[10-year follow-up of a homogeneous series of 467 total hip prostheses of the Charnley-Müller type. Study of 167 cases].

Four hundred and sixty-seven hips were operated upon by the authors between 1969 and 1974 using the Charnley-Müller prosthesis. 167 were reviewed with more than a ten-year follow-up. Eighty-one per cent were satisfactory after the initial procedure. In 56 cases an aseptic loosening had to be revised. At the femoral level, a varus position of the stem and the presence of cement between the calcar and the prosthesis appeared to be the responsible factors. At the acetabular level the causes of the loosening were an excess of cement, more than 10p. 100 uncovering of the cup by the acetabulum and, particularly, asymmetrical wear of the cup of more than one mm. A pathological study of 20 cases showed that particles of cement cause granulomata to develop all round the prosthesis. Polyethylene wear increases the frictional torque and produces micro-fractures of the cement at the bone-cement interface. It is concluded that the femoral stem should be as thick as possible and that the collar of the prosthesis is useless. Frictional torque should be as low as possible. The use of a metal mesh appears to be beneficial for the cementing of the acetabular cup.