Intervertebral prosthetic disc with metallic core

A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

• a core having upper and lower curved surfaces, wherein each of the curved surfaces comprises a metal;
• upper and lower plates, each plate having an outer surface which engages a vertebra and a metallic inner curved surface which is shaped to slide and translate over one of the curved metallic surfaces of the core, wherein a center of rotation of the core is free to move relative to the upper and lower plates;
• and
• a peripheral restraining structure on at least one of the upper plate and the lower plate to hold the core against a curved surface of at least one of the plates during sliding movement of the plates over the core, wherein the restraining structure is adapted to contact an opposing plate to limit relative inclination of the plates during sliding movement of the plates over the core;
• wherein the peripheral restraining structure comprises:
• an annular structure extending over at least a portion of the periphery of the core, and
• a ring structure on one of the upper and lower plates,
• wherein the annular structure has a diameter sized to pass through the ring structure, and wherein the core is retained within the ring structure due to forces placed on the prosthetic disc via the adjacent vertebrae.

A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

• a core having upper and lower curved surfaces, wherein each of the curved surfaces comprises a metal;
• upper and lower plates, each plate having an outer surface which engages a vertebra and a metallic inner curved surface which is shaped to slide and translate over one of the curved metallic surfaces of the core, wherein a center of rotation of the core is free to move relative to the upper and lower plates;
• and
• a peripheral restraining structure on at least one of the upper plate and the lower plate to hold the core against a curved surface of at least one of the plates during sliding movement of the plates over the core, wherein the restraining structure is adapted to contact an opposing plate to limit relative inclination of the plates during sliding movement of the plates over the core;
• wherein the peripheral restraining structure comprises:
• a groove around a lateral edge of the core;
• and
• a ring structure on at least one of the upper and lower plates, said ring structure having a lip which engages the groove.

A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

• a metallic core having upper and lower curved metallic spherical surfaces;
• first and second metallic plates, each plate having an outer surface which engages a vertebra and an inner curved spherical surface which slides and translates over the curved spherical surface of the core, wherein a center of rotation of the core is free to move relative to the upper and lower metallic plates;
• and
• a peripheral restraining structure on at least one of the first and second plates to hold the core against a curved surface of at least one of the plates during sliding movement of the plates over the core, the peripheral restraining structure comprising a peripheral structure extending over at least a portion of the periphery of the core and a projecting structure on one of the first and second plates, which projecting structure engages and retains the peripheral structure,
• wherein the restraining structure is adapted to contact an opposing plate to limit relative inclination of the plates during sliding movement of the plates over the core.

A method for implanting an intervertebral disc prosthesis between adjacent vertebrae, the method comprising:

• implanting an upper metallic plate against a lower surface of an upper vertebral body;
• implanting a lower metallic plate against an upper surface of a lower vertebral body;
• disposing a core between the upper and lower plates, the core having curved surface comprising a metal, wherein disposing the core between the plates comprises passing an annular structure on the core through a ring structure on at least one of the plates, and wherein the annular structure has a diameter sized to pass through the ring structure to restrain peripheral movement of the core;
• and
• allowing the core to float with a mobile center of rotation between spherical cavities in each of the upper and lower plates.

A prosthetic disc for insertion between adjacent vertebrae, the prosthetic disc comprising:

• a core having upper and lower bearing surfaces, wherein each of the bearing surfaces comprises a metal;
• upper and lower plates, each plate having an outer surface which engages a vertebra and a metallic inner bearing surface which is shaped to slide and translate over one of the bearing metallic surfaces of the core, wherein a center of rotation of the core is free to move relative to the upper and lower plates;
• a peripheral restraining structure on at least one of the upper plate and the lower plate to hold the core against a bearing surface of at least one of the plates during sliding movement of the plates over the core, the peripheral restraining structure comprising an annular structure extending over at least a portion of the periphery of the core and a ring structure on one of the upper and lower plates, which ring structure engages and retains the annular structure,
• wherein the restraining structure is adapted to contact an opposing plate to limit relative inclination of the plates during sliding movement of the plates over the core.