Dynamic stabilization system for the spine

• US 20060293663A1
• Filed: 04/21/2006
• Published: 12/28/2006
• Est. Priority Date: 04/21/2005
• Status: Active Grant

• Current Assignee: Spine Wave Incorporated
• Original Assignee: Spine Wave Incorporated
• Inventors: Pafford, John A., Kitchel, Scott H., Comey, Christopher, Walkenhorst, Jared W., Landry, Michael E., Carter, Andrew, Wilson, Thomas G.
• Granted Patent: US 9,237,908 B2
• Time in Patent Office: Days
• US Class Current: 606/257
• CPC Class Codes: A61B 17/7055 connected to sacrum, pelvis or skull
• CPC Class Codes: A61B 17/7064 Devices acting on, attached to, or simulating the effect of, vertebral facets; Tools therefor
• CPC Class Codes: A61B 17/7067 Devices bearing against one or more spinous processes and also attached to another part of the spine; Tools therefor
• CPC Class Codes: A61B 17/842 Flexible wires, bands or straps A61B17/72, A61B17/82, A61B17/86 take precedence
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• CPC Class Codes: A61B 17/90 Guides therefor

Abstract

A system for dynamic stabilization of the spine includes a bone engaging fastener configured to be anchored in a vertebra and a deflectable element mounted on the fastener. The deflectable element or bumper is configured and arranged to contact a portion of an adjacent vertebra, such as the facet, during extension of the spine, while offering no resistance during flexion. In certain embodiments, a cable may be fastened to the bone engaging fastener and arranged to contact a portion of the adjacent vertebra, such as the spinous process, during flexion of the spine. In one surgical technique of the invention, a contralateral approach is used to introduce the bone engaging fastener through the deflectable element and into the vertebra.

Claims

1. A dynamic stabilization system for the spine comprising:

a bone engaging fastener configured to be anchored in a vertebra; and

a deflectable element mounted on the fastener, said deflectable element configured and arranged to contact a portion of an adjacent vertebra during extension of the spine when said fastener is engaged within a vertebra.

2. The dynamic stabilization system of claim 1, wherein said deflectable element is a resiliently deformable.

3. The dynamic stabilization system of claim 2, wherein:

said bone engaging fastener includes;

a shank having bone engaging threads;

a threaded stem; and

a nut configured for engaging said threaded stem; and

said deflectable element defines an opening to receive said threaded stem therethrough, whereby said nut bears on said deflectable element to mount said deflectable element on said fastener.

4. The dynamic stabilization system of claim 3, wherein said threaded stem and said opening in said deflectable element are keyed to prevent relative rotation therebetween.

5. The dynamic stabilization system of claim 3, wherein:

said bone engaging fastener includes a shoulder between said shank and said stem; and

said opening in said deflectable element is sized so that said deflectable element is compressed between said nut and said shoulder when said nut is threaded onto said stem of said fastener.

6. The dynamic stabilization system of claim 1, wherein said deflectable element includes an edge that is contoured to match the shape of the portion of the adjacent vertebra contacted by said deflectable element when said fastener is engaged within the vertebra.

7. The dynamic stabilization system of claim 6, wherein said deflectable element is kidney shaped.

8. The dynamic stabilization system of claim 6, wherein said deflectable element defines a cam edge contacting the adjacent vertebra.

9. The dynamic stabilization system of claim 6, wherein said edge is contoured to match the shape of the facet of the adjacent vertebra.

10. The dynamic stabilization system of claim 1, wherein said deflectable element includes a spring element mounted to said bone engaging fastener.

11. The dynamic stabilization system of claim 10, wherein said spring element is a wound leaf spring.

12. The dynamic stabilization system of claim 10, wherein said spring element includes a coil spring.

13. The dynamic stabilization system of claim 12, wherein said spring element includes two concentric coil springs.

14. The dynamic stabilization system of claim 10, wherein said spring element includes:

an inner ring mounted to the bone engaging fastener;

an outer ring configured to contact the adjacent vertebra; and

a plurality of spring members connecting said outer ring to said inner ring.

15. The dynamic stabilization system of claim 1, wherein said deflectable element is an expandable element having a reduced first configuration and expandable to a larger second configuration for contacting the adjacent vertebra.

16. The dynamic stabilization system of claim 15, wherein said expandable element includes a balloon.

17. The dynamic stabilization system of claim 16, wherein said bone engaging fastener includes a head portion defining a cavity for receiving said balloon in its reduced first configuration.

18. A dynamic stabilization system for the spine comprising:

a pair of bone engaging fasteners configured to be anchored in a vertebra on opposite sides of the spinous process of the vertebra; and

a deflectable element mounted on each fastener, said deflectable element configured and arranged to contact a portion of an adjacent vertebra during extension of the spine when said pair of fasteners is engaged within a vertebra.

19. The dynamic stabilization system of claim 18, further comprising a cable connected at its ends to a corresponding one of said pair of bone engaging fasteners, said cable sized to engage a portion of the adjacent vertebra.

20. The dynamic stabilization system of claim 19, wherein said deflectable element is configured and arranged to contact the facet of the adjacent vertebra.

21. The dynamic stabilization system of claim 19, wherein said cable is sized to engage the spinous process of the adjacent vertebra.

22. The dynamic stabilization system of claim 19, wherein:

said bone engaging fastener includes a shank; and

said ends of said cable define loops sized to receive said shank therethrough.

23. The dynamic stabilization system of claim 19, wherein:

each of said bone engaging fasteners includes a post defining a bore sized to receive said cable therethrough; and

said ends of said cable are configured to pass through said bore in each of said bone engaging fasteners.

24. The dynamic stabilization system of claim 19, wherein:

each of said bone engaging fasteners includes;

a shank having bone engaging threads;

a threaded stem; and

a nut configured to engage the threaded stem, said nut defining a bore for passage of said cable therethrough; and

said deflectable element defines an opening to receive said threaded stem therethrough, whereby said nut bears on said deflectable element to mount said deflectable element on said fastener.

25. A method for providing dynamic stabilization to the spine comprising:

providing a deflectable element having an opening therethrough, the deflectable element sized and configured to contact an adjacent vertebra when the deflectable element is mounted on a vertebra;

positioning the deflectable element on the vertebra; and

introducing a bone engaging fastener through the opening in the deflectable element and into the vertebra from a contralateral direction.

26. The method for providing dynamic stabilization to the spine of claim 25, wherein the step of introducing the bone engaging fastener includes:

supporting a jig on the deflectable element, the jig including a fastener guide movable to variable angular orientations relative to the deflectable element;

aligning the fastener guide to a desired angle relative to the vertebra; and

passing the bone engaging fastener through the fastener guide to drive the fastener into the bone at the desired angle.

27. A method for providing dynamic stabilization to the spine comprising:

anchoring a pair of bone engaging fasteners into a portion of the spine on opposite sides of an axis defined by the spinous processes; and

supporting a deflectable element on each of the bone engaging fasteners, each deflectable element being sized and configured to contact an adjacent vertebra at a location other than the spinous process.

28. The method for providing dynamic stabilization to the spine of claim 27, further comprising:

prior to anchoring the fasteners, placing the spine in flexion; and

subsequently relieving the flexion so that the deflectable elements provide some distraction to the adjacent vertebrae.

29. The method for providing dynamic stabilization to the spine of claim 27, wherein each deflectable element is supported on the respective fasteners to contact a corresponding facet of the adjacent vertebra.

30. The method for providing dynamic stabilization to the spine of claim 27 further comprising connecting a cable to the pair of bone engaging fasteners with the cable arranged to contact the spinous process of the adjacent vertebra at least during flexion of the spine.

31. The method of claim 27, wherein said deflectable elements are supported by said fasteners by mounting said deflectable elements thereto after said fasteners are anchored to said portion of the spine.

32. The method of claim 27, wherein said portion of the spine is the sacrum.

33. The method of claim 27, wherein said portion of the spine is the vertebra immediately inferior to said adjacent vertebra.

34. A kit of parts for providing dynamic stabilization of the spine, comprising:

at least a pair of first bone fasteners configured for anchoring in a vertebra;

at least a pair of second bone fasteners configured for anchoring in the sacrum; and

at least a pair of deflectable elements adapted to be selectively supported on either said first pair of bone fasteners or said second pair of bone fasteners, said deflectable elements being adapted to contact a portion of a superior vertebra when supported by said selected fasteners.

35. The kit of parts of claim 34, further comprising a cable adapted to be selectively connected to either said first pair of bone fasteners or said second pair of bone fasteners and of length to extend around the spinous process of said superior vertebra when said cable is connected to said selected fasteners.