Apparatus for fusing adjacent bone structures

• US 6,436,141 B2
• Filed: 02/20/2001
• Issued: 08/20/2002
• Est. Priority Date: 04/07/2000
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Surgical Dynamics Incorporated (Medtronic Plc)
• Inventors: McDonnell, Christopher, Castro, Salvatore
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): Barrett, Thomas
• Application Number:
  US09/788,693
• Publication Number:
  US 20010032018A1
• Time in Patent Office: 546 Days
• Field of Search: 623/16-1-
• 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 vertebrae, which comprises an implant body dimensioned for positioning within an intervertebral space defined between adjacent vertebrae, the implant body including an outer wall defining a longitudinal axis and at least one thread disposed on the outer wall for facilitating insertion of the implant body within the intervertebral space, the at least one thread having a concave recess defined therein extending radially inwardly relative to the longitudinal axis of the implant body to a depth which is less than a corresponding height of the at least one thread.

2. The apparatus according to claim 1 wherein the at least one thread includes a plurality of individual concave recesses disposed in general longitudinal alignment.

3. The apparatus according to claim 2 wherein the implant body defines substantially circular cross-section.

4. The apparatus according to claim 2 wherein the implant body is substantially cylindrical.

5. The apparatus according to claim 4 wherein the outer wall of the implant body defines an internal cavity for accommodating bone growth inducing substances and having a plurality of apertures extending through the outer wall in communication with the internal cavity.

6. An apparatus for supporting adjacent vertebrae, which comprises:

a first implant body dimensioned for positioning within an intervertebral space defined between adjacent vertebrae to maintain the adjacent vertebrae in predetermined spaced relation during healing, the first implant body including an outer wall defining a longitudinal axis and a threaded configuration, the threaded configuration dimensioned to engage bone tissue of the adjacent vertebrae upon rotation of the first implant body to facilitate advancement within the intervertebral space, the first implant body including a plurality of interrupted concave recesses disposed in spaced relation along the longitudinal axis and arranged in general longitudinal alignment with respect to the longitudinal axis, the concave recesses extending radially inwardly to a depth less than a height of a thread of the threaded configuration, the first implant body being dimensioned to reduce an overall cross sectional dimension of the first implant body to thereby facilitate positioning within the intervertebral space.

7. The apparatus according to claim 6 including first and second series of the interrupted concave recesses disposed in diametrical opposed relation.

8. The apparatus according to claim 6 wherein the outer wall of the first implant body defines an internal cavity for accommodating bone growth inducing substances and having a plurality of apertures extending through the outer wall in communication with the internal cavity.

9. The apparatus according to claim 8 including a second implant body defining a longitudinal axis and having an arcuate outer wall portion correspondingly dimensioned to be received within the concave recesses of the first implant body to permit the first and second implant bodies to be positioned in nested side by side relation within the intervertebral space defined between the adjacent vertebrae.