Apparatus for fusing adjacent bone structures

• US 20010032018A1
• Filed: 02/20/2001
• Published: 10/18/2001
• Est. Priority Date: 04/07/2000
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Inventors: McDonnell, Christopher, Castro, Salvatore
• Granted Patent: US 6,436,141 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• 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 2002/30593 hollow
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30787 inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/3082 Grooves
• CPC Class Codes: A61F 2002/3085 with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30858 Threads interrupted by grooves or sidewalls, e.g. flat sidewalls
• 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 2310/00017 Iron- or Fe-based alloys, e.g. stainless steel
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00179 Ceramics or ceramic-like structures

Abstract

An apparatus for facilitating fusion of adjacent bony structures includes an implant body dimensioned for positioning between adjacent bone structures to maintain the bone structures in desired spaced relation during interbody fusion. The implant body has an outer wall and an external threaded configuration disposed on the outer wall. At least one concave surface at least partially extends along the implant body. The concave surface advantageously reduces the transverse cross-sectional dimension of the implant member thereby facilitating placement of the implant member in restricted intervertebral areas. In addition, the concave surface enables placement of a pair of implants in nested side-by-side relation. Preferably, the threaded configuration has portions removed along an arc section of the outer wall thereby defining a series of generally longitudinally aligned concave surfaces in individual turns thereof. A system and method for facilitating fusion of adjacent vertebrae is also disclosed.

Claims

1. An apparatus for facilitating fusion of adjacent bony structures, which comprises:

an implant body dimensioned for positioning between adjacent bone structures to maintain the bone structures in desired spaced relation during interbody fusion, the implant body defining a longitudinal axis and having an outer wall extending along the longitudinal axis, the outer wall having an external threaded configuration and at least one concave surface at least partially extending along the longitudinal axis, wherein the transverse cross-sectional dimension along a first transverse axis inclusive of the concave surface is less than the transverse cross-sectional dimension along a second transverse axis.

2. The apparatus according to

claim 1

wherein the threaded configuration has portions removed along an arc section of the outer wall thereby defining a series of generally longitudinally aligned concave surfaces in individual turns thereof.

3. The apparatus according to

claim 1

wherein the one concave surface extends substantially along the length of the implant member.

4. The apparatus according to

claim 1

wherein the implant body includes an internal cavity defined within the outer wall for accommodating bone growth inducing substances.

5. The apparatus according to

claim 4

wherein the implant body includes a plurality of apertures extending through the outer wall in communication with the internal cavity.

6. The apparatus according to

claim 5

wherein the apertures extend through the valleys of the individual turns of the thread in communication with the inner cavity to permit immediate contact of the vertebral bone tissue and the bone growth inducing substances within the inner cavity upon insertion of the implant body.

7. The apparatus according to

claim 1

wherein the implant body defines entry and trailing longitudinal end faces, at least one of the end faces having an aperture therein in communication with the internal cavity.

8. The apparatus according to

claim 7

further including an end cap, the end cap being mountable to the one end face to enclose the internal cavity.

9. The apparatus according to

claim 8

wherein each of the leading and trailing end faces include an aperture extending to communicate with the internal cavity.

10. The apparatus according to

claim 9

including first and second end caps mountable to respective leading and trailing end faces.

11. The apparatus according to

claim 2

including a second series of generally longitudinally aligned concave surfaces.

12. The apparatus according to

claim 11

wherein the second series of concave surfaces are disposed in diametrical opposed relation to the first mentioned series of concave surfaces.

13. The apparatus according to

claim 1

wherein the implant body is generally cylindrical.

14. The apparatus according to

claim 1

wherein the implant body is dimensioned and configured for positioning between adjacent vertebrae and to support the vertebrae in adjacent spaced relation.

15. A system for facilitating fusion of adjacent vertebrae, which comprises:

first and second implants dimensioned for positioning between adjacent vertebrae to support the vertebrae in spaced relation, the first implant including an implant body defining a longitudinal axis and an outer wall extending along the longitudinal axis, the outer wall having an external threaded configuration and at least one substantially concave surface portion at least partially extending along the longitudinal axis, the second implant including an implant body defining a longitudinal axis and having an arcuate outer wall portion correspondingly dimensioned to be received within the concave surface portion of the first implant to permit the first and second implants to be positioned in nested side by side relation within an intervertebral space defined between the adjacent vertebrae.

16. The apparatus according to

claim 15

wherein the threaded configuration of the first implant has portions removed along an arc section of the outer wall thereby defining a series of generally longitudinally aligned concave surfaces in individual turns of the threaded configuration.

17. The apparatus according to

claim 15

wherein the implant body of the second implant has an external threaded configuration.

18. A method for fusion of adjacent vertebrae, comprising the steps of:

accessing the intervertebral space defined between adjacent vertebrae;

providing a first implant including an implant body defining a longitudinal axis and an outer wall extending along the longitudinal axis, the exterior wall having at least one substantially concave surface portion at least partially extending along the longitudinal axis;

positioning the first implant within a first lateral side of the intervertebral space;

providing a second implant including an implant body defining a longitudinal axis and having an arcuate outer wall portion correspondingly dimensioned to be received within the concave surface portion of the first implant; and

positioning the second implant within a second lateral side of the intervertebral space and arranging the second implant whereby the arcuate outer wall portion of the second implant is received within the concave surface portion of the first implant.

19. The method according to

claim 18

wherein the exterior walls of the first and second implants each have an external threaded configuration and wherein the steps of positioning includes rotating the respective implant bodies whereby the threaded configurations engage the adjacent vertebrae.

20. The method according to

claim 19

wherein the implant bodies of the first and second implants each define an internal cavity for reception of bone growth inducing substances and have apertures extending through the exterior walls in communication with the internal cavity, and further including the step of permitting bone growth through the apertures to facilitate fusion of the adjacent vertebrae.