Abstract: An internal prosthesis for the partial or total replacement of a bone such as a femur has a rod-like bridging member which spans the major part of the gap between two joints. An abutment member is mounted at either end of the bridging member and each of the abutment members engages a bone adjacent that which is to be partially or totally replaced. Each of the abutment members may constitute part of an artificial joint. The bridging member and/or the abutment members are adjustable so that the prosthesis may be fitted to the particular physical characteristics of a patient. To this end, the bridging member may be composed of sections for the purpose of length adjustment. The abutment members may be rotatable relative to one another and to the bridging member about the longitudinal axis of the latter in order that the abutment members may assume a relative angular orientation best suited to the characteristics of the patient.