Single-legged landing behavior of high school basketball players with chronic ankle instability

Objectives: Anterior cruciate ligament injury is one of the most serious ligamentous injuries. The purpose is to compare the impact of the ankle joint on the knee during landing between athletes with chronic instability and a control group (coper group) and to verify the effects of the kinetic chain from other joints. Design: Prospective study. Setting: High school basketball. Participants: Participants were 62 female high school basketball players who had participated in team sports for >6 months. Main outcome measures: Player joint angles, movements, and moments. Results: The knee valgus moment was significantly higher in the chronic ankle instability group than in the coper group (20%-60% [p < 0.011; 80%-100% [p < 0.051) during landing motion. The knee valgus moment was also significantly higher during the change from the maximum knee joint flexion position to the maximum extension (p < 0.05). In addition, the landing motions of the chronic instability group may have utilized suboptimal compensatory motor strategy on the sagittal plane, depending heavily on the knee joint's abduction moment. Conclusions: Our findings indicate that the chronic ankle instability group uses a different landing strategy pattern than the coper group by changing the joint moment and joint angle during landing, which may increase the risk of anterior cruciate ligament injury.