UNLABELLED: Brief rationale: To assess bone dimensions in the radius over 7 years. MAIN RESULT: Cross-sectional area did not change significantly, but endosteal circumference increased, leading to decreased cortical thickness. Significance of the paper: Bone mineral density loss is associated with a decrease in cortical thickness in the forearm. PURPOSE: To assess site-specific volumetric bone and muscle differences in women with and without forearm fracture in a longitudinal study. METHODS: One hundred four postmenopausal women with a forearm fracture and 99 age-matched controls were included and underwent peripheral quantitative computed tomography (pQCT) in the forearm at a mean age of 65 (range 44-88) years and were invited for a reassessment after mean 7 (6-11) years, at which 80 and 79 women took part, respectively. Three cases had movement artifacts on pQCT
77 cases and 79 controls were finally analysed. RESULTS: Twenty-two of the cases and 20 of the controls sustained a fracture during the follow-up. From baseline to follow-up, bone mineral content and bone mineral density decreased irrespective of group belonging at baseline, both at the 4% and the 66% level in the forearm. Cross-sectional area did not change significantly at the 4% and the 66% level. At the 66% level, periosteal circumference was unchanged and endosteal circumference increased, leading to decreased cortical thickness. Muscle area decreased, while muscle density was unchanged. A high cross-sectional area and low bone volumetric bone mineral density were predictive of fracture during the follow-up. CONCLUSION: Over a mean follow-up of 7 years, postmenopausal women lose bone mineral density, associated with a decrease in cortical thickness in the forearm.