The frontal x-ray shows crowding of the radio capitellar space. The lateral x-ray of the elbow shows disrupted radio capitellar line indicating the presence of a radial head dislocation.

Radial head dislocation can be difficult to appreciate on the AP view but easier on the lateral view.

The radio capitellar line is drawn along the long axis of the proximal radius. The line should pass through the capitellum in both AP & lateral view. If not, the radial head is dislocated.

Reference: Grainger & Allison’s Diagnostic Radiology, 6th Edition