An upper plate includes a depending truncated cone member that supports a ball. A lower plate supports an upstanding truncated cone member that supports a cup socket that the ball is press fitted into. The cup socket embraces the ball to a line above the middle diameter of the ball to prevent the ball from coming free of the socket in normal use. A number of wires form a repeating X pattern between the upper and lower plates about their perimeters and serve to restrain rotational motion. The upper plate includes upwardly projecting spikes and the lower plate includes downwardly projecting spikes. The upper and lower plates each include two anchoring brackets that project outwardly to lie adjacent to an upper and lower spinal disc, and that are fastened to the discs by bone screws. The spikes further anchor the vertebral body prosthesis in the adjacent spinal discs.