The lateral x-ray shows plastic bowing of the forearm bones. There is an associated dislocation of the radial head as indicated by the abnormal radiocapitellar line.
On the AP and lateral elbow x-rays, always pay attention to the radiocapitellar line. A line drawn through the centre of the radial head should always pass through the centre of the capitellum on both the AP and lateral views of the elbow.
Reference: Fundamentals of Diagnostic Radiology by Brant and Helms ,4th Edition