Expandable intervertebral fusion implant having improved stability

• US 6,332,895 B1
• Filed: 03/08/2000
• Issued: 12/25/2001
• Est. Priority Date: 03/08/2000
• Status: Expired due to Term

• Current Assignee: Zimmer Spine, Inc. (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Loubert Suddaby
• Inventors: Suddaby, Loubert
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): BARRETT, THOMAS C
• Application Number:
  US09/521,383
• Time in Patent Office: 657 Days
• Field of Search: 623/17.15, 623/17.11, 623/17.16
• 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 2/447 substantially parallelepipedal, e.g. having a rectangular or trapezoidal cross-section
• CPC Class Codes: A61F 2/4611 of spinal prostheses
• CPC Class Codes: A61F 2002/30487 Circumferential cooperating grooves and beads on cooperating lateral surfaces of a mainly longitudinal connection
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/3052 unrestrained in only one direction, e.g. moving unidirectionally
• CPC Class Codes: A61F 2002/30556 for adjusting thickness
• CPC Class Codes: A61F 2002/30593 hollow
• CPC Class Codes: A61F 2002/30785 parallel
• CPC Class Codes: A61F 2002/30789 perpendicular with respect to each other
• CPC Class Codes: A61F 2002/30841 Sharp anchoring protrusions for impaction into the bone, e.g. sharp pins, spikes
• CPC Class Codes: A61F 2002/30892 parallel
• CPC Class Codes: A61F 2002/30975 made of two halves
• 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 2002/4628 with linear motion along or rotating motion about an axis transverse to the instrument axis or to the implantation direction, e.g. clamping
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• 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 2310/00161 : Carbon; Graphite
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures

Abstract

An expandable intervertebral implant includes two separate shells having corrugated mating surfaces which resist compression and shifting when the parts are distracted by a special installation tool. The shells include two planar wings which provide a large bearing area against adjacent vertebral endplates to prevent the implant from sinking into cancellous bone.

Claims

1. An expandable intervertebral fusion implant comprising

a pair of shells adapted to be assembled to form a hollow body, each of said shells comprising an arcuate central portion, a pair of wings extending in opposite directions from opposite edges of said central portion, and a pair of parallel side walls extending in a common direction from respective outer edges of the wings, and

means on the shells for permitting unidirectional expansion of the implant from a retracted initial height to an expanded installed height,

wherein each of said wings has a width equal to at least 20% of that of the implant.

2. The invention of claim 1, wherein said means comprises interengaging teeth formed in said side walls.

3. The invention of claim 2, wherein said teeth are corrugations in said side walls, said side walls of one shell being substantially aligned with those of the other shell so that said teeth engage one another.

4. The invention of claim 3, wherein the teeth are raked in one direction so as to permit unidirectional expansion during placement of the implant, but to prevent unintended retraction after placement.

5. The invention of claim 4, wherein the skirts of one of said shells nest within those of the other of said shells, and the inner skirts each have an inwardly protruding element, whereby the inner skirts may be grasped and pulled toward one another in order to disengage the skirts when it is desired to remove the implant.