Dynamic Stabilization Device for Spine

• US 20090048631A1
• Filed: 08/17/2007
• Published: 02/19/2009
• Est. Priority Date: 08/17/2007
• Status: Active Grant

• Current Assignee: Jmea Corporation
• Original Assignee: Jmea Corporation
• Inventors: Yeh, Jack Y., Sack, James A., Bhatnagar, Mohit K.
• Granted Patent: US 8,080,038 B2
• Time in Patent Office: Days
• US Class Current: 606/246
• CPC Class Codes: A61B 17/7004 with a cross-section which varies along its length A61B17/7019 takes precedence
• CPC Class Codes: A61B 17/7005 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit in the screw or hook heads
• CPC Class Codes: A61B 17/7007 Parts of the longitudinal elements, e.g. their ends, being specially adapted to fit around the screw or hook heads
• CPC Class Codes: A61B 17/7008 with parts of, or attached to, the longitudinal elements, bearing against an outside of the screw or hook heads, e.g. nuts on threaded rods A61B17/7007 takes precedence
• CPC Class Codes: A61B 17/7019 Longitudinal elements having flexible parts, or parts connected together, such that after implantation the elements can move relative to each other
• CPC Class Codes: A61B 17/702 having a core or insert, and a sleeve, whereby a screw or hook can move along the core or in the sleeve
• CPC Class Codes: A61B 17/7026 with a part that is flexible due to its form
• CPC Class Codes: A61B 17/7028 the flexible part being a coil spring
• CPC Class Codes: A61B 17/7029 the entire longitudinal element being flexible
• CPC Class Codes: A61B 17/7031 made wholly or partly of flexible material
• CPC Class Codes: A61B 17/7032 Screws or hooks with U-shaped head or back through which longitudinal rods pass

Abstract

A dynamic stabilization device is disclosed. The device includes a dual spring member comprising an outer spring and an inner spring that have approximately equal working lengths. The dynamic stabilization device is also configured so that the dual spring member does not undergo stresses greater than an effective fatigue limit that is related to a fatigue limit of the spring.

Claims

1. A dynamic stabilization device configured for implantation into a spine, comprising:

an outer spring and an inner spring, wherein the inner spring is disposed within the outer spring; and

wherein the outer spring has a first working length that is substantially equal to a second working length of the inner spring.

2. The dynamic stabilization device according to claim 1, wherein the inner spring is configured to attach to a first threaded portion of a first rod of the dynamic stabilization device.

3. The dynamic stabilization device according to claim 2, wherein the outer spring is configured to attach to a second threaded portion of a second rod of the stabilization device.

4. The dynamic stabilization device according to claim 3, wherein the first rod is attached to a first anchor configured for implantation into a first vertebra.

5. The dynamic stabilization device according to claim 4, wherein the second rod is attached to a second anchor configured for implantation into a second vertebra.

6. A dynamic stabilization device configured for implantation into a spine, comprising:

a dual spring member including a first end;

a first rod including a first threaded portion; and

wherein the first end of the dual spring member is configured to mechanically attach to the first threaded portion of the first rod.

7. The dynamic stabilization device according to claim 6, wherein a second end of the dual spring member is configured to attach to a second threaded portion associated with a second rod.

8. The dynamic stabilization device according to claim 7, wherein the dual spring member comprises an outer spring and an inner spring.

9. The dynamic stabilization device according to claim 8, wherein the outer spring is configured to connect to a first outer threaded portion of the first rod.

10. The dynamic stabilization device according to claim 9, wherein the inner spring is configured to connect to a first inner threaded portion of the first rod.

11. The dynamic stabilization device according to claim 10, wherein the inner spring and the outer spring are physically connected at the second end of the dual spring member.

12. The dynamic stabilization device according to claim 8, wherein the inner spring and the outer spring have approximately equal working lengths.

13. The dynamic stabilization device according to claim 12, wherein the inner spring and the outer spring are configured to experience stresses that are less than a fatigue limit associated with the inner spring and the outer spring.

14. A dynamic stabilization device configured for implantation into a spine, comprising:

a dual spring member including an outer spring and an inner spring, the dual spring member having a fatigue limit; and

wherein the dynamic stabilization device is configured so that stresses applied to the dual spring member are always below an effective fatigue limit.

15. The dynamic stabilization device according to claim 14, wherein the fatigue limit is associated with a stress selected from a group consisting essentially of shear stresses, tensions stresses, compression stresses, torsional stresses, rotational stresses and any combination thereof.

16. The dynamic stabilization device according to claim 15, wherein the effective fatigue limit is between 10 percent of the fatigue limit and 75 percent of the fatigue limit.

17. The dynamic stabilization device according to claim 16, wherein the dual spring member has a life expectancy that is effectively indefinite.

18. The dynamic stabilization device according to claim 14, wherein the dual spring member is connected to a first outer threaded portion at a first end.

19. The dynamic stabilization device according to claim 18, wherein the dual spring member comprises an outer spring and an inner spring.

20. The dynamic stabilization device according to claim 19, wherein the outer spring has a first working length that is approximately equal to a second working length associated with the inner spring.

21. The dynamic stabilization device according to claim 14, wherein the inner spring comprises an inner coil and wherein the outer spring comprises an outer coil, and wherein the inner coil is different than the outer coil.

22. The dynamic stabilization device according to claim 14, wherein the inner spring has a first shape and wherein the outer spring has a second shape, and wherein the first shape is different than the second shape.

23. A dynamic stabilization device configured for implantation into a spine, comprising:

an anchor configured for implantation into a bone, including a proximal portion and a distal portion;

the proximal portion including threading configured to penetrate a vertebra;

the distal portion including a drive receiving surface;

the distal portion including a first set of recesses configured to receive ridges associated with a rod; and

wherein the first set of recesses is disposed within a drive receiving surface and wherein a cap configured to cover the distal portion includes a second set of recesses configured to receive the ridges.

24. The dynamic stabilization device according to claim 23, wherein the rod is associated with a dual spring member.

25. The dynamic stabilization device according to claim 24, wherein the dual spring member includes an inner spring and an outer spring;

26. The dynamic stabilization device according to claim 23, wherein the inner spring and the outer spring have approximately equal working lengths.

27. The dynamic stabilization device according to claim 23, wherein the dual spring member is configured to attach to a threaded portion of the rod.

28. The dynamic stabilization device according to claim 27, wherein the maximum stress applied to the dual spring member is below an effective fatigue limit that is less than half of a fatigue limit.

29. The dynamic stabilization device according to claim 23, wherein the inner spring and the outer spring are continuously formed at a first end of the dual spring member and at a second end of the dual spring member.

30. The dynamic stabilization device according to claim 23, wherein the inner spring and the outer spring are physically separated at a first end of the dual spring member and at a second end of the dual spring member.

31. The dynamic stabilization device according to claim 23, wherein the inner spring and the outer spring are continuously formed at a first end of the dual spring member and wherein the inner spring and the outer spring are physically separated at a second end of the dual spring member.

32. The dynamic stabilization device according to claim 23, wherein a surface of the rod is textured.

33. The dynamic stabilization device according to claim 23, wherein the ridges have a shape selected from the group consisting essentially of sinusoidal ridges, box-like ridges, triangular ridges, rounded ridges, and any combination thereof.

34. The dynamic stabilization device according to claim 23, wherein the dynamic stabilization device may be used to dynamically treat or correct various deformities.

35. The dynamic stabilization device according to claim 23, wherein the anchor is a screw.

36. The dynamic stabilization device according to claim 23, wherein the anchor is a hook.

37. The dynamic stabilization device according to claim 23, wherein the rod includes threading.

38. The dynamic stabilization device according to claim 23, wherein the rod includes a locking member configured to engage at least one spring.

39. A dynamic stabilization system configured for implantation into a spine, comprising:

a first dynamic stabilization device configured to be attached to adjacent vertebrae, the first dynamic stabilization device being pre-stressed and including a first residual stress;

a second dynamic stabilization device configured to be attached to the adjacent vertebrae, the second dynamic stabilization device being pre-stressed and including a second residual stress; and

wherein the first and second dynamic stabilization devices are configured to apply a force to the adjacent vertebrae thereby adjusting the relative positions of the adjacent vertebrae.

40. The dynamic stabilization system according to claim 39, wherein the first residual stress is different than the second residual stress.

41. The dynamic stabilization system according to claim 39, wherein the first residual stress is tension and the second residual stress is compression, and wherein a rotational force is applied to the adjacent vertebrae whereby scoliosis may be treated.

42. The dynamic stabilization system according to claim 39, wherein the first residual stress is substantially equal to the second residual stress, and wherein a translational force is applied to the adjacent vertebrae whereby spondylolisthesis may be treated.

43. The dynamic stabilization system according to claim 39, wherein the first residual stress is substantially equal to the second residual stress, and wherein a flexion force is applied to the adjacent vertebrae whereby spinal stenosis may be treated.