Accuracy of ultrasound in diagnosing ankle injuries in emergency care

Abstract

Background: Ankle injuries are one of the most common presentations in the ED. Although fractures can be ruled out using the Ottawa Ankle Rules, the specificity is low, which means many patients may still receive unnecessary radiographs. Even once fractures are ruled out, assessment of ankle stability is recommended to rule out ruptures, but the anterior drawer test has only moderate sensitivity and low specificity and should be performed only after swelling has receded. Ultrasound could be a reliable, cheap and radiation free alternative to diagnose fractures and ligamentous injuries. The purpose of this systematic review was to investigate the accuracy of ultrasound in diagnosing ankle injuries.

Methods: Medline, Embase and the Cochrane Library were searched up to 15 February 2022 to include studies of patients of 16 years or older presenting to the ED with acute ankle or foot injury, who underwent ultrasound and had diagnostic accuracy as outcome. No restrictions were applied for date and language. Risk of bias and quality of evidence using the Grading of Recommendations, Assessment, Development and Evaluations approach were assessed.

Results: Thirteen studies evaluating 1455 patients with bony injuries were included. In 10 studies, the reported sensitivity for fracture was >90%, but varied among studies between 76% (95% CI 63% to 86%) and 100% (95% CI 29% to 100%). In nine studies, the reported specificity was at least 91%, but varied between 85% (95% CI 74% to 92%) and 100% (95% CI 88% to 100%).Six studies including 337 patients examined the use of ultrasound for ligamentous injuries and found a sensitivity and specificity >94% and 100%. Overall quality of evidence for both bony and ligamentous injuries was low and very low.

Conclusion: Ultrasound has the potential to be a reliable method for diagnosing foot and ankle injuries, however, higher grade evidence is needed.

Prospero registration number: CRD42020215258.

Keywords: emergency department; extremity; fractures; soft tissue injuries; ultrasonography.