Patent ID: 8771356

Claim:
An intervertebral prosthetic disc for insertion between adjacent vertebrae, the disc comprising: upper and lower plates having outer surfaces locatable against the respective vertebrae and inner bearing surfaces; a core between the plates, the core having upper and lower curved surfaces complementary in shape to the inner bearing surfaces of the plates to allow the plates to slide over the core, wherein a lateral portion of the upper plate and a lateral portion of the lower plate contact one another during sliding movement of the plates over the core; an elongated rib formed on the core, wherein a central axis of the core does not pass through the rib; a channel formed on at least one of the inner bearing surfaces, the channel arranged to receive and cooperate with the rib, wherein the rib and channel are located between a central axis of the plates and an outer periphery thereof, and wherein the channel has a substantially rectangular cross section bottom wall and two opposite side walls extending substantially perpendicular to the bottom wall to retain the core between the plates when the plates slide over the core.