Expandable fusion device and method

• US 20030004575A1
• Filed: 05/20/2002
• Published: 01/02/2003
• Est. Priority Date: 06/23/1999
• Status: Active Grant

• Current Assignee: Zimmer Spine, Inc. (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Sulzer Spine Tech, Inc.
• Inventors: Erickson, Richard A.
• Granted Patent: US 6,830,589 B2
• Time in Patent Office: Days
• US Class Current: 623/17.15
• 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 2/4455 for the fusion of spinal bodies, e.g. intervertebral fusion of adjacent spinal bodies, e.g. fusion cages intervertebral discs A61F2/442
• CPC Class Codes: A61F 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30154 square
• CPC Class Codes: A61F 2002/30266 wedge-shaped parallelepipeds
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30372 with additional means for limiting said translation
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/3055 for adjusting length
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30787 inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30789 perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/448 comprising multiple adjacent spinal implants within the same intervertebral space or within the same vertebra, e.g. comprising two adjacent spinal implants
• 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 2230/0019 : rectangular
• CPC Class Codes: A61F 2230/0021 : square
• CPC Class Codes: A61F 2230/0082 : parallelepipedal

Abstract

The present invention is directed to expandable bone fusion devices and methods of use. In general, a fusion device according to the invention includes a first member and a second member which can be deployed and locked into an expanded configuration to stabilize the adjacent bone during fusion of the bone.

Claims

1. An intervertebral implant having an expanded and non-expanded configuration and comprising:

an external member including;

a leading end and a trailing end,

an external base;

a first external wall and a second external wall spaced apart by a width of the external base, each of the first and second external walls having an external base end nearest the external base and an external edge away from the external base;

an internal member including;

a leading end and a trailing end,

an internal base;

a first internal wall and a second internal wall having a spacing therebetween for the first and second internal walls to fit within the first and second external walls, each of the first and second internal walls having an internal base end nearest the internal base and an internal edge away from the internal base;

a first pin and a second pin projecting from a selected one of the walls of the external member and the walls of the internal member;

a first aperture and a second aperture each positioned in a selected one of the walls of the external members and the walls of the internal members such that the first pin is receivable by the first aperture and the second pin is receivable by the second aperture.

2. An intervertebral implant according to claim 1 wherein:

the first pin projects from the first internal wall and the second pin projects from the second internal wall; and

the first aperture is in the first external wall and the second pin is in the second external wall.

3. An intervertebral implant according to claim 1 wherein the first external member is U-shaped.

4. An intervertebral implant according to claim 1 wherein the internal member is U-shaped.

5. An intervertebral implant according to claim 1 wherein the internal member is tubular.

6. An intervertebral implant according to claim 1 wherein the first and second pins project from the leading end of the internal member and the first and second apertures are at the leading end of the external member.

7. An expandable intervertebral fusion device according to claim 1 wherein when in the expanded configuration, the first pin interdigitates with the first apertures and the second pin interdigitates with the second aperture.

8. An intervertebral implant according to claim 2 wherein when in the non-expanded configuration the first and second internal walls are deflected towards one another.

9. An intervertebral implant according to claim 8 wherein a trailing height of the first and second internal walls, measured from the internal base to the internal edge at the trailing end of the first and second internal walls, is greater than a leading height of the first and second internal walls, measured from the internal base to the internal edge at the leading end of the first and second internal walls.

10. An intervertebral implant according to claim 2 wherein:

the external member includes a third aperture at the trailing end of the first external wall and a fourth aperture at the trailing end of the second external wall; and

the internal member includes a third pin projecting externally from the trailing end of the first internal wall and positioned to be received by the third aperture and a fourth pin projecting externally from the trailing end of the second internal wall and positioned to be received by the fourth aperture.

11. An intervertebral implant according to claim 10 wherein the first aperture is positioned at the leading end and a distance between the external base and the first aperture is less than a distance between the external base and the third aperture.

12. An intervertebral implant according to claim 10 wherein the first pin is positioned at the leading end and a distance between the internal base and the first pin is less than a distance between the internal base and the third pin.

13. An intervertebral implant according to claim 1 wherein the first and second members each have a circular cross section.

14. An intervertebral implant according to claim 1 wherein the internal and external members each have a rectangular cross section.

15. An intervertebral implant according to claim 2 wherein

the first aperture is positioned near the first external edge and the second aperture is positioned near the second external edge;

and

the first external wall includes a first groove extending from the first external base end of the first external wall to the first aperture and the second external wall includes a second groove extending from the second external base end to the second aperture.

16. An intervertebral implant according to claim 14 wherein the first and second grooves are ramped from the first and second external base ends to the first and second apertures, respectively.

17. An intervertebral implant according to claim 1 wherein the internal base and external base each include at least one opening.

18. An intervertebral implant according to claim 1 wherein an exterior surface of the external base and an exterior surface of the internal base each include an engagement arrangement for engaging end plates of adjacent vertebrae.

19. An intervertebral implant according to claim 18 wherein the engagement arrangement comprises a plurality of spikes.

20. A method for stabilizing an intervertebral disc space between adjacent vertebrae, the method comprising a step of:

removing disc material from the disc space;

inserting an expandable fusion implant into the disc space, wherein the fusion implant comprises;

(a) an external member including;

(i) a leading end and a trailing end,

(ii) an external base;

(iii) a first external wall and a second external wall spaced apart by a width of the external base, each of the first and second external walls having an external base end nearest the external base and an external edge away from the external base;

(b) an internal member including;

(i) a leading end and a trailing end,

(ii) a first internal base;

(iii) a first internal wall and a second internal wall having a spacing therebetween for the first and second internal walls to fit within the first and second external walls, each of the first and second internal walls having an internal base end nearest the internal base and an internal edge away from the internal base;

(c) a first pin and a second pin projecting from a selected one of the walls of the external member and the walls of the internal member;

(d) a first aperture and a second aperture each positioned in a selected one of the walls of the external members and the walls of the internal members such that the first pin is receivable by the first aperture and the second pin is receivable by the second aperture.

expanding the fusion device into an expanded configuration.

21. A method according to claim 20 wherein two expandable fusion implants are inserted into the disc space.

22. A method according to claim 20 wherein the expandable fusion implant is packed with a bone support matrix after inserting the fusion implant into the disc space.

23. A method according to claim 20 including a step of forming a bore between adjacent vertebrae before inserting the expandable fusion implant into the disc space.

24. A method according to claim 23 wherein the bore is circular.