Ankle sprains are common injuries. Most involve the ligaments on the outside of the ankle, known as lateral sprains. A high ankle sprain is a distinct and typically more severe injury that affects structures located higher up the leg. This type of sprain is often associated with longer recovery periods, making accurate and timely diagnosis important for a successful return to full activity.
Defining the High Ankle Sprain
A high ankle sprain, medically known as a syndesmotic injury, involves damage to the ligaments connecting the tibia and the fibula, the two long bones of the lower leg. Unlike common sprains that injure ligaments stabilizing the main ankle joint, a high ankle sprain affects the syndesmosis—the group of ligaments and connective tissue above the joint itself.
The primary structures involved are the anterior and posterior inferior tibiofibular ligaments. The interosseous membrane, a broad sheet of tissue running between the two bones, can also be involved. These components keep the tibia and fibula tightly aligned, forming the ankle mortise. When these structures are torn or stretched, the stability of the entire ankle complex is compromised.
The severity of a syndesmotic injury is categorized using a grading system based on joint stability. A Grade I injury involves a mild stretch or partial tear with no instability between the tibia and fibula. A Grade II injury signifies a more substantial tear, potentially resulting in instability. A Grade III injury represents a complete disruption of the ligaments, leading to clear instability and widening of the space between the lower leg bones.
Mechanism of Injury
A high ankle sprain is caused by a specific combination of forces acting on the foot and lower leg. The most common mechanism involves the foot being planted firmly while the leg rotates internally or the foot is forcefully twisted outward. This external rotation, often combined with dorsiflexion (foot pointed slightly upward), forces the ankle bone to press against the ends of the tibia and fibula.
This action drives a wedge between the lower leg bones, putting extreme strain on the syndesmotic ligaments. The forceful widening of the space causes the ligaments to stretch or tear. This mechanism explains why high ankle sprains are frequently seen in contact sports like football and hockey, where a player’s foot is planted and then twisted or rolled over.
The resulting injury is a high-force trauma that can sometimes include a fibula fracture, though the ligament injury is distinct. The external rotation force differentiates a high ankle sprain from a lateral sprain, which is caused by the foot rolling inward. Pain and swelling usually manifest higher up the leg than a common sprain, often radiating along the interosseous membrane.
Immediate Care and Initial Medical Treatment
Initial management follows the standard RICE protocol (rest, ice, compression, and elevation) to limit immediate swelling and pain. However, due to the complexity and potential for instability, a medical evaluation is necessary to confirm the diagnosis and rule out more severe injuries. A healthcare provider will perform a physical examination, including specific tests to assess the integrity of the syndesmosis.
Diagnostic methods include the squeeze test, where compression of the tibia and fibula high up the leg causes pain at the syndesmosis. The external rotation test, where the foot is turned outward, also reproduces pain at the injured ligament site. Imaging tests are ordered to confirm the diagnosis and determine the extent of the damage.
X-rays are used first to check for fractures and widening of the space between the tibia and fibula, a sign of severe disruption. Magnetic Resonance Imaging (MRI) is the preferred test for visualizing soft tissues and assessing the extent of ligament tears. Initial treatment for stable injuries involves a period of non-weight bearing, usually in a boot or brace, to immobilize the joint and allow healing.
The Recovery Process
Recovery for a high ankle sprain is typically longer than for a lateral sprain, often requiring six weeks to six months depending on the injury grade. Recovery begins with protection, requiring the patient to avoid putting weight on the injured leg to prevent further separation of the tibia and fibula. A walking boot or cast is commonly used to maintain immobilization and protect the healing ligaments.
Once pain and swelling decrease, rehabilitation progresses through structured phases focused on restoring joint function. The first stage involves gentle range-of-motion exercises to prevent stiffness without stressing the ligaments. This is followed by a strengthening phase, targeting the muscles surrounding the ankle and lower leg to provide dynamic support.
The final stage focuses on functional training, including balance and agility drills, which are crucial for safely returning to sports or demanding activities. For Grade I and stable Grade II injuries, non-operative management is usually successful, with return to activity occurring within two to three months. Grade III injuries, which involve significant instability, often require surgical intervention to permanently stabilize the bones with screws or a specialized suture device.
If surgery is performed, recovery is extended, often requiring four to six months before a full return to sport is possible. Regardless of the treatment path, a gradual and supervised return to activity is important. This ensures the syndesmosis has regained sufficient strength and stability to handle movement forces. The long-term prognosis is favorable, but recovery demands patience and strict adherence to the rehabilitation plan.