Q: What sign is evident on lateral projection and what is it caused by? show answer

A: The anterior fat pad sign, also known as the sail sign or spinnaker sign. It is the result of a joint effusion elevating the normal anterior fat pad up and out of its normal location in the concavity of the humerus, which takes on a triangular shape on lateral projection.

Q: In an adult what is the most likely diagnosis? What should be done? show answer

A: An undisplaced intra-articular radial head fracture is most likely. The patient should be treated with that as the presumptive diagnosis and a repeat x-ray obtained in 7 to 10 days.

Q: Can you now see the fracture? show answer

A: On the oblique view, a small anterior cortical breach is present.

Q: What classification system is commonly used for radial head fractures? Can you describe it? show answer

A: Mason classification. Type I : non-displaced radial head fractures (or small marginal fractures); type II : partial articular fractures with displacement (>2mm); type III : comminuted fractures involving the entire radial head; type IV : fracture of the radial head with dislocation of the elbow joint.

Q: How are radial head fractures managed? show answer

A: Treatment depends on the degree of displacement and involvement of the articular surface (as well as associated injuries). In general type I (see Mason classification) injuries can be treated conservatively whereas type II injuries require open reduction and internal fixation (ORIF). Type III injuries often require early complete excision of the radial head