Emergency department use of ultrasonography to detect lateral ankle fractures

Abstract

Study objectives: Ankle injuries are commonly treated in the emergency department (ED). There are several published decision rules to aid the emergency physician to determine which patients require radiographs as part of their evaluation. Recently, ultrasonography has been used to evaluate fractures. The purpose of this study is to determine whether emergency physicians with minimal training could accurately determine the presence or absence of lateral ankle fractures in the ED with the use of a bedside ultrasonography. We report preliminary data of an ongoing study. Methods: A convenience sample of adult patients who presented to the ED after trauma and presenting with tenderness and swelling over the lateral malleolus was eligible for inclusion. Verbal consent was obtained. Emergency attending physicians and resident physicians who underwent a 10-minute discussion and demonstration of the use of ultrasonography to evaluate lateral malleolar injuries performed the studies. The physicians were asked after performing the ultrasonography whether they believed there was a fracture. Their responses were then compared with the radiologist's interpretation of the radiograph. Results: There were 12 ultrasonographic examinations performed by emergency attending physicians; 8 were interpreted as negative, and none of these had fractures identified on radiograph. Four were interpreted as positive, 3 had fractures identified on radiograph (positive predictive value 75%, negative predictive value 100%, sensitivity 100%, specificity 88.9%). Of the 16 resident ultrasonographic scans, 12 were interpreted as negative; 1 had a fracture identified on radiograph. Four were interpreted as positive, and 3 of these had fractures identified on radiograph (positive predictive value 75%, negative predictive value 91%, sensitivity 75%, specificity 91%). Conclusion: Preliminary results appear to demonstrate good negative predictive value for detection of lateral ankle fractures. Greater numbers are needed to draw conclusions, and this study is ongoing. However, ultrasonography in combination with physical examination may show promise in identifying which patients may forgo radiograph.