Biomechanic

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.

Background: Dynamic knee valgus (DKV) is due to the weakness of the thigh abductor muscles and the vastus medialis muscle, which increases the internal rotation of the thigh and increases the possibility of anterior cruciate ligament (ACL) injury. The amount of DKV in women is higher than men, which is one of the reasons for the possibility of more injury in women. Aim: The aim of the present study was the effect of acute soccer functional fatigue on knee and trunk kinematic factors in female soccer players with and without DKV during single leg landing. Materials and Methods: The present study is quasi-experimental research conducted on 28 female soccer players who were selected using purposeful and convenience sampling. They were classified into two groups with and without DKV. The subjects performed a single leg soccer landing, and the kinematic changes of the participants' trunk and knees were recorded through high-speed video cameras (SONY camera) in two sagittal and frontal planes and analyzed by Kinovea software. The data were analyzed in SPSS-26 software using a mixed ANOVA statistical test.Results The results revealed a significant interaction effect between fatigue conditions and groups on knee and trunk joint angles in frontal plane in the initial contact with the ground in single leg landing. The results showed that fatigue significantly reduced knee flexion and increased knee valgus and trunk lateral flexion increased significantly after fatigue. Conclusion: The results indicated the acute effect of fatigue on knee and trunk kinematics of female soccer players with DKV. Therefore, by increasing the amount of knee and trunk flexion and correcting the landing technique, the possibility of ACL injury in fatigue can be reduced.