Multipoint fixation implants and related methods
Bone anchor assemblies are disclosed herein that can provide for improved fixation as compared with traditional bone anchor assemblies. An exemplary assembly can include a bracket or wing that extends down from the receiver member. The distal portion of the wing can define a bone anchor opening through which one or more auxiliary bone anchors can be disposed to augment the fixation of the assembly's primary bone anchor. A distal surface of the distal portion of the wing can be obliquely angled relative to a proximal-distal axis of the spanning portion to face one of a caudal direction or a cephalad direction. A distal surface of the distal portion of the wing can be obliquely angled relative to the proximal-distal axis of the spanning portion to face one of a medial direction or a lateral direction. Surgical methods using the bone anchor assemblies described herein are also disclosed.
1. A method of securing a bone anchor assembly to bone, comprising:
driving a bone anchor into bone, the bone anchor having a receiver member coupled to a proximal end thereof;
positioning a rod in a rod seat defined in the receiver member;
attaching a closure mechanism to the receiver member to retain the rod in the receiver member;
coupling a proximal portion of a wing to at least one of the closure mechanism and a proximal terminal end of the receiver member, such that a spanning portion of the wing extends vertically along a side wall of the receiver member between the proximal portion and a distal portion of the wing that extends outward from a distal end of the spanning portion; and
driving an auxiliary bone anchor through a bone anchor opening formed in the distal portion of the wing into bone at an oblique angle in one of a caudal direction or a cephalad direction;
wherein a distal surface of the distal portion of the wing is obliquely angled relative to a proximal-distal axis of the spanning portion to face the caudal direction or the cephalad direction.
2. The method of claim 1 , wherein the bone is part of a first vertebral level and driving the auxiliary bone anchor through the bone anchor opening into the bone comprises driving the auxiliary bone anchor into the bone at an oblique angle in a cephalad direction such that the bone anchor and the auxiliary bone anchor are respectively driven into a same vertebral level.
3. The method of claim 1 , wherein the bone is part of a first vertebral level and driving the auxiliary bone anchor through the bone anchor opening into the bone comprises driving the auxiliary bone anchor into the bone at an oblique angle in a caudal direction such that the bone anchor and the auxiliary bone anchor are respectively driven into adjacent vertebral levels.
4. The method of claim 1 , wherein the closure mechanism comprises a threaded post having a radially extending shoulder portion and wherein coupling the proximal portion of the wing to at least one of the closure mechanism and the proximal terminal end of the receiver member comprises:
disposing at least a portion of the threaded post through the opening formed in the proximal portion of the wing; and
receiving the radially extending shoulder portion that extends at least partially above the proximal terminal end of the receiver member in a counter bore formed about the opening in the distal-facing surface of the proximal portion of the wing.
5. The method of claim 1 , wherein the bone is part of a first vertebral level and driving the auxiliary bone anchor into the bone comprises crossing a facet joint between adjacent vertebral levels.
6. The method of claim 5 , wherein the first vertebral level is a superior to the adjacent vertebral level.
7. The method of claim 1 , wherein the bone is part of a first vertebral level and driving the auxiliary bone anchor through the bone anchor opening into the bone comprises fixing the auxiliary bone anchor into multiple cortical bone layers.
8. The method of claim 7 , wherein the multiple cortical bone layers include at least three cortical bone layers.
9. The method of claim 7 , wherein the multiple cortical bone layers are part of multiple vertebral levels.
10. The method of claim 1 , wherein the distal surface of the distal portion of the wing is obliquely angled inward towards the proximal-distal axis of the spanning portion.
11. The method of claim 1 , wherein the distal surface of the distal portion of the wing is obliquely angled outward towards the proximal-distal axis of the spanning portion.
12. The method of claim 1 , wherein a proximal surface of the distal portion of the wing is substantially parallel to the distal surface of the distal portion.
13. The method of claim 1 , wherein a proximal surface of the distal portion is distal to a distal surface of the proximal portion.
14. The method of claim 1 , further comprising deforming the spanning portion to angle the distal portion of the wing relative to the proximal portion of the wing.
15. The method of claim 14 , wherein deforming the spanning portion of the wing comprises contacting the distal portion of the wing with the bone before the auxiliary bone anchor is driven into the bone.
16. The method of claim 1 , further comprising coupling a surgical instrument to one side of the wing using a unilateral locking interface formed on the proximal portion of the wing.
17. A method of securing a bone anchor assembly to a spine, comprising:
driving a bone anchor into a first vertebra, the bone anchor having a receiver member;
positioning a rod within a recess of the receiver member;
coupling a threaded post to the receiver member to retain the rod within the recess of the receiver member;
coupling a wing to at least one of the threaded post and a proximal portion of the receiver member, such that a spanning portion of the wing extends vertically along a side wall of the receiver member between a proximal portion of the wing and a distal portion of the wing that extends outward from the spanning portion; and
driving an auxiliary bone anchor through a bone anchor opening formed in the distal portion of the wing into bone with a caudal trajectory such that the auxiliary bone anchor crosses a facet joint and extends into one or more adjacent vertebrae.
18. The method of claim 17 , wherein driving the auxiliary bone anchor into bone comprises fixing the auxiliary bone screw into multiple cortical bone layers.
19. The method of claim 18 , wherein the multiple cortical bone layers include at least three cortical bone layers.
20. The method of claim 17 , wherein the first vertebra is superior to the one or more adjacent vertebrae.