Loss of neuromuscular control related to motion in the acutely ACL-injured knee: an experimental study

Abstract

Ligamentomuscular and muscular stretch reflexes are known to contribute to knee joint stability. After anterior cruciate ligament (ACL) injury, a more intense and adjusted muscular response is required to maintain joint stability, but this neuromuscular control of the knee has not been clearly proved. The aim of the study is to record electromyography (EMG) signal and muscular fibre length variations in quadriceps and hamstrings of the knee with and without ACL, and to analyze and integrate the ligament strain and the muscular reaction to forced anterior tibial translation (ATT). In 17 knees from 12 cats, EMG electrodes and ultrasonomicrometry crystals were inserted into four main periarticular muscles, with strain gauges on periarticular ligament insertions. Their output signal was compared before and after ACL surgical section in series of ATT (at 90 degrees and 30 degrees knee flexion), and also during knee flexion and extension. Linear regression analysis was performed between the EMG signal and muscular fibre length variations, and between the EMG signal and the strain on ligament insertions, in the search of this reflex neuromuscular response. In the ACL deficient knees, the studied muscles showed a poor adjustment to motion of EMG firing, inversely to controls. The muscle stretch reflexes showed poorer correlation with post-peak EMG activity than the ligaments. ATT control depended mainly on hamstrings activity in control knees, whereas in unstable knees, quadriceps activity was associated with more tibial translation. Acute ACL-deficient knees showed poor neuromuscular control with weak ligamentomuscular reflexes and no muscular stretch reflexes, suggesting the ineffectiveness of acute muscular reaction to provide early mechanical knee stabilization after injury.

Reduced knee joint moment in ACL deficient patients at a cost of dynamic stability during landing

“…Based on animal models, it is known that transection of the ACL increases the risk for initiation of cartilage breakdown and leads to a degeneration of the structures surrounding the knee joint (Herzog et al, 1993;Brandt et al, 1991;Galois et al, 2004). Consistent with this, recent observations in humans give evidence that ACL deficiency is associated with knee joint instability (Stergiou et al, 2007), afferent sensory dysfunction (Roos et al, 2010;Bonsfills et al, 2008;Konttinen et al, 2006), knee extensor muscle weakness (Suter and Herzog, 2000;Roos et al, 2010) and increases the risk for knee joint pain and osteoarthritis (OA; Herzog et al, 2003;Suter and Herzog, 2000;Roos et al, 2010). Further, it is known that ACLd patients show lower knee joint moments during stance phase for a variety of gait tasks, such as walking (Lewek et al, 2002;Rudolph et al, 2001), running (Rudolph et al, 2001) and stair climbing (Rudolph and Snyder-Mackler, 2004).…”

Functional and Neuromuscular Changes after Anterior Cruciate Ligament Rupture in Rats

“…In this study, we suggested that ACL transection-induced proprioceptive deficits might partially explain our ladder results. Indeed, a previous cat study showed that proprioceptive information was strongly disturbed after ACL rupture (2). Authors found that the information which originated from secondary articular stabilizers to the sectioned ACL could not be enough to ensure a motor control adjustment for stabilizing the knee.…”

“…Given that ACL injury could disturb articular, cutaneous, and mainly muscle mechanosensitive (proprioceptive) information, it was suggested, both in animal and human studies, that these sensitive impairments might contribute to motor reflex alteration (2,4,12). Furthermore, previous studies indicated that the muscle metabosensitive (groups III and IV) afferent activity was also disturbed after medial collateral ligament (MCL) injury in rats, affecting motor reflex activity (16).…”

Neuromuscular efficiency of the vastus lateralis and biceps femoris muscles in individuals with anterior cruciate ligament injuries

“…Likewise, it is well known that ACL injuries are associated with poor neuromuscular control, which leads to diminution of the proprioceptive information as a function of changes to the efficiency of the mechanical receptors responsible for neuromuscular control, 27 disturbances of the somatosensory system 28 and decreased muscle activation and force. 29 According to Hewett et al, 30 coordinated coactivation of the hamstrings and quadriceps has an important role in decreasing the risk of primary injury.…”