Ball and dual socket joint

A spinal implant for placement between adjacent vertebrae for resilient axial support comprising a first plate and a second plate, said first plate having a planar vertebrae engaging side and a disk side, a first fastener on said planar side for engaging a vertebrae, a first interrupted skirt on said disk side extending approximately normal to said plate, said first interrupted skirt formed as opposing arcs, a first centrally located bore in said first plate, an slidable insert in said bore, a depression in said disk side of said insert centrally located between said opposing arcs, said second plate having a second planar vertebrae engaging side and a second disk side, a second fastener on said second planar side for engaging a vertebrae, a second interrupted skirt on said second disk side extending approximately normal to said second plate, said second skirt formed as opposing arcs, a second centrally located bore in said second plate, a second insert in said second bore, a second depression on said second disk side of said second plate centrally located between said opposing arcs, a second centrally located bore in said second plate, a second slidable insert in said second bore, a second depression in said disk side of said second insert centrally located between said opposing arcs, a universally movable ball inserted in said depression and said second depression, said ball, said depression and said second depression forming a bearing surface, a first cover plate mounted on said planar side of said first plate closing said bore and secured to said first plate, an O-ring spring for resilient compression between said insert and said cover plate, a second cover plate mounted on said planar side of said second plate closing said second bore and secured to said second plate, a second O-ring spring for resilient compression between said second insert and said second cover plate, said first interrupted skirt and said second interrupted skirt being concentric in a plane parallel with said first and second plates, said opposed arcs of said first interrupted skirt contacting said opposed arcs of said second interrupted skirt, said opposed arcs of said first interrupted skirt and said opposed arcs of said second interrupted skirt being concentric segments of a circle in a plane perpendicular to said first and second plates whereby said concentric segments of said first interrupted skirt contact said concentric segments of said second interrupted skirt to form an interlocked universal joint.

A method of assembly of a resiliently spinal implant comprising the steps of:

• a) providing a first plate, said first plate having a planar vertebrae engaging side and a disk side, a first interrupted skirt on said disk side extending approximately normal to said plate, said skirt formed as opposing arcs, a depression in said disk side of said plate centrally located between said opposing arcs,
• b) providing a second plate having a second planar vertebrae engaging side and a second disk side, a second interrupted skirt on said second disk side extending approximately normal to said second plate, said second skirt formed as opposing arcs, a second depression in said second disk side of said second plate centrally located between said opposing arcs,
• c) providing a ball and placing said ball in said depression,
• d) orienting said first plate and said second plate parallel with each other with said interrupted skirt of said first plate located between said opposing arcs of said second plate,
• e) moving said interrupted skirt of said first plate between said opposing arcs of said second plate and engaging said protrusion in said depression in axial alignment, and
• f) rotating said first plate and said second plate about the axis relative to each other until said interrupted skirt of said first plate contacts said opposing arcs of said second plate and said ball contacts said first plate and said second plate.

A method of manufacture of a spinal prosthesis comprising the steps of:

• a) forming a plate having a planar surface and a periphery in the general shape of the end wall of a vertebra;
• b) forming a central through bore in said plate;
• c) forming a depending skirt on one side of said plate between said through bore and said periphery;
• d) forming an elongated sleeve having a depression in one end;
• e) inserting said sleeve in said through bore with said skirt being concentric with said depression;
• f) inserting a cover plate in said through bore and bonding said cover plate to said planar surface.