by Edith Cowan University

Credit: Pixabay/CC0 Public Domain

Electrical brain stimulation could be the key to getting athletes back on track following anterior cruciate ligament (ACL) injuries, new research from Edith Cowan University (ECU) has shown.

ACL reconstruction is a common intervention for people with ACL injury, with more than 75% of ACL injuries progressing to surgery. Following ACL surgery, exercise-based rehabilitation is currently the best practice intervention to optimize function and return to sport.

However, even with exercise rehabilitation, people with ACL reconstruction struggle to regain quadriceps strength and voluntary activation, ECU post-doctoral research fellow Dr. Myles Murphy said.

“After reconstructive surgery, one of the biggest issues that patients have is muscle weakness. The biggest driver of this is the brain, which actually stops the contraction of important leg muscles and results in rehabilitation being less effective.

“The brain puts in a tremendous amount of effort to stop the contraction of these muscles. We know that in people with an ACL survey, over a period of time, the brain actually starts to recruit unrelated parts of the brain, like the visual centers, to help activate leg muscles.”

West Coast Eagles Head Team Physician Dr. Casey Whife, co-author and sports medicine physician, emphasized the long-term concerns that led him and Dr. Murphy to devise a novel intervention.

“We know that persisting quadriceps weakness leads to poor long-term outcomes, such as reduced participation in sports and increased rates of osteoarthritis. So we wondered, how can we mitigate these brain changes driving persisting muscle weakness?”

In a world-first, Dr. Murphy and Dr. Whife have shown that by putting a small electrical current (transcranial direct current stimulation) through the part of the brain that is responsible for leg muscles while patients are undertaking standard rehabilitation exercises, muscle strength could be maintained while the work of the brain was eased.

“The technique of electrical brain stimulation has been around for decades and is used a lot in other areas, like for the treatment of mental health disorders or neurological conditions. Because the current is so small, and is delivered externally, patients only report feeling ‘tingling or itchiness’ at the point where the sponges are connected to the head,” Dr. Murphy said.

“This study highlights a significant step forward in addressing the neural barriers to recovery after ACL reconstruction. By targeting cortical inhibition, we are paving the way for more effective and efficient rehabilitation strategies, which could help patients regain strength and function sooner,” Dr. Whife added.

The research, now published in BMJ Open Sport & Exercise Medicine, has shown that electrical brain stimulation appeared effective at improving primary motor cortex dysfunction following ACL reconstruction; however, Dr. Murphy is still reviewing the long-term impact of this type of intervention on injury recovery and outcomes.

“Electrical brain stimulation during rehabilitation could represent a low-cost, simple-to-apply intervention, which could be performed as an adjunct to current exercise rehabilitation that may address maladaptive changes to the primary motor cortex postoperatively,” he added.

While these types of devices are readily available commercially, Dr. Murphy recommends that patients get a formal screen to make sure that the devices are safe for individual use, as patients with cochlear implants, pacemakers or other implanted devices would be unable to use this type of intervention.

More information: Myles Calder Murphy et al, Anodal transcranial direct current stimulation (tDCS) modulates quadriceps motor cortex inhibition and facilitation during rehabilitation following anterior cruciate ligament (ACL) reconstruction: a triple-blind, randomised controlled proof of concept trial, BMJ Open Sport & Exercise Medicine (2024). DOI: 10.1136/bmjsem-2024-002080

Journal information:BMJ Open Sport & Exercise Medicine

Provided by Edith Cowan University

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