Spinal prosthesis

An endoprosthesis comprising:

• a first articulating member formed with a generally concave articulating surface;
• and
• a second articulating member formed with a generally convex articulating surface which articulates with said concave articulating surface, said first and second articulating members each having a generally planar attachment surface for attachment to spine structure;
• wherein the first articulating member comprises a banana-shaped contour defined by a cutting surface that cuts through a portion of the first articulating member at a non-zero angle relative to its attachment surface, and the second articulating member comprises a banana-shaped contour defined by a cutting surface that cuts through a portion of the second articulating member at a non-zero angle relative to its attachment surface, wherein the generally concave articulating surface of said first articulation member is free of any bulbous articulation surfaces and the generally convex articulating surface of said second articulation member comprises a plurality of bulbous articulation surfaces which articulate with the generally concave articulating surface of said first articulation member, wherein the plurality of bulbous articulation surfaces share a common single articulating surface of said first articulation member.