Patient specific analyses of the mechanical properties of bones become increasingly important for the management of patients with osteoporosis. The potential of Composite Finite Elements (CFEs), a novel FE technique, to assess the apparent stiffness of vertebral trabecular bone is investigated in this study.

Segmented volumes of cylindrical specimens of trabecular bone are compared to measured volumes. Elasticity under uniaxial loading conditions is simulated, apparent stiffnesses are compared to experimentally determined values. Computational efficiency is assessed and recommendations for simulation parameters are given.

Validating apparent stiffnesses results in concordance correlation coefficients 0.69 < r_c < 0.92 for resolutions finer than 168µm and an average error of 5.8% between experimental and numerical results at 24µm resolution.

To show the potential, the code was used to compute local, macroscopic stiffness tensors for the trabecular structure of a lumbar vertebra (L4).

The presented technique allows for computing stiffness using smooth FE meshes at resolutions that are well achievable in peripheral high resolution quantitative CTs. Therefore, CFEs could be a valuable tool for the patient-specific assessment of bone stiffness.