Department of Mechanical and Materials Engineering, McLaughlin Hall 305, Queen's University, Kingston, Ontario, Canada K7L 3N6.
J Biomech. 2011 Jun 3;44(9):1722-8. doi: 10.1016/j.jbiomech.2011.03.038. Epub 2011 Apr 16.
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.
自 20 世纪 80 年代末以来，人们一直使用宏观骨重塑算法来完成全髋关节置换术 (THA) 假体组件的计算分析。使用宏观元素需要明显的骨密度来预测松质骨强度，从而防止真实小梁结构的可视化和分析。在这项研究中，我们利用了一种最近开发的结构优化算法，即设计空间优化 (DSO)，对 THA 前后的人体股骨近端进行微观三维有限元骨重塑模拟。该计算模拟便于对 Zimmer Inc. 提供的两种商业可用假体植入物进行直接性能比较：Alloclassic 和 Mayo 保守型。这种新颖的微观方法具有独特的能力，可以在手术后直接观察小梁骨适应，并按区域量化骨矿物质含量的变化。还对术后和稳定固定后的即刻、重塑后条件下的应力屏蔽和应变能分布进行了量化。应力屏蔽在近端区域最高，重塑后保持不变；相反，中远端区域的应力显著增加，表明负荷路径发生了远端转移。与 Alloclassic 相比，Mayo 设计可以保留骨量，同时减少应力屏蔽的发生，这揭示了其独特几何形状的一个关键优势。文献中从临床评估中确定的几个稳定固定的重要因素在两种设计中都很明显：近端骨大量丢失和远端骨密度增加。结果表明，这种新颖的计算框架可以用于比较髋关节假体形状，独特地考虑术后骨重塑作为设计标准。
