Preclinical computational simulation of fracture healing in children

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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.