A criterion for a true lateral radiograph of the elbow in children.

In the search for a fracture of the elbow in children, the position of the anterior humeral line is a valuable aid. It has been stated that a true lateral radiograph is required to use this sign, although no criteria for assessing true laterality have been described. To develop such criteria, the authors examined 74 lateral radiographs of the elbow for 42 patients ranging in age from 9 months to 5 years, 9 months. Thirty-five of the patients did not have supracondylar fractures, and 7 did. In all of the radiographs the direction and degree of rotation, as well as the position of the anterior humeral line, were assessed relative to a series of radiographs of a cadaveric humerus in standardized positions. Examination of the humeral anatomic features in the radiographs showed that superimposition of the posterior supracondylar ridges of the humerus is the best means of confirming true laterality. This criterion is easily applied to lateral radiographs of the elbow in children. Of the radiographs reviewed, only seven were considered to represent true lateral views. Of those exposed in other degrees of rotation, the anterior humeral line gave a false indication of fracture in 19.