Periprosthetic Bone Mineral Density Changes After Implantation of a Curved Bone Preserving Hip Stem Compared to a Standard Length Straight Stem: 5-Yr Results of a Prospective, Randomized DXA-Analysis

140 patients scheduled for total hip arthroplasty were randomized to receive either a short femoral stem tor conventional-length straight femoral stem. The primary interest of this study was change in periprosthetic bone mineral density, and whether BMD loss was significantly smaller in the short stem group. Patients were assessed over 5-year follow-up. Results demonstrated significantly smaller changes in BMD after 5 years in areas of interest corresponding to Gruen zones 3 and 5 in the short stem group compared to the straight stem group, while differences between groups in other regions were non-significant. In particular, the periprosthetic zone with the greatest BMD loss in both groups was that corresponding to Gruen zone 7, and demonstrated an estimated 12.5-16% reduction from baseline after 5 years.