Altered kinematics and coordination patterns of adjacent joints after anterior cruciate ligament injury

Abstract Purpose Anterior cruciate ligament (ACL) injuries typically demonstrate abnormal motion in multiple planes of the joints. The objective of this study is to investigate the kinematic properties of the knee and ankle joints in patients who have suffered ACL injuries. The alterations in knee-ankle coordination patterns after ACL injury will alsobe evaluated. Methods Thirty participants diagnosed with unilateral complete ACL rupture through MRI were included in the study. An optical tracking device was used to measure each joint's kinematics during treadmill gait. Kinematic parameters and joint ranges of motion of participants' knees and ankles were compared. The mean absolute relative phase (MARP) and deviation phase (DP) were further calculated for comparison. Results (1) Knee kinematics: The flexion, external rotation , abductionand lateral translation of the ACL injured knee joint increased during the stance phase. The abduction increased during the swing phase, while the anterior translation and proximal translation decreased. (2) Ankle kinematics: The ankle joints of patients with ACL injuries showed increased external rotation during the stance phase and increased plantarflexion and external rotation during the swing phase. (3) The MARP and DP of ACL-injured patients decreased during the stance phase and increased in the swing phase. Conclusion The findings suggest that ACL injury may alter ankle kinematics in addition to knee kinematics. This leads to adaptive alterations in knee-ankle coordination as well as coordination variability.