Patent ID: 6997955

Claim:
An apparatus for replacing at least a portion of an intervertebral disc in a spinal column, comprising: a first member having a first vertebral contact surface for engagement with an endplate of a first vertebral bone in the spinal column, and having a first articulation surface that is defined by a plurality of concave arcs each having a respective radius of curvature about a corresponding axis substantially perpendicular to an anterior-posterior plane of the spinal column, and a plurality of convex arcs each having a respective radius of curvature about a corresponding axis substantially perpendicular to a lateral plane of the spinal column; and a second member having a second vertebral contact surface for engagement with an endplate of a second vertebral bone in the spinal column, and having a second articulation surface that is defined by a plurality of convex arcs each having a radius of curvature about a corresponding axis substantially perpendicular to the anterior-posterior plane of the spinal column, and a plurality of concave arcs each having a radius of curvature about a corresponding axis substantially perpendicular to the lateral plane of the spinal column, each of the plurality of concave arcs of the first articulation surface opposing one of the plurality of convex arcs of the second articulation surface and each of the concave arcs of the second articulation surface opposing one of the convex arcs of the first articulation surface, the radius of curvature of each of the concave arcs of the first articulation surface being greater than the radius of curvature of the opposing convex arc of the second articulation surface and the radius of curvature of each of the concave arcs of the second articulation surface being greater than the radius of curvature of the opposing convex arc of the first articulation surface, wherein: an intervertebral disc space is defined substantially between the first and second endplates of the first and second vertebral bones, and the radii of curvature of the first and second articulation surfaces are sized such that the first and second articulation surfaces engage one another when the first and second members are disposed in the intervertebral disc space to enable the first and second vertebral bones to articulate in at least one of flexion, extension and lateral bending, wherein the first member has a first center of rotation that remains below the articulation surfaces during flexion/extension in the anterior-posterior plane of the spinal column and a second center of rotation that remains above the articulation surfaces during lateral bending in the lateral plane of the spinal column.