title: Menstrual cycle stage and oral contraceptive effects on anterior tibial displacement in collegiate female athletes.
abstract: OBJECTIVE
  The aim of this study was to establish if differences in anterior tibial displacement exists in collegiate female student-athletes at different stages of the menstrual cycle.
  
  
  METHODS
  
  
  
  METHODS
  a 2 x 3 factorial design with repeated measures on the second factor guided this study. The first independent variable was group with 2 levels (control and oral contraceptive) and the second independent variable was menstrual cycle phase with 3 levels (follicular, ovulation, luteal). The single dependent variable was anterior tibial displacement. All data were collected in a research laboratory.
  
  
  METHODS
  53 female student athletes (control: n=28; oral contraceptive: n=25) with no previous history of knee injury or anomalies with a normal 28-30 day menstrual cycle participated.
  
  
  METHODS
  anterior tibial displacement (mm) measurements were taken on days 1 (follicular phase), 13 (ovulation phase), and 23 (luteal phase) of each subject's menstrual cycle using a KT1000 knee arthrometer.
  
  
  RESULTS
  For the entire group, statistically significant increases in anterior tibial laxity were found (F=4.49; df=52.1; P<0.05) between the follicular cycle (0+/-SD =5.14 mm) and ovulation cycle (0+/-SD=5.81 mm); and follicular cycle (0+/-SD=5.14 mm) and luteal cycle (0+/-SD=5.79 mm). A separate analysis of the non-birth control group revealed no significant difference in anterior tibial laxity throughout the stages of the menstrual cycle.
  
  
  CONCLUSIONS
  The results of this study suggest that: 1) the menstrual cycle does have an influence on laxity of the anterior displacement of the knee; 2) significant increases in anterior displacement are shown during the ovulation and luteal phases of the menstrual cycle; and 3) birth control subjects tend to have increased laxity when compared to those subjects who are not on hormone therapy.
authors.affiliation: Biodynamics Research Laboratory, Department of Kinesiology. The University of North Carolina, Charlotte, NC, USA chicksl@email.uncc.edu
authors.forename: C A
authors.initials: CA
authors.lastname: Hicks-Little
authors.forename: J R
authors.initials: JR
authors.lastname: Thatcher
authors.forename: J M
authors.initials: JM
authors.lastname: Hauth
authors.forename: A J
authors.initials: AJ
authors.lastname: Goldfuss
authors.forename: M L
authors.initials: ML
authors.lastname: Cordova
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D016118:Anterior Cruciate Ligament / Q000502:physiology; D053587:Arthrometry, Articular; D003276:Contraceptives, Oral / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007719:Knee Joint / Q000502:physiology; D008597:Menstrual Cycle / Q000502:physiology*; D010865:Pilot Projects; D013177:Sports; D013977:Tibia / Q000502:physiology*
chemical_list: D003276:Contraceptives, Oral