Threaded frusto-conical interbody spinal fusion implants

• US 7,828,800 B2
• Filed: 05/18/2009
• Issued: 11/09/2010
• Est. Priority Date: 06/07/1995
• Status: Expired due to Fees

• Current Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Original Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Inventors: Michelson, Gary Karlin
• Primary Examiner(s): Brown; Michael A.
• Application Number:
  US12/454,393
• Publication Number:
  US 20090228107A1
• Time in Patent Office: 540 Days
• Field of Search: 606/60, 606/246, 606247-249, 606300-302, 606/53, 623/17.1, 623/17.3
• US Class Current: 606/53
• 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 central longitudinal axis therebetween, and a length along the central longitudinal axis, said body having opposed arcuate portions between said leading and trailing ends adapted to be placed within the implantation space oriented toward the adjacent vertebral bodies, respectively, said opposed arcuate portions having at least one opening therethrough, 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, said body having at least one truncated side extending between said opposed arcuate portions and between said leading and trailing ends; and

a thread along at least a portion of the length of said body adapted to engage said implant to the adjacent vertebral bodies, said thread having a thread height measured from said body which is greatest at said at least one truncated side, said at least one truncated side having a truncated portion between said thread and said leading end.

2. The spinal fusion implant of claim 1, wherein said opposed arcuate portions are in an angular relationship to each other along at least a portion of the length of said implant sufficient to maintain the adjacent vertebral bodies in an angular relationship to each other.

3. The spinal fusion implant of claim 2, wherein said implant is configured to be inserted from a posterior approach to the vertebral bodies.

4. The spinal fusion implant of claim 2, wherein said implant is configured to be inserted from an anterior approach to the vertebral bodies.

5. The spinal fusion implant of claim 1, wherein each of said opposed portions comprises an interior surface, said interior surfaces being spaced apart to define a hollow interior in communication with said openings.

6. The spinal fusion implant of claim 5, wherein said implant includes an access opening for accessing said hollow interior.

7. The spinal fusion implant of claim 6, wherein said access opening is configured to permit introduction of a fusion promoting substance into said hollow interior.

8. The spinal fusion implant of claim 6, further comprising a cap for closing said access opening.

9. The spinal fusion implant of claim 1, wherein said body has a second truncated side opposite to said one truncated side.

10. The spinal fusion implant of claim 1, further in combination with a fusion promoting substance.

11. The spinal fusion implant of claim 10, wherein said fusion promoting substance is bone morphogenetic protein.

12. The spinal fusion implant of claim 10, wherein said fusion promoting substance includes hydroxyapatite.

13. The spinal fusion implant of claim 10, wherein said fusion promoting substance includes hydroxyapatite tricalcium phosphate.

14. The spinal fusion implant of claim 10, wherein said fusion promoting substance is bone.

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, said opposed arcuate portions having at least one opening therethrough, 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; 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 thread having a thread height measured from said body, said thread height varying along more than one turn of said thread.

16. The spinal fusion implant of claim 15, wherein said implant is at least in part bioabsorbable.

17. The spinal fusion implant of claim 15, wherein each of said arcuate portions include a plurality of openings therein.

18. The spinal fusion implant of claim 15, wherein said body has an internal chamber and means for accessing said internal chamber.

19. The spinal fusion implant of claim 18, wherein said internal chamber is capable of containing fusion promoting material.

20. The spinal fusion implant of claim 18, wherein internal chamber said includes a wall surrounding said internal chamber.

21. The spinal fusion implant of claim 20, wherein said wall has a plurality of openings passing therethrough in communication with said internal chamber.

22. The spinal fusion implant of claim 18, wherein said implant has means for closing said accessing means.

23. The spinal fusion implant of claim 15, wherein one of said ends is configured to engage instrumentation for the insertion of said implant.

24. The spinal fusion implant of claim 15, wherein said implant is configured to be placed in close proximity in a side by side alignment to a second spinal fusion implant, said first and second implants when placed together having a combined overall width that is less than the sum of the individual maximum diameters of each of said first and second implants.

25. The spinal fusion implant of claim 15, wherein said body has a first truncated side forming a planar surface parallel to the mid-longitudinal axis.

26. The spinal fusion implant of claim 25, wherein said body has a second truncated side forming a planar surface parallel to the mid-longitudinal axis and opposite to said first truncated side.

27. The spinal fusion implant of claim 26, wherein said thread has a thread height measured from said body which is greatest at at least one of said truncated sides.

28. The spinal fusion implant of claim 25, wherein said thread has a thread height measured from said body which is greatest at said first truncated side.

29. The spinal fusion implant of claim 15, wherein said implant is made of a material that is stronger than bone.

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

31. The spinal fusion implant of claim 30, wherein said fusion promoting substance includes at least one of bone, bone morphogenetic protein, hydroxyapatite, and hydroxyapatite tricalcium phosphate.

32. The spinal fusion 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.

33. The spinal fusion implant of claim 15, wherein said thread is uninterrupted.

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

35. The spinal fusion implant of claim 15, wherein said body has a substantially cylindrical configuration.

36. The spinal fusion implant of claim 15, wherein said thread has a pitch, further comprising a second thread around the mid-longitudinal axis of said body, said second thread having a pitch that is different than the pitch of said thread.

37. The spinal fusion implant of claim 36, wherein said second thread is adapted to engage an associated thread of an implant cap.

38. The spinal fusion implant of claim 36, wherein said second thread is adapted to engage an associated thread of an implant inserter tool.

39. A fusion device for facilitating arthrodesis in the disc space between adjacent vertebrae, comprising:

an elongated body having a length and an outer surface extending along said length, said outer surface including a pair of oppositely disposed arcuate portions and at least one substantially flat portion extending between said pair of arcuate portions, said pair of arcuate portions defining external threads extending substantially entirely along said length of said body, said at least one substantially flat portion extending along a substantial portion of said length of said body, said at least one substantially flat portion terminating adjacent a first end of said elongated body, said external threads defining at least one circumferentially continuous thread extending along a majority of the length of said elongated body.