Sprains to the lateral ligaments of the ankle are responsible for more time lost from sports participation than any other injury, and the rate of the recurrence has been reported to be as high as 80%.
Functional ankle instability is said to occur when the individual repeatedly feels their ankle ‘giving way’ without a specific mechanical cause. It can result from :
- Loss of proprioception. Errors in detecting ankle positions prior to ground contact, technically termed proprioceptive deficit, can impair the athlete’s ability to prepare the ankle to accept and transfer load during challenging athletic tasks such as changing direction or landing from a jump.
- Muscle weaknesses and inhibition. This is a natural reaction after joint damage or soft tissue injury.
- Poor postural control.The body’s postural control system aims to maintain postural equilibrium doing all activities. There is evidence to suggest that the body modifies its posture control system after repeated ankle sprains in effort to preserve balance.
- Altered movement strategies. The ability to pre-emptively stabilize the ankle joint on the ground by force contact is vital when running or going over uneven ground. This anticipatory muscle action is often lost in chronic ankle instability. The peroneal muscles, which should act quickly to provide reactive stability, have often lost this ability for anticipatory action.
Muscle strength should not be used as the benchmark for a return to sport. Studies have shown that altered motor control strategies are preventing people from achieving a stable ankle joint after injury predisposing then to further episodes of instability. E.g, those with chronic ankle instability seem to decrease the amount of dorsiflexion after a jump. It’s as though the brain believes that by making the joint rigid, it’s making it safer, which only predisposes the ankle to further injury as it is less able to absorb landing forces evenly.
Chronic ankle instability is a multi-dimensional problem. It can be the product of interaction between mechanical and functional factors. Rehabilitation of the sprained ankle should aim to avoid subsequent chronic events, not just manage the acute sprain.
The clinical significance of this, multi-dimensional problem is that muscle strength should not be used as the only benchmark for a return to sport. As well as strengthening, rehabilitation should include training of proprioception and balance in a range of functional positions and activities.
knowledge … self-management … prevention