Sonographic detection of radiographically occult fractures in paediatric ankle injuries

In some paediatric ankle injuries, the clinical picture is suggestive of a fracture despite negative three-view radiographs. To determine the effectiveness of high-resolution US to differentiate radiographically occult fractures from sprains. During a 12-month period, children aged 5-13 years who had sustained an acute ankle injury suspicious of a fracture on clinical examination, but with negative radiography, were referred for high-resolution US. Follow-up radiographs were obtained after 2-3 weeks. A total of 20 children were examined. In 13, US did not reveal a fracture; small fractures were detected in 7. All patients with negative US studies had negative follow-up radiographs. In six patients with positive US the follow-up radiographs demonstrated a periosteal reaction. In one child in whom a fracture line identified by US was in the depth of the lateral malleolus, the follow-up radiograph demonstrated an area of increased bone density. US is effective for the detection of radiographically silent fractures of the paediatric ankle. It may be used as an adjunct to radiography in clinically suspicious, but radiographically negative ankle injuries.