Adjustable height fusion device

• US 6,576,016 B1
• Filed: 06/27/2000
• Issued: 06/10/2003
• Est. Priority Date: 05/01/1997
• Status: Expired due to Term

• Current Assignee: Zimmer Spine, Inc. (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Spinal Concepts Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Guyer, Richard D., Hochshuler, Stephen H., Wagner, Erik J., Rashbaum, Ralph F.
• Primary Examiner(s): Isabella, David J.
• Application Number:
  US09/605,200
• Time in Patent Office: 1,078 Days
• Field of Search: 623/17.13, 623/17.15, 623/17.16, 606/61, 606/60, 606/69, 606/70, 606/71
• US Class Current: 623/17.15
• CPC Class Codes: A61B 17/8875 Screwdrivers, spanners or wrenches
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• 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 2/4611 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 2002/30131 horseshoe- or crescent- or C-shaped or U-shaped
• CPC Class Codes: A61F 2002/30143 hexagonal
• CPC Class Codes: A61F 2002/30158 trapezoidal
• CPC Class Codes: A61F 2002/30166 H-shaped or I-shaped
• CPC Class Codes: A61F 2002/30224 cylindrical
• CPC Class Codes: A61F 2002/30261 parallelepipedal
• CPC Class Codes: A61F 2002/30324 differing in thickness
• CPC Class Codes: A61F 2002/30326 differing in height or in length
• CPC Class Codes: A61F 2002/30354 Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
• CPC Class Codes: A61F 2002/3037 Translation along the common longitudinal axis, e.g. piston
• CPC Class Codes: A61F 2002/30387 Dovetail connection
• CPC Class Codes: A61F 2002/30405 made by screwing complementary threads machined on the parts themselves
• CPC Class Codes: A61F 2002/30411 : having two threaded end parts connected by a threaded central part with opposite threads at its opposite ends, i.e. for adjusting the distance between both end parts by rotating the central part
• CPC Class Codes: A61F 2002/30495 : using a locking ring
• CPC Class Codes: A61F 2002/30507 : using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30515 : using a locking wedge or block
• CPC Class Codes: A61F 2002/30538 : for adjusting angular orientation
• CPC Class Codes: A61F 2002/3055 : for adjusting length
• CPC Class Codes: A61F 2002/30556 : for adjusting thickness
• 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 2002/30594 : slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30616 : Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30624 : Hinged joint, e.g. with transverse axle restricting the movement
• 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 2002/30841 : Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• 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 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0033 : made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• 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 2230/0026 : trapezoidal
• CPC Class Codes: A61F 2230/0028 : Shapes in the form of latin or greek characters
• CPC Class Codes: A61F 2230/0069 : cylindrical
• CPC Class Codes: A61F 2230/0082 : parallelepipedal
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• CPC Class Codes: A61F 2250/0036 : differing in thickness
• CPC Class Codes: A61F 2250/0037 : differing in height or in length
• 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 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: Y10S 606/907 : Composed of particular material or coated
• CPC Class Codes: Y10S 606/909 : Bone

Abstract

Method and apparatus for promoting a spinal fusion between neighboring vertebrae. Apparatus may be located within the intervertebral disc space and preferably includes a pair of engaging plates for contacting the vertebrae. An alignment device may be used to alter the vertical distance between the engaging plates to customize the apparatus to fit a given patient. In one embodiment, the alignment device includes a pair of struts having a predetermined height and extending between the engaging plates from an anterior end to a posterior end of the apparatus. In another embodiment, the alignment device includes a rotatable connector and cam pins for adjusting the distance between the engaging plates. The alignment device is preferably adapted to vary the distance between the engaging plates such that the height of the apparatus proximate the anterior end is greater than that proximate the posterior end whereby the natural lordosis of the spine is maintained after the apparatus is installed. The apparatus may further include a load-sharing member to allow stress to be imparted to bone in the vicinity of the apparatus to promote bone growth in accordance with Wolff'"'"'s law.

Claims

1. A spinal implant for facilitating a fusion between neighboring vertebrae of a human spine, comprising:

a pair of engaging plates adapted to fit between and engage the vertebrae to maintain a disc space between the vertebrae during use; and

an alignment device configured to be positioned between the engaging plates, wherein the alignment device is adapted to separate anterior and posterior ends of the engaging plates during use such that a cavity is formed, and wherein the alignment device is configured to compress during use; and

wherein a height between outer surfaces of the pair of engaging plates proximate anterior ends of the engaging plates differs from a height between outer surfaces of the pair of engaging plates proximate posterior ends of the engaging plates when the alignment device is positioned between the engaging plates during use.

2. The spinal implant of claim 1, wherein differing height between outer surfaces of the pair of engaging. plates proximate anterior ends of the engaging plates and outer surfaces of the pair of engaging plates proximate posterior ends of the engaging plates is configured to align the pair of engaging plates such that the engaging plates have a lordotic alignment.

3. The spinal implant of claim 1, wherein the height between the outer surfaces of the pair of engaging plates proximate the anterior ends of the engaging plates is greater than the height between the outer surfaces of the pair of engaging plates proximate the posterior ends of the engaging plates when the alignment device is positioned between the engaging plates.

4. The spinal implant of claim 1, wherein a first engaging plate of the pair of engaging plates further comprises a protrusion, and wherein the protrusion is configured to extend into a vertebra of the neighboring vertebrae.

5. The spinal implant of claim 1, wherein a first engaging plate of the pair of engaging plates further comprises a tapered slot.

6. The spinal implant of claim 5, wherein the alignment device comprises a tapered surface configured to form a locking engagement with the tapered slot.

7. The spinal implant of claim 1, wherein a surface of a first engaging plate of the pair of engaging plates is substantially planar to inhibit subsidence of a vertebra of the neighboring vertebrae.

8. The spinal implant of claim 1, wherein a first engaging plate of the pair of engaging plates comprises a plurality of openings configured to allow bone growth to occur that fuses the implant and the neighboring vertebrae during use.

9. The spinal implant of claim 8, wherein an area of the plurality of openings is greater than about 50 percent of a total outer surface area of the first engaging plate.

10. The spinal implant of claim 1, wherein a first engaging plate of the pair of engaging plates comprises an opening configured to allow bone growth to occur that fuses the implant and the neighboring vertebrae.

11. The spinal implant of claim 1, wherein the alignment device comprises a first strut and a second strut.

12. The spinal implant of claim 1, further comprising a substantially planar retaining plate configured to be positioned between the engaging plates.

40. The spinal implant of claim 11, wherein the first strut and the second strut form locking engagements with the engaging plates.

13. A spinal implant for facilitating fusion of vertebrae, comprising:

a first engaging plate, the first engaging plate having a surface configured to couple to a first vertebra, wherein the first engaging plate comprises a plurality of openings configured to allow bone growth to occur that fuses the spinal implant and the first vertebrae;

an alignment device coupled to the first engaging plate, wherein the alignment device is configured to compress;

a second engaging plate, the second engaging plate having a surface configured to couple to a second vertebra, and wherein the second engaging plate is configured to be coupled to the alignment device; and

wherein the alignment device is adapted to separate anterior and posterior ends of the engaging plates during use, and wherein a height between the surface of the first engaging plate and the surface of the second engaging plate proximate an anterior end of the spinal implant differs from a height between the surface of the first engaging plate and the surface of the second engaging plate proximate a posterior end of the spinal implant.

14. The spinal implant of claim 13, wherein a difference in height between the surface of the first engaging plate and the surface of the second engaging plate proximate an anterior end of the spinal implant differs from a height between the surface of the first engaging plate and the surface of the second engaging plate proximate a posterior end of the spinal implant is adapted to provide lordotic adjustment.

15. The spinal implant of claim 13, wherein the height proximate the anterior end of the spinal implant is greater than the height proximate the posterior end of the spinal implant.

16. The spinal implant of claim 13, wherein the first engaging plate comprises a protrusion, and wherein the protrusion is configured to extend into a vertebra of the neighboring vertebrae.

17. The spinal implant of claim 13, wherein the first engaging plate further comprises a tapered slot.

18. The spinal implant of claim 17, wherein the alignment device comprises a tapered surface configured to form a locking engagement with the tapered slot.

19. The spinal implant of claim 13, wherein the surface of the first engaging plate is substantially planar to inhibit subsidence of the first vertebra.

20. The spinal implant of claim 13, wherein an area of the plurality of openings is greater than about 50 percent of a total surface area of the surface of the first engaging plate.

21. The spinal implant of claim 13, wherein the first engaging plate comprises an opening configured to allow bone growth to occur that fuses the spinal implant and first vertebra.

22. The spinal implant of claim 13, wherein the alignment device comprises a first strut and a second strut.

23. The spinal implant of claim 22, wherein the first strut forms a locking engagement with the first engaging plate during use.

24. The spinal implant of claim 22, wherein the second strut forms a locking engagement with the second engaging plate during use.

25. The spinal implant of claim 13, further comprising a substantially planar retaining plate configured to be positioned between the first engaging plate and the second engaging plate.

26. A fusion implant, comprising:

a pair of engaging plates adapted to fit between and engage a pair of vertebrae during use, wherein a first engaging plate comprises a plurality of openings configured to allow bone growth to occur that fuses the spinal implant and the first vertebrae; and

an alignment device configured to be positioned between the engaging plates, the alignment device adapted to separate anterior and posterior ends of the engaging plates during use, and wherein the alignment device is configured to compress.

27. The fusion implant of claim 26, wherein a height between outer surfaces of the pair of engaging plates proximate an anterior end of the fusion implant differs from a height between outer surfaces of the engaging plates proximate a posterior end of the fusion implant.

28. The fusion implant of claim 26, wherein a difference in the height between outer surfaces of the pair of engaging plates proximate an anterior end of the fusion implant and the height between outer surfaces of the engaging plates proximate a posterior end of the fusion implant provide lordotic adjustment.

29. The fusion implant of claim 27, wherein the height between outer surfaces of the pair of engaging plates proximate the anterior end is greater than the height between outer surfaces of the pair of engaging plates proximate the posterior end.

30. The fusion implant of claim 26, wherein a first engaging plate of the pair of engaging plates comprises a protrusion configured to couple the first engaging plate to a vertebra of the pair of vertebrae.

31. The fusion implant of claim 26, wherein a first engaging plate of the pair of engaging plates comprises an opening configured to allow bone growth that fuses the fusion implant and the vertebrae.

32. The fusion implant of claim 26, wherein an area of the openings is greater than about 50 percent of an upper surface area of the first engaging plate.

33. The fusion implant of claim 26, wherein a first engaging plate of the pair of engaging plates further comprises a tapered slot.

34. The fusion implant of claim 26, wherein the alignment device comprises a tapered surface configured to form a locking engagement with the tapered slot.

35. The fusion implant of claim 26, wherein a surface of a first engaging plate of the pair of engaging plates is substantially planar to inhibit subsidence of a vertebra of the neighboring vertebrae.

36. The fusion implant of claim 26, wherein the alignment device comprises a first strut and a second strut.

37. The fusion implant of claim 36, wherein a height of the first strut differs from a height of the second strut so that a height of a first side of the fusion implant differs from a height of a second side of the fusion implant when the fusion implant is assembled.

38. The fusion implant of claim 36, wherein the first strut and the second strut form locking engagements with the engaging plates.

39. The fusion implant of claim 26, further comprising a substantially planar retaining plate configured to be positioned between the engaging plates.