Distal humeral epiphyseal separation in young children: an often-missed fracture-radiographic signs and ultrasound confirmatory diagnosis.

OBJECTIVE. Distal humeral epiphyseal separation is rare and often misdiagnosed. The purpose of this study was to summarize an experience with radiography and ultrasound of distal humeral epiphyseal separation. MATERIALS AND METHODS. The records of all children younger than 36 months with the diagnosis of distal humeral epiphyseal separation from 2006 to 2013 were identified. Medical and imaging records were reviewed for diagnosis with radiography and ultrasound, cause, treatment, and follow-up. The initial diagnosis, relation of the radius and ulna to the distal humerus, presence of other fractures, and signs of elbow effusion were evaluated. RESULTS. Sixteen patients (10 boys, six girls; mean age, 8.6 months) were evaluated for distal humeral epiphyseal separation. All patients had elbow radiographs. Fifteen (94%) patients had medial and six (38%) had posterior displacement of the radius and ulna. The diagnosis was missed on radiographs of nine (56%) patients. Ultrasound was performed for 12 patients and showed distal humeral epiphyseal separation in all. In 10 (63%) patients, one or more additional humeral fractures were found: bucket-handle fractures in five patients and condylar avulsion fracture in six patients. In the six (38%) patients younger than 1 month, distal humeral epiphyseal separation was secondary to birth trauma. In 4 of the 10 (40%) older patients, nonaccidental trauma was diagnosed. All patients underwent follow-up with a pediatric orthopedist and had full range of motion. Two patients had mild varus deformities. CONCLUSION. The diagnosis of distal humeral epiphyseal separation is often missed on radiographs. Radiologists should be aware that posteromedial displacement of the radius and ulna in young children is highly suggestive of distal humeral epiphyseal separation and that the diagnosis can be confirmed with ultrasound.