A year ago I sprained my right ankle. It doesn't hurt but it gives out on me. What could be causing this?

Ankle sprains can often lead to problems with an unstable ankle lasting months to years later. It usually happens when there's weakness of the ankle muscles and a loss of proprioception.

Proprioception is the sense the joint has of its own position. Studies show ankle sprains result in damage to the receptors that signal the joint about its position. These receptors are located in the ligaments, muscles, and tendons. Injury to any of these structures can result in decreased proprioception.

A rehab program to restore muscle strength and proprioception can be helpful.

Valter Santilli, MD, et al. Peroneus Longus Muscle Activation Pattern During Gait Cycle in Athletes Affected by Functional Ankle Instability. In American Journal of Sports Medicine. August 2005. Vol. 33. No. 8. Pp. 1183-1187.