Preclinical computational simulation of fracture healing in children

计算模拟可用于(儿科)骨科，以模拟生物结构和骨代谢的功能适应。有限元方法可以用来计算数值机械应力。这些模拟能够模拟继发性骨折愈合与骨痂发展、骨重建和生长的关系。现有的算法考虑了细胞分化、细胞外基质的产生和去除、血管形成、细胞迁移和增殖、动态负荷、生长因子、患者特定的模型、脱位骨折和虚拟植入。这些模拟可以预测治疗方案的愈合结果，并用于优化植入物和治疗：一旦模拟结果与患者病例或动物研究高度一致，这些模拟就可以用于测试和改进植入物和治疗，在临床使用或动物试验之前具有成本和时间效益。虽然有许多成人骨折愈合的模拟，但目前还没有儿童骨折愈合的模拟。尽管儿童骨折的愈合过程与成人相同，而且愈合速度往往很快，而且没有并发症，但需要解决特定的生长情况：对齐不良可以更容易地调整，但也可能由于过度生长或生长停滞而发生。另一个并发症是愈合过程中的继发性骨折。在儿科骨固定中，不常用的种植体通过统计学手段加剧了种植体的改进。愈合模拟过程中的虚拟强度测量可以帮助减少重复断裂，并为植入物设计提供需求。有限元软件通过扩散-反应模型计算外力和激素浓度引起的机械应力。该算法定义了结果单元进程。通过这种形态，可以将患者的外部负荷和肌肉力量以及内分泌特征结合在一起。为此，结合了用于生长、重塑和修复模拟的算法。模拟了一根骨干和一根骨骺骨折，并与临床愈合结果进行了比较。

Computational simulations can be used in (pediatric) orthopedics to model functional adaption of biological structures and bone metabolism. Finite element method can calculate numerically mechanical stresses. The simulations are able to model secondary fracture healing with callus development, bone remodeling, and growth. Existing algorithms consider cell differentiation, production and removal of extracellular matrix, vascularisation, cell migration and proliferation, dynamic loads, growth factors, patient specific models, dislocated fractures, and virtual implantation. These simulations can predict healing outcome of treatment options and be used to optimize implants and treatments: Once simulations are validated by high accordance of simulation results with patient cases or animal studies these simulations can be used to test and improve implants and treatments cost- and time-effective previous to clinical use or animal testing. While there are many simulations of fracture healing in adults, at the moment no simulation of fracture healing in children is available. Although pediatric fracture healing proceeds in the same stages as in adults and healing is often fast and without complication, the specific growth situation needs to be addressed: Malalignment can be adjusted easier, but also occur due to overgrowth or growth arrest. Another complication is secondary fracture during healing. Infrequently used implants for pediatric osteosynthesis exacerbate implant improvement by statistical means. Virtual strength measurements during healing simulations can help to reduce refractures and provide needs for implant design. The finite element software calculates mechanical stresses due to external forces and hormone concentration by diffusion-reaction models. The algorithm defines the resulting cell processes. By this morphology, external loads and muscle forces, and endocrine characteristics of a patient can be incorporated. For this purpose algorithms for growth, remodeling, and healing simulation are combined. A shaft and an epiphyseal fracture are simulated and compared to clinical healing outcome.