Abstract: A prosthesis for the replacement of a spinal disk includes a first disk half and a second disk half. The first disk half includes a portion of a socket attached to a first plate. The second disk half includes a portion of a ball attached to a second plate. The socket includes a plurality of expansion slots which expand to allow the portion of a ball to be inserted into the socket and which then contract to retain the portion of a ball therein. A first hole is provided through the first plate, a second hole is provided through the socket, and a third hole is provided through the second plate which together form an opening through the disk. The opening is adapted to receive an insert to either medicate a pair of vertebrae or provide a barrier therein. The disk is fastened to the vertebrae by any preferred combination of pins, tabs, or a first annulus or second annulus, each of which extend from the disk.