Ankle sprains are among the most frequent lower-body injuries. Most involve the ligaments on the outer side of the ankle joint, often referred to as a lateral ankle sprain. A high ankle sprain is a less common but often more complicated and severe variation of this injury. This injury affects a specific set of ligaments, dictating a much longer recovery process. Understanding this difference is important, as a high ankle sprain requires a unique approach to diagnosis and treatment.
Anatomy of the Syndesmosis and Defining the Injury
The ankle joint is formed by three bones: the tibia (shin bone), the fibula, and the talus. A high ankle sprain involves the ligaments that connect the tibia and fibula, a fibrous joint known as the distal tibiofibular syndesmosis. This syndesmosis is a complex of four main ligaments, including the anterior inferior tibiofibular ligament (AITFL) and the posterior inferior tibiofibular ligament (PITFL).
These ligaments act as a strong binding mechanism, holding the two lower leg bones tightly together just above the ankle joint. This stable connection maintains the integrity of the ankle “mortise,” the socket that holds the talus bone. When a high ankle sprain occurs, these syndesmotic ligaments are stretched or torn, causing instability between the tibia and fibula. The injury is called “high” because the pain and ligament damage are located above the ankle joint line, unlike a common lateral sprain.
Common Causes and Identifying Symptoms
A high ankle sprain typically occurs when the foot is planted on the ground and forcibly twisted outward (external rotation), often combined with dorsiflexion. This forceful motion drives the talus bone upward into the mortise, pushing the tibia and fibula apart and tearing the syndesmotic ligaments. This mechanism is common in contact sports like football, lacrosse, and skiing, where the leg is rotated while the foot is fixed.
Symptoms differ from a common sprain, which causes pain primarily on the outer ankle. Pain from a syndesmotic injury is usually felt higher up, between the lower leg bones just above the ankle. This pain is significantly worse when the patient attempts to bear weight or twist the foot outward. Swelling and bruising may be present, but they are often milder than a lateral sprain, which can lead to the severity of the injury being underestimated.
Clinical Diagnosis and Severity Grading
A medical professional begins diagnosis by taking a history of the injury mechanism, followed by a physical examination. Two maneuvers are commonly used to assess the integrity of the syndesmosis: the squeeze test and the external rotation test. The squeeze test involves compressing the tibia and fibula together at the mid-calf, which elicits pain at the syndesmosis if the ligaments are injured. The external rotation test involves rotating the foot outward, also reproducing pain at the site of damage.
Imaging is often necessary to confirm the diagnosis and assess instability. X-rays check for bone fractures and measure the distance between the tibia and fibula; widening suggests a significant ligament tear. An MRI scan may be ordered to visualize soft tissue damage and confirm the extent of the ligament injury. The injury is classified into three grades based on joint stability:
- Grade I involves a mild stretch without joint instability.
- Grade II is a partial tear with some potential for mild instability.
- Grade III is a complete tear resulting in significant joint instability.
Managing the Injury and Recovery Expectations
The treatment approach is determined by the injury grade and the stability of the syndesmosis. For Grade I and many stable Grade II injuries, non-operative treatment is standard. This involves rest, immobilization in a boot or brace, and a period of non-weight bearing. Physical therapy is then initiated to restore range of motion, strength, and balance, using gentle exercises that avoid external rotation and excessive dorsiflexion.
Unstable Grade II and all Grade III injuries, where the tibia and fibula separate significantly, often require surgical intervention. The goal of surgery is to restore the normal alignment and stability of the syndesmosis by fixing the two bones together. This fixation is typically done using specialized screws or a suture button device. Following surgery, a period of strict non-weight bearing is required to allow the ligaments to heal in a stable position.
A high ankle sprain has a prolonged recovery timeline compared to a common ankle sprain. It takes longer to heal because the syndesmotic ligaments have a poor blood supply and are under high mechanical stress. Non-operative recovery for a stable injury ranges from six weeks to three months before a full return to activity is possible. Injuries requiring surgical fixation generally face an even longer recovery, often taking three to six months or more, which is particularly challenging for athletes.