comparison of different hip prosthesis shapes considering micro-level bone remodeling and stress-shielding criteria using three-dimensional design space topology optimization

since the late 1980s, computational analysis of total hip arthroplasty (tha) prosthesis components has been completed using macro-level bone remodeling algorithms. the utilization of macro-sized elements requires apparent bone densities to predict cancellous bone strength, thereby, preventing visualization and analysis of realistic trabecular architecture. in this study, we utilized a recently developed structural optimization algorithm, design space optimization (dso), to perform a micro-level three-dimensional finite element bone remodeling simulation on the human proximal femur pre- and post-tha. the computational simulation facilitated direct performance comparison between two commercially available prosthetic implant stems from zimmer inc.: the alloclassic and the mayo conservative. the novel micro-level approach allowed the unique ability to visualize the trabecular bone adaption post-operation and to quantify the changes in bone mineral content by region. stress-shielding and strain energy distribution were also quantified for the immediate post-operation and the stably fixated, post-remodeling conditions. stress-shielding was highest in the proximal region and remained unchanged post-remodeling; conversely, the mid and distal portions show large increases in stress, suggesting a distal shift in the loadpath. the mayo design conserves bone mass, while simultaneously reducing the incidence of stress-shielding compared to the alloclassic, revealing a key benefit of the distinctive geometry. several important factors for stable fixation, determined in clinical evaluations from the literature, were evident in both designs: high levels of proximal bone loss and distal bone densification. the results suggest this novel computational framework can be utilized for comparative hip prosthesis shape, uniquely considering the post-operation bone remodeling as a design criterion.