Beyond the body: new research looks at the full impact of an ACL injury

A recent study in the Journal of Orthopaedic & Sports Physical Therapy has claimed that to regain full function after an injury to the ACL, or anterior cruciate ligament, goes beyond the physical and actually requires ‘retraining’ the brain.

According to a controlled laboratory study by the Ohio State University Wexner Medical Center released in November 2016, it was determined that parts of the brain which controlled leg movements went into a lag during the recovery period during an ACL injury, particularly when extending and flexing the knee. In other words, instead of relying on movement and spatial awareness, recovering patients had started to over-rely upon their vision when they didn’t need to before. One researcher compared it to walking in the dark: moving with less speed and confidence, with a strong mistrust in their natural instincts.

While it’s only natural to have your confidence knocked after an injury, the idea that you can’t trust your natural instincts adds a huge mental knock to an equally debilitating physical setback, particularly to a sportsperson. So, what’s causing this – and how can it be avoided?

Where seeing is more important than believing

The study, involving 15 people who had undergone ACL surgery and 15 who hadn’t, put participants through repeated cycles of knee flexion and extension, and surmised that the half of the study group that had been through ACL surgery displayed increased activations in the contralateral motor cortex, lingual gyrus, and the ipsilateral secondary somatosensory area (in other words, the parts of the brain that dealt with processing visual stimuli), and diminished activation in the ipsilateral motor cortex and cerebellum – the part of the brain which regulates and coordinates muscular activity. In other words, they were placing more emphasis on what they saw over how they felt.

Could strobe glasses help?

Ohio-State-University-study-into-brain-and-ACL-injuriesOn the surface, there’s a simple explanation for this: when it comes to the human body, you tend not to miss something until it’s gone, or at least stopped working. In the case of ACL injury, there has been a long layoff period: the wait to get treated, the two weeks of zero movement after surgery, and a period of slow rehabilitation that can last up to six months. That’s a long time to be away from the use of a part of your body that you largely took for granted.

Factor in the statistic that sportspersons who have experienced an ACL injury are anywhere between 30 to 40 times more likely to suffer a second injury in that area compared to an equivalent athlete who hasn’t had one, and it’s clear that an element of doubt will be at the back of the mind of anyone who has undergone ACL surgery.

The scientists at Ohio State are trialling an interesting technique to remedy the overreliance on sight: strobe glasses. The idea is to visually distract clients whilst they work out, in an attempt to re-wire their brain back to its pre-injury state and forcing them to rely on instinct once more.