Accuracy of the sonographic fat pad sign for primary screening of pediatric elbow fractures: a preliminary study

Purpose The purpose of this study was to evaluate the diagnostic accuracy of the sonographic fat pad sign (FPS) as a predictor for pediatric elbow fractures. Patients and methods This is a prospective study of children under 14 years with suspected elbow fractures. All participants underwent at first ultrasonography focused on a FPS followed by standard elbow radiographs. US findings were compared to final fracture diagnosis. Results 38 out of 79 children had an elbow fracture. A sonographic FPS predicted an elbow fracture with a sensitivity/specificity of 97.3/90.5 %, positive/negative likelihood ratios (LR) were 10.2/0.03 and correct/false classification rates were 93.7/6.3 %. Primary US findings were later reviewed by a blinded physician giving a congruity of 96.2 %. These secondary US findings predicted an elbow fracture with a sensitivity/specificity of 92.1/92.7 %, positive/negative LRs were 12.6/0.09 and correct/false classification rates were 92.4/7.5 %. Conclusion The sonographic FPS could serve as a useful screening tool in primary evaluation of pediatric elbow injuries. If a fracture is unlikely after clinical and US evaluation, additional radiographs are dispensable, thereby potentially minimizing the radiation burden in childhood and reducing the length of stay in the Emergency Department.