DYNAMIC MOTION SPINAL STABILIZATION SYSTEM

Abstract

Provided is a system for dynamically stabilizing a spine. In one example, the system includes a first bone anchor coupled to a first polyaxial head and a second bone anchor coupled to a second polyaxial head. An axis passing through a center of each polyaxial head is aligned with a center of rotation. A first member has a first end movably coupled to the first polyaxial head and a second end. A second member has a third end coupled to the second polyaxial head and a fourth end moveably coupled to the second end. The first and second members are configured to maintain the alignment of the axes with the center of rotation during three dimensional movement of the first member relative to the second member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of an embodiment of a dynamic stabilization system;

FIG. 2 is a perspective view of one embodiment of a brace that may be used in the dynamic stabilization system of FIG. 1;

FIG. 3 is a view of the brace illustrated in FIG. 2 in an extended position;

FIG. 4 is a cross-sectional view of the brace of FIG. 3.

FIG. 5 is a detailed view of one embodiment of a member of the brace of FIG. 2.

FIG. 6 is a detailed view of one embodiment of a member of the brace of FIG. 2.

FIG. 7 is a side view of one embodiment of the brace of FIG. 2.

FIG. 8 is a side view of one embodiment of the dynamic stabilization system of FIG. 1.

FIG. 9 is an enlarged view of a portion of the dynamic stabilization system of FIG. 8.

FIG. 10 is a cross-sectional view of the portion of the dynamic stabilization system of FIG. 9.

FIG. 11A is a sagittal perspective view of the dynamic stabilization system illustrated in FIG. 1 in a neutral position;

FIG. 11B is a sagittal perspective view of the dynamic stabilization system illustrated in FIG. 1 in a flexion position;

FIG. 12A is a posterior perspective view of the dynamic stabilization system illustrated in FIG. 1 in a neutral position;

FIG. 12B is a posterior perspective view of the dynamic stabilization system illustrated in FIG. 1 in a flexion position;

FIG. 12C is a posterior perspective view of the dynamic stabilization system illustrated in FIG. 1 in a rotation position;

FIG. 12D is a posterior perspective view of the dynamic stabilization system illustrated in FIG. 1 in a lateral bending position;

FIG. 12E is a posterior perspective view of the dynamic stabilization system illustrated in FIG. 1 in an extension position;

FIG. 13 is a perspective view of another embodiment of a dynamic stabilization system;

FIG. 14 is a cross-sectional view of one embodiment of the dynamic stabilization system of FIG. 13;

FIG. 15A is an exploded view of one embodiment of a locking assembly that may be used with the dynamic stabilization system of FIG. 13;

FIG. 15B is a cross-sectional view of one embodiment of the locking assembly of FIG. 15A in an assembled state;

FIGS. 16 and 17 are a cross-sectional view of one embodiment of the dynamic stabilization system of FIG. 13; and

FIG. 18 is a perspective view of one embodiment of the dynamic stabilization system of FIG. 13.

FIG. 19 is a flowchart of one embodiment of a method for using a dynamic stabilization system.

Claims

1. A dynamic stabilization system comprising: a first bone anchor coupled to a first polyaxial head and a second bone anchor coupled to a second polyaxial head, wherein a first axis passing through a center of the first polyaxial head is aligned with a center of rotation and a second axis passing through a center of the second polyaxial head is aligned with the center of rotation;a first member having a first end movably coupled to the first polyaxial head and a second end; anda second member having a third end coupled to the second polyaxial head and a fourth end moveably coupled to the second end, wherein the first and second members are configured to maintain the alignment of the first and second axes with the center of rotation during three dimensional movement of the first member relative to the second member.

2. The dynamic stabilization system of claim 1 further comprising a first bearing post coupling the first end and the first polyaxial head, wherein the first bearing post is rotationally coupled to the first end and immovably coupled to the first polyaxial head, and wherein a first longitudinal axis of the first bearing post intersects the center of rotation.

3. The dynamic stabilization system of claim 2 wherein the first bearing post locks a position of the first bone anchor relative to the first polyaxial head.

4. The dynamic stabilization system of claim 2 wherein the third end is immovably coupled to the second polyaxial head.

5. The dynamic stabilization system of claim 2 further comprising a second bearing post coupling the third end and the second polyaxial head, wherein the second bearing post is rotationally coupled to the third end and immovably coupled to the second polyaxial head, wherein a second longitudinal axis of the second bearing post intersects the center of rotation, and wherein the first and second members are configured to maintain the alignment of the first and second longitudinal axes with the center of rotation during three dimensional movement of the first member relative to the second member.

6. The dynamic stabilization system of claim 5 wherein the first bearing post is inserted into a first aperture of the first end and the second bearing post is inserted into a second aperture of the third end.

7. The dynamic stabilization system of claim 6 further comprising first and second bushings inserted into the first and second apertures, respectively, wherein each of the first and second bushings includes a threaded bore configured to engage threads of the first and second bearing posts, respectively, and wherein each of the first and second bushings rotates freely with respect to the first and second apertures, respectively.

8. The dynamic stabilization system of claim 7 further comprising first and second locking caps securing the first and second bearing posts, respectively, to the first and second bushings.

9. The dynamic stabilization system of claim 1 further comprising a pin coupling the first and second members, wherein the pin is inserted into an aperture in each of the second and fourth ends, and wherein the pin forms a pivot point around which the first and second members rotate relative to one another.

10. The dynamic stabilization system of claim 9 wherein the second end includes first and second arms forming a yoke, wherein the fourth end fits between the first and second arms, and wherein the pin extends through the first and second arms.

11. The dynamic stabilization system of claim 1 further comprising a third member coupling the first and second members, wherein the third member has a fifth end movably retained in a cavity in the second end and a sixth end movably retained in a cavity in the fourth end.

12. A dynamic stabilization device comprising: a first member having first and second ends, wherein the first end is configured to movably couple to a first polyaxial head and includes a first axis that extends through the first end and intersects a center point;a second member having a third end configured to couple to a second polyaxial head, wherein the third end includes a second axis that extends through the third end and intersects the center point, and a fourth end moveably coupled to the second end; anda third member movably coupling the second and fourth ends, wherein the first, second, and third members are configured to maintain the intersection of the first and second axes with the center point as the center point moves along a curved three dimensional surface during movement of the first member relative to the second member.

13. The dynamic stabilization device of claim 12 wherein the third member is a pin that rotationally couples the first and second members, wherein the pin is received by a first aperture in the second end and a second aperture in the fourth end.

14. The dynamic stabilization device of claim 12 wherein the third member includes a first portion slideably received by a first aperture in the second end and a second portion slideably received by a second aperture in the fourth end.

15. The dynamic stabilization device of claim 14 further comprising a retaining means for retaining at least one of the first and second portions in the first and second apertures, respectively.

16. The dynamic stabilization device of claim 12 wherein the first end includes an aperture configured to receive a bearing post.

17. The dynamic stabilization device of claim 16 further comprising a bearing element retained in the aperture, wherein the bearing element includes a threaded bore configured to engage threads of the bearing post and wherein the bearing element rotates freely with respect to the aperture.

18. The dynamic stabilization device of claim 12 wherein the third end is configured to movably couple to the second polyaxial head.

19. The dynamic stabilization device of claim 12 wherein the first and second members each have a curvature defined to maintain the intersection of the first and second axes with the center point as the center point moves along the curved three dimensional surface.

20. A method comprising: identifying a center of rotation between first and second vertebrae;coupling a first member of a dynamic stabilization device to a first polyaxial head;coupling a second member of the dynamic stabilization device to a second polyaxial head;orienting an axis of the first polyaxial head with the center of rotation;orienting an axis of the second polyaxial head with the center of rotation; andsecuring the first and second members relative to the first and second polyaxial heads, respectively, to maintain the orientation of the first and second axes with the center of rotation.

21. The method of claim 20 wherein securing the first member relative to the first polyaxial head includes locking a height of the first member relative to the first polyaxial head.

22. The method of claim 20 further comprising inserting a first bone anchor coupled to the first polyaxial head and inserting a second bone anchor coupled to the second polyaxial head.