Construction of finite element vertebral models from x-rays

Finite element modeling has proven to be an effective but expensive method to monitor vertebral body strength. This study proposes a method for updating existing finite element models (FEMs) using periodic sets of x-rays for longitudinal monitoring in osteoporotic patients. The present study uses a CT scan of a single human lumbar vertebra, numerically generated 2-D x-rays, with an introduced density error in the original dataset. Reconstruction was done using an algebraic reconstruction technique (ART) applied to the projections. The ART and the subsequent FEM were able to predict vertebral body stiffness to within 4%, providing the error introduced does not exceed 30%. Annual bone loss in osteoporotic patients averages approximately 2-3%, well within the range of effectiveness for the ART used.