Contralateral Limb Differences in Knee Kinetics after Anterior Cruciate Ligament Reconstruction

INTRODUCTION The Anterior Cruciate Ligament (ACL) is the ligament that connects the anterior portion of the tibia to the posterior section of the femur, stabilizing the joint and limiting anterior translation of the tibia. Certain activities involving motions that suddenly strain the knee such as cutting or jumping in basketball or football, can result in an ACL tear. ACL reconstructions (ACLR) are common procedures used to restore joint function in the knee after an injury. Approximately 175,000 reconstructions are conducted annually [1]. Even though ACLR are routine, patients still often have kinematic and mechanical differences in their reconstructed joint compared to their joint pre-injury. These differences are thought to cause variations in joint surface interactions that result in abnormal loading patterns, increasing the risk of premature osteoarthritis (OA) [2]. In order to further improve ACL reconstruction surgeries and understand how these variations in joint surface interactions and loading patterns occur, it is essential to properly investigate the kinetics that occur at patients’ reconstructed and non-reconstructed contralateral knees. Kinetic data can then be used in addition to previously collected bone kinematics, joint surface data, and patient pain scores to further understand knee functionality post ACL reconstruction. A common way to assess the differences in knee kinetics is to look at the knee moments that occur in the sagittal and coronal plane. A moment is defined as the tendency of a force to cause rotation about an axis. From previous studies, it has been thought that an increase in knee adduction moment in the coronal plane can increase the chance of OA development [3]. This is because increasing knee adduction moment results in increased loading of the medial compartment of the knee. From the data observed in this study, the progression of knee joint inconsistencies in function can be measured after surgery. Significant differences between reconstructed and nonreconstructed knee moments are indicative of changes in gait and loading that patients may have due to their response to ACLR. The findings in this study will then be compared to other collected patient data such as the mentioned bone kinematics, joint surface, and pain score data, in order to further understand the degeneration of the knee joint and subsequent development of osteoarthritis.