Effect of perturbations on the biomechanics of lower limb in relation to anterior cruciate ligament (ACL) injuries

Abstract

The knee is the most injured joint in the body with injuries often caused by a tear in the anterior cruciate ligament (ACL). Over 70% of ACL injuries are non-contact, meaning that an excessive amount of force or moment is generated by the individuals themselves, which induces the tear. Non-contact ACL injuries most commonly occur following a perturbation. Perturbations make the athlete unbalanced or at loss of control, which ultimately alters their normal neuromuscular control and can lead to injury.

In order to understand the effect of this unconscious neuromuscular response, this study aimed to induce unanticipated perturbations during walking in 10 male and 10 female athletes. Moreover, the effect of prophylactic knee braces was examined during these perturbations. Musculoskeletal modelling in OpenSim was used to calculate kinematics, kinetics, and muscle forces during these perturbations.

Females portrayed muscle force patterns during perturbations, that are likely to increase the risk of ACL injury. Furthermore, females exhibited a larger difference in muscle forces between their dominant and non-dominant limbs. Finally, prophylactic knee braces significantly reduced peak quadriceps and soleus muscle forces during perturbations.

Unlike planned movements in laboratory studies, unexpected perturbations provide with deeper insight in the mechanism of ACL injuries. Although ACL injuries do not typically occur during walking, potentially injurious movement patterns during a disturbance to natural balance while walking, could provide insight on what may be reproduced, on a higher scale, during high impact and high-speed athletic tasks that can effectively tear the ACL.