Patent ID: 8197547

Claim:
A spinal implant for replacing the natural nucleus of a disc comprising: a layered hydrogel material with at least one layer of the hydrogel material having powdered radiopaque material therein, the implant having an uppermost and lowermost surface and outer side surfaces which contact a disc annulus extending therebetween; and the powdered radiopaque material incorporated into the at least one layer of the hydrogel material in the form of at least one discrete planar layer, an upper and lower side of the at least one discrete planar layer including radiopaque powder contacts a layer of the hydrogel material not containing radiopaque powder, the at least one planar layer containing radiopaque powder extends the entire length of the layer to the outer side surfaces of the implant which contact the disc annulus, the powdered radiopaque material in the at least one hydrogel layer having radiopaque material are in a concentration of less than 0.5 gram of radiopaque powdered material to 1 gram of hydrogel and moves with the hydrogel body as the body changes dimensions and geometry under load, the upper and lowermost layers of the implant having no radiopaque powder.