Distinct Cortical Microstructure in Postmenopausal Women with Distal Radius and Proximal Humerus Fractures.

Distal radius fractures and proximal humerus fractures are common fractures in postmenopausal women with osteoporosis. The question of whether bone microstructural deficits are reflected in specific changes in bone microstructure at peripheral skeletal sites has not yet been investigated. In this retrospective study, treatment-naïve postmenopausal women with distal radius fractures (DRF) or proximal humerus fractures (PHF) were included. Of more than 500 patients screened, 30 patients with DRF and 30 patients with PHF were included in the final analysis following propensity score matching. All participants underwent biochemical testing, dual-energy X-ray absorptiometry assessment, and bone microstructural evaluation by high-resolution peripheral quantitative computed tomography. After propensity score matching, both groups showed no significant differences in terms of age, weight, height, BMI, and lowest T-score (all p > 0.05). Mean age was 64.4 ± 10.7 years in the DRF group and 66.7 ± 9.0 years in the PHF group (p = 0.365). In both groups, the lowest mean T-score was - 2.9 (p = 0.539). Overall, both groups showed a reduction in total BMD and microarchitectural parameters compared to reference values at the distal radius and tibia. The PHF group exhibited significantly reduced bone geometry at the distal radius compared with the DRF group, including lower total area (p = 0.004), trabecular area (p = 0.021), and cortical area (p = 0.006), as well as reduced cortical thickness at both the distal radius (p = 0.031) and tibia (p = 0.024). PHF are characterized by reduced cortical thickness and unfavorable bone geometry, which is independent of areal bone mineral density.