Abstract
BackgroundThe aim of this study was to compare muscle activation onset times of knee muscles between the involved and uninvolved knee of patients with unilateral anterior cruciate ligament reconstruction (ACLR), and the uninjured knees of healthy subjects after a controlled perturbation at the ankle level.MethodsFifty male amateur soccer players, 25 with unilateral ACLR using semitendinosus-gracilis graft (age = 28.36 ± 7.87 years; time after surgery = 9 ± 3 months) and 25 uninjured control subjects (age = 24.16 ± 2.67 years) participated in the study. Two destabilizing platforms (one for each limb) generated a controlled perturbation at the ankle of each participant (30°of inversion, 10°plantarflexion simultaneously) in a weight bearing condition. The muscle activation onset times of semitendinosus (ST) and vastus medialis (VM) was detected through an electromyographic (EMG) analysis to assess the neuromuscular function of knee muscles.ResultsSubjects with ACLR had significant delays in EMG onset in the involved (VM = 99.9 ± 30 ms; ST = 101.7 ± 28 ms) and uninvolved knee (VM = 100.4 ± 26 ms; ST = 104.7 ± 28 ms) when compared with the healthy subjects (VM = 69.1 ± 9 ms; ST = 74.6 ± 9 ms). However, no difference was found between involved and uninvolved knee of the ACLR group.DiscussionThe results show a bilateral alteration of knee muscles in EMG onset after a unilateral ACLR, responses that can be elicited with an ankle perturbation. This suggests an alteration in the central processing of proprioceptive information and/or central nervous system re-organization that may affect neuromuscular control of knee muscles in the involved and uninvolved lower limbs.
Highlights
Anterior cruciate ligament (ACL) injuries are common in sporting activities, and are of concern in orthopedic and sports medicine (Kaeding, Léger-St-Jean & Magnussen, 2017)
Investigating muscle activation patterns in the contralateral non-injured leg of anterior cruciate ligament reconstruction (ACLR) patients may help to reveal the role of central nervous system (CNS) adaptations after ACL injury and reconstruction (Dingenen et al, 2015; Dingenen et al, 2016; Grooms et al, 2017; Needle, Lepley & Grooms, 2017)
Significant differences were found for vastus medialis (VM) (P < 0.01) and ST (P < 0.01) in the onset times between the uninvolved knee of the ACLR subjects (VM = 100.4 ± 26 ms; ST = 104.7 ± 28 ms) with the same knee side from uninvolved subjects (VM = 74.4 ± 11 ms; ST = 73.0 ± 8 ms)
Summary
Anterior cruciate ligament (ACL) injuries are common in sporting activities, and are of concern in orthopedic and sports medicine (Kaeding, Léger-St-Jean & Magnussen, 2017). The aim of this study was to compare muscle activation onset times of knee muscles between the involved and uninvolved knee of patients with unilateral anterior cruciate ligament reconstruction (ACLR), and the uninjured knees of healthy subjects after a controlled perturbation at the ankle level. The results show a bilateral alteration of knee muscles in EMG onset after a unilateral ACLR, responses that can be elicited with an ankle perturbation This suggests an alteration in the central processing of proprioceptive information and/or central nervous system re-organization that may affect neuromuscular control of knee muscles in the involved and uninvolved lower limbs
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