The influence of the bone mineral density (BMD) on the mechanical behavior of bones can be examined using computer tomography (CT) data and finite element (FE) simulations, because the BMD correlates with the Hounsfield scale (HU) of the CT data. Therefor the material mapping strategy, which is required to assign the HU values to the FE mesh, is of crucial importance. In this study a nodal mapping strategy was analyzed concerning its sensitivity towards FE mesh parameters and an averaging of HU values from the area around the respective nodes. The FE simulation is based on CT data of a human proximal femur. Once the bone shape was reconstructed, the resulting model was meshed with quadratic tetrahedral elements in ABAQUS/CAE and all nodes were assigned an HU value from the CT data by using the respective node coordinates. In this process, the mesh density, the threshold, which could be used to exclude connective tissue and fat from the material mapping process, the considered volume around the nodes and the method of averaging were varied. The material assignment was realized by an HU value dependent, linear elastic material definition. The femur model was clamped at the level of the isthmus and a displacement of 0.5 mm was applied at the femoral head. The evaluation was based on the resulting reaction forces.Introduction
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