Sagittal lower extremity kinematics during single-leg landing in athletes with anterior cruciate ligament reconstruction: A pilot study
The purpose of the study was to investigate the lower extremity angles of sagittal plane during single-leg landing in various directions. Six athletes (four males, two females) with anterior cruciate ligament reconstruction (ACLR) participated. They have returned to sports completely. They were asked to perform single-leg landing from 30-cm height platform in four directions (forward, 30o diagonal, 60o diagonal, and lateral directions). Jump-landing tests were collected using a Vicon™ motion analysis system. Lower extremity angles at initial contact and at peak vertical ground reaction force (GRFv) were reported and compared among directions of jump landing. The statistical analysis was analyzed using the repeated measures ANOVA. At initial contact, knee flexion exhibited a trend of increase while hip flexion angle was showing a decrease from forward to lateral direction. Knee flexion angles were 10.4o, 12.2o, 13.2o, and 15.2o. Hip flexion angles were 34.2o, 35.9o, 33.6o, and 30.7o. At peak GRFv, jump-landing direction significantly influenced ankle dorsiflexion. Significant greater ankle dorsiflexion was observed in lateral (19.1o) and 60o diagonal (14.2o) directions than forward (5.7o) direction. Hip flexion angles showed a trend of increase while knee was showing decrease from forward to lateral direction. However, jump-landing direction did not significantly influence hip and knee flexion angles at both phases. This study showed that, in the situation of returning to sports in athletes with ACLR, a decreased hip flexion and an increased ankle dorsiflexion might lead to increase a risk of knee injury during single-leg landing in diagonal and lateral directions. Physical therapy and rehabilitation program should address these risks of recurrent injury and should develop treatment to prevent the recurrent ACL injury.