Patent ID: 8377134

Claim:
A spinal disc implant, comprising: a first component comprising a first bearing surface and another surface for abutment to a vertebral body; and a second component comprising a second bearing surface and another surface for abutment to another vertebral body, one of said first and second bearing surfaces having an at least partially convex shape for articulation with the other of said first and second bearing surfaces having an at least partially concave shape; wherein at least one of said first and second bearing surfaces comprises a biocompatible ceramic material comprising doped silicon nitride having a flexural strength greater than about 700 Mega-Pascal (MPa) and a toughness greater than about 7 Mega-Pascal root meter (MPam 0.5), wherein at least one of said first and second bearing surfaces has a cross sectional shape defined by laterally spaced-apart, offset radii to include a generally flattened base segment interposed between a pair of curved sides, said bearing surfaces facing each other and extending generally on orthogonal axes relative to each other.