Single Leg Landing Coordination Variability and Second Injury in Young Athletes After Primary Anterior Cruciate Ligament Reconstruction

Introduction: Young, active individuals who undergo anterior cruciate ligament (ACL) reconstruction (ACLR) after an ACL injury often experience suboptimal outcomes, including high risk of second ACL injury. Coupling angle variability has been used previously to investigate the interactions between joints and their relative coordination, but it has not yet been used to investigate future risk of subsequent ACL injury during dynamic tasks post-ACLR. As such, the purpose of this work was to examine the relationship between coordination variability and second ACL injury outcomes in young athletes after primary ACLR along with uninjured controls. Methods: This work represents a secondary analysis from a larger parent study that included motion capture data at the time of return to sport (RTS) and second ACL injury incidences over a two-year period after RTS in young athletes post-ACLR. We utilized kinematic data during landing to calculate coordination variability with a modified vector coding technique. For this analysis, coordination variability during the landing phase of a single leg landing task was compared among three groups: uninjured control participants (CTRL), participants with ACLR that did not sustain a subsequent second ACL injury (ACL1), and participants with ACLR that sustained a second ACL injury (ACL2). Results: On the uninvolved limb, CTRL demonstrated lower coordination variability compared to ACL1 and ACL2. On the involved limb, CTRL demonstrated the lowest coordination variability and ACL2 demonstrated the highest coordination variability of the three groups. Conclusions: The higher coordination variability seen in the ACLR groups suggests lower consistency of movement strategies. Additional research is needed to further investigate how coordination variability may impact subsequent injury risk after primary ACLR.