Longitudinal Analysis of Inter-Limb Coordination Before and After Anterior Cruciate Ligament Injury: The JUMP-ACL Study

Purpose Inter-limb coordination may provide insight into why patients with anterior cruciate ligament reconstructive sur-gery(ACLR)have an increased risk for future injury and osteoarthritis.The purpose of this study was to compare inter-limb coordination prior-to anterior cruciate ligament(ACL)injury and following ACLR.Methods Unilateral lower extremity biomechanics during a double-leg jump landing were collected prior-to ACL injury(baseline)and after ACLR,rehabilitation,and return to physical activity(follow-up).Sixty-nine participants were included in this analysis:31 participants suffered an ACL injury since baseline:12 injured the leg tested at baseline[ACLR-injured leg(ACLR-INJ),n=12]and 19 injured the leg that was not tested at baseline[ACLR-uninjured leg(ACLR-UNINJ)n=19];38 participants served as matched controls.Inter-limb coordination-calculated as the mean coupling angle-between the hip and knee were measured in the respective leg of each defined group and compared amongst groups at baseline and follow-up.Results We observed no significant change in sagittal or frontal plane inter-limb coordination amongst groups or across time(P>0.05).A significant decrease in inter-limb coordination in the transverse plane from baseline and follow-up was observed but limited to the ACLR-INJ group(P=0.016).Conclusion The primary finding of this study is that inter-limb coordination between the hip and knee in the sagittal and frontal plane is unchanged by ACL injury and ACLR.This may help explain previous observations of changes in kinemat-ics at both the hip and knee in this population.Our observation of alterations in the transverse plane should be interpreted with caution,but may provide additional evidence for potential mechanisms that lead to the development of osteoarthritis in ACLR patients.