Knee transverse plane movements and muscle activity post-anterior cruciate ligament reconstruction

Abstract

Background: The anterior cruciate ligament (ACL) is a supporting ligament of the knee whose role is to limit anterior and internal movement of the tibia over the femur. Those who rupture their ACL, a common sports injury, often choose to undergo reconstruction surgery in an attempt to restore function and prevent complications. Changes in the biomechanics at the knee are seen to persist despite surgery and it is these changes that may be the cause for re-injury and early joint degeneration. Aim: This study aims to investigate the transverse plane rotation of the ACL reconstructed knee at two time frames post surgery - one year and two years. It also aims to track the activity of two major muscles around the knee joint at the same time frames post ACLr. Setting: Controlled laboratory study. Subjects: 11 subjects who underwent anterior cruciate ligament reconstruction (ACLr) at one year (5 subjects) or two years (6 subjects) post surgery. Methods: Three dimensional motion analysis with an optoelectronic motion capture system system was used to capture gait and sidestep turn analysis. Electromyography (EMG) activity for the quadriceps and hamstrings was recorded for the gait cycle. From analysed data, a symmetry index between the operated and non-operated limbs was calculated. Results: During gait, the operated knee showed less amounts of rotation in the transverse plane. This was more evident at one year post ACLr when compared to two years. During a sidestep turn, when acting as the leading leg the operated knee showed less amounts of rotation. This was of equal amount at one and two years post ACLr. When acting as the supporting leg, at one year post ACLr there was more rotation in the operated knee while at two years post ACLr there was less rotation in the operated knee. During the gait cycle, quadriceps asymmetry is present during 100% at one year and 80% at two years post ACLr. During the gait cycle, hamstring asymmetry is present during 70% of the gait cycle at one and two years post ACLr. Conclusion: Following ACLr there are significant differences in the range of rotation in the transverse plane at the knee at one and two years following surgery, both during gait and sidestep turns. There is also asymmetry in the muscle activity of quadriceps and hamstrings during gait post ACLr.