I had a severe ankle sprain during a tennis match last year. The ankle feels unsteady to me, like I can't trust it. It also rolls in without warning. Why is this, and what can be done for it?

Ankle sprains are notorious for happening again once you've had one. When the ankle is first hurt, the sprained ligament gets stretched or torn, and the area swells. This can cause the ankle to feel unsteady and roll inward occasionally. This condition is called "give-way" and happens when the ligaments don't support the joint. This is a sign that the nerve sensors that give a sense of position, called "joint sense," have been harmed. Once injured, they don't recover. The loss of position sense puts the joint at further risk of injury.

Proprioceptive exercises help retrain the sense of joint position, by getting the other sensors in the area to do the work of the damaged sensors. These exercises are similar to balance training. Examples include balancing on one leg with your eyes open and then closed, walking on uneven or soft surfaces, and practicing on a special balance board. If the problem continues, you may need the help of a physiotherapist who will design a program that includes these kinds of exercises.