We measured polyethylene wear in 231 porous-coated uncemented acetabular cups. We divided the hips into two groups according to the fixation of the femoral component, by cementing (n = 97) or press-fit (n = 134). Follow-up was from three to five years. The patients in two sub-groups were matched for weight, diagnosis, sex, age and length of follow-up. The linear wear rate of cups articulated with uncemented femoral components (0.22 mm/year) was significantly higher than the wear rate (0.15 mm/year) of cups articulated within cemented femoral components (p < 0.05). These results can be compared with previously reported wear rates of 0.08 mm/year for cemented all-polyethylene cups and 0.11 mm/year for cemented metal-backed cups. The higher wear rates of uncemented arthroplasties could jeopardize the long-term results of this type of hip replacement.

We examined radiographic polyethylene wear in 233 cemented total hip arthroplasties (201 patients) with either a metal-backed or a non-metal-backed acetabular cup. All patients had identical cemented one-piece titanium femoral stems with a femoral head diameter of 28 mm. The mean linear wear rate was 0.11 mm/yr in metal-backed sockets and 0.08 mm/yr in non-metal-backed sockets (p = 0.0002). The mean volumetric wear rate was 66.2 mm3/yr in the metal-backed sockets and 48.2 mm3/yr in the polyethylene sockets (p = 0.0002). The addition of metal backing to a cemented acetabular cup therefore resulted in a 37% increase in mean polyethylene wear rates which may partially explain the higher failure rate of cemented metal-backed cups. Linear regression analysis also implicated increased follow-up time (log), gross acetabular migration, metal backing and male gender in increasing polyethylene wear. We advocate the use of an all-polyethylene cup in cemented total hip arthroplasty. The increased polyethylene wear must also cause concern about the wear rate of uncemented metal-backed acetabular sockets.

We used the stainless steel cable grip system described by Dall and Miles in 1983 to fix trochanters in 40 hips after total arthroplasty with trochanteric osteotomy. The cable broke in 32.5% of the hips; the trochanter failed to unite in 37.5%. Significantly more cables broke when placed inside the femoral canal than when the cable was placed round the femoral shaft (58% as against 9.5%, difference p less than 0.01). The high incidence of breakage may have resulted from contact between the stainless steel cable and the titanium prosthesis, from the acute angulation, or because of the lower fatigue strength of stainless steel. Better results have been obtained using cables with a higher fatigue strength, passed outside the proximal femur.