Multipoint fixation implants
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 and accommodates one or more auxiliary bone anchors that augment the fixation of the assembly's primary bone anchor. Another exemplary assembly can include a plate that is seated between the receiver member and the rod and accommodates one or more auxiliary bone anchors that augment the fixation of the assembly's primary bone anchor. Another exemplary assembly can include a hook that extends out from the receiver member to hook onto an anatomical structure or another implant to augment the fixation of the assembly's primary bone anchor. Surgical methods using the bone anchor assemblies described herein are also disclosed.
1. A bone anchor connector, comprising:
a body having a proximal-facing surface, a distal-facing surface, a first opening surrounded by the body at the proximal-facing surface, and a second opening laterally offset from the first opening, wherein:
a proximal end of the first opening terminates at the proximal-facing surface of the body;
a distal end of the first opening and a distal end of the second opening terminate at the distal-facing surface of the body;
the first opening includes a first central axis extending therethrough;
the second opening includes a second central axis that extends therethrough at an oblique angle with respect to the first central axis; and
a recessed lead-in surface that extends from the proximal-facing surface of the body towards a proximal-most surface of the second opening around at least a portion of a circumference of the second opening.
2. The connector of claim 1 , wherein the second opening is partially threaded.
3. The connector of claim 2 , wherein the partial threads of the second opening begin distal to the proximal-facing surface of the body.
4. The connector of claim 1 , wherein the proximal-facing surface of the body that surrounds the first opening is parallel to the proximal-facing surface of the body that surrounds the second opening.
5. The connector of claim 1 , wherein the first opening includes a smooth, non-threaded interior surface that allows the body to receive one or more elements therethrough.
6. The connector of claim 5 , wherein the body is configured to be rotated about the one or more elements disposed within the first opening.
7. The connector of claim 1 , wherein the second opening is configured to receive an auxiliary bone anchor therethrough.
8. The connector of claim 7 , wherein the auxiliary bone anchor is configured to be locked coaxially with the second central axis of the second opening.
9. The connector of claim 7 , wherein the auxiliary bone anchor includes a variable-angle locking screw having a threaded proximal head configured to engage threads of the second opening.
10. The connector of claim 9 , wherein the threaded proximal head is partially spherical having a thread with a profile that follows an arc-shaped radius of curvature of the spherical portion of the threaded proximal head.
11. The connector of claim 7 , wherein the auxiliary bone anchor has a length of 6 mm to 100 mm.
12. The connector of claim 1 , wherein the second central axis extends at an angle of between 0 degrees and 15 degrees with respect to the distal-facing surface.
13. The connector of claim 1 , wherein the second central axis extends at an angle of between 15 degrees and 45 degrees with respect to the distal-facing surface.
14. The connector of claim 1 , wherein the first central axis through the first opening is substantially perpendicular to the distal-facing surface of the body.
15. The connector of claim 1 , wherein the distal-facing surface of the body includes one or more surface features to enhance grip of the body to an object on which the body is disposed.
16. The connector of claim 1 , wherein the body is monolithic.
17. The connector of claim 1 , wherein the body includes only two openings.
18. The connector of claim 1 , wherein a distance between the first and second openings is such that bone anchors that extend through the first and second openings are received in a single vertebral level.
19. The connector of claim 1 , wherein at least a portion of a proximal-most extent of the second opening is distal to the first opening.
20. A bone anchor connector, comprising:
a body having a proximal-facing surface defining a first plane, a distal-facing surface defining a second plane, three sidewalls extending from the proximal-facing surface to the distal-facing surface, a first opening, and a second opening laterally offset from the first opening, wherein:
a proximal end of the first opening terminates at the proximal-facing surface of the body;
a distal end of the first opening and a distal end of the second opening terminate at the distal-facing surface of the body;
the first opening includes a first central axis extending therethrough;
the second opening includes a second central axis that extends therethrough at an oblique angle with respect to the first central axis; and
a first portion of the proximal end of the second opening is recessed with respect to the proximal-facing surface of the body;
wherein each of the three sidewalls extends from the first plane to the second plane continuously along its length.
21. The connector of claim 20 , wherein a second portion of the proximal end of the second opening is level with respect to the proximal-facing surface of the body.