INTERVERTEBRAL PROSTHETIC DISC
A prosthetic disc for insertion between adjacent vertebrae includes upper and lower plates, a core disposed between the plates, and at least one projection extending from at least one of the upper and lower curved surfaces of the core into at least one recess of one of the inner surfaces of the plates. The recess is oversize with respect to the projection to allow sliding movement of the plate over the core while retaining the core between the plates during such sliding movement. The projection(s) may include a rod extending through an axial hole in the core, multiple surface features of the core, or the like.
1 . 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, and lateral portions;
a core between the plates, the core having upper and lower surfaces complementary in shape to the inner bearing surfaces of the plates to allow the plates to slide over the core;
formations on at least one of the bearing surfaces of the plates and on the core which cooperate with one another to retain the core between the plates when the plates slide over the core, such formations including a rib on at least one of the plates and a channel in the core, wherein the rib is located within the channel to hold the core captive between the plates when the plates slide over the core, and wherein the rib and channel are located between a central axis of the plates and an outer periphery thereof.