High (Syndesmotic) Ankle Sprain

A high ankle sprain is a tear of the ligaments that hold the two lower-leg bones (the tibia and fibula) together just above the ankle, the syndesmosis. This is different from the much more common lateral ankle sprain, which involves the ligaments on the outside of the ankle below the joint. High ankle sprains usually happen when the foot is forcefully twisted outward or pushed up. They typically take two to three times longer to heal than a standard lateral sprain, and unstable ones often need surgery.

They are most common in American football, rugby, and ice hockey. An associated fracture higher up the fibula (called a Maisonneuve fracture) always has to be ruled out: the same twisting force can break the bone several inches above the ankle.

Pain sits higher than a regular ankle sprain, above the ankle joint, along the front and outside of the lower leg between the two tibias. Walking is much more painful than with a standard lateral sprain, and the swelling often appears higher up the leg rather than around the ankle bone. Pushing off or rotating the foot outward typically reproduces the pain.

Unlike a lateral ankle sprain, which often feels better within a week or two, a high ankle sprain lingers. Many athletes describe a deep ache that worsens when they try to cut or pivot. If the syndesmosis is unstable, meaning the gap between the two leg bones has widened, the ankle may feel like it gives way or won’t support pushing-off forces during running.

A focused physical exam of the ankle looks for tenderness above the ankle on the outside of the leg. X-rays show whether the gap between the two leg bones at the ankle has widened, and standing X-rays of both ankles together help identify subtle instability. MRI and CT confirm ligament injury and any widening. X-rays of the entire fibula are essential to rule out the Maisonneuve fracture.

The first question we answer is whether the injury is stable or unstable, because that single fact decides the whole plan. A stable high ankle sprain, where the two leg bones have not separated, heals on its own with protection and time. An unstable one, where the gap between the bones has widened, needs surgery to hold the bones together while the ligaments heal. The steps below cover the stable path; the unstable path is described under Surgical options.

Either way, expect this to take longer than an ordinary ankle sprain. A high ankle sprain typically heals two to three times slower than a standard lateral sprain, so patience through the early phase is part of the treatment.

Any widening of the gap between the leg bones at the ankle (called diastasis) needs surgical stabilization, usually a screw or a flexible "tightrope" that holds the two bones together while the ligaments heal. Without that, the ankle will heal in a permanently unstable position and arthritis follows.

External patient-education references and related OSI pages for additional background:

• AAOS OrthoInfo, patient education library
• OSI glossary, orthopedic terminology in plain language