LAUSR

Background Limited evidence exists regarding calcaneal bone mineral density (cBMD) and lower extremity overuse bone injury (LEOBI). Objective Determine if there is an association between LEOBI (stress fractures and MTSS) and cBMD. Design Prospective cohort design. Setting NCAA Division I University. Patients (or Participants) 84 (64 females, 20 males) intercollegiate athletes and 103 (82 females, 21 males) non-athlete college students. Inclusion criteria: ≥18 years of age and no current lower extremity injury. Interventions (or Assessment of Risk Factors) In Phase I, athlete surveys regarding injury history and for females, menstrual history, and height and weight were measured. Athletes were followed for 9–10 months to identify the occurrence of LEOBI. In Phase II, non-athlete college students completed injury history, physical activity, and, for females, menstrual history surveys, and height and weight were measured. Main Outcome Measurements cBMD was assessed using ultrasound densitometry. At the end of the study, athletes received a second cBMD measurement. Results In Phase I, there was no difference in initial cBMD (p>0.05) between athletes with and without LEOBI, but there was a trend towards decreased cBMD in athletes with LEOBI. At the end of the study, right cBMD (p=0.05) and left cBMD (p=0.07) were lower in athletes with LEOBI. In Phase II, non-athletes had significantly lower bilateral cBMD (p=.000) and speed of sound (SOS) (p=0.000) than athletes. Sub-analysis revealed highly significant differences in SOS (p=0.000) and cBMD (p=0.000) for females (non-athletes vs. athletes). Being a female non-athlete was a significant risk factor for a negative cBMD T-score for both the right (RR=2.2, 95% CI=1.4–3.3) and left (RR=1.7, 95% CI=1.1–2.6). Conclusions Athletes who did not experience LEOBI had significantly higher cBMD than non-athletes and athletes experiencing LEOBI. Future research should include larger sample sizes and adolescent subjects to identify influences on bone response to loading over time.