Frictional Properties of Artificial Hip Joints

Abstract

A new generation of hip replacements has been designed incorporating compliant layers to promote fluid film lubrication when the joints are implanted in patients. Tests in the Durham hip function simulator show that the friction in these joints is up to an order of magnitude lower than in currently used prostheses, and because this is due to complete separation of the rubbing surfaces, wear ought to be vastly reduced. Experiments have shown that the best results are achieved with compliant surfaces of hardness between 4 and 8 N/mm 2 . Such surfaces produce coefficients of friction of the order of 5 × 10 -3 .