An expandable spinal prosthesis is provided for insertion unilaterally into an annulotomy hole created laterally in a spinal disc between two abutting vertebrae. The prosthesis is composed of an elongated rod having first threading at one end and second threading at its other end. A first member is threaded on the threading at one end of the rod. A second member is threaded on the threading at the other end of the rod. The members are disengageably engaged for rotation together. The first member has a plurality of resilient bands extending longitudinally between the two members, which are dependent on the spacing between the two members. The first member and the elongated rod define engagements for coupling of drivers to relatively rotate the members and rod in one sense so that the two members will move toward each other to cause the resilient bands to bend outwardly to expand the prosthesis and in an opposite sense so that the two members will move apart to cause the resilient bands to become unbent and collapse the prosthesis. A method for implanting the prosthesis from one side only and a method for explanting the prosthesis from one side only.
