Lateral areal bone mineral density (BMD) can identify microstructural heterogeneities that are independent of age and has advantages over anterior-posterior dual-energy X-ray absorptiometry (DXA) scanning for fracture risk assessment, according to study results published in Bone.
Bone densitometry is limited in its ability to identify elderly individuals who are at an immediate risk for experiencing a fracture, and there is a need for better diagnostic tools. The current study was conducted in an effort to improve clinical assessment of vertebral fracture risk, and researchers sought to determine how the DXA-based 2-dimensional parameter Trabecular Bone Score (TBS) relates to subregional variability in 3-dimensional trabecular microstructure in both young and elderly females vs areal BMD. Thoracic vertebrae were obtained from 29 women (11 women aged 32 ± 6 years and 18 women aged 71 ± 5 years) post mortem. DXA-scanned anterior-posterior and lateral projection measurements were performed for the ex vivo vertebrae, and vertebral areal BMD and TBS were calculated.
TBS and areal BMD were also measured for horizontal subregions (superior, midhorizontal, and inferior) and vertical subregions (anterior, midvertical, and posterior) and related to 3-dimensional microstructure indices. These included bone volume/tissue volume, trabecular number, and trabecular thickness.
There were significant differences observed for trabecular parameters between the 2 cohorts. For the horizontal subregions, bone volume/tissue volume was lower superiorly, trabecular thickness was higher midhorizontally compared with inferior and superior subregions, and trabecular number was lowest midhorizontally and highest in the inferior subregion. The researchers also found that areal BMD varied between horizontal subregions, whereas TBS differed only in lateral projections among the older group, with significantly higher values seen for the inferior subregion vs other subregions. In vertical subregions, bone volume/tissue volume, trabecular number, and areal BMD were highest posteriorly in both groups. TBS did not differ between vertical subregions.
“[O]ur findings confirm the capacity for improved fracture risk assessment using lateral scans and additionally highlight the potential for assessing the susceptibility to specific fracture types by subregional evaluation of [areal BMD], less so for TBS,” the researchers concluded.
Vom Scheidt A, Seifert EFG, Pokrant C, et al. Subregional areal bone mineral density (aBMD) is a better predictor of heterogeneity in trabecular microstructure of vertebrae in young and aged women than subregional trabecular bone score (TBS). Bone. 2019;122:156-165.