Predicting strengths of the femur and vertebra in patients with postmenopausal osteoporosis by a CT based finite element method - The predicted fracture load of the proximal femur is correlated with that of the lumber vertebra -

Introduction: Clinically available methods for estimating bone strength include bone densitometry techniques such as dual energy X-ray absorptiometry and peripheral quantitative computed tomography, and other diagnostic imaging procedures such as radiographic imaging. These techniques evaluate regional bone density and morphology, which are partly related to fracture risk, but are of limited value for quantifying structural strength [1]. We focused on a computed tomography-based finite element method (CT/FEM) to quantify structural strength, developing a nonlinear CT/FEM to achieve accurate assessment of strength in the proximal femur and lumbar vertebrae [2, 3]. In the clinical application of CT/FEM, strengths of the proximal femur and lumbar vertebrae are most frequently evaluated, because fracture risk in these regions is a matter of serious concern [4-8]. No other CT/finite element model that can be applied to both the proximal femur and the vertebrae has been reported. Therefore, data were unavailable regarding correlations between femoral and vertebral predicted fracture loads (PFLs). Examining strength at multiple sites in a number of patients using screening by CT/FEM may be time-consuming, because several hours is needed to analyze bone strength at each site. One of the purposes of the present study was thus to validate our model by comparing PFLs in our model to fracture loads derived from mechanical testing in previous studies. The other goal was to clarify whether either femoral or vertebral strength in postmenopausal osteoporosis patients is predictable by CT/FEM of only one of the two sites. We thus investigated whether femoral PFL could be utilized to estimate vertebral PFL.