A Biomechanical Comparison of Epiphyseal Versus Metaphyseal Fixed Bone-Conserving Hip Arthroplasty

Background: The Birmingham Mid-Head Resection (BMHR) is a bone-conserving, short-stem alternative to hip resurfacing for patients with abnormal femoral head anatomy. Methods: The current study examines whether a bone-preserving femoral component that is fixed into the femoral neck metaphysis provides a mechanical advantage in terms of resisting femoral neck fracture in comparison with a conventional hip resurfacing implant in a human cadaveric femoral model. Results: Femora with a BMHR femoral component failed at an average of 23% less load than those prepared with a conventional hip resurfacing component (mean and standard deviation, 5434 ± 2297 compared with 7012 ± 2619 N; p < 0.001). Conclusions: An uncemented, metaphyseal fixed, bone-conserving femoral implant does not provide superior mechanical strength or increased resistance to femoral neck fracture in comparison with a conventional hip resurfacing arthroplasty.