Knee abduction angles and landing kinematics in badminton jump smash: A study of ACL injury risk factors

Anterior cruciate ligament (ACL) injuries can occur in non-contact conditions (e.g., jump-landing) and are common among junior badminton players. The knee abduction angle has been widely identified as a biomechanical risk factor that likely contributes to this injury mechanism. Purpose: This study aims to examine the relationship between the trunk and lower limb landing kinematics and the peak knee abduction angle following a jumping smash. Method: Twenty-one male junior badminton players performed jump smashes on an instrumented badminton court. Anthropometry was measured; trunk and lower limb single-leg landing kinematics and kinetics were collected using a motion capture system. Pearson’s correlation was performed to identify the variables significantly correlated to peak knee abduction angle, followed by stepwise multiple regression to identify the most important combination of predictors. Results: Regression analysis showed that knee external rotation angle at foot contact and peak knee internal rotation angle were associated with peak knee abduction angle. A separate analysis also showed that landing time was positively associated with peak knee abduction angle. Conclusions: Assessing ACL injury risk and developing injury prevention strategies for jump landings in badminton should focus on knee motion in the frontal and transverse planes, as well as landing time.