Vertebral trabecular microarchitecture changes in the normally ageing population

Trabecular microarchitecture is a primary contributor to bone strength. The aim of this study was to characterize the trabecular microarchitecture of the normally ageing population by sex using multi-detector computed tomography (MDCT) scans.

We retrospectively searched the medical records of patients receiving routine MDCT scans with the spine protocol between 2014 and 2021. The final random cohort without systemic diseases, consisting of 360 participants (180 women) aged 50 to 80 years and matching sex, was divided into six groups (each group containing a 5-year interval). The L1 vertebra was used for trabecular microarchitecture analysis with European Conformity (CE)-marked software.

We observed differences by sex in trabecular thickness (Tb.Th) mean, trabecular separation (Tb.Sp) mean, and trabecular number (Tb.N) in two age groups (55-59 and 75-80 years). We found that, in both sexes of older adults, Tb.N was significantly negatively correlated with age. From age 60 to 69 years, bone volume to total volume (BV/TV) percentage, Tb.N, fractal dimensions [two-dimensional fractal dimension (D2D) and three-dimensional fractal dimension (D3D)] gradually decreased, whereas Tb.Th mean, and Tb.Sp mean increased. Remarkably, the rates of decline in Tb.N and D2D were greater compared to the others, and the rates of increase in Tb.Sp mean were greater compared to the others. D3D was the most sensitive trabecular microarchitecture parameter, consistently detecting sex-related differences across age group of 50 to 69 years.

This study demonstrates that vertebral trabecular microarchitecture undergoes significant age- and sex-specific changes that are detectable using clinical high-resolution computed tomography (CT). The identification of critical remodelling phases-particularly in men between 55-59 and 75-80 years-and the consistent sensitivity of D3D to sex differences highlight the value of CT-based architectural assessment. These findings suggest that routine abdominal CT, when enhanced with advanced reconstruction techniques, may serve as a useful tool for early detection of bone fragility and support individualized strategies for fracture risk assessment.