title: Alterations in knee joint laxity during the menstrual cycle in healthy women leads to increases in joint loads during selected athletic movements.
abstract: BACKGROUND
  It has been speculated that the hormonal cycle may be correlated with higher incidence of ACL injury in female athletes, but results have been very contradictory.
  
  
  OBJECTIVE
  Knee joint loads are influenced by knee joint laxity (KJL) during the menstrual cycle.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Serum samples and KJL were assessed at the follicular, ovulation, and luteal phases in 26 women. Knee joint mechanics (angle, moment, and impulse) were measured and compared at the same intervals. Each of the 26 subjects had a value for knee laxity at each of the 3 phases of their cycle, and these were ordered and designated low, medium, and high for that subject. Knee joint mechanics were then compared between low, medium, and high laxity.
  
  
  RESULTS
  No significant differences in knee joint mechanics were found across the menstrual cycle (no phase effect). However, an increase in KJL was associated with higher knee joint loads during movement (laxity effect). A 1.3-mm increase in KJL resulted in an increase of approximately 30% in adduction impulse in a cutting maneuver, an increase of approximately 20% in knee adduction moment, and a 20% to 45% increase in external rotation loads during a jumping and stopping task (P < .05).
  
  
  CONCLUSIONS
  Changes in KJL during the menstrual cycle do change knee joint loading during movements. Clinical Relevance Our findings will be beneficial for researchers in the development of more effective ACL injury prevention programs.
authors.affiliation: Human Performance Laboratory, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Sang-Kyoon
authors.initials: SK
authors.lastname: Park
authors.forename: Darren J
authors.initials: DJ
authors.lastname: Stefanyshyn
authors.forename: Barbara
authors.initials: B
authors.lastname: Ramage
authors.forename: David A
authors.initials: DA
authors.lastname: Hart
authors.forename: Janet L
authors.initials: JL
authors.lastname: Ronsky
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D001265:Athletic Injuries / Q000209:etiology; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D004967:Estrogens / Q000097:blood / Q000502:physiology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000097:blood / Q000145:classification / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D007719:Knee Joint / Q000503:physiopathology*; D008597:Menstrual Cycle; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
chemical_list: D004967:Estrogens