Interbody spinal fusion implants

• US 5,593,409 A
• Filed: 02/17/1995
• Issued: 01/14/1997
• Est. Priority Date: 06/13/1988
• Status: Expired due to Term

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Sofamor Danek Group, Inc. (Medtronic Plc)
• Inventors: Michelson, Gary K.
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US08/390,131
• Time in Patent Office: 697 Days
• Field of Search: 606/60, 606/61, 606/72, 606/73, 606/74, 606/75, 606/76, 606/77, 623/16, 623/17, 623/18, 623/66
• US Class Current: 606/247
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/8888 at its central region
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2090/036 abutting on tissue or skin
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/30771 applied in original prostheses, e.g. holes or grooves
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• 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 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• 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 2002/3013 figure-"8"- or hourglass-shaped
• CPC Class Codes: A61F 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30148 lozenge- or diamond-shaped
• CPC Class Codes: A61F 2002/30235 tubular, e.g. sleeves
• CPC Class Codes: A61F 2002/30405 : made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30593 : hollow
• CPC Class Codes: A61F 2002/30604 : modular
• CPC Class Codes: A61F 2002/30774 : internally-threaded
• CPC Class Codes: A61F 2002/30777 : Oblong apertures
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30795 : Blind bores, e.g. of circular cross-section
• CPC Class Codes: A61F 2002/30797 : internally-threaded
• CPC Class Codes: A61F 2002/30836 : knurled
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30879 : Ribs
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• CPC Class Codes: A61F 2002/30906 : shot- sand- or grit-blasted
• 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 2002/449 : comprising multiple spinal implants located in different intervertebral spaces or in different vertebrae
• CPC Class Codes: A61F 2002/4619 : for extraction
• CPC Class Codes: A61F 2002/4627 : with linear motion along or rotating motion about the instrument axis or the implantation direction, e.g. telescopic, along a guiding rod, screwing inside the instrument
• CPC Class Codes: A61F 2002/4629 : connected to the endoprosthesis or implant via a threaded connection
• CPC Class Codes: A61F 2002/4681 : by applying mechanical shocks, e.g. by hammering
• CPC Class Codes: A61F 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/001 : Figure-8-shaped, e.g. hourglass-shaped
• CPC Class Codes: A61F 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• 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
• CPC Class Codes: A61F 2310/00796 : Coating or prosthesis-covering structure made of a phosphorus-containing compound, e.g. hydroxy(l)apatite

Abstract

The present invention discloses a spinal fusion implant that is at least partially cylindrical, made of material appropriate for human implantation and having preferably, but not necessarily, one closed end and one end capable of being closed, such that an internal chamber can be filled and hold any natural or artificial osteoconductive, osteoinductive, osteogenic, or other fusion enhancing material. The partially cylindrical implant directly participates and is incorporated in the ensuing fusion. In the preferred embodiment, the implant of the present invention relies on surface roughenings of the outer surface to enhance its stability and resist dislodgement from within the disc space between two adjacent vertebrae. The implant of the present invention incorporates at its rear end, an engagement means to facilitate insertion or extraction of the implant. The implant may be filled with, coated with, and/or composed of, fusion promoting substances. Finally, the implant of the present invention does not require rotation for its insertion and can be seated by linear advancement.

Claims

1. A partially cylindrical spinal fusion implant made of a material appropriate for human implantation, said implant comprising a cylinder having a longitudinal central axis and at least a first flat side parallel to said central axis.

2. The spinal fusion implant of claim 1 in which said implant has a plurality of flat sides.

3. The spinal fusion implant of claim 1 in which said implant has a second flat side diametrically opposite said first flat side.

4. The spinal fusion implant of claim 1 in which said implant has and internal chamber.

5. The spinal fusion implant of claim 4 in which said internal chamber is capable of containing fusion promoting material.

6. The spinal fusion implant of claim 4 in which said implant comprises a wall surrounding said internal chamber.

7. The spinal fusion implant of claim 6 in which said wall has a plurality of openings passing therethrough in communication with said internal chamber.

8. The spinal fusion implant of claim 1 having a plurality of openings capable retaining fusion promoting material.

9. The spinal fusion implant of claim 1 in which said implant has a major diameter larger than the disc space between two adjacent vertebrae.

10. The spinal fusion implant of claim 1 including a plurality of surface roughenings for engaging said two adjacent vertebrae and for maintaining said implant in place, said surface roughenings being present on at least a portion of the exterior of said implant.

11. The spinal fusion implant of claim 10 in which said surface roughenings include a plurality of ratchetings.

12. The spinal fusion implant of claim 11 in which said ratchetings face one direction.

13. The spinal fusion implant of claim 10 in which said surface roughenings include knurling.

14. The spinal fusion implant of claim 1 in which said implant comprises a bone ingrowth material.

15. The spinal fusion implant of claim 4 in which said implant has at least one removable cap for closing at least one end of said internal chamber.

16. The spinal fusion implant of claim 1 in which one end of said implant includes an engagement means for engaging instrumentation for the insertion of said implant.

17. The spinal fusion implant of claim 1 in which said cylinder includes first and second diametrically opposed arcuate portions that are arcs of the same circle.

18. A hollow partially cylindrical spinal fusion implant made of a material appropriate for human implantation, comprising:

a cylinder having a longitudinal central axis and at least a first flat side parallel to said central axis, said implant having a major diameter larger than the height of the disc space between two adjacent vertebrae and a width measured from said first flat side to a diametrically opposed segment of said cylinder, said width being smaller than said major diameter.