DXA-based 3D finite element models predict hip fractures better than areal BMD in elderly women

Bone strength is a major contributor to fracture risk. Areal bone mineral density (aBMD) obtained from dual-energy X-ray absorptiometry (DXA) is used as a surrogate for bone strength in fracture risk prediction. 3D finite element (FE) models predict bone strength better than aBMD but need 3D computed tomography and are not automated. We have earlier developed a method to automatically reconstruct the 3D hip anatomy from a 2D hip DXA image, followed by subject-specific FE-based prediction of proximal femoral strength. In this study, we evaluate the method's ability to predict incident hip fractures in a population-based cohort of women (OSTPRE). We used a sub-cohort including 46 cases with a hip fracture (<10 years from DXA scan) and 2 healthy controls to each hip fracture case, matched by age, height, and body mass index. We automatically reconstructed the 3D hip anatomy and predicted proximal femoral strength using FE analysis for all the subjects of the sub-cohort. The FE-predicted proximal femoral strength was a significantly better predictor of incident hip fractures than aBMD (difference in area under the receiver operating characteristics curve, ΔAUROC = 0.10). This is the first time that 3D FE models obtained from a 2D hip DXA scan outperform aBMD in predicting incident hip fractures in a population-based prospectively followed cohort of women. Our approach provided an improved fracture risk prediction in a clinically feasible manner (only one single DXA image is needed) and without additional costs compared to the current clinical approach.