Patent ID: 7537614

Claim:
An intervertebral implant for implantation between first and second vertebra, said implant comprising: a first end plate having an inner side and a first bone contacting surface, said first bone contacting surface being sized and configured to contact said first vertebra; a second end plate having an inner side and a second bone contacting surface, said second bone contacting surface being sized and configured to contact said second vertebra; a first member having a first end and a second end, said first end being sized and configured to contact said first end plate, said second end having a first saddle-shaped contact surface having a compound radius with at least two inflection points; and a second member having a first end and a second end, said first end being sized and configured to contact said second end plate, said second end having a second saddle-shaped contact surface for contacting said first saddle-shaped contact surface of said first member, said first and second saddle-shaped contact surfaces being sized and configured to permit said first member to articulate with respect to said second member along said first and second saddle-shaped contact surfaces; wherein said inner side of said first end plate includes a recess, the recess having a diameter and said first end of said first member has a diameter, the diameter of the recess being larger than the diameter of the first end of the first member so that said first member is receivable within said recess and moveable with respect to said first end plate even after implantation.