Diagnostic Value of Dynamic Ultrasound in Supination-External Rotation Injuries

Ankle syndesmosis injuries are common and range in severity from subclinical to grossly unstable. Definitive diagnosis of these injuries can be made with plain film radiographs if the injury is severe enough, but often is missed when severity or image quality is low. Computed tomography (CT) and magnetic resonance imaging (MRI) can provide early definitive diagnosis regardless of severity, but are costly and introduce the patient to radiation when CT is used. Ultrasound diagnosis may circumvent many of these disadvantages by being inexpensive, efficient, and able to detect subtle injuries without radiation exposure. This study evaluates the ability of ultrasound to detect subtle supination-external rotation (SER) ankle syndesmosis injuries with a dynamic external rotational stress test. Nine all male fresh frozen specimens were secured to an ankle rig and stress tested to 10 Nm of external rotational torque with ultrasound monitoring at the tibiofibular clear space. The ankles were subjected to syndesmosis ligament sectioning and repeat stress measurements of the tibiofibular clear space at peak torque. Stress tests and measurements were repeated three times and averaged. Data was analyzed using a two-way repeated measures ANOVA.