Arthrogenic muscle inhibition (AMI) is a neurological phenomenon that impedes the rehabilitation of injured joints. It is manifested by an inability to voluntarily activate the muscles surrounding an injured joint, even in the absence of direct structural damage to these muscles. Paradoxically, this protective mechanism can prolong recovery and compromise joint function.
Why does AMI arise?
After a joint injury or surgery, the body seeks to protect the affected joint. In addition to pain and inflammation, the brain may inhibit contraction of the surrounding muscles to limit movement and prevent further damage. This process, while protective in the short term, can become problematic if it persists, as it prevents the muscle strengthening necessary to stabilize the joint.
Impact of AMI on rehabilitation
AMI is particularly common in patients who have suffered a rupture of the anterior cruciate ligament (ACL), affecting over 55% of them. It can lead to muscle atrophy, reduced strength and impaired joint function, prolonging the rehabilitation process. What's more, AMI can create a vicious circle: muscular inhibition leads to weakness, which in turn reduces joint stability, thus maintaining the inhibition.
Identify and process AMI
It is crucial to detect and treat AMI at an early stage of rehabilitation. Surface electromyography (EMG) is a valuable tool for quantifying and visualizing muscle activity, helping to identify inhibited and over-activated muscles. By providing real-time visual feedback, EMG helps patients to reactivate inhibited muscles and improve motor control.
Therapeutic strategies to overcome MAI
Several approaches can be used to treat MAI:
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- Manual therapy: Techniques to improve joint mobility and reduce pain.
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- Muscle-strengthening exercises: Specific programs to reactivate inhibited muscles.
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- EMG biofeedback: Using EMG to provide visual and auditory feedback, helping to restore muscle control.
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- Neuromuscular electrical stimulation: Application of electrical currents to stimulate muscles and reduce inhibition.
A combined approach, tailored to the patient's individual needs, is often the most effective way to overcome MAI.
Conclusion
Arthrogenic muscle inhibition is a major challenge in rehabilitation, but with early detection and appropriate interventions, it is possible to restore muscle function and improve patient outcomes. The use of tools such as EMG offers promising prospects for optimizing rehabilitation and helping patients regain optimal joint function.
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Resources and articles
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- Sonnery-Cottet, Bertrand & Ripoll, Thomas & Cavaignac, Etienne. (2023). Prevention of knee stiffness after ligamentoplasty: what is arthrogenic muscle inhibition (AMI)? Revue de Chirurgie Orthopédique et Traumatologique. 109. 10.1016/j.rcot.2023.07.003.
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- Lepley AS, Lepley LK. Mechanisms of Arthrogenic Muscle Inhibition. J Sport Rehabil. 2021 Sep 1;31(6):707-716. doi: 10.1123/jsr.2020-0479. PMID: 34470911.
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- Hopkins, J. & Ingersoll, Christopher. (2000). Arthrogenic Muscle inhibition: A Limiting Factor in Joint Rehabilitation. Journal of Sport Rehabilitation. 9. 135-159. 10.1123/jsr.9.2.135.