Syndesmotic

Syndesmotic is an adjective that relates to the syndesmosis, the fibrous joint formed by the distal tibia and fibula and their connecting ligaments. The syndesmosis stabilizes the ankle mortise and maintains the proper alignment of the leg bones during weight bearing and movement.

Anatomy surrounding the distal tibiofibular joint includes the interosseous ligament, the anterior tibiofibular ligament, the posterior tibiofibular ligament, and the transverse tibiofibular ligament. Together these structures hold the tibia and fibula together above the ankle and allow a small amount of motion while preventing separation of the bones. The interosseous membrane extends proximally from the tibia and fibula and contributes to distal stability.

Injury to the syndesmotic complex, commonly referred to as a syndesmotic injury or high ankle sprain, typically results from external rotation and dorsiflexion of the foot, or a direct blow to the leg. Symptoms include pain and tenderness above the ankle, particularly at the syndesmosis, swelling, and difficulty with weight bearing. Diagnosis relies on clinical examination and imaging. Physical tests such as the squeeze or external rotation test may indicate instability. Radiographs in the mortise view can show widening of the tibiofibular clear space; MRI or CT can assess ligament rupture and associated injuries.

Treatment depends on the degree of instability. Stable injuries may be managed with protected weight bearing, immobilization, and rehabilitation. Unstable injuries or those with disruption of the posterior or other stabilizing ligaments may require surgical stabilization, such as screw or suture-button fixation, followed by a structured rehabilitation program. Recovery can be prolonged compared with other ankle sprains, with return to full activity taking several weeks to months depending on severity.