Patent ID: 7682393

Claim:
A system for maintaining a nucleus prosthesis within an annulus having a defect, the system comprising: a first blocking plate for preventing migration of the nucleus prosthesis through the defect in the annulus, the first blocking plate sized to be positioned substantially within an intervertebral disc space defined by a pair of adjacent vertebral endplates, the first blocking plate having a height less than a distance between the adjacent vertebral endplates but greater than half of the distance between the adjacent vertebral endplates such that the first blocking plate prevents migration of the nucleus prosthesis through the defect in the annulus without limiting the natural flexion and extension of the adjacent vertebral endplates, the first blocking plate comprising: a substantially planar retaining face, a substantially planar mounting face extending substantially perpendicular to the retaining face for engagement with a single one of the adjacent vertebral endplates, and an aperture extending through the first blocking plate and through a portion of the mounting face, wherein the first blocking plate comprises a rigid, non-resorbable biocompatible material; a fastener sized and shaped for extending through the aperture in the first blocking plate and into the single one of the adjacent vertebral endplates to securely attach the first blocking plate to the single one of the adjacent vertebral endplates; and an annular plug sized and shaped for positioning between the nucleus prosthesis and the first blocking plate at least partially within the defect in the annulus.