The Differences of Mechanical Properties of Femur Using Two Material Assignment Methods Based on CT Data

The mechanical properties of bone depend on the material assignment in mechanical finite element (FE) analysis. The aim of this study is to investigate the differences of mechanical properties of femur using two material assignment methods. The CT data of bone were used in both methods. The three-dimensional FE model was also established based on the femur CT data and the physiologic loads were applied to the FE model. The analysis results had shown that the mechanical properties of bone were significantly affected by the material assignment method. The mean HU, maximal von Mises stress, and mean strain energy density of the whole femur obtained with the sampling method was 22.0% larger, 42.9% and 72.7% smaller respectively than those obtained with the averaging method. The mean error percentage and correlation coefficient of HU were 36.2% and 0.86 respectively. So, the more accurate material assignment method is needed in further bone mechanical analysis.