Spinal fusion device

• US 6,102,948 A
• Filed: 08/20/1997
• Issued: 08/15/2000
• Est. Priority Date: 01/16/1996
• Status: Expired due to Term

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Surgical Dynamics Incorporated (Medtronic Plc)
• Inventors: Brosnahan, Robert E. III
• Primary Examiner(s): Isabella, David J.
• Application Number:
  US08/915,061
• Time in Patent Office: 1,091 Days
• Field of Search: 623/16, 623/17, 623/18, 606/61
• US Class Current: 623/17.16
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• 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 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30733 Inserts placed into an endoprosthetic cavity, e.g. for modifying a material property
• CPC Class Codes: A61F 2002/30777 Oblong apertures
• CPC Class Codes: A61F 2002/308 oblong
• CPC Class Codes: A61F 2002/30805 Recesses of comparatively large area with respect to their low depth
• 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 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2230/0019 rectangular
• CPC Class Codes: A61F 2230/0069 cylindrical
• CPC Class Codes: A61F 2310/00293 containing a phosphorus-containing compound, e.g. apatite
• CPC Class Codes: A61F 2310/00395 : Coating or prosthesis-covering structure made of metals or of alloys
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

An implant for insertion into at least one bore formed between opposing vertebrae of a spine where the vertebrae are separated by a space and each vertebrae has end plates. The implant is in the shape of a solid generally cylindrical body having a first and a second end, an outer surface, opposing sides and a longitudinal axis. The body has threads on a portion of the outer surface between the first and second ends with the threads being configured for threading into bone. The body includes at least two indentations on its outer surface with the indentations having a surface with each indentation containing a bone attachment material for the attachment of bone to the bone attachment material within the indentations. Each of the indentations are positioned on generally opposing sides of the body so as to provide contact with the end plates of the opposing vertebrae when the implant is inserted into at least one bore formed between the opposing vertebrae.

Claims

1. An implant for insertion into a bore formed between opposing vertebrae of a spine where the vertebrae are separated by a space and each vertebrae has end plates and bone tissue, the implant comprising:

a) a solid generally cylindrical body having a first and a second end, an outer surface, a length measured from the first end to the second end and a longitudinal axis;

b) the body having threads on the outer surface between the first and second ends and along a major portion of the length of the body, the threads configured for threading into bone and having a thread diameter that defines the outer diameter of the body along a major portion of its length;

c) wherein the body comprises a first substantially rigid material and a second biocompatible porous material, the second biocompatible porous material being disposed on at least opposed surface portions of the outer surface of the body and arranged to substantially contact the end plates of the opposing vertebrae when the body is inserted into the bore formed between the opposing vertebrae;

to permit bone tissue of the end plates to chemically bond directly to the outer surface of the body.

2. The implant of claim 1, wherein the second biocompatible porous material includes bioactive hydroxyapatite-polymer composites.

3. The implant of claim 2, wherein the hydroxyapatite-polymer composites includes hydroxyapatite reinforced polyethylene composites.

4. The implant of claim 1, wherein two implants are inserted into two bores formed between opposing vertebrae of a spine.

5. The implant of claim 1, wherein the second end of the body has a centrally located internal opening configured to receive a tool receiving and mounting device for securing the body to a tool for inserting the implant into at least one bore formed between opposing vertebrae of a spine.

16. The implant of claim 1 wherein the outer surface of the body includes first and second recesses defined therein and arranged in general diametrical opposed relation and wherein the second biocompatible porous material is disposed within the first and second recess.

17. The implant of claim 16 wherein the second biocompatible porous material is selected from a group consisting of biocompatible metals, ceramics, polymers and composites thereof.

18. The implant of claim 17 wherein the ceramic material is a hydroxylapatite.

19. The implant of claim 18 wherein the hydroxylapatite is a calcium hydroxylapatite.

6. An implant for insertion between adjacent vertebral bodies, which comprises:

an implant body dimensioned for insertion between the adjacent vertebral bodies to support the adjacent vertebral bodies in spaced relation during healing, the implant body defining a longitudinal axis and having entry and exit ends, the implant body including an outer surface having at least first and second non-communicating recesses therein and a biocompatible porous bone attachment material disposed within each recess, the first and second recesses being arranged in general diametrical opposed relation such that upon positioning of the implant body between the adjacent vertebral bodies, the bone attachment material within each recess contacts respective vertebral portions of the adjacent vertebral bodies.

7. The implant of claim 6 wherein the implant body is generally-cylindrically shaped.

8. The implant of claim 7 wherein the implant body includes at least two pairs of first and second recesses defined in the outer surface thereof.

9. The implant of claim 7 wherein the outer surface of the implant body includes a threaded portion to facilitate insertion between adjacent vertebral portions.

10. The implant of claim 6 wherein the bone attachment material comprises a biocompatible porous material.

11. The implant of claim 10 wherein the porous material is selected from a group consisting of biocompatible metallic, ceramics, polymers and composites thereof.

12. The implant of claim 11 wherein the ceramic material is a hydroxylapatite.

13. The implant of claim 11 wherein the hydroxylapatite is a calcium hydroxylapatite.

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

providing a fusion apparatus including an implant body having an outer surface with at least first and second recesses defined therein and arranged in general diametrical opposed relation, and a biocompatible porous bone attachment material disposed within each recess;

accessing adjacent vertebral portions; and

positioning the fusion apparatus between the adjacent vertebral portions in a manner whereby

the bone attachment material within the first and second recesses is adjacent respective vertebral portions to achieve immediate contact therewith, to thereby facilitate bonding and subsequent fusion of the implant body with the vertebral portions.

15. The method according to claim 14 wherein the implant body includes an external threaded portion and wherein the step of positioning includes screwing the implant body within a preformed bore defined by the vertebral portions.