High ankle sprain

Lore & Background

The mechanism of a high ankle sprain involves the talus, which is wider anteriorly than posteriorly, being forced into the mortise created by the tibia and fibula. When the foot is dorsiflexed and simultaneously externally rotated, the widening talus stresses the syndesmotic ligaments. This can occur in sports such as hockey when a player's skate strikes the boards, or in football when a rotational force is applied to the heel of a player on the ground.

Reader's Guide

Diagnosis of a high ankle sprain can be challenging because swelling is often minor or nonexistent, and the injury may be mistaken for a more common lateral ankle sprain. Clinical tests such as the squeeze test, dorsiflexion with compression, and external rotation test are used, but no single test is sufficient; diagnosis typically combines multiple tests with imaging. Plain X-rays may show widening of the mortise or associated fractures, but normal X-rays do not rule out significant ligament injury. Ultrasound or MRI can visualize the ligament directly. Treatment depends on severity, ranging from rest, ice, compression, and elevation to surgery with internal fixation for unstable injuries. Rehabilitation focuses on protecting healing ligaments by limiting external rotation, using casts or walking boots, and gradually permitting weight-bearing. Early resistance exercise and electrical stimulation may combat muscle atrophy.

Did You Know?

• High ankle sprains comprise approximately 15% of all ankle sprains.
• The most common mechanism is external rotation of the lower leg and foot.
• The anterior inferior tibio-fibular ligament is the most vulnerable structure in this injury.
• In one study, the ratio of diagnostic X-ray to known syndesmotic injury was only one in 17.

Anatomy and the Mechanics of Injury

A high ankle sprain, formally called a syndesmotic ankle sprain, targets the ligaments that bind the tibia and fibula together in the lower leg. These ligaments form what is essentially a mortise-and-tenon joint for the ankle, and because the injury sits above the ankle joint itself, the term "high" is used. Roughly fifteen percent of all ankle sprains fall into this category. The mechanism differs sharply from the more familiar lateral sprain: rather than an inward twist of the foot, a high ankle sprain results from external rotation—the lower leg and foot twisting outward. The geometry of the joint makes this particularly dangerous. The talus bone is broader at its front than at its back, so when the foot is dorsiflexed and simultaneously forced into external rotation, the widening talus presses against the already-constrained mortise, concentrating enormous stress on the anterior inferior tibio-fibular ligament. That ligament can stretch, partially tear, or rupture completely, and if the force continues, damage can propagate up the interosseous membrane to the top of the fibula, producing a Maisonneuve fracture.

The Diagnostic Puzzle

Diagnosing a high ankle sprain is notoriously difficult, and many cases are initially missed or mislabeled as a routine lateral ankle injury. Patients typically report pain along the outer-front of the lower leg, just above the ankle, with discomfort that worsens when the foot is twisted outward. A complicating factor is that visible swelling is often minimal or entirely absent, making the injury easy to overlook. Clinicians have developed several physical tests—the squeeze test, dorsiflexion with compression, and a seated external-rotation maneuver—but none on its own is reliable enough to confirm or rule out the injury. Diagnosis therefore usually requires combining multiple clinical findings with imaging. Plain X-rays can reveal widening of the tibio-fibular mortise, a medial malleolus fracture, or a Maisonneuve fracture, yet a completely normal radiograph does not exclude significant ligament damage; one study found that only one in seventeen known syndesmotic injuries showed up on X-ray. Ultrasound offers the advantage of visualizing the ligament under stress, while MRI can directly demonstrate the torn or stretched tissue when clinical suspicion persists.

Treatment Pathways and Rehabilitation

Management of a high ankle sprain ranges from a few days of rest to as long as six months of recovery, depending on severity. The traditional first-line approach involves rest, icing, compression, and elevation, but a growing alternative called H.E.M.—standing for healthy blood flow, eliminate swelling, and mobility—challenges the use of ice, arguing that prolonged cold application increases lymphatic vessel permeability and actually drives more fluid into the injured area, worsening swelling and pain. Instead, H.E.M. promotes proactive rehabilitation to restore range of motion, stability, and strength, citing research that macrophages are essential for muscle to return to its pre-injury state. Two critical decisions must be made early: whether the ankle is stable or unstable, and how much weight the patient can bear. Instability may necessitate specialist referral, surgery, and internal fixation. Rehabilitation is especially important because a significant share of these sprains also involve medial or lateral ligament damage, making slow recovery and lingering symptoms common. Protecting the healing ligaments from further external rotation is a primary concern, typically managed with short-leg casts, walking boots, or custom orthoses.

On the Field: Sports Scenarios and Injury Progression

High ankle sprains have a strong association with specific sports situations. In hockey, the classic scenario involves a player's skate blade striking the boards while the foot is simultaneously forced into external rotation, generating the exact combination of dorsiflexion and outward twist that overloads the syndesmotic ligaments. In football, a player may be on the ground with the leg trailing behind, the foot at a right angle to the shin, when a sudden rotational force is applied to the heel—such as when another player falls on the foot. In many cases the movement happens so rapidly that the athlete never consciously registers what caused the injury. The damage follows a predictable cascade. The anterior inferior tibio-fibular ligament, which anchors the lower tibia to the fibula and is vital for maintaining the mortise, is the first structure to give way. If the force continues, the medial malleolus and medial collateral ligament on the inner ankle provide some resistance, but if they too fail, the load travels up the interosseous membrane that holds the two bones together along their length, potentially exiting at the upper end of the fibula as a Maisonneuve fracture.