Bone mineral density in girls with forearm fractures

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.