Lipphaus Andreas, Witzel Ulrich
Research Group of Biomechanics, Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Universitätstr. 150, Bochum, DE 44801, Germany.
Anat Rec (Hoboken). 2018 Dec;301(12):2112-2121. doi: 10.1002/ar.23893. Epub 2018 Nov 1.
Computational simulations of fracture healing are a valuable tool to improve fracture treatment and implants. Several finite-element models have been established to predict callus formation due to mechanobiological rules. This work provides a comprehensive simulation for virtual implantation through the combination of callus simulation and finite-element structural synthesis (FESS) of (re-)modeling during and after healing based on Pauwel's theory of histogenesis and Wolff's law. The simulation is based on a linear elastic material model and includes generation of fracture hematoma and initial mesenchymal stem cell concentration out of an unspecified solid, cell proliferation, migration, and differentiation due to mechanical stimuli and time-dependent axial loading. Three nondisplaced femoral shaft fractures with initial interfragmentary movement of 0.2, 0.6, and 1 mm and one fracture with 4 mm translation are modeled. The predictions of interfragmentary movement during fracture healing, healing success, and healing time agree with observed clinical outcome, animal models, and other numerical models. Initial interfragmentary movement between 0.2 and 1 mm leads to healing success, with the fastest healing occurring at 0.2 mm. The model of the dislocated fractures shows no further bending after remodeling and is loaded with physiological stress of -13 MPa. Ideal load-time graphs may give insight into the bone's ability to withstand loads as healing time progresses, and thus holds potential for applications in rehabilitation planning. Better knowledge of the forces present during fracture healing is needed to deploy simulations for surgical planning and manufacturing of patient individualized implants. Anat Rec, 301:2112-2121, 2018. © 2018 Wiley Periodicals, Inc.
骨折愈合的计算机模拟是改善骨折治疗和植入物的一项有价值的工具。已经建立了几个有限元模型来根据机械生物学规则预测骨痂形成。这项工作通过结合骨痂模拟和基于Pauwel组织发生理论和Wolff定律的愈合期间及愈合后（重新）建模的有限元结构合成（FESS），为虚拟植入提供了全面的模拟。该模拟基于线性弹性材料模型，包括骨折血肿的生成以及从未指定的固体中产生初始间充质干细胞浓度、细胞增殖、迁移以及由于机械刺激和随时间变化的轴向载荷导致的分化。对3例初始骨折块间移动分别为0.2、0.6和1 mm的无移位股骨干骨折以及1例有4 mm平移的骨折进行了建模。骨折愈合期间骨折块间移动、愈合成功情况和愈合时间的预测结果与观察到的临床结果、动物模型以及其他数值模型相符。初始骨折块间移动在0.2至1 mm之间会导致愈合成功，其中在0.2 mm时愈合最快。移位骨折模型在重塑后不再有进一步弯曲，并且承受-13 MPa的生理应力。理想的载荷-时间图可以深入了解随着愈合时间的推移骨骼承受载荷的能力，因此在康复计划中具有应用潜力。为了将模拟用于手术规划和患者个体化植入物的制造，需要更好地了解骨折愈合期间存在的力。《解剖学记录》，301:2112 - 2121，2018年。© 2018威利期刊公司。
