Identifying sex-specific risk factors for stress fractures in adolescent runners.

PURPOSE: Adolescent females and males participating in running represent a population at high risk of stress fracture. Few investigators have evaluated risk factors for prospective stress fracture in this population.

METHODS: To better characterize risk factors for and incidence of stress fractures in this population, we collected baseline risk factor data on 748 competitive high school runners (442 girls and 306 boys) using an online survey. We then followed them prospectively for the development of stress fractures for a mean ± SD of 2.3 ± 1.2 total seasons of cross-country and track and field; follow-up data were available for 428 girls and 273 boys.

RESULTS: We identified prospective stress fractures in 5.4% of girls (n = 23) and 4.0% of boys (n = 11). Tibial stress fractures were most common in girls, and the metatarsus was most frequently fractured in boys. Multivariate regression identified four independent risk factors for stress fractures in girls: prior fracture, body mass index < 19, late menarche (age menarche ≥15 yr), and previous participation in gymnastics or dance. For boys, prior fracture and increased number of seasons were associated with an increased rate of stress fractures, whereas prior participation in basketball was associated with a decreased risk of stress fractures.

CONCLUSIONS: Prior fracture represents the most robust predictor of stress fractures in both sexes. Low body mass index, late menarche, and prior participation in gymnastics and dance are identifiable risk factors for stress fractures in girls. Participation in basketball appears protective in boys and may represent a modifiable risk factor for stress fractures. These findings may help guide future translational research and clinical care in the management and prevention of stress fractures in young runners.