Prosthetic intervertebral motion disc having dampening

Claim 1

An intervertebral motion disc comprising: a) a first prosthetic vertebral endplate comprising: i) an outer surface adapted to mate with a first vertebral body, ii) an inner surface having a first articulation surface, iii) a body portion connecting the inner and outer surfaces, b) a second prosthetic vertebral endplate comprising: i) an outer surface adapted to mate with a second vertebral body, and ii) an inner surface comprising a first articulation surface, and iii) a body portion connecting the inner and outer surfaces, and c) a laterally expandable core member comprising: a first articulation surface adapted for articulation with the first articulation surface of the first endplate, a second articulation surface adapted for articulation with the first articulation surface of the second endplate, wherein the core member is oriented therein to produce a first articulation interface between the first articulation surface of the first endplate and the first articulation surface of the core member, and a second articulation interface between the first articulation surface of the second endplate and the second articulation surface of the core member, and a height H between the outer surfaces of the prosthetic endplates, and wherein the laterally expandable core member expands laterally when the disc is subjected to axial load of about 750 pounds force (3.4 kN) to reduce the height of the device between 0.5 and 2.0 mm; and wherein the core member comprises: i) an annulus having an inner diameter, and ii) an inner articulation member comprising a plurality of articulation components, each articulation component comprising: an outer radius adapted to sear upon the inner diameter of the expandable annulus, a first articulation surface adapted for articulation with the first articulation surface of the first endplate, a second articulation surface adapted for articulation with the first articulation surface of the second endplate.