Bone Mineral Density in Girls with Forearm Fractures

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Abstract

In childhood, the most common site of fracture is the distal forearm. To determine whether young girls with these fractures have low bone density more commonly than fracture-free controls, we measured bone density at the radius, spine, hip, and whole body and total body bone mineral content, lean tissue mass, and fat mass by dual-energy X-ray absorptiometry in 100 Caucasian girls aged 3–15 years with recent distal forearm fractures and 100 age- and gender-matched controls. Bone density (age-adjusted ratios of all cases:controls with 95% confidence intervals) was lower in cases at the ultradistal radius 0.963 (0.930–0.996), 33% radius 0.972 (0.945–0.999), lumbar spine 0.945 (0.911–0.980), hip trochanter 0.952 (0.918–0.988), and total body 0.978 (0.961–0.995). Moreover, osteopenia (defined as Z score below −1), was more common in cases than controls (p < 0.05) in the forearm, spine, and hip, with one third of fracture cases having low spinal density. Odds ratios (95% confidence intervals) for low bone density were: ultradistal radius, 2.2 (1.1–4.6); lumbar spine, L2-L4, 2.6 (1.3–4.9); and femur trochanter, 2.0 (1.0–3.9). Fracture patients aged 8-10 years weighed more (mean ± SD) than age-matched controls (37.2 ± 8.0 kg vs. 32.5 ± 6.6 kg, p < 0.01) while older patients reported lower current and past calcium intakes than matched controls (p < 0.05). We conclude that low bone density is more common throughout the skeleton in girls with forearm fractures than in those who have never broken a bone, supporting the view that low bone density may contribute to fracture risk in childhood.

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