Ultrasound Assessment of Ankle Syndesmotic Injuries in a Pediatric Population.OBJECTIVE
 To determine sensitivity and specificity for anterior-inferior tibiofibular ligament (AiTFL) integrity and tibiofibular clear-space (TFCS) cut-off points for dynamic evaluation using ultrasound (US) in a pediatric population.


 Prospective cohort study.


 Tertiary care university-affiliated pediatric hospital patients between the ages of 12 and 18 sustaining acute ankle trauma with syndesmotic injury.


 Participants were assigned to the syndesmotic injury protocol that included a standardized MRI and US.


 MAIN OUTCOME MEASURES
 Anterior-inferior tibiofibular ligament integrity for static assessment and TFCS measurements for dynamic assessment on US.  For dynamic assessment, the distance between the distal tibia and fibula was first measured in neutral position and then in external rotation for each ankle.  The US results on AiTFL integrity were compared with MRI, considered as our gold standard.  Optimal cut-off points of TFCS values were determined with receiver operating characteristics curve analysis.


 Twenty-six participants were included.  Sensitivity and specificity for AiTFL integrity were 79% and 100%, respectively (4 false negatives on partial tears).  For dynamic assessment, the cut-off points for the differences in tibiofibular distance between the 2 ankles in  1) neutral position (TFCS N I-U) and  2) external rotation (TFCS ER I-U) were 0.2 mm (sensitivity = 83% and specificity = 80%) and 0.1 mm (sensitivity = 83% and specificity = 80%), respectively.


 CONCLUSIONS
 Static US could be used in a triage context as a diagnostic tool for AiTFL integrity in a pediatric population as it shows good sensitivity and excellent specificity.
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