Anterior expandable spinal fusion cage system

• US 6,835,206 B2
• Filed: 05/13/2002
• Issued: 12/28/2004
• Est. Priority Date: 04/18/2000
• Status: Expired due to Fees

• Current Assignee: Warsaw Orthopedic Incorporated (Medtronic Plc)
• Original Assignee: Roger P. Jackson
• Inventors: Jackson, Roger P.
• Primary Examiner(s): Pellegrino, Brian E
• Application Number:
  US10/144,483
• Publication Number:
  US 20020138146A1
• Time in Patent Office: 960 Days
• Field of Search: 623/17.16, 623/17.11, 623/17.15, 623/908, 606/61
• US Class Current: 623/17.11
• 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 2/446 having a circular or elliptical cross-section substantially parallel to the axis of the spine, e.g. cylinders or frustocones
• CPC Class Codes: A61F 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• 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 2002/30507 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 2002/30517 using a locking plate
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• 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 2002/30604 modular
• CPC Class Codes: A61F 2002/30616 Sets comprising a plurality of prosthetic parts of different sizes or orientations
• CPC Class Codes: A61F 2002/30774 internally-threaded
• CPC Class Codes: A61F 2002/30779 : arcuate
• CPC Class Codes: A61F 2002/30785 : parallel
• CPC Class Codes: A61F 2002/30787 : inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/3079 : Stepped or enlarged apertures, e.g. having discrete diameter changes
• CPC Class Codes: A61F 2002/3085 : with a threaded, e.g. self-tapping, bone-engaging surface, e.g. external surface
• CPC Class Codes: A61F 2002/30904 : serrated profile, i.e. saw-toothed
• 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 2230/0013 : Horseshoe-shaped, e.g. crescent-shaped, C-shaped, U-shaped
• CPC Class Codes: A61F 2230/0017 : Angular shapes
• CPC Class Codes: A61F 2250/0006 : for adjusting angular orientation
• CPC Class Codes: A61F 2250/0009 : for adjusting thickness
• 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 2310/00131 : Tantalum or Ta-based alloys
• CPC Class Codes: Y10S 623/908 : Bone

Abstract

An apparatus and method for implanting an intervertebral cage containing a bone graft and fusing adjacent vertebrae together while maintaining or correcting the angular alignment and balance of the spine. An improved method for anterior interbody fusion to form a fused bone segment having a predetermined fixed angular orientation. The apparatus has a fusion cage and has a set of expansion caps that operably expand the cage from which one is selected to adjust the orientation between adjacent vertebrae with facing surfaces at a predetermined angle relative to each other. A connecting bolt is threaded to the rear of the cage unit to hold the cap in position.

Claims

1. An implant apparatus for positioning between adjacent vertebrae and comprising:

a) an anterior inserted fusion cage having a pair of legs interconnected at one end each by a posterior wall having a threaded bore, said legs having free ends opposite said wall, said cage being adapted for implanting between said adjacent vertebrae with outer surfaces of said legs engaging said vertebrae respectively;

each of said leg free ends including a stop;

b) an anterior expansion cap having a wedge member positioned between said free ends of said legs in such a manner that movement of said wedge member toward said wall urges said leg free ends apart;

said wedge member having a base sized and shaped to engage said stops of said legs, so as to provide a fixed degree of expansion for said cage when inserted therein; and

c) a fastener engaging said wedge member and extending between said wedge member and said wall;

said fastener having a shank that is posteriorly threaded so as to be threadedly received in a threaded bore in said wall;

said fastener being rotatable so as to advance in said bore to selectively urge said wedge member toward said wall.

2. The apparatus according to claim 1 wherein:

a) said expansion wedge member is selected from a set of a plurality of interchangeable wedge members; and

b) each wedge member being sized to form said legs into a different predetermined angle relative to each other.

3. The apparatus according to claim 1 wherein:

a) said cage member includes an interior chamber for receiving bone fragments; and

b) a plurality of radially positioned apertures for permitting bone fragments in said chamber to join and fuse with bone in the adjacent vertebrae.

4. The apparatus according to claim 1 wherein:

a) each of said legs free ends includes a neck portion a slopping forwardly and outwardly from and adjacent to a respective stop; and

b) said expansion cap includes a surface that slopes forwardly and outwardly from said base and is sized and shaped to mate with said neck portions for a given degree of expansion of said cage so that said cap supports said neck portions during use.

5. A method of stabilizing and promoting bone fusion between two adjacent vertebrae comprising the steps of:

a) providing an implant adapted to promote bone growth;

b) anteriorly implanting said implant between a pair of adjacent vertebrae;

c) providing a set of anteriorly positioned expansion caps with each cap of said set being adapted for expanding an anterior portion of upper and lower legs of said implant to a predetermined and different angle relative to each other cap;

d) inserting a first of said caps into said implant that produces a smaller comparative angle and checking the alignment of the spine;

e) removing the first cap when additional expansion is required and inserting a second cap;

f) continuing step e until alignment of the spine is in a desired configuration;

g) providing a fastener that extends between said cap and a posterior wall of said implant with said fastener being threadedly connected to said posterior wall; and

h) coupling said expansion cap with said implant and rotating said fastener so as to advance said fastener to expand an anterior end of said implant by operation of said expansion cap to position said legs in a predetermined angle relative to each other to produce a change in the alignment of the adjacent vertebrae.

6. An implant apparatus for positioning between adjacent vertebrae and comprising:

a) an anteriorly inserted fusion cage having a pair of legs interconnected at one end of each leg by a posterior wall, said legs having free ends opposite said wall with a stop associated with at least one free end, said cage being adapted for implanting between said adjacent vertebrae with outer surfaces of said legs engaging said vertebrae respectively; and

b) an expansion cap positioned between said free ends of said legs and including a stop mating surface thereon that mates with said stop upon insertion of said expansion cap into said cage so as to provide for a preselected degree of expansion of the anterior ends of said cage legs;

said expansion cap also including a fastener extending between said cap and said wall;

said fastener being threadably received in said wall and advanceable so as to urge said cap toward said wall, whereby said leg free ends are urged apart and the spacing between the top and bottom of said cage at an anterior end thereof is increased, said cap not expanding the size of said cage from side to side or at a posterior end thereof.