Association of Menstrual-Cycle Hormone Changes with Anterior Cruciate Ligament Laxity Measurements

OBJECTIVE: To determine whether anterior cruciate ligament (ACL) laxity (as evaluated with the KT-2000 and radiographic measures) is associated with concentrations of reproductive hormones during the menstrual cycle and whether the KT-2000 knee arthrometer is a valid measurement technique, compared with radiographic techniques. DESIGN AND SETTING: A within-subjects linear model was used. Venipuncture was conducted in an exercise science laboratory. The KT-2000 and radiographic measurements were performed in a hospital radiology laboratory. SUBJECTS: Twelve females presented with a dominant right leg free of injury. They were mild to moderately active and had a 12-month history of normal menstrual cycles (28-35 days). Subjects had not used hormonal therapy for the previous 3 months. MEASUREMENTS: Subjects were tested at the onset of menses, near ovulation, and on day 23 of the midluteal phase of the menstrual cycle. At each session, 14 mL of blood was obtained by venipuncture. Blood samples were analyzed via radioimmunoassay to determine the relative levels of each hormone. Anterior cruciate ligament laxity was simultaneously measured by KT-2000 and radiographic techniques. RESULTS: Anterior cruciate ligament laxity measurements were significantly greater with the KT-2000 than with radiographic measurement. No significant differences were noted between menstrual-cycle phase and ACL laxity for either method. The concentration of luteinizing hormone was negatively correlated with laxity at the onset of menses using the radiographic technique. CONCLUSIONS: We found no associations between follicular-, ovulatory-, and luteal-phase hormonal concentrations and ACL laxity as measured on the KT-2000 and radiographs; no effects of menstrual-cycle phase on ACL laxity as measured by the KT-2000 and radiographs; and significant differences between KT-2000 and radiographic measures of ACL laxity.