HR-pQCT-based homogenised finite element models provide quantitative predictions of experimental vertebral body stiffness and strength with the same accuracy as μFE models

This study validated two different high-resolution peripheral quantitative computer tomography (HR-pQCT)-based finite element (FE) approaches, enhanced homogenised continuum-level (hFE) and micro-finite element (mu FE) models, by comparing them with compression test results of vertebral body sections. Thirty-five vertebral body sections were prepared by removing endplates and posterior elements, scanned with HR-pQCT and tested in compression up to failure. Linear hFE and mu FE models were created from segmented and grey-level CT images, and apparent model stiffness values were compared with experimental stiffness as well as strength results. Experimental and numerical apparent elastic properties based on grey-level/segmented CT images (N = 35) correlated well for mu FE (r(2) = 0.748/0.842) and hFE models (r(2) = 0.741/0.864). Vertebral section stiffness values from the linear mu FE/hFE models estimated experimental ultimate apparent strength very well (r(2) = 0.920/0.927). Calibrated hFE models were able to predict quantitatively apparent stiffness with the same accuracy as mu FE models. However, hFE models needed no back-calculation of a tissue modulus or any kind of fitting and were computationally much cheaper.