Development of a Carbon‐Carbon Hip Prosthesis

Abstract

This article deals with the use of carbonfiber‐reinforced‐carbon materials for the manufacture of hip prosthesis stems. It considers the manufacturing process of carbon‐carbon (C—C) composites made of carbon fibers infiltrated either with dense pyroiytic carbon or sili‐ con carbide (SiC) through chemical vapor infiltration. The chemicophysical properties of these composites are examined according to their structures. The long‐term response (2 years) of cortical bone to various types of carbon‐carbon was evaluated mainly for bone contact and ingrowth. Carbon‐carbon coated with calcium phosphate was found to speed up the bone formation as compared to pyroiytic carbon or SiC coatings. The low modulus of elasticity of the C—C materials could be responsible for quicker bone contact as compared to a much stiffer material like sintered aluminum oxide. The biomechanical performance of C—C hip stems was assessed through (a) implantations into cadaver femurs, (b) fatigue testing, and (c) finite element analysis. These tests showed: (a) a better stress transfer as compared to a metal prosthesis having the same design, (b) no fatigue damage, (c) a computerized stem stress distribution in accordance with the fractures obtained during static mechanical testing.