Bone remodeling is different in metaphyseal and diaphyseal-fit uncemented hip stems

Femoral component stability in uncemented total hip arthroplasties depends on periprosthetic bone remodeling. Stem design is an important factor influencing bone remodeling, however the design that promotes the most bone remodeling is unclear. We examined metaphyseal and diaphyseal-fit stems to determine the effect of stem design on bone remodeling and stability. Twenty-three patients who had total hip arthroplasties (28 hips) with metaphyseal-fit stems were matched with 27 patients (32 hips) who had uncemented total hip arthroplasties with diaphyseal-fit stems. We assessed preoperative radiographs for canal fill, canal shape, and bone quality. We then assessed postoperative radiographs for periprosthetic bone remodeling including spot welds, cortical hypertrophy, and pedestal formation. Patients were examined clinically using a modified Harris hip score. Patients with metaphyseal stems had increased cortical hypertrophy 1 year postoperatively. However, there was no functional difference 2 years postoperatively. Both stem designs resulted in bone remodeling by 2 years postoperatively with similar clinical results.