Patent ID: 8403989

Claim:
Intervertebral disc prosthesis for total replacement of an intervertebral disc within a lumbar or cervical spine, comprising a first sliding partner and a second sliding partner which are adapted to firmly assemble to either an upper or lower vertebral body, wherein said first and second sliding partners articulate with each other via a respective sliding area, and wherein a) the first sliding partner has a side for assembly with a vertebral body, and a convexity on the opposite side, wherein a radius of curvature of the convexity in a frontal view and a radius of curvature of the convexity in the transversal view are identical and the convexity results from rotation around a secant of a segment of a first circle, wherein the segment corresponds to an entirety of the convexity and has a height, wherein the height is less than the radius of the first circle, and a radius of curvature of the convexity corresponds in a sagittal view to a radius of curvature of a second circle, wherein the radius of the second circle corresponds to the height of the segment of the first circle, and the convexity is enclosed by a surrounding edge, and b) the second sliding partner has a concavity defined by a recess corresponding to the convexity of the first sliding partner and wherein the concavity is enclosed by a surrounding edges, and c) the surrounding edges of the first and second sliding partners, which extend between an outer rim and the convexity/concavity define, upon assembly, an outwardly opening aperture angle, with a. the aperture angles differing in a central frontal section compared to a central sagittal section due to different inclinations of the edges of the first and second sliding partners to allow a maximal possible area of contact of the edges during terminal motion of the first and second sliding partners, and b. the different inclinations of the edges of the first and second sliding partners seamlessly transiting, wherein, at equal aperture angles in a vertical section, on both sides of the sliding area an inclination of the edges is equal or different, and d) a motion angle is greater in a dorsoventral direction than in a laterolateral direction resulting from the different radii of curvature defined by the first and second circle, and e) a maximal possible motion of the sliding partners toward each other is determined by a. the radius of curvatures and height of the convexity of the first sliding partner relative to its surrounding edge, b. the design of the corresponding concavity of the second sliding partner relative to its surrounding edge and shape of the concavity with respect to the corresponding convexity, and c. the edges surrounding the convexity and the concavity running angular or horizontally.