More broken bones: A 4-year double cohort study of young girls with and without distal forearm fractures

Predictors of childhood fractures have not been investigated previously. Th is study was undertaken to determine whether a previous history of forearm fracture, low bone mineral density (BMD; both areal bone mineral density [a BMD, g/cm(2)] and volumetric bone mineral apparent density [BMAD, g/cm(3)]) , or anthropometry, influence fracture risk in young girls. At baseline, tw o cohorts of girls, aged 3-15 years, were evaluated: 100 had recently broke n a forearm (group 1) and 100 were fracture free (group 2). Four years late r we restudied 170 of these girls (82 from group 1 and 88 from group 2). We now report the relationships of previous fracture history, baseline BMD (m easured by dual-energy X-ray absorptiometry), baseline weight, and height t o risk of new fracture. More new fractures occurred in group 1 (37 fracture s in 24 girls) than in group 2 (8 fractures in 7 girls; p = 0.0007). The in dependent predictors for occurrence of a new fracture at any skeletal site in a multivariate model adjusting for age, weight, total body aBMD, and fra cture history were previous fracture (hazard ratio [HR], 3.28; 95% CI, 1.41 -7.64); age (HR per 1-year increase, 0.91; 95% CI, 0.84-0.99); total body a BMD (HR per 1 SD decrease, 1.92; 95% CI, 1.31-2.81); and body weight (HR pe r 1 SD increase, 1.49; 95% CI, 1.06-2.08). Girls with two risk factors toge ther had substantially greater fracture risk: previous fracture and low spi nal BMAD (HR, 9.4; 95% CI, 2.8-32.0), previous fracture and high body weigh t (HR, 10.2; 95% CI, 2.8-37.6), or previous fracture and low total body aBM D (HR, 13.0; 95% CI, 3.9-43.1). We conclude that previous forearm fracture, low total body aBMD, low spinal BMAD, and high body weight each increase r isk of new fractures within 4 years in young girls. Interventions to reduce the risk of fractures, particularly forearm fractures, in girls warrant fu rther study.