An ankle sprain is an acute injury of the ankle caused by a twisting or rolling of the ankle. This occurs most commonly when the ankle rolls on the outer side (inversion sprain) and the ligaments are either partially or totally torn. It is usually accompanied by significant swelling and pain.

Ankle sprains are classified by Grades. A Grade 1 sprain has no instability. A Grade 2 sprain has a partial ligament tear and Grade 3 involves a total ligament tear. There is also a high ankle sprain with tearing of the ligaments between the two leg bones (the tibia and fibula).

Diagnosis is made by history of injury, clinical examination, and x-ray to rule out a fracture. In chronic sprains, an MRI may be ordered to evaluate the extent of damage to the ligaments.

The initial treatment consists of rest, ice, compression and elevation. A removable pneumatic cast boot is used for a week or two depending on the severity of the injury. This helps to stabilize the ankle and reduce pain and swelling. Early range of motion exercises and physical therapy will strengthen the ligaments. Wearing an ankle brace when participating in sports may help prevent repeat injury. In extreme cases of chronic recurrent sprains, surgical repair may be necessary.