High (Syndesmotic) Ankle Sprain

A high ankle sprain is an injury to the syndesmotic ligaments that bind the distal tibia and fibula together above the ankle joint — distinct from the far more common lateral ankle sprain which injures the ligaments below the joint. The syndesmosis is stressed by external rotation and forced dorsiflexion. High ankle sprains take significantly longer to heal than lateral sprains (months vs. weeks) and are more likely to require surgery in unstable cases.

They are common in American football, rugby, and ice hockey. Associated fibula fractures (Maisonneuve) must always be excluded.

Tenderness above the ankle at the syndesmosis, the squeeze test (compressing tibia and fibula at mid-calf reproduces ankle pain), and the external rotation stress test. Mortise X-ray assesses tibiofibular clear space widening. Standing bilateral ankle X-rays help identify subtle instability. MRI and CT confirm ligament injury and widening. The entire fibula must be X-rayed to exclude Maisonneuve fracture.

Any tibiofibular widening (diastasis) requires surgical stabilization to restore mortise congruity.

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

• Britannica — Sprain
• Britannica — Ankle (anatomy)
• AAOS OrthoInfo — patient education library
• OSI glossary — orthopedic terminology in plain language