Point-of-Care Ultrasonography for Ankle Injuries in Children

Objectives The aim of the study was to determine whether point-of-care ultrasound (US) can decrease x-rays in children with ankle injuries. Secondary objectives were to determine the test performance characteristics for ankle US, analyze diagnostic errors, and compare US with the Ottawa Ankle Rules (OAR). Methods This was a prospective study of children younger than 21 years presenting to an emergency department with an ankle injury requiring x-rays. Pediatric emergency medicine physicians received a 1-hour training session, performed ankle US with a standardized scanning protocol of the distal tibia and fibula, and described the US as positive, negative, or equivocal for fracture. Ankle x-ray interpretation by a radiologist was the reference standard for fracture. Results One hundred twenty patients with a mean age of 13.5 (+/- 4.0) years were enrolled. Nine patients (7.5%) had an ankle fracture on x-ray, and 56 patients (47%) had open physes. Ankle US would reduce x-rays by 81 (67.5%), missing 2 intra-articular, nondisplaced, tibial fractures in patients with open physes. Ankle US had a sensitivity of 78% (95% confidence interval [CI], 40%-97%), specificity of 71% (95% CI, 62%-79%), likelihood ratio for a positive test of 2.7 (95% CI, 1.7-4.3), and likelihood ratio for a negative test of 0.31 (95% CI, 0.09-1.07). The OAR would reduce x-rays by 21 (17.5%), missing one fracture. Ultrasound with OAR would reduce x-rays by 20 (17%) with no missed fractures. Conclusions Point-of-care US has the potential to reduce x-rays for children with ankle injuries; however, nondisplaced, intra-articular tibial fractures may be missed. Ultrasound with OAR may reduce radiographs without missed fractures in this population.