Threaded interbody spinal fusion implant

• US 8,057,475 B2
• Filed: 11/09/2010
• Issued: 11/15/2011
• Est. Priority Date: 06/07/1995
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Brown; Michael A.
• Application Number:
  US12/942,671
• Publication Number:
  US 20110054529A1
• Time in Patent Office: 371 Days
• Field of Search: 606/53, 606/240, 606/246, 606/60, 623/17.1, 623/17.3
• US Class Current: 606/60
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/32 Surgical cutting instruments A61B18/042 takes precedence; suture cutters A61B17/0467; instruments for ligaturing or cutting A61B17/128; instruments for rupturing the amniotic membrane A61B17/4208; specially adapted knives for eye surgery A61F9/0133
• CPC Class Codes: A61B 17/3468 for implanting or removing devices, e.g. prostheses, implants, seeds, wires devices for implanting seeds A61M37/0069
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• CPC Class Codes: A61B 2017/0256 for the spine
• CPC Class Codes: A61B 2017/922 Devices for impaction, impact element
• 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 2/442 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 2/4637 for connecting or disconnecting two parts of a prosthesis
• 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 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• 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 2002/3021 : frustoconical
• CPC Class Codes: A61F 2002/30217 : hollow cones, e.g. tubular-like cones
• CPC Class Codes: A61F 2002/30224 : cylindrical
• 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 2002/30426 : Bayonet coupling
• 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 2002/30808 : parallel
• CPC Class Codes: A61F 2002/3081 : inclined obliquely with respect to each other
• 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 2002/30861 : having threads of increasing or decreasing height
• CPC Class Codes: A61F 2002/30879 : Ribs
• CPC Class Codes: A61F 2002/30892 : parallel
• CPC Class Codes: A61F 2002/30894 : inclined obliquely with respect to each other
• 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 2002/30909 : Nets
• 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 2002/4649 : Bone graft or bone dowel harvest sites
• CPC Class Codes: A61F 2002/4681 : by applying mechanical shocks, e.g. by hammering
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• 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 2230/0067 : conical
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2250/0063 : Nested prosthetic parts
• 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 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• 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
• CPC Class Codes: A61F 2310/00976 : Coating or prosthesis-covering structure made of proteins or of polypeptides, e.g. of bone morphogenic proteins BMP or of transforming growth factors TGF

Abstract

The present invention is directed to a variety of interbody spinal fusion implants having at least a partially frusto-conical configuration. An external thread is employed to increase implant stability and implant surface area, and for the purpose of advancing the spinal fusion implant into the fusion site. The spinal fusion implants of the present invention may be relatively solid or hollow and may have surface roughenings to promote bone ingrowth and stability. The spinal fusion implants of the present invention may have wells extending into the material of the implant from the surface for the purpose of holding fusion promoting materials and to provide for areas of bone ingrowth fixation.

Claims

1. An interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between adjacent vertebral bodies of a human spine, said implant comprising:

a body having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis through said leading and trailing ends, and opposed arcuate portions between said leading and trailing ends adapted to be placed within the implantation space oriented toward the adjacent vertebral bodies, respectively, one of said opposed arcuate portions adapted to contact one of said adjacent vertebral bodies, and the other of said opposed arcuate portions adapted to contact the other said adjacent vertebral bodies, said opposed arcuate portions maintaining a spaced relationship between the adjacent vertebral bodies in the implantation space; and

a thread extending from at least adjacent said leading end to at least adjacent said trailing end, said thread adapted to engage said implant to the adjacent vertebral bodies and to facilitate rotation of said implant from a first position to a second position during insertion thereof into the implantation space, said body having a plurality of openings between one complete turn of said thread, each of said openings having a maximum cross sectional dimension, the maximum cross sectional dimension of at least two of said openings being different, at least two of said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

2. The implant of claim 1, wherein the maximum cross sectional dimension of one of said openings is more than twice the maximum cross sectional dimension of another of said openings.

3. The implant of claim 1, wherein the maximum cross sectional dimension of one of said openings is generally the same as the distance between two adjacent turns of said thread.

4. The implant of claim 1, wherein said body includes a length parallel to the mid-longitudinal axis, at least two of said openings being positioned adjacent one another along the length of said implant and between two adjacent turns of said thread.

5. The implant of claim 4, wherein said adjacent openings each have a diameter, the diameter of said adjacent openings being the same.

6. The implant of claim 4, wherein said adjacent openings form a pair of openings, further comprising a plurality of said pairs of openings between said two adjacent turns of said thread.

7. The implant of claim 4, wherein each of said plurality of openings has a central longitudinal axis, said plurality of openings including at least two larger openings each having a maximum cross sectional dimension larger than the cross sectional dimension of each of said adjacent openings, the central longitudinal axes of said two larger openings forming a line therethrough bisecting the distance between the central longitudinal axes of said adjacent openings.

8. The implant of claim 1, wherein said body has an internal chamber capable of containing fusion promoting material.

9. The implant of claim 1, wherein said thread has a variable height along each turn of said thread about the mid-longitudinal axis of said body.

10. The implant of claim 1, wherein said thread is uninterrupted.

11. The implant of claim 1, wherein an outer locus of said thread has a substantially cylindrical configuration.

12. The implant of claim 1, wherein said body has a substantially cylindrical configuration.

13. The implant of claim 1, wherein said implant is at least in part bioabsorbable.

14. The implant of claim 1, in combination with a fusion promoting substance.

15. An interbody spinal fusion implant for insertion within an implantation space formed across the height of a disc space between adjacent vertebral bodies of a human spine, said implant comprising:

a body having a leading end for insertion first into the disc space, a trailing end opposite said leading end, a mid-longitudinal axis through said leading and trailing ends, and opposed arcuate portions between said leading and trailing ends adapted to be placed within the implantation space oriented toward the adjacent vertebral bodies, respectively, one of said opposed arcuate portions adapted to contact one of said adjacent vertebral bodies, and the other of said opposed arcuate portions adapted to contact the other said adjacent vertebral bodies, said opposed arcuate portions maintaining a spaced relationship between the adjacent vertebral bodies in the implantation space; and

a thread extending from at least adjacent said leading end to at least adjacent said trailing end, said thread adapted to engage said implant to the adjacent vertebral bodies and to facilitate rotation of said implant from a first position to a second position during insertion thereof into the implantation space, said body having a plurality of openings being along a helical path between turns of said thread and around the mid-longitudinal axis, each of said openings having a maximum cross sectional dimension, the maximum cross sectional dimension of at least two of said openings being different along said helical path, at least two of said openings being in communication with one another to permit for the growth of bone from adjacent vertebral body to adjacent vertebral body through said implant.

16. The implant of claim 15, wherein the maximum cross sectional dimension of one of said openings is more than twice the maximum cross sectional dimension of another of said openings.

17. The implant of claim 15, wherein the maximum cross sectional dimension of one of said openings is generally the same as the distance between two adjacent turns of said thread.

18. The implant of claim 15, wherein said body includes a length parallel to the mid-longitudinal axis, at least two of said openings being positioned adjacent one another along the length of said implant and between two adjacent turns of said thread.

19. The implant of claim 18, wherein said adjacent openings each have a diameter, the diameter of said adjacent openings being the same.

20. The implant of claim 18, wherein said adjacent openings form a pair of openings, further comprising a plurality of said pairs of openings between said two adjacent turns of said thread.

21. The implant of claim 18, wherein each of said plurality of openings has a central longitudinal axis, said plurality of openings including at least two larger openings each having a maximum cross sectional dimension larger than the cross sectional dimension of each of said adjacent openings, the central longitudinal axes of said two larger openings being along a line therethrough bisecting the distance between the central longitudinal axes of said adjacent openings.

22. The implant of claim 15, wherein said body has an internal chamber capable of containing fusion promoting material.

23. The implant of claim 15, wherein said thread has a variable height along each turn of said thread about the mid-longitudinal axis of said body.

24. The implant of claim 15, wherein said thread is uninterrupted.

25. The implant of claim 15, wherein an outer locus of said thread has a substantially cylindrical configuration.

26. The implant of claim 15, wherein said body has a substantially cylindrical configuration.

27. The implant of claim 15, wherein said implant is at least in part bioabsorbable.

28. The implant of claim 15, in combination with a fusion promoting substance.