Patent ID: 8313511

Claim:
A system for replacing at least a portion of a natural facet of a first vertebra, the system comprising: a first prosthesis comprising: a fixation element implantable in the first vertebra, the fixation element having a longitudinal axis, the fixation element comprising an implantable portion having a largest cross section perpendicular to the longitudinal axis; and a first superior articular surface shaped to articulate with a first inferior articular surface on a second vertebra; wherein the first superior articular surface is connectable to the fixation element such that the entire first superior articular surface is positioned medially of a projection of the largest cross section extending posteriorly along the longitudinal axis; wherein the first superior articular surface faces medially; wherein the first superior articular surface is offset from the longitudinal axis; wherein the first superior articular surface is not formed as a single piece with any inferior articular surface.