Knee joint mechanics after anterior cruciate ligament reconstruction

Introduction: There is a scarcity of information on the long term adaptations in lower limb biomechanics during game specific movements after an anterior cruciate ligament (ACL) reconstruction. Particularly, variables such as knee abduction moments and transverse plane knee motion have not been studied during a game specific landing and cutting task after ACL reconstruction. The purpose of this study was to compare the hip and knee mechanics between the ACL reconstructed (ACLr) group and a healthy control group. Methods: 38 athletes (18 ACLr, 18 control) participated in the study. Three dimensional hip, knee and ankle angles were calculated during a maximal drop jump land from a 0.30 m box and unanticipated cutting task at 45°. Results: During the landing phase ACLr participants had increased hip flexion (p <0.003) and transverse plane knee range of motion (p = 0.027). During the cutting phase, ACLr participant’s previously injured limb had increased internal knee abduction moment compared to the control group (p = 0.032). No significant differences were reported between the previously injured and contralateral non-injured limb. Conclusions: Previously injured participants demonstrated higher knee abduction moment and transverse plane ROM when compared to control participants during a game specific landing and cutting task. Based on these data it appears that the surgical and rehabilitation interventions were successful in allowing the ACLr participants to regain similar lower limb biomechanics in both the ACL reconstructed limb and contralateral limb, but significant differences remain between the ACLr and control populations. These altered lower-limb biomechanics characterized by the ACLr group may therefore be risk factors of the occurrence of repeated ACL injury.