Landing adaptations after ACL reconstruction

Purpose: The purpose of this study was to determine whether fully rehabilitated ACL reconstructed (ACLr) recreational athletes utilize adapted lower-extremity joint kinematics and kinetics during a high-demand functional task. Methods: The kinematic and kinetic performance of 11 healthy and 11 hamstring ACLr recreational athletes were compared during a 60-cm vertical drop landing. Results: At initial ground contact, the ACLr group demonstrated greater hip extension and ankle plantarflexion compared with the healthy group. The peak vertical ground-reaction force was not different between groups, but the ACLr group delayed the time to its occurrence. The knee extensors provided the major energy absorption function for both groups; however, the ACLr group performed 37% more ankle plantarflexor work and 39% less hip extensor work compared with the healthy group. Conclusions: The hamstring ACLr recreational athletes utilized an adapted landing strategy that employed the hip extensor muscles less and the ankle plantarflexor muscles more. The harvesting of the medial hamstring muscles for ACL reconstruction may contribute to the utilization of this protective landing strategy.