Evaluation of an IMU-Based Wearable Device for ACL Injury Research | Advances in Orthopedics and Sports Medicine (AOASM) Journal

Anterior cruciate ligament (ACL) injuries are common, costly and have long-term health consequences. Despite decades of ACL injury research, ACL injury incidence remains high, highlighting the need for new approaches. We hypothesize that many non-contact ACL injuries result from an overuse, fatigue failure mechanism and that advances in wearable technology provide an exciting opportunity to obtain data needed to test this hypothesis. In this study, we created and evaluated an inertial measurement unit (IMU) based wearable device to collect a clinically relevant metric of ACL loading events from athletes in the field. The wearable device measures relative anterior tibial acceleration (RATA), a surrogate measure of ACL loading defined as the relative acceleration between a point on the proximal tibia and a point on the distal femur. The device was evaluated using a mechanical test system designed to simulate human leg movement, and then used to quantify peak RATA profiles for two participants performing six common athletic movement tasks associated with relatively low and high levels of ACL loading. The wearable device successfully tracked in-vivo the frequency and magnitude of ACL loading events and thus provides a tool to acquire data needed to test fatigue failure mechanism theories of ACL injury.