title: Comparison of different hip prosthesis shapes considering micro-level bone remodeling and stress-shielding criteria using three-dimensional design space topology optimization.
abstract: 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.
authors.affiliation: Department of Mechanical and Materials Engineering, McLaughlin Hall 305, Queen's University, Kingston, Ontario, Canada K7L 3N6.
authors.forename: Christopher
authors.initials: C
authors.lastname: Boyle
authors.forename: Il Yong
authors.initials: IY
authors.lastname: Kim
mesh_terms: D000465:Algorithms; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D015519:Bone Density; D016723:Bone Remodeling; D001862:Bone Resorption; D003198:Computer Simulation; D005269:Femur / Q000473:pathology / Q000503:physiopathology; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D016348:Osseointegration; D011312:Pressure; D019736:Prostheses and Implants; D011474:Prosthesis Design; D014057:Tomography, X-Ray Computed / Q000379:methods