Identification of Stress Fracture Risk Factors in Female College Dance Majors

Abstract

PURPOSE: The high physical demands of collegiate-level dance place females at risk for stress fractures just when they should be at their peak bone health. The purpose of this study was to estimate the prevalence of stress fracture in female college dance majors. A secondary objective was to identify risk factors for stress fracture in this population. METHODS: A cross-sectional study was conducted at an urban Midwestern university. Female college dance majors who had completed at least one semester in the program by the spring of 2005 were eligible. Participants completed a self-administered written survey for history of stress fracture, demographics, health and menstrual history, and a three-day diet history. Height and weight were directly measured, and bone mineral density (BMD) assessed via dual emission x-ray absorptiometry (DXA) scanning. All statistical analyses were performed in SPSS (V.12) or SAS (V.8.2). The study protocol was approved by the participating institutions' IRBs. RESULTS: The mean age of the 51 participants was 20.2 ±1.8 years (± SD). 96.1% (n=49) were Caucasian. Mean body mass index (BMI) was 21.9 ± 3.0 kg/m2. Mean age of menarche was 12.6 ± 1.4 years; however 17.6% (n=9) participants recalled a history of oligomenorrhea (denned as 9 or fewer menstrual cycles per year). 37.2% (n=19) of the participants reported current hormonal use. Mean caloric intake was 1757 ± 969 kcal/day, with mean calcium and vitamin D intake 637 ±337 mg/day and 101 ± 126 IU/day, respectively. 5.9% (n=3) participants reported a history of stress fracture. On DXA measurement, the mean lumbar spine (L1-L4) BMD Z-score was 0.83 ± 1.09 and the total body BMD Z-score was 0.75 ± 0.89. 7.8% (n=4) of the participants had a “low BMD,” denned as lumbar spine BMD Z-score <-1.0. Participants with a history of stress fracture had a significantly lower mean lumbar spine Z-score (−0.09 vs. 0.94, p=0.003) than those without. 66.7% of the individuals with a history of stress fracture had a low BMD, compared with only 4.2% of individuals who did not, for an odds ratio of 46.0 [95% confidence interval (2.8, 746.6)]. No other risk factors were significantly associated with stress fracture. CONCLUSIONS: This is the first study to assess the prevalence of stress fracture in the female college dance major. Low BMD was found to be significantly associated with a history of stress fracture, suggesting that DXA scanning may be warranted in the medical evaluation of stress fracture in this population. Further research is needed to determine if screening for low BMD via DXA is indicated to prospectively identify which young adult female dancers may be at increased risk of suffering this devastating injury.