Extra-articular extrusion of an osteochondral fragment of the talar dome.

Osteochondral fractures of the talus are uncommon. They are classified according to Berndt and Harty, as progressing in severity through four stages. This classification, however, does not address extra-articular extrusion of the osteochondral fragment. We report an osteochondral lesion of the talar dome which presented as an extruded extra-articular fragment in a closed injury of the ankle. This type of lesion may offer a continuation to the four original stages. Clinicians should be aware that this pattern of fracture can occur, and thus allow a more accurate diagnosis and the provision of some aid in the treatment of these injuries.