title: Ultrasound for paediatric distal forearm fracture diagnosis
Creators: name: Snelling, Peter J
Publisher: name: Griffith University
Year: 2024
Subjects: subject: paediatric
subject: diagnosis
subject: point-of-care ultrasound
subject: distal forearm

description: Background Forearm fractures in children account for almost 2% of all paediatric emergency department presentations and typically involve the distal third. Children's bones have a malleable 'soft' cortex, which can result in buckle (torus) fractures. These fractures can be managed akin to a soft tissue injury, with no routine requirement for follow-up. Radiography (X-ray) is the current reference standard for diagnosis, but point-of-care ultrasound (POCUS) has emerged as an alternative. Ultrasound is portable, accessible and radiation-free. The aims of this Thesis were to investigate the use of ultrasound by emergency clinicians to diagnose paediatric distal forearm fractures with regards to diagnostic accuracy, the utility of ultrasound secondary signs and its effectiveness. Methods Three prospective studies were conducted between February 2018 and November 2021 in which children presenting to the emergency department with clinically non-deformed distal forearm fractures were recruited. First, a diagnostic study evaluated the accuracy of ultrasound conducted by nurse practitioners, compared to X-ray as the reference standard, in a tertiary hospital paediatric emergency department. Second, a prospective cohort study described a novel ultrasound sign, the pronator quadratus haematoma (PQH) sign, and its association with cortical breach fractures, with its presence/absence and muscle thickness (compared to the unaffected side). Third, a multicentre randomised controlled trial (RCT) compared initial diagnosis with ultrasound conducted by a variety of emergency department clinicians (nurse practitioner, physiotherapist, or emergency physician), against X-ray. This RCT was conducted in four hospitals in South East Queensland, including a large tertiary paediatric hospital, two large mixed academic hospitals with dedicated paediatric treatment areas within their emergency departments, and one mixed hospital without a dedicated paediatric treatment area. The effectiveness of ultrasound compared with X-ray as the initial imaging modality was delineated in the RCT by evaluating the physical function of the arm at 4 weeks post injury, measured using the validated Pediatric Upper Extremity Short Patient-Reported Outcomes Measurement Information System (PROMIS) score (range, 8-40, with higher score indicating better function); the noninferiority margin was 5 points. Nested within the main RCT were two further studies: a second RCT and a diagnostic study. The RCT compared diagnostic accuracy of ultrasound with radiography against the reference standard of an expert panel diagnosis. The diagnostic study investigated ultrasound secondary signs within the group who received ultrasound. Results Diagnostic accuracy was determined in both the prospective diagnostic study and the nested RCT. The diagnostic study recruited 204 participants, 129 of whom had X-ray diagnosed fractures. The sensitivity and specificity for nurse practitioner-performed ultrasound compared to radiography reference standard were 94.6% (95% confidence interval [CI] 89.2% to 97.3%) and 85.3% (95% CI 75.6 to 91.6%), respectively. The RCT recruited 270 participants. Ultrasound was more accurate than radiography when determined with an expert panel reference standard (sensitivity 100% [95%CI 95.8-100%], specificity 97.9% [95%CI 89.1-99.6%] versus sensitivity 97.8% [95%CI 92.3-99.4%], specificity 79.5% [95%CI 65.5-88.8%] respectively). The RCT considering the effectiveness of ultrasound, recorded primary outcome data for 262 (97%) participants. Ultrasound was noninferior to X-ray with regards to recovery of arm function at 4 weeks (PROMIS score mean 36.4 and 36.3 points, respectively; mean difference 0.1 point; 95%CI -1.3 to 1.4). No important fractures were missed on ultrasound. Secondary signs were evaluated in both the prospective cohort study and the ultrasound group in the RCT. The prospective cohort recruited 38 participants, with all 22 participants with cortical breach fractures having the PQH sign present (100%; 95%CI 85-100%), while all 16 participants without cortical breach fractures having an absent PQH sign (100%; 95%CI 79-100%). In the RCT ultrasound group, the PQH sign demonstrated high sensitivity and moderate specificity (91%; 95%CI 78% to 97% and 82%; 73% to 88%) for cortical breach fractures and the Fracture-Physis Distance of &lt;1cm showed perfect sensitivity and moderate specificity (100%, 95%CI 80% to 100% and 85%, 78% to 90%) for Salter-Harris II fractures. Discussion This Thesis demonstrates that ultrasound has high diagnostic accuracy with noninferior recovery of arm function in comparison to X-ray, when used as initial imaging for children and adolescents with distal forearm fractures. Additionally, several ultrasound secondary signs were able to accurately diagnose either cortical breach fractures or Salter-Harris II fractures. This Thesis provides a proof of concept that ultrasound provides a safe and effective alternative to X-ray for initial imaging of paediatric distal forearm injuries. Furthermore, it may be of benefit in settings where radiography is less available or more costly. Given the training and resource requirements associated with ultrasound as compared with the current availability of X-ray, the cost-effectiveness of using ultrasound initially should be clarified before implementation into other settings.