The data from the musculoskeletal simulations were used in conjunction with the generated geometric models to compare the biomechanical scenarios using the software environment Abaqus (Dassault Systemes, Velizy-Villacoublay, France). To investigate the influence of the four different fibular configurations on the von Mises stress distribution of the intramedullary nail, the four models were simulated for high axial loading (midstance of the gait cycle) and high loading with non-axial forces (at the end of the terminal stance of the gait cycle). In this context, von Mises equivalent stress was chosen as scalar quantity representing a measure of local loading which can be interpreted a metric for the distribution of forces. In addition, for these two loading scenarios, the mechanical stimuli and the local micromechanics in the fracture gap of the tibia were investigated with respect to the mechanical conditions for fracture healing. The simulations also allow a comparison between partial and full weight-bearing by adjusting the boundary conditions in each case, which was herein performed for the two load cases of the FibOP model. In addition, the Anybody results were used to simulate complete gait cycles for the three different velocities of the patient on the treadmill. This allowed for an analysis of the fracture healing parameters over the complete gait cycles and, thus, the dynamic influence of gait velocity on the fracture gap and its micromechanics. For this purpose, the hydrostatic strain and the octahedral shear strain were computed for each mesh cell of the callus area, and classified into the different classes with respect to the values given previously by Shefelbine et al., 2005 (link) (Shefelbine et al., 2005 (link)). According to this classification, the volumes of the mesh cells were added to calculate the percentages of the total callus volume.
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