MODEL RELEASED. Sprained ankle. Woman holding her sprained ankle. A sprain occurs when a sudden, violent movement at a joint causes the over- stretching of the joint's ligaments. The joint becomes swollen and difficult to move. Bruising often accompanies the injury. Sprained ankles are a very common injury and are not usually serious. The swelling can be reduced using an ice-pack, bandages, painkillers and rest. It can take several months for a sprain to heal.