Talar Osteochondral Lesion

A talar osteochondral lesion (OLT, also called an osteochondral defect of the talus) is a focal injury to the articular cartilage and subchondral bone of the talar dome.

It is a common cause of ankle pain that persists after a sprain. Most lesions follow trauma, but some arise without a clear injury, probably from repetitive microtrauma or a subchondral vascular insult.

Lesions sit on a weight-bearing surface, can fragment into loose bodies and may contribute to post-traumatic ankle osteoarthritis if missed. Most patients are young, active adults. Juvenile osteochondritis dissecans (open physes) heals more often with strict conservative care.

The talar dome articulates with the tibial plafond and both malleoli in the ankle mortise. Talar cartilage is thin and heals poorly, and the talus has no muscle attachments and a limited blood supply.

Lesions cluster in 2 sites:

• •Lateral (anterolateral): dorsiflexion and inversion; shallow and wafer-shaped, and almost always traumatic
• •Medial (posteromedial): plantarflexion and inversion; deeper and cup-shaped, more often cystic, and less often traumatic

Injury progresses from subchondral bruising and microfracture through cartilage softening and cyst formation to fragment separation and a loose body. Cysts form as joint fluid is pumped through cartilage fissures into bone under load. Prognosis depends on size, containment, cystic change, chronicity, instability, malalignment and degenerative change, not on side alone.