Trunk and Lower Limb Muscle Contributions to ACL Loading During Single-Leg Landing

Anterior cruciate ligament injuries often led to long-term consequences including early knee osteoarthritis, abnormal neuromuscular function, and reduced athletic participation. Approximately 70% of ACL injuries occurred via non-contact mechanisms, frequently during single-leg landing tasks. During such movements, ACL loading was influenced by joint kinematics, external forces, and neuromuscular coordination of both trunk and lower limb muscles. This study adopted a two-level approach. First, standard biomechanical analyses were conducted to evaluate the relationship between functional core strength and knee joint biomechanics, including knee valgus angle and knee abduction moment during SLL. Second, a musculoskeletal modelling approach was employed to quantify the contribution of individual trunk and lower limb muscles to ACL loading.

Participants performed standardized single-leg landing tasks while wearing inertial motion sensors and surface electromyography electrodes. Ground reaction forces were recorded using a force platform. A full-body musculoskeletal model was scaled to participant anthropometry and used to estimate muscle forces and ACL loading during the landing phase. Statistical analyses included linear regression and linear mixed-effects modelling to examine relationships between muscle forces, knee biomechanics, and ACL loading.