Muhib Farhan, Williams Kylie E, LaBelle Steven A, Lin Angela S P, Guldberg Robert E, Weiss Jeffrey A
Department of Biomedical Engineering, University of Utah, 36 S. Wasatch Drive, Rm. 3100, Salt Lake City, UT, 84112, USA; Scientific Computing and Imaging Institute, University of Utah, 72 S Central Campus Drive, Room 3750, Salt Lake City, UT, 84112, USA.
Phil and Penny Knight Campus for Accelerating Scientific Impact, Department of Bioengineering, University of Oregon, 1505 Franklin Boulevard, Eugene, OR, 97403, USA.
J Mech Behav Biomed Mater. 2025 Sep;169:107065. doi: 10.1016/j.jmbbm.2025.107065. Epub 2025 May 19.
Longitudinal estimation of local strain distributions within the regenerative niche of segmental femoral fractures is important for understanding mechanobiology principles for bone healing to design more effective rehabilitation regimens and mitigate nonunion complications. Finite element (FE) modeling is the standard for investigating these biomechanical parameters, yet most existing models lack clinical relevance due to their use of generic data and computational inefficiency. This study developed a subject-specific FE workflow aimed at accurate biomechanical predictions based on subject-specific data while addressing the limitations of previous approaches. For the experimental study, near-critical-sized segmental bone defects were created in the femurs of Wistar rats and stabilized with internal fixators before rehabilitation. Subject-specific geometries of the defect were generated from in vivo micro-CT scans, which were also used to assign material coefficients. Generalized geometries of the cortical and trabecular bone and fixator were integrated to increase computational efficiency. In addition, axial strain data from strain gauges on the fixators were used to define subject-specific boundary conditions, enabling a longitudinal study of the healing process. Sensitivity analyses revealed that incorporating subject-specific boundary conditions significantly enhanced model accuracy, a factor often overlooked in conventional approaches. The workflow was used to build six defect models to approximate compressive strains within the defect and the joint contact force. Strain distributions correlated with experimentally observed mineralization and better predicted functional bone bridging (union) compared to bone volume metrics. This efficient workflow facilitates the assessment of local biomechanics during bone healing and highlights their influence on adaptive regeneration. Further, the findings support the potential application of the subject-specific modeling workflow to guide clinical decision-making and improve therapeutic outcomes for treating bone fractures.
纵向评估股骨节段性骨折再生微环境内的局部应变分布对于理解骨愈合的力学生物学原理、设计更有效的康复方案以及减少骨不连并发症至关重要。有限元（FE）建模是研究这些生物力学参数的标准方法，但由于使用通用数据和计算效率低下，大多数现有模型缺乏临床相关性。本研究开发了一种针对个体的有限元工作流程，旨在基于个体特异性数据进行准确的生物力学预测，同时解决先前方法的局限性。在实验研究中，在Wistar大鼠的股骨中制造接近临界尺寸的节段性骨缺损，并用内固定器固定，然后进行康复治疗。从体内微型计算机断层扫描（micro-CT）生成缺损的个体特异性几何形状，这些扫描还用于指定材料系数。整合皮质骨、小梁骨和固定器的通用几何形状以提高计算效率。此外，使用固定器上应变片的轴向应变数据来定义个体特异性边界条件，从而能够对愈合过程进行纵向研究。敏感性分析表明，纳入个体特异性边界条件显著提高了模型准确性，这是传统方法中经常被忽视的一个因素。该工作流程用于构建六个缺损模型，以近似缺损内的压缩应变和关节接触力。与骨体积指标相比，应变分布与实验观察到的矿化相关，并且能更好地预测功能性骨桥接（愈合）。这种高效的工作流程有助于评估骨愈合过程中的局部生物力学，并突出它们对适应性再生的影响。此外，研究结果支持针对个体的建模工作流程在指导临床决策和改善骨折治疗效果方面的潜在应用。
