications where a longer thread with maximum strength is desired. One such application is the "SAI" orbital, i.e., a procedure in which the bone anchor is introduced through the sacral wing so that the distal end of the bone anchor reaches the ilium. In such a procedure, it may be desirable to provide an extended second part 5006 that does not have threads and has maximum strength to resist the applied forces. Thus, a threadless second part 5006 can be provided having a diameter only slightly less than the maximum outer diameter of the threaded first part 5004.

[0113] Figure 54 illustrates a bone anchor assembly 5000 in an angled state, where the proximal-distal axis A1 of the receiving member 2002 is angled obliquely with respect to the proximal-distal axis A2 of the bone anchor 5002. This is in contrast to the positioning shown in Figures 50 to 53, where axes A1 and A2 are aligned and coaxial with each other. As described above, the “preferred angle” configuration of the receiving member 2002 can allow for a greater degree of angle formation in one direction compared to the second opposite direction. For example, a greater degree of angle formation in the direction shown in Figure 54, where the distal portion of axis A2 is positioned to the left of axis A1 in the plane of the figure, is possible compared to the opposite direction of angle formation where the distal portion of axis A2 is positioned to the right of axis A1 in the plane of the figure.

[0114] Figure 55 illustrates yet another embodiment of the large-diameter, preferred-angle bone anchor assembly 5500 according to the present disclosure. In this embodiment, the receiving member 2002, the locking sphere 2006, the compression member 2008, and the resistance ring 2010 may be the same as those described above in relation to the embodiments of Figures 20, 46, and 50, but bone anchors or shanks 5502 with different configurations may be provided. In particular, the bone anchor assembly 5500 may include a fenestrated bone anchor 5502. That is, the bone anchor 5502 may include a cannula or passage extending along the longitudinal axis of the bone anchor 5502 from the proximal end to the distal end of the bone anchor 5502. In addition, the bone anchor 5502 may include one or more outlets 5504 formed along the length of the bone anchor that can intersect with the cannula or passage formed in the bone anchor. One or more outlets 5504 can allow a fluid material, such as bone cement or other material, to be introduced into the region surrounding the bone anchor by injecting it into a cannula or passage at the proximal end of the bone anchor. One or more outlets 5504 can be positioned along any portion of the bone anchor 5502. In the illustrated embodiments, the outlets 5504 are shown positioned along the distal portion of the bone anchor 5502, having opposing outlets that form a through-hole in the bone anchor intersecting with a central cannula or passage formed within the bone anchor. In some embodiments, the lateral outlets 5504 can be omitted so that the bone anchor 5502 includes a single cannula extending from openings formed at the proximal end 5508 and its distal end 5506 of the bone anchor 5502.

[0115] The thread configuration of the bone anchor 5502 is similar to that of the embodiment shown in Figure 46, but the illustrated fenestration of the bone anchor can also be incorporated into any of the various bone anchor configurations disclosed herein. For example, providing a fenestrated screw shank having the configuration shown in either the embodiment of Figure 20 or Figure 50 is also within the scope of this disclosure. This means that this disclosure encompasses any combination of solid, cannula-like, and / or fenestrated bone anchors having so-called “double-lead” threads (as shown in the embodiment of Figure 20), “corticostatic” threads (as shown in the embodiment of Figure 46), and / or “partial” threads (as shown in the embodiment of Figure 50).

[0116] Figure 56 illustrates another embodiment of the large-diameter, preferred-angle bone anchor assembly 5600 according to the present disclosure. In this embodiment, the locking sphere 2006, compression member 2008, resistance ring 2010, and bone anchor 2004 are the same as those described above in relation to the embodiment of Figure 20, but a different configuration of the receiving head 5602 is provided. In particular, the receiving member 5602 may include one or more extension tabs 5604 protruding from the proximal end of the receiving head to facilitate the operation of the receiving head and the introduction of components such as set screws or other devices or components that help to reposition and secure the rod to the receiving member 5602. One or more tabs 5604 may be formed integrally with the receiving member 5602 or may be coupled to the receiving member 5602. In some embodiments, one or more tabs may be configured to separate from the receiving member 5602 when desired, for example, at the end of the implantation procedure after the rod has been secured to the receiving member. In some embodiments, this can be achieved by the user breaking the tab at a predetermined location or otherwise separating the tab from the rest of the receiving member 5602.

[0117] Similar to the window-opening feature described above, the use of extension tabs may be included in any of the various embodiments described herein. For example, one or more extension tabs may also be included in the receiving member of either embodiment shown in Figures 46 and 50.

[0118] Figures 57–66 illustrate additional embodiments of the bone anchor assembly according to the present disclosure. These embodiments utilize many of the features described above. Similar to the embodiments described above, the bone anchor assemblies of these embodiments may generally include a receiving member or head, a compression member or cap, and a shank. In certain embodiments, resistance features may also be incorporated, for example, by including resistance rings, spring clips, etc., positioned within the receiving member and around the spherical proximal head of the shank to provide resistance against the multiaxial motion of the receiving member relative to the screw shank.

[0119] Figures 57 to 62 illustrate different diagrams of one embodiment of the bone anchor assembly 5700 according to this disclosure, and Figures 63 to 66 illustrate detailed diagrams of the compression cap of the assembly. More specifically, Figures 57 and 58 provide opposing perspective views of the bone anchor assembly 5700. Figures 59A, 59B, and 60 provide detailed diagrams of the proximal portion of the assembly, Figure 61 provides an exploded view of the bone anchor assembly 5700, and Figure 62 provides a cross-sectional view of the bone anchor assembly 5700.

[0120] Looking at Figure 57, the receiving member 5702 of the bone anchor assembly 5700 may have a proximal end 5703 defined by a pair of spaced arms 5712, 5714 that form a U-shaped recess 5719 (also called a rod receiving recess or slot) between them for receiving a spinal fixation element (not shown), such as a spinal rod. A multiaxial seat 6202 may be formed at the distal end 5711 of the receiving member 5702 to multiaxially seat the proximal portion 5706 of the bone anchor / shank 5704. The bone anchor assembly 5700 may further include a compression member or cap 5708 and a resistance ring 5710 disposed within the receiving member 5702, each of which can contact the proximal portion 5706 and exert a frictional force thereon that can selectively resist and / or prevent any relative movement of the receiving member 5702 with respect to the bone anchor 5704.

[0121] Similar to the receiving member 102, the receiving member 5702 may include at least one unilateral mounting feature 5718 that allows a surgical instrument to be coupled to or engaged with the receiving member 5702 in a manner that leaves the rod receiving slot 5719 unobstructed, for example, by enabling the attachment of an instrument to the receiving member 5702 by engaging only one arm 5712 or 5714 of the receiving member 5702. In one embodiment, the receiving member 5702 may include unilateral mounting features 5718 on four proximal quadrants of the receiving member 5702. Similar to the unilateral mounting feature 408, the unilateral mounting feature 5718 may be formed on the opposing lateral edges of each of the spaced-apart arms 5712, 5714. Surgical instruments can be attached to two adjacent unilateral features 5718 on one side of the receiving member 5702, leaving the rod receiving slot 5719 open to receive a spinal fixation rod and / or set screw introduced distally from the proximal end 5703 of the receiving member 5702, as described above.

[0122] As also shown in Figures 59A and 59B, each one-sided mounting feature 5718 may have a distal planar surface 5711 at an angle of approximately 90 degrees to the planar sidewall surface 5713, with a small radius concave surface 5902 connecting the two planar surfaces. The one-sided mounting feature 5718 may also include an internal planar surface 5904 positioned at an angle of approximately 90 degrees to the planar surfaces 5711 and 5713. Such a configuration can provide an improved bracing option for a device coupled to the receiving member 5702 using the one-sided mounting feature 5718. This can allow the device to be securely coupled to the receiving member 5702 even when using only a relatively small area for engagement.

[0123] Figures 59A and 59B also illustrate further features of the rod slot 5719. In particular, the horizontal plane center or bottom surface 5905 of the U-shaped notch separating the arms 5712, 5714 of the receiving member 5702 is connected to the plane vertical surface 5908 of each arm by a curved surface 5906. Including the plane center surface 5905 allows for the use of a curved surface 5906 with a smaller radius, which ensures that the curved surface 5906 does not interfere with the spine rod when pressing the compression cap 5708, even when the rod is of the maximum size that can be accommodated, for example, when it occupies the entire width of the slot 5719 between the vertical surfaces 5908.

[0124] Figure 59B illustrates the external shape of the spinal fixation rod in a first position 5910a when it is distally reduced into the rod slot 5719 of the receiving member 5702. In the first position, the rod can contact the planar upper surfaces 6104, 6106 of the compression cap 5708. It can also, at its maximum size, contact the vertical surfaces 5908 of each arm 5712, 5714. When the rod is further reduced using an instrument such as the rocker reduction device or set screw described above, it can be moved to a second position 5910b, as indicated by arrow 5911. Doing so can bias the compression cap 5708 distally, thereby exerting a locking force on the shank 5704. In the second position 5910b, the rod can reach its maximum distal position, contacting the central planar surface 5905. As shown, the inclusion of the central planar surface 5905 allows the use of a curved surface 5906 with a smaller radius to transition to the vertical surface 5908, which ensures that there is a gap 5912 between the curved surface 5906 and the rod, even at the second position 5910b of maximum distal advance relative to the receiving member 5702. If a larger radius, for example, a single curved bottom surface connecting the vertical surface 5908, were used, the rod might collide with the curved surface at a lateral position before reaching the desired position of maximum distal advance, thereby reducing the locking force exerted on the compression cap 5708.

[0125] As described above, Figure 60 illustrates that the receiving member 5702 includes a first pair of opposing sides 6004, 6006 having a substantially straight cylindrical contour with no taper in diameter along the longitudinal axis of the receiving member 5702. The second pair of opposing sides, offset from the first sides 6004, 6006, may be planar and may include a taper such that the distance between the opposing sides of the second pair decreases as it moves proximal along the longitudinal axis of the receiving member 5702. The first opposing sides 7004 (opposing side 7006 is hidden from opposing side 7004) can be seen in Figures 59A and 59B, and their configuration is similar to that shown in Figure 7.

[0126] Figures 63 to 66 illustrate the compression member or cap 5708 of the assembly 5700. Figures 63 and 64 are perspective views of one embodiment of the compression member 5708, Figure 65 is a front view of the compression member 5708, and Figure 66 is a front cross-sectional view of the compression member 5708. Similar to the compression cap 202, the outer surface of the compression cap 5708 can receive material from the receiving member 5702 which is displaced during swaging, and which can form a second rocker feature 5722. However, the configuration of the compression cap 5708 differs from the compression cap 202 in that it includes an opposing flat surface 6102 instead of a recess 304. The opposing flat surface 6102 can simplify manufacturing and allow for a larger surface area for contact. The opposing flat surface 6102 can be recessed relative to the maximum outer diameter of the compression cap 5708, and a protruding lip 6103 can be formed distal to the opposing flat surface. Therefore, the material displaced from the receiving member 5702, which is moved inward during the swaging process, comes into contact with the opposing flat surface 6102 and interferes with the lip 6103, thereby preventing the compression cap 5708 from coming off proximal to the receiving member. Distal advancement of the compression cap 5708 remains possible, for example, while the set screw is tightened onto the rod located in the slot 5719. The configuration of the opposing flat surface 6102 and the receiving member 5702 can be seen in the cross-sectional view of Figure 62.

[0127] The proximal portion of the compression cap 5708, like the cap 202, can form a seat for receiving a spinal rod. More specifically, the two planar surfaces 6104, 6106 of the compression cap 5708 can be angularly offset from each other to form a substantially "V" shaped groove. The substantially flat planar surfaces 6104, 6106 can provide a seat for accommodating spinal rods of various diameters. The bottom surface 6108 of the compression member 5708 may include a substantially spherical surface configured to contact and exert a frictional force on the locking sphere 5706 when the compression member 5708 is advanced distally relative to the receiving member 5702 (for example, by the user tightening a set screw on threads formed on the proximal portion of the receiving member).

[0128] The various devices and methods disclosed herein can be used in minimally invasive surgery and / or incisional surgery. Although the various devices and methods disclosed herein are generally described in the context of surgery in human patients, the methods and devices disclosed herein can be used in any of the various surgical or non-surgical procedures with any human or animal subject.

[0129] The various devices disclosed herein may be composed of any of a variety of known materials. Exemplary materials include metals such as stainless steel, titanium, nickel, cobalt-chromium, or alloys and combinations thereof; polymers such as PEEK; ceramics; carbon fiber; and other materials suitable for use in surgical applications. Furthermore, a variety of manufacturing methods may be utilized, including 3D printing or other additive manufacturing techniques, as well as more conventional manufacturing techniques such as molding, stamping, casting, and machining.

[0130] Various devices or components disclosed herein may be designed to be discarded after a single use, or they may be designed to be used multiple times. However, in either case, various devices or components may be refurbished for reuse after at least one use. Refurbishment may include any combination of steps of disassembly, subsequent cleaning or replacement of specific parts, and subsequent reassembly. In particular, devices or components may be disassembled, and any number of specific parts or components may be selectively replaced or removed in any combination. Upon cleaning and / or replacement of specific parts, devices or components may be reassembled for subsequent use in a refurbishment facility or by a surgical team immediately before a surgical procedure. Refurbishment of devices or components may utilize various techniques for disassembly, cleaning / replacement, and reassembly. The use of such techniques and the resulting refurbished devices or components are within the scope of this disclosure.

[0131] The various devices or components described herein can be processed before use in surgical procedures. For example, new or used devices or components can be obtained and cleaned as necessary. Devices or components can be sterilized. In one sterilization technique, devices or components can be placed in a closed and sealed container, such as a plastic bag or TYVEK bag. The container and its contents can be placed in a radiation field that can penetrate the container, such as gamma rays, X-rays, or high-energy electrons. The radiation can kill bacteria on the device or component and within the container. Sterilized devices or components can be stored in a sterilization container. The sealed container can keep the device or component sterile until it is opened in a medical facility. Other forms of sterilization are also possible, including beta rays or other radiation, ethylene oxide, steam, or liquid baths (e.g., cold immersion). Certain forms of sterilization techniques may be more suitable for use with different devices or components or parts thereof, due to the materials used, the presence of electrical components, etc.

[0132] In this disclosure, phrases such as “at least one of ~” or “one or more of ~” may be used with a contiguous list of elements or features preceding them. The term “and / or” may also be used with lists of two or more elements or features. Unless otherwise implicitly or explicitly contradicted by the context in which it is used, such phrases are intended to mean any of the enumerated elements or features individually, or any of the enumerated elements or features in combination with any of the other enumerated elements or features. For example, the phrases “at least one of A and B,” “one or more of A and B,” and “A and / or B” are intended to mean “A alone, B alone, or A and B together,” respectively. The same interpretation is intended for lists containing three or more items. For example, the phrases "at least one of A, B, and C," "one or more of A, B, and C," and "A, B, and / or C" are intended to mean "A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together," respectively. In addition, the use of the term "based on" is intended to mean "at least partially based on," so that features or elements not listed are also acceptable.

[0133] Further features and advantages based on the embodiments described above are possible and are within the scope of this disclosure. Therefore, this disclosure is not limited to what is specifically shown and described. All publications and references cited herein are incorporated herein by reference in their entirety, except in the event that any definition, waiver or denial of subject matter occurs, and unless the incorporated material conflicts with the express disclosure herein, in which case the language of this disclosure shall prevail.

[0134] Examples of the embodiments described above may include the following: 1. A bone anchor assembly, A bone anchor having a proximal head portion and a distal threaded bone engagement portion, A receiving member comprising: a proximal end defined by a pair of spaced arms forming a U-shaped recess between them; a distal end having a multi-axis seat formed internally for multi-axis seating of the head portion of a bone anchor; grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm; a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove; and a second recess formed on the outer surface of the receiving member distal to the first recess; A bone anchor assembly, the first recess and the second recess are configured to connect to surgical instruments. 2. The assembly according to claim 1, wherein at least a portion of the first recess of each arm extends proximal to the groove. 3. The assembly according to claim 1 or 2, wherein each of the second recesses is longitudinally aligned with one of the first recesses. 4. The assembly according to any one of claims 1 to 3, wherein the first recess is configured to be pivotably coupled to a surgical instrument. 5. The assembly according to any one of claims 1 to 4, wherein a pair of second recesses are configured to be pivotably coupled to a surgical instrument. 6. The assembly according to any one of claims 1 to 5, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. 7. The assembly according to any one of claims 1 to 6, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the lateral recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. 8. The assembly according to claim 7, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arms. 9. The assembly according to claim 7, wherein each lateral recessed portion has a concave distal surface. 10. The assembly according to claim 7, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them. 11. The assembly according to any one of claims 1 to 10, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. 12. The assembly according to any one of claims 1 to 11, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 13. The assembly according to any one of claims 1 to 11, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. 14. The assembly according to claim 13, wherein the second pair of opposing sides of the receiving member include a proximal-distal axis and have a second taper with respect to a second plane that is offset from a first plane. 15. The assembly according to claim 14, wherein the first plane is perpendicular to the second plane. 16. The assembly according to any one of claims 1 to 15, further comprising a resistance ring disposed within a receiving member, wherein the resistance ring is configured to exert a frictional force on the head portion of the bone anchor. 17. The assembly according to any one of claims 1 to 16, further comprising a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. 18. The assembly according to claim 17, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. 19. The assembly according to claim 18, wherein the displaced material is received in a corresponding recess formed in the compression member. 20. The assembly according to any one of claims 1 to 19, further comprising a pair of retraction tabs extending proximal to a pair of spaced arms. 21. The assembly according to any one of claims 1 to 20, further comprising a fixing element having a male square screw configured to be received between spaced arms of a receiving member. 22. The assembly according to any one of claims 1 to 21, wherein the bone anchor includes a hole extending proximal to the distal tip of the bone engagement portion. 23. The assembly according to claim 22, wherein the hole extends through the entire length of the bone anchor. 24. The assembly according to claim 22, wherein the holes are blind holes. 25. The assembly according to any one of claims 1 to 24, wherein the distal bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to its distal tip. 26. A bone anchor assembly, A bone anchor having a proximal head portion and a distal threaded bone engagement portion, A receiving member comprising a proximal end defined by a pair of spaced arms that form a U-shaped recess configured to receive a spinal fixation element between them, and a distal end having a multi-axis seat formed internally for multi-axis seating of the head portion of a bone anchor, A bone anchor assembly in which the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 27. The assembly according to claim 26, wherein the first pair of opposing lateral surfaces of the receiving member have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. 28. The assembly according to claim 27, wherein the second pair of opposing lateral surfaces of the receiving member include a proximal-distal axis and have a second taper with respect to a second plane offset from a first plane. 29. The assembly according to claim 28, wherein the first plane is perpendicular to the second plane. 30. The receiving member further comprises grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove, and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. The assembly according to any one of claims 26 to 29, wherein the first recess and the second recess are configured to be coupled to a surgical instrument. 31. The assembly according to claim 30, wherein at least a portion of the first recess in each arm extends proximal to the groove. 32. The assembly according to claim 30 or 31, wherein each of the second recesses is longitudinally aligned with one of the first recesses. 33. The assembly according to any one of claims 30 to 32, wherein the first recess is configured to be pivotably coupled to a surgical instrument. 34. The assembly according to any one of claims 30 to 33, wherein a pair of second recesses are configured to be pivotably coupled to a surgical instrument. 35. The assembly according to any one of claims 26 to 34, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. 36. The assembly according to any one of claims 26 to 35, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the lateral recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. 37. The assembly according to claim 36, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arms. 38. The assembly according to claim 36, wherein each lateral recessed portion has a concave distal surface. 39. The assembly according to claim 38, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them. 40. The assembly according to any one of claims 26 to 39, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. 41. The assembly according to any one of claims 26 to 40, further comprising a resistance ring disposed within a receiving member, wherein the resistance ring is configured to exert a frictional force on the head portion of the bone anchor. 42. The assembly according to any one of claims 26 to 41, further comprising a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. 43. The assembly according to claim 42, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. 44. The assembly according to claim 43, wherein the displaced material is received in a corresponding recess formed in the compression member. 45. The assembly according to any one of claims 26 to 44, further comprising a pair of retraction tabs extending proximal to a pair of spaced-apart arms. 46. ​​The assembly according to any one of claims 30 to 45, further comprising a fixing element having a male square screw configured to be received between spaced arms of a receiving member. 47. The assembly according to any one of claims 30 to 46, wherein the bone anchor includes a hole extending proximal to the distal tip of the bone engagement portion. 48. The assembly according to claim 47, wherein the hole extends through the entire length of the bone anchor. 49. The assembly according to claim 47, wherein the holes are blind holes. 50. The assembly according to any one of claims 30 to 49, wherein the distal bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to its distal tip. 51. A bone anchor assembly, A bone anchor having a proximal head portion and a distal threaded bone engagement portion, A receiving member comprising a proximal end defined by a pair of spaced arms that form a U-shaped recess configured to receive a spinal fixation element between them, and a distal end having a multi-axis seat formed internally for multi-axis seating of the head portion of a bone anchor, The proximal ends of the spaced arms are located along a common circular circumferential path, forming a bone anchor assembly. 52. The receiving member further comprises grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove, and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. The assembly according to claim 51, wherein the first recess and the second recess are configured to be coupled to a surgical instrument. 53. The assembly according to claim 52, wherein at least a portion of the first recess in each arm extends proximal to the groove. 54. The assembly according to claim 52 or 53, wherein each of the second recesses is longitudinally aligned with one of the first recesses. 55. The assembly according to any one of claims 51 to 54, wherein the first recess is configured to be pivotably coupled to a surgical instrument. 56. The assembly according to any one of claims 51 to 55, wherein a pair of second recesses are configured to be pivotably coupled to a surgical instrument. 57. The assembly according to any one of claims 51 to 56, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. 58. The assembly according to any one of claims 51 to 57, wherein each spaced-out arm has a transverse recess formed on both side edges of the arm, each transverse recess facing away from the central proximal-distal axis of the receiving member, and the transverse recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. 59. The assembly according to claim 58, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arms. 60. The assembly according to claim 58, wherein each lateral recessed portion has a concave distal surface. 61. The assembly according to claim 60, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them. 62. The assembly according to any one of claims 51 to 61, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 63. The assembly according to any one of claims 51 to 61, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. 64. The assembly according to claim 63, wherein the second pair of opposing sides of the receiving member include a proximal-distal axis and have a second taper with respect to a second plane that is offset from a first plane. 65. The assembly according to claim 64, wherein the first plane is perpendicular to the second plane. 66. The assembly according to any one of claims 51 to 65, further comprising a resistance ring disposed within a receiving member, wherein the resistance ring is configured to exert a frictional force on the head portion of the bone anchor. 67. The assembly according to any one of claims 51 to 66, further comprising a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. 68. The assembly according to claim 67, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. 69. The assembly according to claim 67, wherein the displaced material is received in a corresponding recess formed in the compression member. 70. The assembly according to any one of claims 51 to 69, further comprising a pair of retraction tabs extending proximal to a pair of spaced arms. 71. The assembly according to any one of claims 51 to 70, further comprising a fixing element having a male square screw configured to be received between spaced arms of a receiving member. 72. The assembly according to any one of claims 51 to 71, wherein the bone anchor includes a hole extending proximal to the distal tip of the bone engagement portion. 73. The assembly according to claim 72, wherein the hole extends through the entire length of the bone anchor. 74. The assembly according to claim 72, wherein the holes are blind holes. 75. The assembly according to any one of claims 51 to 74, wherein the distal bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to the distal tip of the bone engagement portion. 76. A bone anchor assembly, A bone anchor having a proximal head portion, a distal bone engagement portion having a male thread extending to the distal tip of the bone anchor, and a hole in the center of the distal bone engagement portion extending proximally from the distal tip of the bone anchor, A bone anchor assembly comprising a receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess configured to receive a spinal fixation element between them, and a distal end having a multiaxial seat formed internally for multiaxially seating the head portion of a bone anchor. 77. The receiving member further comprises grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove, and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. The assembly according to claim 76, wherein the first recess and the second recess are configured to be coupled to a surgical instrument. 78. The assembly according to claim 77, wherein at least a portion of the first recess in each arm extends proximal to the groove. 79. The assembly according to claim 77 or 78, wherein each of the second recesses is longitudinally aligned with one of the first recesses. 80. The assembly according to any one of claims 77 to 79, wherein the first recess is configured to be pivotably coupled to a surgical instrument. 81. The assembly according to any one of claims 77 to 80, wherein a pair of second recesses are configured to be pivotably coupled to a surgical instrument. 82. The assembly according to any one of claims 76 to 81, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. 83. The assembly according to any one of claims 76 to 82, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the lateral recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. 84. The assembly according to claim 83, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arms. 85. The assembly according to claim 83, wherein each lateral recessed portion has a concave distal surface. 86. The assembly according to any one of claims 76 to 85, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. 87. The assembly according to any one of claims 76 to 86, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 88. The assembly according to any one of claims 76 to 86, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. 89. The assembly according to claim 88, wherein the second pair of opposing sides of the receiving member include a proximal-distal axis and have a second taper with respect to a second plane offset from a first plane. 90. The assembly according to claim 89, wherein the first plane is perpendicular to the second plane. 91. The assembly according to any one of claims 76 to 90, further comprising a resistance ring disposed within a receiving member, wherein the resistance ring is configured to exert a frictional force on the head portion of the bone anchor. 92. The assembly according to any one of claims 76 to 91, further comprising a compression member disposed within a receiving member, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. 93. The assembly according to claim 92, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. 94. The assembly according to claim 93, wherein the displaced material is received in a corresponding recess formed in the compression member. 95. The assembly according to any one of claims 76 to 94, further comprising a pair of retractable tabs extending proximal to a pair of spaced-apart arms. 96. A bone anchor assembly, A bone anchor having a proximal head portion, a distal bone engagement portion having a male thread extending to the distal tip of the bone anchor, and a hole in the center of the distal bone engagement portion extending proximally from the distal tip of the bone anchor, A receiving member comprising: a proximal end defined by a pair of spaced arms forming a U-shaped recess between them; a distal end having a multi-axis seat formed internally for multi-axis seating of the head portion of a bone anchor; grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm; a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with the groove; and a second recess formed on the outer surface of the receiving member distal to the first recess; A resistance ring positioned within a receiving member, configured to exert frictional force on the head portion of a bone anchor, A compression member disposed within a receiving member, the proximal portion of which includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element, The first recess and the second recess of the receiving member are configured to be connected to a surgical instrument. Each spaced arm has transverse recesses formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the transverse recesses are configured to engage with surgical instruments such that the U-shaped recess remains unobstructed. A bone anchor assembly in which the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 97. The assembly according to claim 96, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. 98. The assembly according to claim 96 or 97, wherein the compression member is locked in place to resist disengaging from the interior of the receiving member. 99. A bone anchor assembly, A bone anchor having a proximal portion and a distal threaded bone engagement portion, A locking sphere configured to connect to the proximal portion of the bone anchor, A receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess between them, and a distal end having a multi-axis seat formed internally for multi-axis seating of a locking sphere, A resistance ring is positioned within the receiving member and configured to exert frictional force on the locking sphere, A compression member is disposed within a receiving member, A bone anchor assembly in which the distal-facing surface of the receiving member is angled obliquely with respect to the central proximal-distal axis of the receiving member to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to a second opposite direction. 100. The receiving member includes grooves formed on the outer surface of each spaced arm at the proximal end of each spaced arm, The receiving member includes a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects with a groove, and a second recess formed on the outer surface of the receiving member distal to the first recess. The assembly according to claim 99, wherein the first recess and the second recess are configured to be coupled to a surgical instrument. 101. The assembly according to claim 100, wherein at least a portion of the first recess in each arm extends proximal to the groove. 102. The assembly according to claim 100 or 101, wherein the second recess is longitudinally aligned with one of the first recesses. 103. The assembly according to any one of claims 100 to 102, wherein the first recess is configured to be pivotably coupled to a surgical instrument. 104. The assembly according to any one of claims 100 to 103, wherein the second recess is configured to be pivotably coupled to a surgical instrument. 105. The assembly according to any one of claims 99 to 104, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. 106. The assembly according to any one of claims 99 to 105, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, each of which faces away from the central proximal-distal axis of the receiving member, and the lateral recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. 107. The assembly according to claim 106, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arms. 108. The assembly according to claim 106, wherein each lateral recessed portion has a concave distal surface. 109. The assembly according to claim 108, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them. 110. The assembly according to any one of claims 99 to 109, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. 111. The assembly according to any one of claims 99 to 110, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. 112. The assembly according to any one of claims 99 to 111, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane containing the proximal-distal axis of the receiving member. 113. The assembly according to claim 112, wherein the second pair of opposing sides of the receiving member include a proximal-distal axis and have a second taper with respect to a second plane offset from a first plane. 114. The assembly according to claim 113, wherein the first plane is perpendicular to the second plane. 115. The assembly according to any one of claims 99 to 114, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. 116. The assembly according to claim 115, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. 117. The assembly according to claim 116, wherein the displaced material is received in a corresponding recess formed in the compression member. 118. The assembly according to any one of claims 99 to 117, further comprising a pair of retraction tabs extending proximal to a pair of spaced-apart arms. 119. The assembly according to any one of claims 99 to 118, further comprising a fixing element having a male screw configured to be received between spaced arms of a receiving member. 120. The assembly according to any one of claims 99 to 119, wherein the bone anchor includes a hole extending proximal to the distal tip of the bone engagement portion. 121. The assembly according to claim 120, wherein the hole extends through the entire length of the bone anchor. 122. The assembly according to claim 121, wherein the bone anchor includes at least one exit formed on its lateral surface intersecting the hole. 123. The assembly according to claim 120, wherein the holes are blind holes. 124. The assembly according to any one of claims 99 to 123, wherein the distal bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to its distal tip. 125. The assembly according to any one of claims 99 to 124, wherein the compression member is configured to exert force on the locking sphere when the compression member advances distally relative to the receiving member. 126. The assembly according to any one of claims 99 to 125, wherein the bone anchor comprises a first-pitch thread formed along a first bone engagement portion and a second-pitch thread formed along a second bone engagement portion located proximal to the first bone engagement portion. 127. The assembly according to claim 126, wherein the first pitch is greater than the second pitch. 128. The bone anchor includes a thread formed on its first distal portion and a second unthreaded portion positioned between the first and proximal portions of the bone anchor. The assembly according to any one of claims 99 to 127, wherein the length of the second portion without threads is at least about 30% of the length of the first portion having threads formed thereon. 129. The assembly according to claim 128, wherein the length of the second part is approximately 30% to approximately 90% of the length of the first part.

[0135] [Implementation Method] (1) A bone anchor assembly, A bone anchor having a proximal portion and a distal threaded bone engagement portion, A locking sphere configured to connect to the proximal portion of the bone anchor, A receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess between them, and a distal end having a multi-axis seat formed inside for multi-axis seating the locking sphere, A resistance ring is disposed within the receiving member and configured to exert a frictional force on the locking sphere, The receiving member comprises a compression member disposed within the receiving member, A bone anchor assembly wherein the distal surface of the receiving member is angled obliquely with respect to the proximal-distal axis of the receiving member in order to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to a second opposite direction. (2) The receiving member includes grooves formed on the outer surface of each of the spaced arms at the proximal end of each of the spaced arms, The receiving member includes a first recess formed on the outer surface of each arm, wherein at least a portion of the first recess intersects the groove, and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. The assembly according to Embodiment 1, wherein the first recess and the second recess are configured to be coupled to a surgical instrument. (3) The assembly according to Embodiment 2, wherein at least a portion of the first recess in each arm extends proximal to the groove. (4) The assembly according to Embodiment 2, wherein the second recess is aligned longitudinally with one of the first recesses. (5) The assembly according to Embodiment 2, wherein the first recess is configured to be pivotably coupled to a surgical instrument.

[0136] (6) The assembly according to Embodiment 2, wherein the second recess is configured to be pivotably coupled to a surgical instrument. (7) The assembly according to Embodiment 1, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes. (8) The assembly according to Embodiment 1, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, each of the lateral recesses facing away from the central proximal-distal axis of the receiving member, and the lateral recess is configured to engage with a surgical instrument such that the U-shaped recess remains unobstructed. (9) The assembly according to Embodiment 8, wherein each of the lateral recesses extends distally from the proximal end of the spaced-apart arm. (10) The assembly according to Embodiment 8, wherein each lateral recessed portion has a concave distal surface.

[0137] (11) The assembly according to Embodiment 10, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them. (12) The assembly according to Embodiment 1, wherein the proximal ends of the spaced arms are located along a common circular circumferential path. (13) The assembly according to Embodiment 1, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member. (14) The assembly according to Embodiment 1, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane including the proximal-distal axis of the receiving member. (15) The assembly according to embodiment 14, wherein the second pair of opposing sides of the receiving member include the proximal-distal axis and have a second taper with respect to a second plane that is offset from the first plane.

[0138] (16) The assembly according to embodiment 15, wherein the first plane is perpendicular to the second plane. (17) The assembly according to Embodiment 1, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element. (18) The assembly according to embodiment 17, wherein the material displaced in the formation of the second recess is configured to restrict the movement of the compression member relative to the receiving member. (19) The assembly according to embodiment 18, wherein the displaced material is received in a corresponding recess formed in the compression member. (20) The assembly according to Embodiment 1, further comprising a pair of retraction tabs extending proximal to the pair of spaced arms.

[0139] (21) The assembly according to Embodiment 1, further comprising a fixing element having a male screw configured to be received between the spaced arms of the receiving member. (22) The assembly according to Embodiment 1, wherein the bone anchor includes a hole extending proximal to the distal end of the bone engagement portion. (23) The assembly according to embodiment 22, wherein the hole extends through the entire length of the bone anchor. (24) The assembly according to embodiment 23, wherein the bone anchor includes at least one exit formed on the lateral surface of the bone anchor intersecting the hole. (25) The assembly according to embodiment 22, wherein the hole is a blind hole.

[0140] (26) The assembly according to Embodiment 1, wherein the distal bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to the distal tip of the bone engagement portion. (27) The assembly according to Embodiment 1, wherein the compression member is configured to exert force on the locking sphere when the compression member advances distally relative to the receiving member. (28) The assembly according to Embodiment 1, wherein the bone anchor includes a first-pitch thread formed along a first bone engagement portion and a second-pitch thread formed along a second bone engagement portion located proximal to the first bone engagement portion. (29) The assembly according to embodiment 28, wherein the first pitch is greater than the second pitch. (30) The bone anchor includes a thread formed on a first distal portion thereof and a second unthreaded portion positioned between the first portion and the proximal portion of the bone anchor, The assembly according to Embodiment 1, wherein the length of the second portion without threads is at least about 30% of the length of the first portion having threads formed on top of it.

[0141] (31) The assembly according to embodiment 30, wherein the length of the second portion is about 30% to about 90% of the length of the first portion.

Claims

1. A bone anchor assembly, A bone anchor having a proximal portion and a distal threaded bone engagement portion, A locking sphere configured to connect to the proximal portion of the bone anchor, A receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess between them, and a distal end having a multi-axis seat formed inside for multi-axis seating the locking sphere, A resistance ring is disposed within the receiving member and configured to exert a frictional force on the locking sphere, The receiving member comprises a compression member disposed within the receiving member, The distal-facing surface of the receiving member is angled obliquely with respect to the proximal-distal axis of the receiving member in order to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to the second opposite direction. The receiving member includes a first recess formed on the outer surface of each arm and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. In the formation of the second recess, the portion of the receiving member that is displaced is configured to restrict the movement of the compression member relative to the receiving member. The receiving member includes grooves formed on the outer surface of each of the spaced arms at the proximal end of each of the spaced arms, A bone anchor assembly in which a portion of the first recess intersects with the groove.

2. A bone anchor assembly, A bone anchor having a proximal portion and a distal threaded bone engagement portion, A locking sphere configured to connect to the proximal portion of the bone anchor, A receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess between them, and a distal end having a multi-axis seat formed inside for multi-axis seating the locking sphere, A resistance ring is disposed within the receiving member and configured to exert a frictional force on the locking sphere, The receiving member comprises a compression member disposed within the receiving member, The distal-facing surface of the receiving member is angled obliquely with respect to the proximal-distal axis of the receiving member in order to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to the second opposite direction. The receiving member includes a first recess formed on the outer surface of each arm and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. In the formation of the second recess, the portion of the receiving member that is displaced is configured to restrict the movement of the compression member relative to the receiving member. The receiving member includes grooves formed on the outer surface of each of the spaced arms at the proximal end of each of the spaced arms, At least a portion of the first recess intersects with the groove, A bone anchor assembly in which at least a portion of the first recess in each arm extends proximal to the groove.

3. A bone anchor assembly, A bone anchor having a proximal portion and a distal threaded bone engagement portion, A locking sphere configured to connect to the proximal portion of the bone anchor, A receiving member having a proximal end defined by a pair of spaced arms that form a U-shaped recess between them, and a distal end having a multi-axis seat formed inside for multi-axis seating the locking sphere, A resistance ring is disposed within the receiving member and configured to exert a frictional force on the locking sphere, The receiving member comprises a compression member disposed within the receiving member, The distal-facing surface of the receiving member is angled obliquely with respect to the proximal-distal axis of the receiving member in order to provide a greater degree of angle formation of the bone anchor with respect to the receiving member in the first direction compared to the second opposite direction. The receiving member includes a first recess formed on the outer surface of each arm and a second recess formed on the outer surface of the receiving member at a distal position to the first recess. In the formation of the second recess, the portion of the receiving member that is displaced is configured to restrict the movement of the compression member relative to the receiving member. The receiving member includes grooves formed on the outer surface of each of the spaced arms at the proximal end of each of the spaced arms, At least a portion of the first recess intersects with the groove, A bone anchor assembly wherein the second recess is aligned longitudinally with one of the first recesses.

4. The bone anchor assembly according to claim 1, wherein the U-shaped recess is configured to receive spinal fixation elements of various sizes.

5. The bone anchor assembly according to claim 1, wherein each spaced-out arm has a lateral recess formed on both side edges of the arm, and each of the lateral recesses faces away from the central proximal-distal axis of the receiving member.

6. The bone anchor assembly according to claim 5, wherein each of the lateral recessed portions extends distally from the proximal end of the spaced-apart arm.

7. The bone anchor assembly according to claim 5, wherein each lateral recessed portion has a concave distal surface.

8. The bone anchor assembly according to claim 7, wherein each lateral recessed portion has a first planar surface, a second planar surface substantially perpendicular to the first planar surface, and a curved surface between them.

9. The bone anchor assembly according to claim 1, wherein the proximal ends of the spaced arms are located along a common circular circumferential path.

10. The bone anchor assembly according to claim 1, wherein the opposing lateral sides of the receiving member taper inward toward the proximal end of the receiving member.

11. The bone anchor assembly according to claim 1, wherein the first pair of opposing sides of the receiving member have a first taper with respect to a first plane including the proximal-distal axis of the receiving member.

12. The bone anchor assembly according to claim 11, wherein the second pair of opposing sides of the receiving member include the proximal-distal axis and have a second taper with respect to a second plane offset from the first plane.

13. The bone anchor assembly according to claim 12, wherein the first plane is perpendicular to the second plane.

14. The bone anchor assembly according to claim 1, wherein the proximal portion of the compression member includes opposing planar surfaces that are angularly offset from each other and form a seat for receiving a spinal fixation element.

15. The bone anchor assembly according to claim 1, wherein a portion of the displaced receiving member is received in a corresponding recess formed in the compression member.

16. The bone anchor assembly according to claim 1, further comprising a pair of tabs extending proximal to the pair of spaced arms.

17. The bone anchor assembly according to claim 1, further comprising a fixing element having a male square screw configured to be received between the spaced arms of the receiving member.

18. The bone anchor assembly according to claim 1, wherein the bone anchor includes a hole extending proximal to the distal end of the bone engagement portion.

19. The bone anchor assembly according to claim 18, wherein the hole extends throughout the entire length of the bone anchor.

20. The bone anchor assembly according to claim 19, wherein the bone anchor includes at least one exit formed on the lateral surface of the bone anchor intersecting the hole.

21. The bone anchor assembly according to claim 18, wherein the aforementioned hole is a blind hole.

22. The bone anchor assembly according to claim 1, wherein the bone engagement portion further comprises a male screw that extends distally along the bone engagement portion to the distal tip of the bone engagement portion.

23. The bone anchor assembly according to claim 1, wherein the compression member is configured to exert force on the locking sphere when the compression member advances distally relative to the receiving member.

24. The bone anchor assembly according to claim 1, wherein the bone engagement portion of the bone anchor includes a first bone engagement portion having a first pitch thread and a second bone engagement portion located proximal to the first bone engagement portion and having a second pitch thread.

25. The bone anchor assembly according to claim 24, wherein the first pitch is greater than the second pitch.

26. The bone anchor includes a non-threaded portion positioned between the bone engagement portion and the proximal portion, The bone anchor assembly according to claim 1, wherein the length of the non-threaded portion is at least about 30% of the length of the bone engagement portion.

27. The bone anchor assembly according to claim 26, wherein the length of the portion without threads is approximately 30% to approximately 90% of the length of the bone engagement portion.

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