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

Abstract

Purpose 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. Methods 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. Results 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). Conclusions 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. Level of evidence III.

Association between Kinesiophobia and Gait Asymmetry after ACL Reconstruction: Implications for Prevention of Reinjury

“…Early after injury, patients employ a stiffened knee strategy by decreasing the motion at the knee and co-contracting the scaffolding musculature in a probable effort to support the injured knee against repeated instability while doing normal activities [47,48]. These maladaptations continue despite ACLR [3,4,19,49]. The compensatory movement acts of patients with ACLR are not limited to the rebuilt limb.…”

“…The compensatory movement acts of patients with ACLR are not limited to the rebuilt limb. While doing low-demand activities, such as gait, and high-demanding activities like bilateral jump landings, patients with ACLR change their biomechanical demands from the injured limb to their uninjured limb [3,4,50,51]. The compensatory strategies found between the limbs of the patients with ACLR imply that a unilateral ACL injury can extract a bilateral kinetic response [45] through which injured patients also employ another strategy for the uninjured limb.…”

“…Ground reaction forces (GRF) data were collected using force plates with a sampling frequency of 500 Hz. GRF data were filtered using a fourth-order, zero-lag, low-pass Butterworth filter with a 20 Hz cut-off frequency [4]. The chosen threshold for ground contact was defined as the time when vertical GRF (vGRF) exceeds 10 N. Peak vGRF were calculated during the walking for each subject trial, and normalized to the subject's body weight (%BW).…”

“…The surface electromyography (EMG) data were measured using EMG system (MT8 Model, MIE, UK) synchronized with the force plates. The EMG data were collected at 1000 Hz and filtered using a 10-450 Hz fourth-order band pass Butterworth filter and were smoothed using a 50 ms moving window root mean square (RMS) algorithm [4]. All of the trials were normalized to 100% of stance.…”

“…Gait asymmetries following ACLR are evident at 6 months after surgery [3,4] and can persist for many years [5,6]. Asymmetry of lower-limb movements may contribute to the development of OA and increase the risk for reinjury in people with ACL-injured knees [6][7][8].…”