Abstract: An expandable intervertebral fusion implant includes a pair of semi-cylindrical shells having mating surfaces which resist shifting when the parts are assembled. The cylinder thus formed is placed on a special installation tool, which is first used to place the cylinder in the intervertebral space. Thereafter, the tool is actuated to spread the shells, and a spacer of appropriate size and taper is slid over the tool shaft, and in between the shells to maintain their spacing after the tool is removed. Having spacers of different height and taper allow the surgeon to adapt the implant to various situations.

Abstract: An expandable intervertebral implant includes two separate components having corrugated mating surfaces which resist compression and shifting when the parts are distracted by a special installation tool.

Abstract: An expandable intervertebral fusion implant includes a pair of semi-cylindrical shells having mating surfaces which resist shifting when the parts are assembled. The shells have pillars provided with teeth which permit the shells to be ratcheted outward after they have been placed between spinal elements. The pillars are curved, or extend from their shells at a non-perpendicular angle, so that the resulting implant is tapered, to accommodate non-parallel spinal element end plates and thus maintain proper spinal curvature.