Prediction of mechanical properties of cortical bone by quantitative computed tomography

Abstract 

The relevance of Finite-Element models for hip fracture prediction should be increased by the recent subject-specific methods based on computed tomography (CT-scan), regarding the geometry as well as the material properties. The present study focused on the prediction of subject-specific mechanical parameters of cortical bone (Young's modulus and ultimate strength) from the bone density measured by CT. A total of 46 compression and 46 tension samples from 13 donors (mean age±S.D.: 81.8±12.7 years) were harvested in the femoral mid-diaphysis and tested until failure. The Young's modulus and ultimate strength were linearly correlated with the bone density measured by CT, for tension as well as compression (0.43<r²<0.72, p<0.001). To take into account the remaining uncertainties on the mechanical properties prediction, the standard error of the estimate (S.E.E.) was evaluated in each case (2694–2788MPa for Young's modulus, 13–16MPa for ultimate strength). The significant correlations obtained in the present study and the quantification of the errors will be helpful for the assessment of the cortical mechanical properties from the CT-scan data in order to create subject-specific FE-models.

Keywords: Biomechanics, Cortical bone, Mechanical properties, Young's modulus, Computed tomography, Density, Human femur