Ultrasound diagnosis of supracondylar fractures in children

K. Eckert, N. Janssen, O. Ackermann, B. Schweiger, E. Radeloff, P. Liedgens

The objective of our study was to evaluate the safety and accuracy of ultrasound (US) compared to standard radiographs in diagnosing supracondylar fractures (SCFs) of the humerus in children. A total of 106 children (aged between 1 and 13 years) with clinically suspected SCF of the humerus were primarily examined by US followed by standard two-plane radiographs of the elbow. US was conducted with a linear scanner viewing the distal humerus from seven standardized sectional planes. US fracture diagnosis was established either by a cortical bulging or cortical gap, or by a positive dorsal fat pad (dFP) sign. X-ray diagnosis was stated by an independent pediatric radiologist and, afterwards, compared to our US findings. Sonographic and radiographic findings were collected in a contingency table. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) for US fracture diagnosis were calculated according to the radiographs. In addition, by identifying significant angulation and/or disrupture, SCFs were classified as non-operative/stable and operative/instable SCFs according to the AO Pediatric Fracture Classification System. By US, a SCF could be excluded in 43 patients and in 63 patients, a fracture was diagnosed. In contrast, by radiographs, an SCF could be excluded in 46 patients and in 60 patients, a fracture was diagnosed. For US fracture diagnosis in comparison to radiographs, we calculated a sensitivity of 100 %, a specificity of 93.5 %, an NPV of 100 %, and a PPV of 95.2 %. Thirty-nine SCFs were sonographically classified as stable grades 1/2 SCFs and confirmed in 37 patients by X-rays. All four operative/instable SCFs were correctly identified by US. By identifying a positive dFP sign and/or cortical lesions of the distal humerus, SCFs can be detected very sensitively by US. Even the estimation of fracture displacement seems to be possible. We suggest US as an applicable alternative method in the primary evaluation of suspected SCF in children, guiding further diagnostics, where appropriate. After minor injuries, if clinical assessment for an elbow fracture is low and US examination is negative for fracture, additional radiographs are dispensable. Thereby, the amount of X-ray burden during childhood can be reduced, without loss of diagnostic safety.