Surface replacement of the hip with the Tharies system. Two to five-year results.

The two to five-year clinical results of 200 Tharies surface replacements were comparable to those of conventional total hip replacement. The incidence of systemic complications, dislocations, and sepsis was low. There were ten cases of aseptic and one case of septic loosening. Nine minor secondary procedures were required in the series. In two patients the femoral component shifted asymptomatically into varus angulation, but no revision was needed. Fifty-five per cent of patients for whom serial radiographs were available had some progression of radiolucency, but there was poor correlation between the width of the zone and loosening until the patient became symptomatic. Improved techniques of preparation of the interface and of delivery, compression, and containment of the cement have improved the postoperative radiographic appearance of the more recently treated patients.