Journal Club: Ultrasound is not reliable for diagnosing ankle fractures

Compared with the gold standard radiograph, point-of-care ultrasound (POCUS) has high specificity but poor sensitivity for detecting pediatric ankle fractures in children and so is an inadequate screening tool for detecting such fractures, according to a recent report. The prospective observational study, conducted in the emergency departments of 2 children’s hospitals, also determined that POCUS is not superior to radiographs as a screening tool even when combined with the Ottowa Ankle Rules (OAR).

The study group included 118 patients with a median age of 12 years who had a chief complaint of acute ankle injury or ankle pain. Investigators obtained 6 US views in longitudinal and transverse dimensions for each patient and considered a cortical defect, discontinuity, avulsion, or axial deviation of the bone surface as a fracture. US findings were documented before ordering an X-ray or reviewing the radiologist’s X-ray interpretation, which was the reference standard. Fractures considered clinically significant were displaced fractures, tibia or medial talar fractures, talar dome fractures, and distal fibular diaphyseal fractures.

A total of 17 fractures among 15 patients were identified, 8 of which were clinically significant. The study found that for detecting all ankle fractures, POCUS had a sensitivity of 60%, a specificity of 96%, a positive predictive value of 69.2%, and a negative predictive value of 94.3. As for detecting clinically significant fractures, POCUS had a sensitivity of 87.5%, specificity of 94.6%, a positive predictive value of 53.9%, and a negative predictive value of 99.1.

The study also found that while using POCUS alone can reduce the number of x-rays by 89%, both for all fractures and for clinically significant fractures, in this study, it missed 6 fractures, including 1 that was clinically significant. Investigators concluded that POCUS alone or combined with OAR does not eliminate the need for ankle radiography for evaluation of acute ankle injuries.

THOUGHTS FROM DR. FARBER

As readers of my column should have figured out, I am very fond of US, but this appears to be 1 area where it should not be used for screening. As an aside, I note that the authors also did not think OAR was useful as a screening tool, contrary to several other studies.

Reference

Smith KM, Zimmerman E, Trotter Z, Wai S. Diagnostic accuracy of point-of-care ultrasound for acute pediatric ankle injuries. Pediatr Emerg Care. 2025; Jul9. doi:10.1097/PEC.0000000000003439. Online ahead of print.