Vertical ground reaction force and knee muscle activation asymmetries in patients with ACL reconstruction compared to healthy individuals.

Abstract

Gait analysis is an important index in the clinical treatment of people with anterior cruciate ligament (ACL) injury. Following unilateral ACL reconstruction (ACLR), the knee kinetic asymmetries are likely to affect the gait cycle. Therefore, the aim of this study was to examine the symmetries of vertical ground reaction force (vGRF) and select the knee muscle activity in gait cycles in participants with and without unilateral ACLR. In this cross-sectional study, vGRF and muscle activity data in difference gait cycles were collected from 56 male subjects (28 with unilateral ACLR and 28 healthy subjects) using force plate and electromyography (EMG), respectively. MATLAB software was used for data analysis and independent t test was employed to compare the two groups. No significant difference was seen between the two groups in the variable of first peak force symmetry (n.s). However, there was a significant difference in the second-peak force symmetry index between the two groups (p ≤ 0.001). Regarding muscle activity symmetry in the braking phase of gait, a significant difference was observed in rectus femoris between the two groups (p ≤ 0.001), while no difference was seen in medial gastrocnemius and biceps femoris activity (n.s). In the propulsive phase of gait, there was a significant difference in medial gastrocnemius and biceps femoris muscles activity between the two groups (p ≤ 0.001), while no difference was found in rectus femoris muscle activity (n.s). The results revealed that unilateral ACLR creates asymmetry in vGRF and muscle activities in different phases of the gait cycle. So, more attention should be paid to this problem in clinical settings, and also to the use of therapeutic interventions to reduce the amount of kinetic asymmetries. III.