Vertebral fractures and trabecular bone loss are hallmarks of osteoporosis. However, 80% of fractures are non-vertebral and 70% of all bone loss is cortical and is produced by intracortical remodeling. The resulting cortical porosity increases bone fragility exponentially. Denosumab, a fully human anti-RANKL antibody, reduces the rate of bone remodeling more than alendronate. The aim of this study was to quantify the effects of denosumab and alendronate on cortical and trabecular bone. Postmenopausal women, mean age 61years (range 50 to 70), were randomized double blind to placebo (n=82), alendronate 70mg weekly (n=82), or denosumab 60mg every 6months (n=83) for 12months. Porosity of the compact-appearing cortex (CC), outer and inner cortical transitional zones (OTZ, ITZ), and trabecular bone volume/total volume (BV/TV) of distal radius were quantified in vivo from high-resolution peripheral quantitative computed tomography scans. Denosumab reduced remodeling more rapidly and completely than alendronate, reduced porosity of the three cortical regions at 6months, more so by 12months relative to baseline and controls, and 1.5- to 2-fold more so than alendronate. The respective changes at 12months were [mean (95% CI)]; CC: -1.26% (-1.61, -0.91) versus -0.48% (-0.96, 0.00), p=0.012; OTZ: -1.97% (-2.37, -1.56) versus -0.81% (-1.45, -0.17), p=0.003; and ITZ: -1.17% (-1.38, -0.97) versus -0.78% (-1.04, -0.52), p=0.021. Alendronate reduced porosity of the three cortical regions at 6months relative to baseline and controls but further decreased porosity of only the ITZ at 12months. By 12months, CC porosity was no different than baseline or controls, OTZ porosity was reduced only relative to baseline, not controls, while ITZ porosity was reduced relative to baseline and 6months, but not controls. Each treatment increased trabecular BV/TV volume similarly: 0.25% (0.19, 0.30) versus 0.19% (0.13, 0.30), p=0.208. The greater reduction in cortical porosity by denosumab may be due to greater inhibition of intracortical remodeling. Head to head studies are needed to determine whether differences in porosity result in differing fracture outcomes.

Gender-affirming hormone therapy aligns physical characteristics with an individual's gender identity, but sex hormones regulate bone remodeling and influence bone morphology. We hypothesized that trans men receiving testosterone have compromised bone morphology because of suppression of ovarian estradiol production, whereas trans women receiving estradiol, with or without anti-androgen therapy, have preserved bone microarchitecture. We compared distal radial and tibial microarchitecture using high-resolution peripheral quantitative computed tomography images in a cross-sectional study of 41 trans men with 71 cis female controls, and 40 trans women with 51 cis male controls. Between-group differences were expressed as standardized deviations (SD) from the mean in age-matched cisgender controls with 98% confidence intervals adjusted for cross-sectional area (CSA) and multiple comparisons. Relative to cis women, trans men had 0.63 SD higher total volumetric bone mineral density (vBMD; both p = 0.01). Cortical vBMD and cortical porosity did not differ, but cortices were 1.11 SD thicker (p < 0.01). Trabeculae were 0.38 SD thicker (p = 0.05) but otherwise no different. Compared with cis men, trans women had 0.68 SD lower total vBMD (p = 0.01). Cortical vBMD was 0.70 SD lower (p < 0.01), cortical thickness was 0.51 SD lower (p = 0.04), and cortical porosity was 0.70 SD higher (p < 0.01). Trabecular bone volume (BV/TV) was 0.77 SD lower (p < 0.01), with 0.57 SD fewer (p < 0.01) and 0.30 SD thicker trabeculae (p = 0.02). There was 0.56 SD greater trabecular separation (p = 0.01). Findings at the distal radius were similar. Contrary to each hypothesis, bone microarchitecture was not compromised in trans men, perhaps because aromatization of administered testosterone prevented bone loss. Trans women had deteriorated bone microarchitecture either because of deficits in microstructure before treatment or because the estradiol dosage was insufficient to offset reduced aromatizable testosterone. Prospective studies are needed to confirm these findings. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

The aim of this study was to explore the reliability and precision of body compartment measures, in particular visceral adipose tissue, in weight stable adults over a range of BMIs using GE-Lunar iDXA. Weight-stable participants aged 18–65 years had a total body composition scan on GE-Lunar iDXA either on three separate occasions over a three month period (n = 51), or on a single occasion for duplicate scans with repositioning (n = 30). The coefficient of variation (CV%) and least significant change (LSC) of body compartments were calculated. The CV was higher for all measures over three months (range 0.8–5.9%) compared with same-day precision-scans (all < 2%). The CV for visceral adipose tissue (VAT) was considerably higher than all other body compartments (42.2% three months, 16.2% same day scanning). To accurately measure VAT mass using the GE iDXA it is recommended that participants have a BMI ≥ 25 kg/m², or VAT mass > 500 g. Changes observed in VAT mass levels below 500 g should be interpreted with caution due to lack of precision and reliability. All other compartmental measures demonstrated good reliability, with less than 6% variation over three months.