Have the correct radiographs been obtained?
The AP (mortice view) and lateral film are enough to make the diagnosis, but if calcaneal injury is suspected, a dedicated calcaneal view should be obtained.
Describe the abnormality.
On the AP film, there is depression of the lateral portion of the talar dome. A retained fragment can be seen adjacent to the defect.
What is the underlying pathology?
The talar dome has been injured with damage to the cartilage and adjacent subchondral bone.
What is the difference between osteochondritis dessecans and an osteochondral defect?
Osteochondritis dissecans is the end result of aseptic separation of an osteochondral fragment which then causes gradual fragmentation of the articular surface. It is often associated with intraarticular loose bodies.
Depression of the lateral aspect of the right talar dome with a fragment of bone within.