The purpose of this study was to evaluate the long-term results of cemented Muller prostheses using a 32 mm metal femoralhead.

We reviewed 43 (31 patients) of 76 (55 patients) consecutive THAs, which were performed between April 1978and September 1985. The average duration of follow-up was 148 months (range, 65-279 months). The average age at the time of indexoperation was 44.4 years. Preoperative diagnosis was osteonecrosis in 31 hips, posttraumatic osteonecrosis in 8 hips, osteoarthritis in 2hips, and rheumatoid arthritis in 2 hips. We assessed cases clinically by Harris hip scores and radiographically by loosening and osteolysis, and measured polyethylene wear by the Livermore method. Kaplan-Meier analysis was used to evaluate survivability. We analyzedthe relationship and the statistical difference between wear and age, weight, height, body mass index, diagnosis, polyethylenethickness, and cup inclination (Pearson correlation's analysis, Student t-test, ANOVA test). The p-value was set p<0.05.

The mean preoperative Harris hip score was 38.7 points, which improved to 86 points at a postoperative one year, and then decreased to 54.5 points at the latest follow-up. There were total 34 (79%) loosenings and osteolysis was present in 36 hips (84%). The average linear and volumetric wear rate were 0.14 mm/yr and 123 mm3/yr respectively, and a 10-year cumulative survival rate was 72%(67-80%, 95% confidence interval). Revision surgery was performed in 27 hips (63%) and the mean time from index operation to revision was 129 months. The linear and volumetric wear rates increase significantly as body mass index increased (p<0.05). There was asignificant relationship between polyethylene wear and the nontraumatic osteonecrosis group, and with the abnormal cup inclination group (<35 ° or >50 °) (p<0.05).

Cemented Muller THAs using a 32 mm metal head showed poor survivability after an average follow-up of 12 years, due to the high incidence of loosening, the high rate of polyethylene wear and osteolysis. These results seem to be due to the relatively largenumber of operation for osteonecrosis of the femoral head in young patients and shortcomings of curved femoral stem design and the first generation cementing technique.