Distinguishing Bone Characteristics in Female Athletes with and without Stress Fractures Using Sector Analysis of 3D Tibia Images

Open Access
Author:
Yannarell, Katie Marie
Area of Honors:
Kinesiology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Mary Jane De Souza, Thesis Supervisor
  • Mary Jane De Souza, Honors Advisor
  • Nancy I. Williams , Faculty Reader
Keywords:
  • Female Athlete Triad
  • Bone Marker
  • Sector Analysis
  • Stress Fracture
Abstract:
More than 20% of sports-related injuries are stress fractures, which begin as microstructural level cracks that accumulate and propagate into cortical fractures. Incurring one stress fracture increases the likelihood of sustaining a subsequent stress fracture, and there is a significantly higher prevalence of stress fractures in female athletes and military recruits compared to males. There are several risk factors that contribute to the increased prevalence in females, especially those associated with the Female Athlete Triad (the Triad). The Triad consists of three interrelated conditions: low energy availability (EA) with or without an eating disorder, low bone mineral density (BMD), and menstrual disturbances. The purpose of this study was to distinguish bone characteristics in female athletes with and without stress fractures. Specifically, we assessed serum markers of bone formation (P1NP) and resorption (CTX) since bone is a metabolically active tissue that undergoes a remodeling. Additionally, we performed sector analyses of pQCT images to assess regional vBMD and bone geometry of the tibia at 4 sites: 4%, 14%, 38%, and 66% from the distal endplate of the tibia. Female athletes that were recently diagnosed with a stress fracture (SFx) (n=19) were matched by age, sport type, and exercise volume with healthy female athletes (Control) (n=11), resulting in a cohort of n=30 female athletes. Women were between the ages of 18 and 35 years who presented with or without a lower extremity bone stress injury, participated in at least 2 hours of exercise per week, and were free of chronic illness impacting bone metabolism. There were no significant differences in basic demographics or body composition between the two groups (p>0.05). Bone marker measurements demonstrated no significant differences in P1NP or CTX between the Control and SFx groups (p>0.05). There were no differences between the Control and SFx groups in pQCT measurements of the total, cortical, or trabecular bone when assessing each cross-section of the bone as a whole. However, sector analysis revealed that there were significant differences within certain regions of cross-sections between the groups at the proximal tibial sites (38% and 66%), but not the distal sites (4% and 14%); the most differences were observed in the medial regions of the cross-sections (p<0.05). These results suggest that sector analysis is a valuable tool that can be used to gain a greater understanding of bone characteristics that may increase an athlete’s susceptibility to fracture.