Patent ID: 8016888

Claim:
An intervertebral disc prosthesis for total replacement of an intervertebral disc within a lumbar or cervical spine, comprising an upper sliding partner adapted to firmly assemble to an upper vertebral body and a lower sliding partner adapted to firmly assemble to a lower vertebral body and a middle sliding partner located between the upper and lower sliding partners, wherein said sliding partners articulate with respect to each other and wherein a) the middle sliding partner has an upper and lower surface where the upper and lower surfaces each have a convexity, and b) the upper and lower sliding partner each has a concavity corresponding to the convexity of the upper and lower surfaces of the middle sliding partner, respectively, and the convexities of the upper and lower surfaces of the middle sliding partner and the concavities of the upper and lower sliding partners correlate to a cylinder along its longitudinal axis laterally from right to left, wherein the cylinder has a transversal ventrally directed arched curvature and the concavities of the upper and lower sliding partners are surrounded dorsally, ventrally and laterally, at both sides, by edges, c) wherein the edges extend between an outer rim and each concavity of the upper and lower sliding partners define an outwardly opening aperture angle upon assembly, and wherein a. no inclination of the upper and lower sliding partners towards each other in the lateral direction is possible, and b. a maximal possible motion of the sliding partners in dorsoventral direction is limited by a gap-closure of the outwardly opening aperture angle defined by the edges of the upper and lower sliding partners, and d) wherein rotation of the upper, middle and lower sliding partners towards each other is limited by a tolerance laterally right and left of the convexities and concavities.