(A) On the lateral view of this elbow, the posterior fat pad is faintly visible (arrow) and the anterior fat pad is elevated and anteriorly displaced (thick arrow), consistent with a joint effusion. These findings indicate a fracture about the elbow that, in an adult, should be in the radial head. (B) An oblique view shows the fracture of the radial head (arrowhead). Even without seeing the fracture on the radiographs, it should be surmised to be present when the posterior fat pad is visualized in the setting of trauma. The elevated and displaced anterior fat pad has been termed a sail sign.
