A POROUS SURFACED DIAPHYSEAL PROSTHESIS FOR LONG BONES

Abstract

This chapter describes a project that is currently underway in which segmental femoral prostheses made of cast solid core zimalloy with a replamineform porous coating replicated from the microstructure of astreopora are being tested. This gives a surface with average pore diameters of 300–500 urn. For production of these prostheses in the cobalt, chrome, molybdenum alloy, the machined coral aragonite is sintered to form CaO by dissociation of C02 without destruction or degradation of the original coral microstructure. Based on the measurements of the length and outer and inner diameters of the femora of more than twenty 15 kg adult dogs, a cylindrical stemmed prosthesis designed to replace the majority of the femoral diaphysis was manufactured. In all but three animals, there was evidence of radiolucency around one of the stems. This study represents one of the longer clinical trials in which segmental porous coated prosthetic replacements for long bones under true physiologic weight bearing stresses have been carried out. The results recommend that replacement for long bones can be made that will become fixed via bony ingrowth and produce a satisfactory clinical result.