Bone structural parameters as measured by 3D-DXA are superior in Black women and demonstrate unique associations with prior fracture versus White women.

Purpose: Black patients fracture less than White patients at any given BMD. This may be related to superior bone structure; however, bone structure is challenging to measure in clinical practice. Advances in 3D modeling have allowed for the measurement of trabecular and cortical parameters from DXA. This technology, known as 3D-DXA, may provide a way to assess hitherto unexplained differences in bone structure between Black and White patients.

Methods: This is a secondary analysis of 775 women (368 Black, 407 White) previously recruited from an osteoporosis clinic. All women had undergone DXA and VFA, and 3D-DXA was run retrospectively on the proximal femur BMD scan. Participants were classified as having a prior fracture if there was a fracture on VFA or a self-reported history of fragility fracture.

Results: Black women had generally superior 3D-DXA parameters, with the largest differences in cortical thickness of the femoral neck (FN) and buckling ratio of the FN. There were substantial differences in associations between fracture and 3D-DXA parameters in Black as compared to White women. After adjusting for age, glucocorticoids, and areal BMD T-score, cortical thickness of the FN was significantly associated with prior fracture (OR 1.4 per standard deviation decline, 95% CI 1.0-1.9, p=0.04) in Black but not White women.

Conclusion: 3D-DXA parameters were superior in Black than White women, and cortical thickness of the femoral neck was associated with fractures only in Black women. 3D-DXA may improve fracture risk assessment in Black patients.