A modified method for assigning material properties to FE models of bones

Abstract 

The aim of the present study is to compare the results from subject-specific finite element analysis (FEA) of a human femur to experimental measurements, using two different methods for assigning material properties to the FE models. A modified material mapping strategy allowing for spatial variation of material properties within the elements and Young's modulus surface corrections is presented and compared to a more conventional strategy, whereby constant material properties are assigned to each element. The accuracy of the superficial stress–strain predictions was evaluated against experimental results from 13 strain gauges and five different load cases. Both methods predicted stresses with acceptable accuracy (R²=0.92, root mean square error, RMSE<10%), with the conventional method performing slightly better. The modified method performed better in strain prediction (R²=0.85, RMSE=23% versus R²=0.79, RMSE=31%).

Keywords: Finite element analysis, Femur, Material properties, Computed tomography, Experimental validation, Human bones, Mesh convergence