Diagnostic accuracy of ultrasound for upper extremity fractures in children: A systematic review and meta-analysis

Abstract

Objective

Ultrasound has an excellent diagnostic accuracy for fractures that is reportedly comparable to plain radiographs. We aim to summarize the diagnostic accuracy of ultrasound for upper extremity fractures in children.

Methods

Databases were searched from inception through November 2019 using pre-defined index terms, including “ultrasound,” “fractures of upper extremities” and “children”. The study is reported using Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies (PRISMA-DTA). Meta-analysis of the diagnostic accuracy of ultrasound for fractures was conducted using the random-effects bivariate model. Subgroup analysis of fracture site (elbow vs non-elbow fractures) was also performed. Meta-regression was performed to determine if the site of fracture affected the diagnostic accuracy.

Results

Thirty-two studies were identified in the meta-analysis. Ultrasound for fractures of the upper extremities has a sensitivity: 0.95 (95% CI: 0.93–0.97), specificity: 0.95 (95% CI: 0.91–0.98), positive likelihood ratio: 21.1 (95% CI: 10.8–41.5) and negative likelihood ratio: 0.05 (95% CI: 0.03–0.07), with an area under ROC (AUROC) curve of 0.98 (95% CI: 0.97–0.99). Subgroup analysis for elbow fracture showed ultrasound has a sensitivity: 0.95 (95% CI: 0.86–0.98), specificity: 0.87 (95% CI: 0.76–0.94), positive likelihood ratio: 7.3 (95% CI: 3.7–14.4) and negative likelihood ratio: 0.06 (95% CI: 0.02–0.16), with an AUROC of 0.96 (95% CI: 0.94–0.97). Meta-regression suggested the fracture sites would affect diagnostic accuracy of ultrasound (elbow vs non-elbow, p < 0.01).

Conclusions

Current evidence suggests ultrasound has excellent diagnostic accuracy for non-elbow upper extremity fractures in children, serving as an alternative diagnostic modality to plain radiographs.

Introduction

Acute bone fractures in children are a common reason for emergency department visits. The most common site of pediatric fractures is the distal forearm, accounting for 20–36% of all fractures [1,2]. The annual incidence of forearm fractures is estimated at 151–240 per 10,000 children [1]. The estimated costs related to treating childhood distal forearm fractures exceed two billion dollars per year in the United States [3], which does not include incalculable costs in lost workforce productivity from parents, lost school days, and other aspects [3,4].

Currently, plain radiographs serve as the gold standard to diagnose fractures of the upper extremities. However, the diagnosis of these fractures can be challenging in children as the bones of younger children are not completely ossified and have both more haversian canals and stronger periosteum, making some minor fractures difficult to visualize radiographically [[5], [6], [7], [8]].

The prevalence of occult ankle fractures in children was reported 24% in one meta-analysis, and another prospective study reported occult elbow fractures in children to be 13% [9,10]. Furthermore, certain pediatric fractures, including type I and type V Salter Harris fractures through the growth plate, may not be visible on X-ray, and radiography exposes children to ionizing radiation associated with adverse outcomes in the future [11]. Alternatively, magnetic resonance imaging (MRI) has superior diagnostic accuracy for not only fractures but also surrounding soft tissue abnormalities and unossified structures without exposure of ionization [11]. However, this is an impractical imaging modality given the cost and time associated with MRI as well as the potential need for anesthesia [11]. Additionally, in certain resource-limited settings, there is limited access to radiography, computed tomography (CT) or MRI.

Ultrasound may serve as a useful alternative imaging modality as it possesses excellent diagnostic accuracy for musculoskeletal pathologies [12]. Ultrasound does not use ionizing radiation, and it allows real-time bedside assessment, making it an appealing option for certain pathologies in children [[13], [14], [15]]. It has been increasingly studied as an alternative imaging modality for the diagnosis of fractures of the upper extremities [[16], [17], [18], [19]]. Previous meta-analyses have supported the use of ultrasound for upper extremity fracture diagnosis in adults [6,20]. However, as is often the case, the pediatric-specific literature on this topic is more limited. It is also unclear if the specific fracture site affects the diagnostic accuracy of ultrasound to detect fractures in children. The evidence for the use of ultrasound for fractures of the elbow was mixed in previous prospective studies and a recent meta-analysis, given the surrounding complex anatomy and the variation in ossification centers in pediatric elbows [[21], [22], [23], [24], [25], [26]]. Therefore, the objective of this meta-analysis is to both evaluate the diagnostic accuracy of ultrasound for upper extremity fractures in children and determine if the site of fracture affects its accuracy.