Differences in stability and bone remodeling between a customized uncemented hydroxyapatite coated and a standard cemented femoral stem

Thirty-seven patients (38 hips) with non-inflammatory arthritis were randomized to the uncemented custom made Unique® stem or the Elite Plus stem inserted with cement. The patients have been followed clinically as well as with radiostereometry (RSA) and Dual-energy X-ray Absorptiometry (DXA) for 2 years. After 2 years the RSA result showed minimal translation and rotation for the Unique® stem while the Elite Plus rotated slightly (mean 1.05°) into retroversion. Compared to previous studies the Elite Plus was as stable as the Charnley prosthesis. The DXA results showed a significantly higher proximal and total (10% for the Unique versus 5% for Elite) bone loss for the Unique® stem compared to the Elite Plus. Thus the optimal proximal press-fit of the custom made stem did secure a stable fixation, but did not decrease the proximal bone loss.