Gender differences in controlling knee wobbling: implications for anterior cruciate ligament injury risk

BACKGROUND: Identifying high-risk movement pattern is necessary to prevent non-contact ACL injury. Previous studies identified only knee position at initial contact and peak flexion during landing as risk factors for ACL injury. Establishing further assessments to detect deficits in knee neuromuscular control is useful for more effective determination of ACL injury risk in female athletes. The purpose of this study was to examine gender differences in basketball players regarding knee valgus angle and dynamic knee wobbling.METHODS: Ten participants were recruited from intercollegiate basketball teams. Two 2D-videocameras were used to capture the participants performing 3 trials of controlled single-leg squat. An incident of knee wobbling was defined as when the valgus angular velocity crossed zero. Frontal plane projection angle (FPPA), valgus excursion range, and frontal angular velocity divided by sagittal angular velocity (F/S Ratio) during wobbling were compared between genders.RESULTS: The valgus excursion angle was significantly larger in females than males (0.8° vs. 0.1°, P=0.011), and the F/S Ratio was significantly larger in females than males (212.1% vs. 16.7%, P=0.011). There was no difference in the FPPA or the frequency of knee wobbling between males and females.CONCLUSIONS: Greater knee excursion angle and knee wobbling during a single-leg squat test were observed in female basketball players. To determine the risk of ACL injury in female athletes during screening, knee wobbling and F/S Ratio during the eccentric phase of single-leg squats can be more useful than static angular assessments.