Once you’ve sprained an ankle, there’s a good chance you’ll sprain it again. And each time the ankle is injured, the more likely it is that you’ll develop chronic ankle sprains. The orthopedic term for this condition is functional ankle instability (FAI). People with FAI report episodes where the foot and ankle just collapse, give way, or roll under them.
Lateral ankle sprains are the most common. Lateral refers to the outside ankle or the side away from the other leg. Physical therapists and athletic trainers help patients regain normal muscle activation and joint proprioception</i after ankle sprains. This type of rehab program is a strategy for preventing future (repeat) ankle sprains. Joint proprioception refers to the joint's sense of its own position.
But sometimes even after rehab, people end up spraining the ankle again. This is a puzzle. If rehab isn't effective, is it because it's the wrong rehab program? Or is there something else going on in the nervous system that can't be changed with rehab? Or maybe there's a need for a different approach altogether.
A recent study at the School of Kinesiology (University of Michigan-Ann Arbor) did some tests to help figure out where the problem was coming from. They specifically focused on muscle activation of the peroneal muscles. The peroneal muscles evert the foot and ankle. Evert means to move it away from the other foot. The idea was to check for a deficit of muscle activation called arthrogenic muscle inhibition (AMI).
AMI refers to the fact that the peroneal muscles are not being activated with sufficient force for a strong muscle contraction. Without this dynamic activation, the ankle is more likely to be unstable, giving way without warning. If the muscle isn’t getting the nerve messages needed to contract, why not? Is there a problem with local control of the nerve to muscle communication pathway? Or is the breakdown occurring more centrally in the spinal cord of the nervous system?
After conducting the experiment, it became clear that the problem was still in the peroneal muscles. It wasn’t a matter of neuromuscular inhibition or processing at the central nervous system interfering with ankle stability. That means we are back to the drawing board reviewing rehab protocols. Obviously current approaches are not restoring peroneal muscle function as needed to prevent reinjury.
If you are following what your trainer gave you, then you probably haven’t been doing anything wrong. And most likely, he or she gave you the most up-to-date program. This study helps point out the need to identify specific exercises, activities, or interventions that target and return peroneal muscle activation to normal. What’s being done traditionally may not be enough or just right for some patients like yourself.