Articulated vertebral body spacer

Claim 1

An articulated vertebral body spacer comprising: upper and lower joint pieces to be inserted between vertebras, and at least one intermediate vertebral body interposed between said upper and lower joint pieces, said spacer defining first and rear sides, said lower joint piece including a convex portion formed on a central portion of an upper surface thereof and having a convex sliding contact surface, a stopper surface surrounding the convex portion, and a plurality of projections provided on a lower surface of the lower joint piece, said upper joint piece including a concave portion formed on a central portion of a lower surface thereof and having a concave sliding contact surface, an abutment surface which surrounds the concave portion, and a plurality of projections provided on an upper surface of the upper joint piece, and said intermediate vertebral body including a concave portion formed on a central portion of a lower surface thereof and having a concave sliding contact surface which is in sliding contact with the convex sliding contact surface of said lower joint piece, an abutment surface surrounding the concave portion and abutting against the stopper surface of said lower joint piece, a convex portion formed on a central portion of an upper surface of said intermediate vertebral body and having a convex surface which is in sliding contact with the concave sliding contact surface of said upper joint piece, and a stopper surface surrounding the convex portion and abutting against the abutment surface of said upper joint piece, wherein the stopper surface of said lower joint piece and the abutment surface of said intermediate vertebral body and between the abutment surface of said upper joint piece and the stopper surface of said intermediate vertebral body define gaps such that said gaps formed in said front side are larger than said gaps formed in said rear side.