A prosthetic device adapted for fusing together adjoining vertebrae connected by tissue of a collapsed disc includes an inert generally rectangularly shaped support body adapted to be seated on hard end plates of vertebrae. The support body has top and bottom faces. A first peg is movably mounted in a first aperture located in the support body. The first aperture terminates at one of the top and bottom faces of the support body. The first peg projects away from the one of the top and bottom faces and into an adjacent first vertebra to secure the support body in place relative to the first vertebra. The support body is preferably hollow so as to allow the ingrowth of osseous tissue.