Radial head fracture
Radial head fracture. In this example, the effusion is clearly visible on the standard lateral view (left), with the sail sign anteriorly (white arrows) and a visible (and therefore abnormal) posterior fat pad (yellow arrows). The presumed fracture is not visible on this image, as is often the case. When a radial head or neck fracture is suspected, we occasionally perform additional oblique (‘radial head’) views, which may show the injury. In this case, the oblique view on the right confirmed the fracture (arrow).