Patent ID: 7771478

Claim:
An artificial intervertebral disc prosthesis having an anterior portion and a posterior portion, comprising: a first endplate having an upper surface and a lower relatively flat, uninterrupted surface; a second endplate having an upper surface and a lower surface, wherein an axis perpendicular to said first endplate and said second endplate is a longitudinal axis; a visco-elastic cushion interposed between and adhered to said first and second endplates, wherein said visco-elastic cushion is annular and comprises a cavity therein defining a visco-elastic cushion internal space bounded by a visco-elastic cushion internal surface substantially parallel to said longitudinal axis; a first projection extending from said lower surface of said first endplate terminating in a first distal end, said first projection having at least one side wall parallel to said visco-elastic cushion internal surface; a second projection extending from said upper surface of said second endplate and into said cavity and substantially aligned with said first projection, said second projection having at least one side wall parallel to said visco-elastic cushion internal surface, said second projection terminating at a second distal end to form, in an unloaded condition, a gap between said first distal end and said second distal end, said gap having a predetermined dimension; and wherein direct contact between first distal end of said first projection and said second distal end of said second projection limits said first endplate and said second endplate from moving relatively closer to one another.