Arthrogenic Muscle Inhibition (or motor inhibition) refers to a persistent inability to fully activate a muscle (such as the knee or ankle). This usually occurs following an injury or surgery. This neurological process results in dysfunctional motor inhibition and triggers various compensatory mechanisms within the nervous system. Detecting AMI before or immediately after surgery is therefore essential for limit the risk of developing postoperative stiffness, loss of knee mobility and muscle weakness.
The AMI classification of the knee
In June 2022, Dr. Bertrand Sonnery-Cottet and his team published the first classification of Arthrogenic Muscle Inhibition for the knee. This announcement improves the clinical recognition of arthrogenic muscle inhibition and facilitates its management.
The classification consists of 4 grades, themselves divided into sub-grades:
- Grade 0: at this stage, a normal contraction of the vastus medialis oblique (VMO) is observed;
- Grade 1: Motor inhibition of the VMO is observed, without a deficit in knee extension. This grade is divided into sub-grades, depending on the type of inhibition detected:
- Grade 1A: the inhibition is reversible here once the patient starts performing assisted extension exercises;
- Grade 1B: the inhibition is refractory to simple exercises and requires the implementation of a more advanced rehabilitation process to be addressed;
- Grade 2: At this level, motor inhibition of the vastus medialis oblique is observed, along with a deficit in knee extension, generally induced by involuntary hamstring contraction. In this case, there are also two sub-grades for analyzing this range of motion deficit:
- Grade 2A: the loss of range of motion is reversible by performing some exercises designed to fatigue the hamstrings;
- Grade 2B: the implementation of a more intensive rehabilitation program is necessary to regain the range of motion;
- Grade 3: This grade designates a chronic deficit of passive extension, induced by retraction of the posterior capsule of the joint.
In addition to highlighting the importance of detecting AMI pre- and post-operatively, this classification is essential to consider in order to ensure the implementation of appropriate rehabilitation based on the patient's clinical picture.
The causes of the onset of Arthrogenic Muscle Inhibition
Arthrogenic Muscle Inhibition (AMI) can have several causes. However, trauma and surgery are the most common causes of AMI. These events can lead to inflammation or damage to the knee joint, swelling, or impairment of sensory receptors, even if the initial surgery was successful. This can result in quadriceps muscle weakness and reflex hamstring contracture.
How to treat arthrogenic muscle inhibition?
The management of an AMI involves a phase of knee rehabilitationfollowed by a physiotherapist. The latter is indeed able to offer different exercises and advice to be applied according to the patient's situation. The rehabilitation process aims to strengthen the muscles around the knee, improve joint, facial, and ligament mobility, and reduce the feeling of stiffness that can be caused by arthrogenic muscle inhibition. It also helps the patient understand behaviors that could worsen their injury, in order to eliminate them in their daily life.
The Allyane method to accelerate the processing of an AMI
In addition to the standard treatment pathway, the Allyane neuromotor reprogramming method can accelerate the management of arthrogenic muscle inhibition of the knee. A clinical study presented at the ECOSEP sports medicine congress in November 2021 suggests that an Allyane session increases VMO muscle activity (measured by surface EMG*) by approximately 41%, a statistically significant increase (p<0,001). It also demonstrates that a neuromotor reprogramming session promotes an average reduction in knee flexion contracture of 9,01 statistically significant degrees (p<0,001).
A second study, published in the scientific journal Sports HealthThis study highlights the clinical benefits of a 1-hour Allyane neuromotor reprogramming session for knee AMI (Acute Muscle Imaging). A 17,5% increase in knee function and a 45% increase in vastus medialis oblique (VMO) activation were observed at the end of this session using the Allyane method.
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* Average of three isometric contractions of the Vastus Medialis Oblique