Ankle sprains are very common, most often resulting from turning the foot inward (inversion). Common findings are pain, swelling, and tenderness, which are maximal at the anterolateral ankle. Diagnosis is by clinical evaluation and sometimes x-rays. Treatment is protection, rest, ice, compression, and elevation (PRICE) and early weight bearing for mild sprains and immobilization followed by physical therapy for moderate and severe sprains; some very severe sprains require surgical repair.
The most important ankle ligaments are the following:
Ligaments of the ankle
Inversion (turning the foot inward) tears the lateral ligaments, usually beginning with the anterior talofibular ligament. Most tears result from inversion. Severe 2nd- and 3rd-degree sprains sometimes cause chronic joint instability and predispose to additional sprains. Inversion can also cause talar dome fractures, with or without an ankle sprain.
Eversion (turning the foot outward) stresses the joint medially. This stress often causes an avulsion fracture of the medial malleolus rather than a ligament sprain because the deltoid ligament is so strong. However, eversion can also cause a sprain. Eversion also compresses the joint laterally; this compression, often combined with dorsiflexion, may fracture the distal fibula or tear the syndesmotic ligaments between the tibia and fibula just proximal to the ankle (called a high ankle sprain). Sometimes eversion forces are transmitted up the fibula, fracturing the fibular head just below the knee (called a Maisonneuve fracture).
Recurrent ankle sprains can damage ankle proprioception and thus predispose to future ankle sprains. Most ankle sprains are mild (1st- or 2nd-degree).
How to Examine the Ankle
Ankle sprains cause pain, swelling, and sometimes muscle spasms. The location of pain and swelling varies with the type of injury:
Generally, tenderness is maximal over the damaged ligaments rather than over the bone; tenderness that is greater over bone than over ligaments suggests fracture.
In mild (1st-degree) ankle sprains, the pain and swelling are minimal, but the ankle is weakened and prone to reinjury. Healing takes hours to days.
In moderate to severe (2nd-degree) ankle sprains, the ankle is often swollen and bruised; walking is painful and difficult. Healing takes days to weeks.
In very severe (3rd-degree) ankle sprains, the whole ankle may be swollen and bruised. The ankle is unstable and cannot bear weight. Nerves may also be damaged. Articular cartilage may be torn, resulting in long-term pain, swelling, joint instability, early arthritis, and occasionally gait abnormalities. Healing of very severe ankle sprains usually takes 6 to 8 weeks.
Diagnosis of ankle sprains is primarily clinical; not every patient requires x-rays.
Stress testing to evaluate ligament integrity is important. However, if patients have marked pain and swelling or spasm, the examination is typically delayed until x-rays exclude fractures. Also, swelling and spasm may make joint stability difficult to evaluate; thus, reexamination after several days is helpful. The ankle may be immobilized until examination is possible.
The ankle anterior drawer test is done to evaluate the stability of the anterior talofibular ligament and thus help differentiate between 2nd- and 3rd-degree lateral ligament sprains. For this test, patients sit or lie supine with the knee at least slightly flexed; one of the clinician's hands prevents forward movement of the anterior distal tibia while the other hand cups the heel, pulling it anteriorly. Forward movement of the foot indicates a 3rd-degree tear.
High ankle sprains injuring the anterior inferior tibiofibular and posterior inferior tibiofibular ligaments and the interosseous membrane should be considered when eversion is the mechanism and when eversion reproduces pain; the distal tibiofibular joint, just proximal to the talar dome, may be tender.
