Prospective comparison of differences in bone mineral density adjacent to two biomechanically different types of cementless femoral stems.

We compared the differences in bone mineral density (BMD) adjacent to two biomechanically different cementless femoral stems (Spotorno and Evolution-K). Measurements were performed within the first week after surgery and 3, 6, 12, and 24 months postoperatively in a prospective study of 31 patients with 37 total hip arthroplasties. A modified Harris hip score and a visual analogue score for patient satisfaction was used to evaluate the clinical outcome. For both stems, dual X-ray absorptiometry measurements revealed a decrease in BMD in Gruen zone 7. Patients with a Spotorno stem also had a significant decrease in BMD in zones 1 and 2. In patients with an Evolution-K stem, there was a positive correlation between the clinical outcome and BMD in Gruen zones 1 and 4. Our data suggest that periprosthetic bone loss is equal to if not less pronounced adjacent to the Evolution-K stem as compared to the Spotorno stem.