Composite fixation of salvage prostheses for the hip and knee

A composite fixation method for a porous-coated modular segmental bone/joint prosthetic system was developed to improve fixation at revision surgery of the hip and knee after failure of the original implant with resulting massive bone loss. The porous coating is limited only to the segmental shoulder region of the prosthesis, while bone cement is used to provide initial implant stability. Autogenous bone grafts are applied over the porous-coated region to achieve extracortical bone bridging and ingrowth for long-term biologic fixation. Bench tests, theoretical analysis, and animal experiments were performed to validate this fixation concept. Clinical, roentgenographic, and functional results of revision patients using these prostheses and the underlying fixation principle are very encouraging. A number of limiting factors were identified and further improvements are being investigated to foster this concept as a viable salvage alternative.