Ultrasound Secondary Signs for the Diagnosis of Pediatric Distal Forearm Fractures: A Diagnostic Study.

OBJECTIVE: To evaluate the diagnostic accuracy of ultrasound secondary signs of fractures in pediatric patients aged 5-15 y presenting to the emergency department with a clinically non-deformed distal forearm injury.

METHODS: This diagnostic study was conducted in South East Queensland, Australia. Emergency clinicians performed point-of-care ultrasound on eligible patients and recorded secondary signs of fractures (pronator quadratus hematoma [PQH] sign, periosteal hematoma, visible angulation) or physeal fractures (fracture-to-physis distance [FPD], physis alteration). The reference standard was the final fracture diagnosis determined by expert panel. The primary outcome was the diagnostic accuracy of secondary signs for cortical breach and physeal fractures. Diagnostic statistics were reported for each relevant secondary sign.

RESULTS: A total of 135 participants were enrolled. The expert panel diagnosed 48 "no" fracture, 52 "buckle" fracture and 35 "other" fracture. All "other" fractures were cortical breach fractures and included 15 Salter-Harris II fractures. The PQH sign demonstrated high sensitivity and moderate specificity to diagnose cortical breach fractures (91%, 95% Confidence Interval [CI] 78%-97% and 82%, 73%-88%). Poor sensitivity but high specificity was observed for the visible angulation and periosteal hematoma secondary signs. FPD <1cm showed perfect sensitivity and moderate specificity (100%, 80%-100% and 85%, 78%-90%) for diagnosis of Salter-Harris II fracture. Conversely, physis alteration showed poor sensitivity but excellent specificity (40%, 20%-64% and 99%, 95%-100%) for the diagnosis of Salter-Harris II fractures.

CONCLUSION: Ultrasound secondary signs showed good diagnostic accuracy for both cortical breach fractures and Salter-Harris II fractures. Future research should consider optimal use of secondary signs to improve diagnostic accuracy.