Asymmetry of Inter-joint Coordination during Single Leg Jump after Anterior Cruciate Ligament Reconstruction

Little is known about the contralateral asymmetry in inter-joint coordination after anterior cruciate ligament reconstruction (ACL-R) during multi-segmental movements. This study aimed to evaluate inter-joint coordination asymmetry between the injured (IL) and non-injured leg (NIL) in patients after ACL-R during single-leg jumping. 12 male patients having undergone ACL-R (7.3 months post-surgery) and 12 healthy males performed maximal vertical single-leg jumps with the right and left leg. The kinematics of each jump were recorded. The inter-joint coordination between the ankle, knee and hip joints was assessed by computing the continuous relative phase (CRP) and its variability. The effect of the group and leg was tested with a mixed linear model. The CRP and its variability were similar between the dominant and non-dominant leg of the healthy group. By contrast the CRP of the coupling ankle/knee and ankle/hip was smaller (p<0.01) for IL in comparison to NIL in the ACL-R group (-30% and -22% respectively). The CRP variability of the couplings ankle/knee and knee/hip was greater (p<0.05) for IL compared to NIL (+23% and +40% respectively). In conclusion, the jumping strategy assessed through the analysis of inter-joint coordination was still affected in ACL-R patients, which may be a cause of re-injury.