Proximal femoral bone mineral density after resurfacing total hip arthroplasty and after standard stem-type cementless total hip arthroplasty, both having similar neck preservation and the same articulation type.

To examine whether the Freeman cementless total hip arthroplasty (THA), with femoral neck preservation and a large metal head, can prevent stress shielding in a manner similar to resurfacing THA, we compared femoral bone mineral density (BMD) change in 10 resurfacing THA patients (group A) and 16 cementless THA patients (group B). Six and twelve months postoperatively, the mean BMD ratio in zone 1 was significantly higher in group A (97% +/- 10%, 95% +/- 11%) than in group B (79% +/- 15%, 77% +/- 20%); at 12 months, the mean BMD ratio in zone 7 was significantly higher in group A (104% +/- 15%) than in group B (84% +/- 21%). The cementless THA might not be a substitute for the resurfacing THA with respect to prevention of proximal femoral bone loss at the femoral neck, although it may prevent some major complications after resurfacing THA such as neck fracture and avascular necrosis of the femoral head.