Is knee neuromuscular activity related to anterior cruciate ligament injury risk? A pilot study

Abstract

Background: There is limited evidence on neuromuscular risk factors for anterior cruciate ligament (ACL) injuries, with most work mainly focusing on hamstrings and quadriceps muscle strength. This prospective pilot study explored if neuromuscular activation patterns of the quadriceps and hamstrings during a drop vertical jump influence ACL injury risk. Methods: Forty-six female athletes performed a drop vertical jump at baseline. Injuries were monitored throughout a one-year follow-up. Neuromuscular activation patterns of the vastus medialis, vastus lateralis, hamstrings medialis and hamstrings lateralis, and selected landing kinematic and kinetic profiles (knee flexion, knee abduction and hip flexion angles, and knee abduction moments), were compared between athletes who sustained a non-contact ACL injury and those who remained injury free. Electromyogram vector fields were created to represent neuromuscular activation patterns of muscle pairs around the knee joint rather than only considering individual muscle activations, and compared using Statistical Parametric Mapping. Results: Four athletes sustained an ACL injury. Significantly greater {hamstrings medials, hamstrings lateralis}, {vastus lateralis, hamstrings lateralis} and {hamstrings lateralis, vastus medialis} activations, mainly due to greater hamstrings lateralis activation, were found in the injured group around peak loading and just before take-off (P b 0.001). No group differences were found in knee flexion, knee abduction and hip flexion angles, or knee abduction moments. Conclusions: This pilot study revealed initial evidence that athletes already showed altered neuromuscular activation patterns prior to sustaining an ACL injury, namely increased lateral and posterior muscle activations.