[en] Full text: Factors which modify the known rapid peri-prosthetic bone loss following total hip arthroplasty (THA) are not well understood. We compared the magnitude of peri-prosthetic bone loss in 28 subjects who had undergone one of three different uncemented THA. Peri-prosthetic bone mineral density (BMD) was measured in the 7 Gruen Zones using DXA (Lunar DPXL, Madison Wl), in corresponding 'Gruen' sites in the contralateral non-operated proximal femur, as well as in the contralateral femoral neck. Measurements were obtained within 2 weeks of surgery and then at intervals for a mean interval of 102 weeks (range 71-179). Change in peri-prosthetic BMD was calculated compared to the initial post-operative BMD. There was a rapid loss of BMD post-operatively in Gruen Zones 1 and 7, but no significant loss in Gruen Zones 2-6. There was no significant change in peri-prosthetic BMD between 1 and 2 years post-operatively. The loss at 2 years was analysed using multiple regression analysis, which included weight, height, age, initial BMD and contralateral proximal femur BMD. None of these variables were predictors of peri-prosthetic bone loss. In Gruen Zone 1, there were significant differences in the loss of peri-prosthetic BMD between the different prosthetic types. There were no significant differences in bone loss with the different prosthetic types in Gruen Zones 2-7. In conclusion, the data suggest that prosthesis design has a greater effect on peri-prosthetic loss than other factors such as age, weight and initial bone mineral density