Expandable intervertebral spacers and methods of use

• US 20070255415A1
• Filed: 05/01/2006
• Published: 11/01/2007
• Est. Priority Date: 05/01/2006
• Status: Active Grant

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: Cooper, Lloyd, Edie, Jason, Dawson, John, Walker, Don, Windham, Jerrod
• Granted Patent: US 7,708,779 B2
• Time in Patent Office: Days
• US Class Current: 623/17.160
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61F 2/442 Intervertebral or spinal discs, e.g. resilient non-disc-shaped intervertebral inflatable pockets A61F2/441; non-disc-shaped intervertebral fusion implants A61F2/4455
• CPC Class Codes: A61F 2/4465 having a circular or kidney shaped cross-section substantially perpendicular to the axis of the spine
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2002/30471 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2002/30523 by means of meshing gear teeth
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30601 telescopic
• CPC Class Codes: A61F 2002/4627 with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2220/0091 connected by a hinged linkage mechanism, e.g. of the single-bar or multi-bar linkage type
• CPC Class Codes: A61F 2250/0006 for adjusting angular orientation
• CPC Class Codes: A61F 2310/00796 Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite
• CPC Class Codes: A61F 2310/00976 Coating or prosthesis-covering structure made of proteins or of polypeptides, e.g. of bone morphogenic proteins BMP or of transforming growth factors TGF

Abstract

An intervertebral spacer is inserted between vertebral members in a compact configuration and expanded post-insertion to contact the adjacent vertebral members. The intervertebral spacer comprises a first member and a second member movable with respect to the first member between retracted and extended positions.

Claims

1. An intervertebral spacer comprising:

first and second members having respective contact surfaces to contact adjacent vertebral bodies, said second member being movable with respect to the first member between a retracted position and an extended position;

a screw jack interposed between said first and second members, said screw jack comprising a screw shaft fixed to one of said first and second members, and an internally threaded ring gear meshed with said screw shaft such that rotation of said ring gear in a first direction moves said second member away from said first member, and such that rotation of said ring gear in a second direction moves said second member towards said first member; and

a drive gear mounted in said second member and meshed with said ring gear, said drive gear accessible to a surgeon post-insertion to actuate said screw jack to move said second member between said retracted and extended positions.

2. The intervertebral spacer of claim 1 wherein said drive gear comprises a worm gear meshed with gear teeth formed on an outer surface of said ring gear.

3. The intervertebral spacer of claim 1 further comprising a guide member fixed to one of said first and second members to maintain alignment of said first and second members.

4. The intervertebral spacer of claim 3 wherein said guide member comprises a guide rod fixed to one of said first and second members, said guide member configured for insertion into a guide channel formed in the other of said first and second members.

5. The intervertebral spacer of claim 1 including at least two screw jacks.

6. The intervertebral spacer of claim 5 wherein two or more screw jacks are engaged and driven by a single drive gear.

7. The intervertebral spacer of claim 1 wherein said first and second members are configured to engage an insertion when said second member is in a retracted position, and to release said insertion tool when said second member is moved to an extended position.

8. The intervertebral spacer of claim 7 wherein said first and second members each include an opening for engagement by said insertion tool when said second member is in the retracted position.

9. The intervertebral spacer of claim 8 wherein said intervertebral spacer is rotatable relative to said insertion tool when it is engaged by said insertion tool.

10. The intervertebral spacer of claim 1 wherein at least one of the first and second members includes a portion that is porous to promote in-growth of bone into the intervertebral spacer.

11. The intervertebral spacer of claim 1 wherein the contact surface on at least one of said first and second members includes a texture to grip an adjacent intervertebral body.

12. A method of inserting an intervertebral spacer between two vertebral members, said method comprising:

inserting an intervertebral spacer having first and second members into an intervertebral space, said intervertebral spacer including a screw jack for moving said first and second members relative to one another between a retracted position and an extended position, said screw jack comprising a screw shaft fixed to one of said first and second members, and an internally threaded ring gear meshed with said screw shaft such that rotation of said ring gear in a first direction moves said second member away from said first member, and such that rotation of said ring gear in a second direction moves said second member towards said first member; and

expanding the intervertebral spacer post-insertion by actuating a drive gear meshed with said ring gear to spread apart the first and second members.

13. The method of claim 12 wherein the intervertebral spacer comprises at least two screw jacks, and wherein actuating expanding the intervertebral spacer comprises actuating each of said screw jacks to spread apart the first and second members.

14. The method of claim 13 wherein actuating each of said screw jacks to spread apart the first and second members comprises actuating two or more screw jacks by rotating a single drive gear.

15. An intervertebral spacer comprising:

first and second members having respective contact surfaces to contact adjacent vertebral bodies, said first and second members being movable with respect to one another between a retracted position and an extended position; and

said first and second members configured to engage an insertion tool when said first and second members are in a retracted position, and to release said tool when said first and second members are moved to an extended position.

16. The intervertebral spacer of claim 15 wherein each of said first and second members includes a tool-engaging element to capture a head of an insertion tool by moving said first and second members from an extended position to the retracted position.

17. The intervertebral spacer of claim 16 wherein said tool-engaging element on said first and second members comprises an opening to receive the head of said insertion tool.

18. The intervertebral spacer of claim 16 wherein said tool engaging elements are configured to permit rotation of said intervertebral spacer about an axis.

19. The intervertebral spacer of claim 16 further comprising a jack mechanism to move said first and second members between said retracted and extended positions.

20. The intervertebral spacer of claim 19 wherein said jack mechanism comprises a screw jack.

21. The intervertebral spacer of claim 20 including at least two screw jacks.

22. The intervertebral spacer of claim 15 further comprising a guide member fixed to one of said first and second members to maintain alignment of said first and second members.

23. The intervertebral spacer of claim 22 wherein said guide member comprises a guide rod fixed to one of said first and second members, said guide member configured for insertion into a guide channel formed in the other of said first and second members.

24. The intervertebral spacer of claim 15 wherein at least one of the first and second members includes a portion that is porous to promote in-growth of bone into the intervertebral spacer.

25. The intervertebral spacer of claim 15 wherein the contact surface on at least one of said first and second members includes a texture to grip an adjacent intervertebral body.

26. A method of inserting an intervertebral spacer between two vertebral members, said expandable intervertebral spacer comprising first and second members movable relative to one another between a retracted position and an extended position, said method comprising:

engaging an expandable intervertebral spacer with an insertion tool with the first and second members in a retracted position;

inserting the intervertebral spacer into an intervertebral space; and

releasing the insertion tool by expanding the intervertebral spacer.

27. The method of claim 26 wherein engaging an expandable intervertebral spacer with an insertion tool with the first and second members in a retracted position comprises engaging a cylindrical head of the insertion tool with corresponding openings in the first and second members.

28. The method of claim 27 wherein the cylindrical head of the insertion tool is configured to permit rotation of the intervertebral spacer about an axis.