Peri-prosthetic bone adaptation has usually been predicted using subject-specific finite element analysis in combination with remodelling algorithms and assuming isotropic bone material property. The objective of the study is to develop an orthotropic bone remodelling algorithm for evaluation of peri-prosthetic bone adaptation in the uncemented implanted femur. The simulations considered loading conditions from a variety of daily activities. The orthotropic algorithm was tested on 2D and 3D models of the intact femur for verification of predicted results. The predicted orthotropic directionality, based on principal stress directions, was in agreement with the trabecular orientation in a micro-CT data of proximal femur. The validity of the proposed strain-based algorithm was assessed by comparing the predicted results of the orthotropic model with those of the strain-energy-density-based isotropic formulation. Despite agreement in cortical densities \((R = 0.71)\), the isotropic remodelling algorithm tends to predict relatively higher values around the distal tip of the implant as compared to the orthotropic model. Both formulations predicted 4–8% bone resorption in the proximal femur. A linear regression analysis revealed a significant correlation \((R = 0.99)\) between the stresses and strains on the cortex of the proximal femur, predicted by the isotropic and orthotropic formulations. Despite reasonable agreement in peri-prosthetic bone density distributions, the quantitative differences with isotropic model predictions highlight the combined influences of bone orthotropy and mechanical stimulus in the adaptation process.

通常使用特定主题的有限元分析结合重塑算法并假设各向同性骨材料特性来预测假体周围骨适应。该研究的目的是开发一种正交各向异性骨重建算法，用于评估未骨水泥植入股骨的假体周围骨适应。模拟考虑了来自各种日常活动的负载条件。正交各向异性算法在完整股骨的 2D 和 3D 模型上进行了测试，以验证预测结果。基于主应力方向的预测正交各向异性方向与股骨近端显微 CT 数据中的小梁方向一致。通过比较正交各向异性模型的预测结果与基于应变能量密度的各向同性公式的预测结果，评估了所提出的基于应变的算法的有效性。尽管皮层密度一致\((R = 0.71)\)，与正交各向异性模型相比，各向同性重塑算法倾向于预测种植体远端周围的值相对较高。两种制剂均预测股骨近端有 4-8% 的骨吸收。线性回归分析揭示了由各向同性和正交各向异性公式预测的股骨近端皮质上的应力和应变之间的显着相关性\((R = 0.99)\)。尽管假体周围骨密度分布存在合理的一致性，但各向同性模型预测的定量差异突出了骨正交性和机械刺激在适应过程中的综合影响。