Although not the standard of care, ultrasonography (US) is gaining traction as a means of investigating the integrity of the syndesmotic ligaments. US is inexpensive, readily available in many clinics, allows for dynamic testing, and avoids radiation exposure.7 However, US requires a skilled sonographer with experience in the ankle joint for an accurate diagnosis. If the workup with advanced imaging is inconclusive, but a high degree of suspicion remains for an unstable syndesmotic injury, consider arthroscopy to directly visualize and assess the syndesmotic structures.1,2,5,7,8
Grading the severity of the injury and pursuing appropriate Tx
Typically, the severity of a syndesmotic injury is classified as fitting into 1 of 3 categories: Grade I and II injuries are the most common, each accounting for 40% of syndesmotic injuries, while 20% of high ankle sprains are classified as Grade III.12
A Grade I injury consists of a stable syndesmotic joint without abnormal radiographic findings. There may be associated tenderness to palpation over the distal tibiofibular joint, and provocative testing may be subtle or normal. These injuries are often minor and able to be treated conservatively.
A Grade II injury is associated with a partial syndesmotic disruption, typically with partial tearing of the AITFL and interosseous ligament. These injuries may be stable or accompanied by mild instability, and provocative testing is usually positive. X-rays are typically normal with Grade II injuries, but may display subtle radiographic findings suggestive of a syndesmotic injury. Treatment of Grade II injuries is somewhat controversial and should be an individualized decision based upon the patient’s age, activity level, clinical exam, and imaging findings. Therefore, treatment of Grade II syndesmotic injuries may include a trial of conservative management or surgical intervention.
A Grade III injury represents inherent instability of the distal tibiofibular joint with complete disruption of all syndesmotic ligaments, with or without involvement of the deltoid ligament. X-rays will be positive in Grade III syndesmotic injuries because of the complete disruption of syndesmotic ligaments. All Grade III injuries require surgical intervention with a syndesmotic screw or other stabilization procedure.1,6-8,15
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