Patent ID: 8100974

Claim:
An intervertebral disc prosthesis for replacing the natural disc of a human spine, comprising: a first end plate securable to a first vertebral body, the first end plate comprising a second bearing surface comprising a second straight section; a second end plate securable to a second vertebral body; and a nucleus positionable between the first and second end plates, the nucleus comprising a first bearing surface that articulates with the second bearing surface, the first bearing surface comprising a first straight section sloping between and contiguous with first and second convexly curved sections of the first bearing surface, the nucleus further comprising a planar third bearing surface opposite the first bearing surface; wherein the height of the nucleus between the first bearing surface and the third bearing surface at the junction of the first convexly curved section and the first straight section is greater than the height of the nucleus between the first bearing surface and the third bearing surface at the junction of the second convexly curved section and the first straight section; wherein the first straight section rests against the second straight section in a relative orientation between the first and second end plates that provides a preferred lordotic angle between the first and second vertebral bodies.