Protective Hip and Knee Kinematics during Unilateral and Bilateral Landings after Neuromuscular Training in Acl-reconstructed Subjects

INTRODUCTION Anterior cruciate ligament (ACL) injury leads to significant reductions in patient function, and biomechanical asymmetries that frequently persist for two years or longer after ACL-reconstruction. [1] Recent reports indicate that as many as one in four ACL-reconstructed patients will suffer a second ACL injury to either the affected or contralateral limb within their first year of return to sport. [2] Furthermore, patients who suffer a second injury have significantly poorer short-to-long term outcomes. Hip, knee, and ankle kinematics are critical modifiable factors that affect ACL injury risk. Previous research indicates that landing with the hip and knee near full extension, and reaching lower levels of peak hip and knee flexion increase the likelihood for injury. In addition, stiffer landings transmit greater forces and torques through the joints, and likely contribute to increased injury risk. Neuromuscular training (NMT) protocols that target high-risk biomechanics and impairments in neuromotor control effectively reduce rates of primary ACL injury. [3] Furthermore, subjects that participate in these training protocols demonstrate a number of associated improvements in functional biomechanical control. [4] Despite success in large, prospective analyses of healthy athletes, few studies have investigated the impact of NMT on functional biomechanics in ACL-reconstructed subjects. The goal of this study was to quantify lower extremity kinematics during unilateral and bilateral landing in ACL-reconstructed subjects prior to and after participation in NMT.