A spinal prosthesis includes first and second spinal attachment members attachable to first and second spinal structures, respectively. One or more adjustable stopper elements are assembled on one or both of the first and second spinal attachment members. The one or more adjustable stopper elements are formed with a bore through which either of the first and second spinal attachment members is slidable. The one or more adjustable stopper elements include structure that limits relative movement between the one or more adjustable stopper elements and the spinal attachment member on which the one or more adjustable stopper elements are mounted.