Patent ID: 8252058

Claim:
A spinal implant, comprising: a pair of implant components adapted for affixation respectively to adjacent vertebral structures and including inter-engageable articulatory bearing members; said bearing members including a convex articulatory surface and a concave articulatory surface both defined by a non-circular, generally elliptical profile shape in an anterior-posterior direction along a first plane, a non-circular, generally elliptical profile shape in a medial- lateral direction along a second plane, and a non-circular, generally elliptical profile shape when viewed on a third plane, the third plane being perpendicular to the first plane and second plane, wherein said convex articulatory surface and said concave articulatory surface are configured such that each of relative angular displacement, relative axial rotation, and simultaneous relative angular displacement and relative axial rotation of said articulatory surfaces results in a counteracting force which resists further relative angular displacement, relative axial rotation, or both, respectively, of the implant components and urges the articulatory surfaces back toward a neutral position.