Is there a joint effusion present?
Yes - there is a sail sign of a large joint effusion.
Is there a fracture?
Yes - radial head. Even if no fracture was visible on xray, this would be treated as a occult undisplaced radial head fracture. No further imaging would be necessary to confirm a fracture.
A large joint effusion is present (anterior fat-pad is elevated) an intra-articular fracture through the radial head with a 1 mm step/gap is noted. There is slight dorsal angulation of the radial head.