Apparatus and method for spinal fusion using implanted devices

• US 20020032483A1
• Filed: 06/04/2001
• Published: 03/14/2002
• Est. Priority Date: 05/06/1998
• Status: Active Grant

• Current Assignee: Alphatec Spine Incorporated (Alphatec Holdings Incorporated)
• Original Assignee: CORTEK, Inc. (Alphatec Holdings Incorporated)
• Inventors: Nicholson, James E., Whipple, Dale E., Tromanhauser, Scott G.
• Granted Patent: US 6,679,887 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/0642 for bones, e.g. for osteosynthesis or connecting tendon to bone
• CPC Class Codes: A61B 17/1604 Chisels; Rongeurs; Punches; Stamps
• CPC Class Codes: A61B 17/1659 Surgical rasps, files, planes, or scrapers
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 2017/00544 pneumatically
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2017/924 Impact element driving means
• CPC Class Codes: A61B 2090/033 Abutting means, stops, e.g. abutting on tissue or skin
• CPC Class Codes: A61B 2090/0801 Prevention of accidental cutting or pricking
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• 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 2/4455 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 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• 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 2002/286 Bone stimulation by mechanical vibrations for enhancing ossification
• CPC Class Codes: A61F 2002/30004 the prosthesis being made from materials having different values of a given property at different locations within the same prosthesis
• CPC Class Codes: A61F 2002/30075 swellable, e.g. when wetted
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30154 : square
• CPC Class Codes: A61F 2002/30177 : W-shaped, M-shaped or sigma shaped
• CPC Class Codes: A61F 2002/30261 : parallelepipedal
• CPC Class Codes: A61F 2002/30329 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2002/30448 : using adhesives
• CPC Class Codes: A61F 2002/305 : Snap connection
• CPC Class Codes: A61F 2002/30565 : having spring elements
• CPC Class Codes: A61F 2002/30579 : with mechanically expandable devices, e.g. fixation devices
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30883 : dovetail-shaped
• CPC Class Codes: A61F 2002/30975 : made of two halves
• CPC Class Codes: A61F 2002/4648 : Means for culturing bone graft
• CPC Class Codes: A61F 2210/0061 : swellable
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/005 : using adhesives
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0021 : square
• CPC Class Codes: A61F 2230/0056 : W-shaped, e.g. M-shaped, sigma-shaped
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0014 : having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
• CPC Class Codes: A61F 2310/00023 : Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00293 : containing a phosphorus-containing compound, e.g. apatite

Abstract

A spinal implant replaces excised tissue removed during spine surgery. This implant includes fasteners which firmly attach it to vertebrae adjacent to excised tissue so as to transmit tension and torsional loads to and from those vertebrae. The body of the implant has through cavities into which bone growth material is placed during surgery. The body of the implant also has a finite modulus of elasticity in compression so as to share compressive loads with emplaced bone growth material and with new bony growth facilitated by the emplaced material and the load sharing.

Claims

1. An implant for mechanically attaching to the end surfaces of and promoting bony fusion of at least two vertebrae adjacent to a space left by surgically removed spinal tissue, comprising

a. a load-sharing body comprising a structure having

i. a combination of structural elements fabricated from at least one material having finite moduli of elasticity, the combination comprising at least a top surface and a bottom surface;

ii. said combination of structural elements establishing for the structure as a whole a composite non-zero elasticity at least in compression in directions generally normal to said top surface and said bottom surface;

iii. said combination of structural elements further comprising at least one cavity communicating with both said top surface and said bottom surface in a configuration suitable as a receptacle for bone implant and growth material; and

b. on each of said top surface and said bottom surface at least one fastener capable of mechanically anchoring the body to said adjacent vertebrae and transmitting tensile and torsional loads to and from said adjacent vertebrae.

2. The implant of claim 1 in which said at least one fastener on each of said top surface and said bottom surface comprises a dovetail protrusion shaped so as to mate slidingly with a groove of substantially the same shape.

3. The implant of claim 1 in which said at least one fastener on each of said top surface and said bottom surface comprises a horseshoe shaped dovetail tongue with segments on the outboard portions of the body, said tongue shaped so as to mate slidingly with a groove of substantially the same shape.

4. The implant of claim 1 in which said at least one fastener on each of said top surface and said bottom surface comprises a plurality of dovetail protrusions, each of which plurality is shaped so as to mate slidingly with a groove of substantially the same shape.

5. The implant of claim 1 in which said at least one fastener on each of said top surface and said bottom surface comprises at least one tack and staple devices.

6. The implant of claim 1 in which said at least one fastener on each of said top surface and said bottom surface comprises at least one bone anchor.

7. The implant of claim 1 in which the combination of elements comprises an assembly of at least three modular components, the first modular component comprising a right partial separator, the second modular component comprising a left partial separator, each having at least a top surface and a bottom surface, and the third modular component comprising a retainer/keeper.

8. The implant of claim 7 in which the right partial dovetail separator and the left partial dovetail separator each has a on each of said top surface and said bottom surface at least one fastener capable of mechanically anchoring the partial separator to said adjacent vertebrae.

9. The implant of claim 7 in which the right partial separator and the left partial separator each has a on each of said top surface and said bottom surface at least one fastener such that in concert the fasteners form a structure capable of mechanically anchoring the implant to said adjacent vertebrae.

10. The implant of claim 1 in which the top surface and the bottom surface are oriented with respect to one another such that the implant maintains spinal lordosis after insertion.

11. The implant of claim 1 in which the at least one material having finite moduli of elasticity from which the combination of structural elements is fabricated is selected from the group PEEK (Polyesther Esther Ketone), Acetyl (delrin), polysulphone, Ultra High Molecular Weight polyethylene (UHMW Poly), and composites involving high strength carbon fibers or glass filaments.

12. The implant of claim 1 in which the at least one material having finite moduli of elasticity from which the combination of structural elements is fabricated comprises human bone allograft material.

13. The implant of claim 1 additionally comprising at least one retractable barb in each of said top surface and said bottom surface, said at least one barb retractably engaging the surface of said adjacent vertebra so as to prevent the implant from dislodging.

19. The dovetail tome apparatus of claim 17 comprises at least a shaft, a guide, and a tome.

20. The tome of claim 18 additionally comprising an inclined blade which parts bone removed by the tool so as to prevent jamming of the tool.

21. The dovetail tome apparatus of claim 17 additionally comprising a single element interlock which prevents rotation of the shaft outside of the guide and which prevents withdrawal of the tool while the shaft is rotated.

14. The method of mechanically attaching and promoting bony fusion of two vertebrae adjacent to a space left by surgically removed tissue comprising the implantation of a load-sharing implant which shares compressive loads with said adjacent vertebrae so as to promote growth of bony material between said adjacent vertebrae and which is fastened to said adjacent vertebrae with shear and tensile load transmitting fasteners so as to permit relative movement during and after healing.

15. The method of attaching both vertebrae adjacent to a space left by excised spinal tissue to a hollow elastic implant filled with bone chips and/or bone growth medium designed to promote and accelerate fusion of the adjacent vertebrae in such a manner as to share compressive loads with the bone chips and/or bone growth medium.

16. A device for separating and fastening vertebrae adjacent to a space left by surgically removed spinal tissue, comprising

a. a body elastic to compression loads and comprising spaces for the emplacement of bone growth material;

and

b. fasteners which attach securely to adjacent vertebrae and transmit tension and torsional loads to and from the adjacent vertebrae.

17. A device for separating and fastening vertebrae adjacent to a space left by surgically removed spinal tissue, comprising

a. means for separating adjacent vertebrae while yielding elastically to compression loads;

b. means for the emplacement of bone growth material; and

c. means for attaching the device securely to adjacent vertebrae and transmitting tension and torsional loads to and from the adjacent vertebrae.

18. A dovetail tome apparatus which cuts at least two dovetail grooves in bone simultaneously.

22. A guide means for stabilizing vertebrae adjacent to a space left by surgically removed spinal tissue and for establishing references for a tome apparatus.

23. A tome apparatus driver device providing a plurality of small impacts axially to a bone cutting device.