A mobile device is adapted to at least partially replace the motion characteristics of a natural inter-vertebral disc positioned in a disc space. In an embodiment, a receptacle is coupled to the bearing surface. The receptacle is adapted to accept an implantable material without the removal of the bearing surface, wherein the implantable material contacts the abutment surface of each of the vertebral bodies adjacent to the disc space and leads to fusion and immobilization of two vertebral bodies adjacent the disc space.
