Can 3D measurements obtained by lumbar DXA predict fractures in the dorsal vertebrae?

Objective: To assess the relation between three-dimensional (3D) measurements obtained by lumbar dual energy X-ray absorptiometry (DXA) and osteoporotic fractures in dorsal vertebrae. Material and methods: We analysed retrospectively 32 postmenopausal women, allocated to two groups: 16 women in the experimental group, who presented incident fractures of the dorsal vertebrae, and 16 women in the control group, who did not show any type of fracture. Measurements of the (aBMD) of vertebrae L1 through L4 were taken at the initial visit (i.e., prior to the fracture event) by lumbar dual-energy x-ray absorptiometries (DXA). 3D measurements obtained by DXA were evaluated using 3D modelling software (3D-SHAPER). Volumetric bone mineral density (vBMD) was calculated in the trabecular, cortical and integral bone. Cortical thickness and cortical surface BMD (sBMD) were also measured. Differences in measurements derived from the DXA between the experimental and control groups were assessed using an unpaired Student t-test. The odds ratio (OR) and the area under the receiver operating characteristic curve (AUC) were also determined. Results: In the present age-adjusted case-control study, no significant differences were found between the experimental and control groups in terms of weight (rho=0.44), height (rho=0.25) and aBMD (rho=0.11). However, significant differences (rho<0.05) were found in the integral and trabecular vBMD and in the cortical sBMD. Trabecular vBMD in the vertebral body was the measure that best discriminated between both groups, with an AUC of 0.733, compared to 0.682 of the aBMD. Conclusion: This study shows the ability of 3D models resultant from lumbar DXAs to discern between subjects with incident fractures in the dorsal vertebrae and control subjects. It is necessary to analyse larger cohorts to establish if these measurements could improve the prediction of fracture risk in clinical practice.