Loading patent…
AssigneeHumboldt-Universitaet zu Berlin
InventorsKarin Buettner-Janz, Bernd Derr, Klaus-Peter Erkel, Hans-Joachim Helisch, Kurt Schellnack, Roland Schumann
Estimating the term…
An intervertebral disc endoprothesis comprises two symmetrical, concave end plates with an intermediate convex spacing piece. The end plates and the spacing piece have a plane guide rim. The end plates either have an edge shoulder or an annular groove for a toroid provided on the spacing piece. Alternatively, the intervertebral disc endoprothesis comprises two asymmetric end plates and a spacing piece, however, the two areas of movement are offset by 90.degree. in relation to each other and are partial surfaces of a cylinder. In the third variation, the two symmetrical end plates are convex, the spacing piece is cylindrical as well as concave at the two ends and has a durable cover.
Intervertebral disc endoprosthesis comprising first and second end plates and a spacing piece, said spacing piece having top and bottom surfaces, said first end plate having a first surface adjacent the top surface of said spacing piece and said second end plate having a second surface adjacent the bottom surface of said spacing piece, said top, bottom, first and second surfaces each being partial surfaces of a cylinder, said top surface and said first surface adjacent the top surface being congruent and defining a first cylinder-shaped movement surface and said bototm surface and said second surface adjacent the bototm surface being congruent and defining a second cylinder-shape movement surface, said first and second movement surfaces being rotationally-offset 90.degree. with respect to each other about a central axis passing through said spacing piece and said end plates.
Dependencies are inferred from the claim text.