Introduction: The return to sport after Anterior Cruciate Ligament Reconstruction (ACLR) is among the main issues encountered by rehabilitation medicine, injured athletes, and coaches. A main factor preventing safe return to sports is a biomechanical asymmetry between the limbs during reconstruction, which plays a significant role in the risk of re-injury. Accordingly, injury-related biomechanical changes were systematically examined in individuals with ACLR as performed functional tasks. Materials and Methods: Articles relevant to biomechanical asymmetries between (ACLR & uninjured) limbs in English were searched in the Google Scholar, Science Direct, PubMed MEDLINE, and Scopus databases without time limit until 2021, using the following keywords: “Anterior cruciate ligament reconstruction”, “ACL reconstruction”, “biomechanical”, “Kinetic”, “Kinematic”, and “Asymmetry”. Results: In total, 122 articles were found, of which 18 met the inclusion (PRISMA) criteria. Most of the kinetic and kinematic parameters were observed in the intervals of 3, 6, 9, 12, and 18 months after ACLR between the athletes’ vertical Ground Reaction Force (vGRF), peak hip abduction moment, peak knee valgus angle, peak knee flexion moment and angle, during the functional tasks; also changes were detected in the articles up to 28 months, although research in this area was limited. Conclusion: The present systematic review suggested that biomechanical variables may vary among the limbs of patients with ACLR, between 18 and over 28 months. Accordingly, an asymmetry between the limbs increases the risk of re-injury. Therefore, a better understanding of the biomechanics of the limbs in the time intervals after ACLR can provide a safer and sooner return to sports activities.
