2026 Volume 4 Issue 1 Pages 79-84
Objective: Anterior cruciate ligament (ACL) injuries often occur when the knee is in a slightly flexed and valgus position. The larger vertical ground reaction force（vGRF） also increases the risk of ACL injuries. ACL injuries are common in basketball players, especially during landing. Rebound-jumps in games often involve body rotation in mid-air. A previous study reported during rebound-jump landings with body rotation toward the takeoff leg (TL), the non-takeoff leg (NTL) showed smaller knee flexion and greater valgus angles than the TL. However, direction of rotation was limited in previous study, but multidirectional body rotation may occur. Therefore, this study aimed to investigate differences in knee joint angles and vGRF during rebound-jump landings under different rotational conditions.
Methods: Eleven female basketball players participated in this study. Three-dimensional motion analysis was used to calculate knee joint angles. Participants performed the rebound-jump landing under 3 conditions: (1) front-facing, (2) body rotation at 90° toward the TL (TL-side), and (3) body rotation at 90° toward the NTL (NTL-side). Measurements were taken every 10 ms from initial contact (IC) up to 40 ms.
Results: In the TL-side condition, the NTL demonstrated significantly smaller knee flexion angles and larger vGRF than the TL. In the NTL-side condition, the TL exhibited significantly greater knee valgus angles and larger vGRF than the NTL.
Conclusion: Knee joint angles during rebound-jump landings vary with body rotation direction. These directional differences may be involved in injury risk.
