Devices and methods for implanting fusion cages

• US 6,719,760 B2
• Filed: 06/17/2003
• Issued: 04/13/2004
• Est. Priority Date: 08/26/1999
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: SDGI Holdings Incorporated (Medtronic Plc)
• Inventors: White, John L., Berry, Bret M., Ray, Eddie F. III, Dorchak, John D.
• Primary Examiner(s): O'Connor, Cary E.
• Assistant Examiner(s): STOKES, CANDICE CAPRI
• Application Number:
  US10/463,299
• Publication Number:
  US 20030212404A1
• Time in Patent Office: 301 Days
• Field of Search: 606/57, 606/90, 606/60, 606/61
• US Class Current: 606/90
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 17/1659 Surgical rasps, files, planes, or scrapers
• CPC Class Codes: A61B 17/1671 for the spine
• CPC Class Codes: A61B 17/1757 for the spine
• CPC Class Codes: A61B 17/32002 with continuously rotating, oscillating or reciprocating cutting instruments
• 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 2/442 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/2817 Bone stimulation by chemical reactions or by osteogenic or biological products for enhancing ossification, e.g. by bone morphogenetic or morphogenic proteins [BMP] or by transforming growth factors [TGF]
• 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 2002/3021 frustoconical
• CPC Class Codes: A61F 2002/30217 hollow cones, e.g. tubular-like cones
• 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 2002/30774 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 2002/30789 : perpendicular with respect to each other
• CPC Class Codes: A61F 2002/3082 : Grooves
• CPC Class Codes: A61F 2002/30858 : Threads interrupted by grooves or sidewalls, e.g. flat sidewalls
• CPC Class Codes: A61F 2002/30861 : having threads of increasing or decreasing height
• CPC Class Codes: A61F 2002/30873 : Threadings machined on non-cylindrical external surfaces
• 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 2002/4627 : 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 2220/0025 : Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2230/0067 : conical

Abstract

Methods and instrumentation for spinal interbody fusion are disclosed. The instruments and methods are particularly adapted for interbody fusion in an unreamed disc space. One instrument is a distractor assembly including a first distractor and a second distractor configured to be inserted in side-by-side relation in the disc space. Fusion cages adapted for insertion into an unreamed disc space are provided to enhance load distribution between adjacent vertebral bodies and lateral stability of the spinal column. The fusion cages may be inserted after distracting the disc space with the distractor assembly. Instruments for preparing the disc space through the inserted fusion cages or for use with the distractor assembly are also provided.

Claims

1. A method for distracting a spinal disc space, the method comprising:

inserting a first distractor in the spinal disc space;

inserting a second distractor in the spinal disc space; and

maintaining a spacing between the first distractor and the second distractor during insertion with a guide surface medially offset from one of the first and second distractors.

2. The method of claim 1, wherein the first and second distractors have a central axis extending therethrough when in side-by side relation and the guide surface is offset from the central axis.

3. The method of claim 1, wherein inserting the first distractor and inserting the second distractor distracts the disc space to a desired disc space height.

4. The method of claim 1, wherein one of the first and second distractors includes a medially extending portion extending therealong that includes the guide surface.

5. The method of claim 1, further comprising anchoring at least one of the first and second distractors to an adjacent vertebrae.

6. The method of claim 1, further comprising:

removing one of the first and second distractors; and

guiding insertion of at least one implant into a distraction channel formed in the spinal disc space after withdrawal of the one of the first and second distractors.

7. The method of claim 1, wherein:

the first distractor includes a body portion having a length extending between a leading end and a trailing end, the first distractor including a connecting portion extending from the trailing end of the body portion; and

the second distractor includes a body portion having a length extending between a leading end and a trailing end, the second distractor including a connecting portion extending from the trailing end of the body portion, the connecting portion of the second distractor including a guide member extending proximally therefrom.

8. The method of claim 7, wherein the guide member includes the guide surface.

9. The method of claim 1, wherein the guide surface includes a concave shape.

10. A method for distracting a spinal disc space, comprising:

providing a first distractor including a guide surface extending therealong;

providing a second distractor;

assembling the first and second distractors with the second distractor abutting the guide surface to form a distractor assembly, the distractor assembly having a central axis with the guide surface of the first distractor offset from the central axis; and

inserting the first and second distractors into the spinal disc space.

11. The method of claim 10, wherein the first distractor comprises a medially extending portion including the guide surface.

12. The method of claim 10, further including preparing a starter channel at the anterior lip of the spinal disc space adjacent the distractor insertion locations.

13. The method of claim 10, further comprising removing the second distractor from the spinal disc space to form a distraction channel in the spinal disc space at the second distractor location.

14. The method of claim 13, further comprising:

providing a fusion cage having a trailing end and a leading end; and

inserting the fusion cage in the spinal disc space while maintaining lateral positioning of the fusion cage in the spinal disc space with the guide surface.

15. The method of claim 14, further comprising further comprising removing the first distractor from the spinal disc space to form a distraction channel in the spinal disc space at the first distractor location.

16. The method of claim 15, further comprising:

providing a second fusion cage having a leading end and a trailing end; and

inserting the second fusion cage in the spinal disc space in the distraction channel of the removed first distractor.

17. The method of claim 16, wherein the inserted fusion cages each include at least one opening providing communication between a hollow interior of the cage and the adjacent vertebral endplates and further comprising removing bony material from the adjacent vertebral endplate through the opening.

18. The method of claim 17, further comprising placing bone growth material in the hollow interior of the fusion cages.

19. A distractor assembly for performing a surgical procedure in a spinal disc space, the distractor assembly having a central axis extending therethrough, said distractor assembly comprising:

first distractor insertable in the spinal disc space at a first implant location offset to a first side of the central axis; and

a second distractor positionable adjacent said first distractor and insertable in the spinal disc space at a second implant location offset to a second side of the central axis, at least one of said first and second distractors including a medially extending portion to separate said first and second distractors from one another on opposite sides of the central axis.

20. The distractor assembly of claim 19, wherein said medially extending portion includes a guide surface offset a distance from the central axis toward the other of said first and second distractors.

21. The distractor assembly of claim 19, wherein said first distractor includes a first shaft and a first body portion at a distal end of said first shaft and said second distractor includes a second shaft and a second body portion at a distal end of said second shaft.

22. The distractor assembly of claim 21, wherein said first body portion includes a first width at a trailing end thereof and said second body portion includes a second width at a trailing end thereof, said first width being greater than said second width.

23. The distractor assembly of claim 21, wherein each of said first and second body portions includes a tapered leading end to facilitate insertion of said body portion into the spinal disc space.

24. The distractor assembly of claim 21, wherein each of said first and second body portions includes upper and lower surfaces, said upper and lower surfaces being roughened therealong to contact adjacent vertebral endplates.

25. The distractor assembly of claim 21, wherein said medially extending portion extends from one of said first and second shafts.

26. The distractor assembly of claim 25, wherein said first and second shafts are removably attached to said body portions.

27. The distractor assembly of claim 21, wherein each of said first and second body portions includes a lateral spacer extending therefrom opposite the other of said first and second body portions, said lateral spacers each including a width that tapers from a maximum width at a trailing end of said body portion thereof to a minimum width at a distal end of said body portion thereof.

28. The distractor assembly of claim 27, wherein said medially extending portion extends from one of said first and second body portions.

29. The distractor assembly of claim 21, wherein said medially extending portion extends from one of said first and second body portions.

30. The distractor assembly of claim 29, wherein each of said first and second body portions includes a length extending between a leading end and a trailing end, said each of said first and second body portions further including a height along said length sufficient to distract the spinal disc space to a desired disc space height.

31. The distractor assembly of claim 30, wherein said medially extending portion includes a height less than the height of said first and second body portions of said one of said first and second distractors.

32. The distractor assembly of claim 31, wherein said medially extending portion extends from said trailing end of said one of said first and second body portions to a position proximate said leading end of said one of said first and second body portions.