A pilot finite element study of an osteoporotic L1-vertebra compared to one with normal T-score

In this paper, two patient-specific finite element (FE) models of both an L1 vertebra with a normal T-score and a mildly wedging, osteoporotic one were created and analysed under usual action. Utilising commercial software packages for image processing and FE analysis (FEA) along with in house computer codes for a posteriori assignment of material properties, in vivo high-resolution spiral computed tomography of the entire vertebrae and FEA were combined. Using the vertebra with a normal T-score as baseline it was found that the maximum value of the von Mises stress in the osteoporotic vertebra was 60% higher but still far below bone strength, while the maximum value of von Mises strain in the same vertebra was 148% higher than that of the vertebra with normal T-score. In the vertebra with normal T-score, 17% of its volume exhibited values of von Mises strain higher than the threshold of 4500 μstrains, referenced by Homminga et al. as a threshold of fracture risk, while in the osteoporotic one this percentage was raised up to 37%. The results suggested that the osteoporotic vertebra is susceptible to fracture due to raised strains and not stresses.