Classification of these injuries is based on examination; radiographs are often not required to guide management. The most common mechanism is an inversion stress that injures, in order, the anterior talofibular, calcaneofibular, and posterior talofibular ligaments. The medial deltoid is the strongest ligament; therefore, isolated injuries are rare, and medial ankle sprains are often associated with lateral malleolar or syndesmotic injuries.
Management and Disposition
Examination should include an anterior drawer test to assess the integrity of the anterior talofibular ligament. The Ottawa Ankle Rules recommend radiographs for: (1) tenderness over the lateral or medial malleolus, or (2) inability to bear weight for four steps both immediately after injury and in the ED. If able to bear weight, injuries are treated with ice packs, elevation, air cast or splint, and early mobilization. If unable to bear weight despite normal radiographs, use a posterior splint, crutches, and close follow-up with orthopedics.
Ankle injuries are the most common musculoskeletal problem in emergency medicine.
Complications include instability, persistent pain, recurrent sprains, and peroneal tendon dislocation.
Both malleoli, the proximal fibula, and the 5th metatarsal should be examined for tenderness when evaluating a patient with an ankle sprain.
Ankle Sprain. Note the dependent ecchymosis and swelling in this patient with a grade 2 left lateral ankle sprain. (Photo contributor: Lawrence B. Stack, MD.)
Medial Ankle Sprain. An eversion injury in a professional athlete caused this rare isolated deltoid ligament sprain. Note localized ecchymosis. Tarsal tunnel syndrome developed over several weeks, taking months to resolve. (Photo contributor: Mimi Knoop.)
Ankle Sprain. Marked swelling and ecchymosis in a patient with a probable grade 3 ankle sprain. (Photo contributor: Selim Suner, MD, MS.)