New, specific ultrasonographic findings for the diagnosis of pulled elbow

OBJECTIVE Among infants and preschool children with complaint of upper extremity immobility, pulled elbow, also known as nursemaid's elbow or radial head subluxation is the most common cause presenting to pediatric emergency departments. However, proper tools to diagnose pulled elbow remain limited. We conducted a study to determine the feasibility of ultrasonography in diagnosing pulled elbow. METHODS Infants and preschool children presenting to an urban emergency department with the complaint of upper extremity immobility between April and July 2013 were enrolled. The following ultrasonographic information was recorded: (1) whether there was a change in the shape of the supinator muscle, (2) whether there was an annular ligament in place, and (3) whether there was an enlargement of the synovial fringe. We used the affected arms' ultrasonographic images as the study group and opposite arms' ultrasonographic images as the control group. RESULTS When we diagnosed pulled elbow using ultrasonographic findings (i.e., the annular ligament was not in place), we found the following results: sensitivity, 64.9% (95% CI, 47.5% to 79.8%); specificity, 100.0% (95% CI, 90.5% to 100.0%); positive predictive value, 100.0% (95% CI, 85.8% to 100.0%); and negative predictive, 74.0% (95% CI, 59.7% to 85.4%). CONCLUSION A pulled elbow can easily be confirmed by ultrasonography when the annular ligament is displaced.