The invention relates to a prosthesis shaft for receiving an amputation stump of an extremity, comprising connecting means for a distal prosthesis device (2), wherein the prosthesis shaft (1) comprises at least one shell (11, 12), which has an arched, open cross-section and the shell ends of which in the applied state overlap each other at least partially, at least one tensioning means (14, 15) being disposed on the shell (11, 12), said means acting in the circumferential direction and tensioning the shell ends relative to each other, and the shell (11, 12) being made of a dimensionally stable plastic having regions with varying elasticity.

An intervertebral disc includes a superior endplate having an upper vertebral contacting surface and a lower bearing surface, wherein the upper vertebral contacting surface of the superior endplate has a central portion that is raised relative to a peripheral portion of the superior endplate, and wherein the lower bearing surface has a concavity disposed opposite the raised central portion. The disc includes an inferior endplate having a lower vertebral contacting surface and an upper surface, wherein the lower vertebral contacting surface of the inferior endplate has a central portion and wherein the upper bearing surface has a concavity disposed opposite the central portion. A core is positioned between the upper and inferior endplates, the core having upper and lower core bearing surfaces configured to mate with the bearing surfaces of the upper and inferior endplates. The upper vertebral contacting surface of the superior end plate has a different shape than the lower vertebral contacting surface of the inferior end plate.