Age- and Sex-Specific Bone Structure Patterns Portend Bone Fragility in Radii and Tibiae in Relation to Osteodensitometry: A High-Resolution Peripheral Quantitative Computed Tomography Study in 385 Individuals

BACKGROUND: Age- and sex-specific 3D bone structure patterns in human radii and tibiae were investigated with respect to individuals' osteodensitometric status to unravel associations with site-specific fracture occurrences and underlying loading patterns.

METHODS: A sample of 385 patients (121 men and 264 women, age range: 23-91 years) were investigated. The patients were classified according to dual X-ray absorptiometry T-scores in three groups: control (n = 60), osteopenia (n = 160), and osteoporosis (n = 165). Bone architecture and geometry were assessed by high-resolution peripheral quantitative computed tomography of the cortical and trabecular compartments in distal radii and tibiae.

RESULTS: We found site-dependent age- and sex-related trends regarding bone architecture and geometry. Females displayed more pronounced age-related changes than males. Specifically, female radii showed both cortical and trabecular structural deterioration with aging, whereas the tibiae demonstrated exclusively cortical deterioration. The mean cortical perimeter revealed a significant age-related increase for both sexes even after adjusting for body height and weight, which suggests that periosteal expansion can be observed in both the tibia and also in the radius. Osteopenia and osteoporosis cases did not reveal higher cortical perimeters in comparison to controls.

CONCLUSIONS: The tomographic assessment of bone structure further clarifies the architectural basis for increased bone fragility at distal radii and tibiae with advanced age leading to fracture predilection in females. Our findings may represent a morphological link to epidemiological data on age-dependent fracture incidences. Our data support the presence of periosteal apposition at both skeletal sites despite different loading magnitudes, and challenges the view on periosteal expansion just as a compensatory mechanism to counterbalance bone loss.