Changes in Stretch Reflex Excitability Are Related to “Giving Way” Symptoms in Patients With Anterior Cruciate Ligament Rupture

Abstract

A rupture of the anterior cruciate ligament (ACL) usually leads to an altered stretch reflex excitability of the thigh muscles that stabilize the knee. The purpose of this study was to quantitatively assess reflex activity in the m. semitendinosus/semimembranosus after anterior tibial translation in 21 patients with isolated ACL ruptures. The patients were divided into a group with "giving way" symptoms (noncopers, n = 12) and a group without "giving way" symptoms (copers, n = 9). While the patients were standing upright with 30 degrees knee flexion, a force of 300 N was applied to the knee to induce posterior-anterior tibial translation. Activity of m. semitendinosus/semimembranosus was measured using surface electromyography (EMG). A linear potentiometer was placed on the tibial tuberosity and measured maximum tibial translation during standing (i.e., functional condition). In addition, knee laxity was assessed with a KT1000 arthrometer under passive conditions. After ACL rupture, the short-latency response (SLR) latency remained unchanged (P = 0.21), whereas for the medium-latency response (MLR) it was significantly longer (P < 0.001). Significantly longer MLR latencies were noted for noncopers compared with copers (P < 0.01), whereas SLR latencies were similar. Significant differences between healthy and injured legs were noted after tibial translations using KT1000 (P < 0.001) and during stance (P < 0.001). Mechanical knee instability was found to be unchanged between copers and noncopers (KT1000: P = 0.97; tibial translation: P = 0.31). These results indicate that ACL rupture is associated with altered stretch reflex excitability, which may lead to "giving way" symptoms, and that altered stretch reflex excitability may be more important for the development of "giving way" than the mechanical instability of the knee.

Do peak torque angles of muscles change following anterior cruciate ligament reconstruction using hamstring or patellar tendon graft?

“…There is a direct link among the ACL, the muscles around the knee, [19,20] and the cruciate ligament receptors via the reflex modulation of the gamma-muscle-spindle system, which may participate in the regulation and preprogramming of the muscular stiffness around the knee joint. [21] Moreover, it has been demonstrated that muscular contraction or inhibition of the muscle activity in the contracting muscles could be elicited with nonpainful electrical stimuli to the ACL in humans.…”

Decreased Quadriceps Activation Measured Hours Prior to a Noncontact Anterior Cruciate Ligament Tear

“…30 Ultimately, these changes accentuate hazardous jumping, cutting, and landing patterns, 3,18,22,23,32 leading to increased obtained on the left knee, which revealed a complete rupture of the ACL with intact collateral and posterior cruciate ligaments and intact menisci. This case was unique because preinjury data were available from 2 separate, unrelated studies, of which the main objective was not to prospectively examine ACL injuries but to provide insight into neuromuscular characteristics prior to injury.…”

An Extensive Evaluation of Different Knee Stability Assessment Measures: A Systematic Review

“…On the other hand, Melnyk and Gollhofer [73] concluded that it was hamstring muscle fatigue during submaximal isometric exercises that was the reason behind the longer latencies of the hamstring stretch reflex and not the existing ACL injury. Despite the argument in the literature on its usefulness for detecting the aforementioned variables, the authors suggested that this technique has room for improvement in terms of its applicability in a clinical setting to guide rehabilitation protocols [3,11,74].…”

“…The "giving way" phenomenon associate with knee joint instability has been shown to result from injury to mechanical constraints and associated neuromuscular impairment [3]. At present, an objective and universally-accepted measure of knee joint stability does not exist.…”