A Descriptive Analysis of the Seasonal Patterns of Bone Stress Injury Incidence in Division I Collegiate Distance Runners.

BACKGROUND A bone stress injury (BSI) is a common overuse injury in collegiate athletes, particularly cross-country and track and field runners. Limited work describes the seasonality of BSIs or the differences in rates and anatomic locations of BSIs in collegiate runners. PURPOSE To describe seasonally related trends in anatomic locations of BSIs in National Collegiate Athletic Association (NCAA) Division I male and female middle- and long-distance runners. STUDY DESIGN Descriptive epidemiological study. METHODS Data from a 7-year prospective study of 2 NCAA Division I cross-country and track and field programs characterized BSIs over the years 2013 to 2020. Femoral neck, pelvic, sacral, lumbar spine, and calcaneal BSIs were considered trabecular-rich. All remaining BSIs were classified as cortical-rich. Total athlete-years of follow-up were calculated by subtracting the number of days an athlete was unable to run from the number of total study participation days. Annual incidence rates were calculated by dividing the number of BSIs by the total athlete-years of follow-up for that year, and monthly incidence rates were calculated by dividing the number of BSIs in a given month by the total athlete-years of follow-up for that month. RESULTS Participants included 221 collegiate distance runners (114 female, 107 male). There were 154 BSIs across 482 total athlete-years, resulting in an incidence rate of 32 BSIs per 100 athlete-years. The female BSI rate was more than double that of the male BSI rate: 45 versus 20 BSIs per 100 athlete-years, respectively. The highest monthly BSI rates occurred during competitive months, with the lowest monthly BSI rates occurring during noncompetitive months. Tibial and femoral shaft BSI rates peaked during the early competitive phases of each season, whereas metatarsal BSI rates remained relatively constant. Cortical-rich BSI rates varied by sex and seasonal phase, whereas trabecular-rich BSI rates remained relatively consistent. CONCLUSION BSIs were common in collegiate distance runners, especially among female athletes, with higher rates during the competitive phases of the running season. Tibial and femoral shaft BSI rates were highest during the competitive phases and lowest during the noncompetitive phases, while metatarsal BSI rates remained consistent throughout the season. Cortical-rich BSI rates varied by seasonal phase and sex, whereas trabecular-rich BSI rates were relatively constant.