Osteochondral Lesion of the Talus
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Direct answer
An osteochondral lesion of the talus is a cartilage and subchondral bone injury of the talar dome, most often posteromedial, that follows an ankle sprain or fracture. It is staged on radiographs by the Berndt and Harty classification, in which stage IV is a displaced fragment. Small, stable lesions may settle with protected weight-bearing, while unstable or large lesions need arthroscopic fixation, microfracture or grafting.
What you must remember
- Location: posteromedial lesions are the commonest, while anterolateral lesions are more often linked to inversion injuries.
- Berndt and Harty staging: stage I is compression, stage II is partial detachment, stage III is complete but undisplaced detachment, and stage IV is a displaced fragment.
- Plain films: the mortise view is the key projection, and early lesions can be invisible, so persistent pain calls for further imaging.
- MRI: the most sensitive test, showing the cartilage defect, subchondral oedema and whether the fragment is stable.
- CT: characterises loose fragments and cystic change where MRI is equivocal, and is useful for surgical planning.
- Arthroscopy: both diagnostic and therapeutic, with anterolateral lesions reached from standard anterior portals and posteromedial lesions sometimes needing a posterior approach or a malleolar osteotomy.
- Microfracture: creates bleeding channels in the subchondral bone for fibrocartilage repair, which suits small contained lesions.
Choosing treatment after persistent talar pain
A 32-year-old footballer has ankle pain and catching for four months after a sprain that never settled. The pathway matches the imaging stage and the stability of the fragment to the treatment.
- Image the mortise: plain radiographs of the mortise and lateral views show the crater or fragment, and the Berndt and Harty stage is assigned from them.
- Confirm with MRI: MRI defines the cartilage defect, marrow oedema and whether the fragment is stable or displaced.
- Add CT where needed: CT characterises loose fragments and cystic change when MRI leaves the picture unclear.
- Assess stability: a stable, non-displaced lesion may be managed with immobilisation and protected weight-bearing for a period.
- Fix unstable fragments: arthroscopic fixation of a displaced but viable fragment, or debridement, is chosen when the lesion is unstable.
- Match repair to size: microfracture suits small contained defects, while osteochondral autograft or allograft is used for large ones.
- Rehabilitate gradually: weight-bearing and return to sport follow over several months under the surgeon's protocol.
Where the exam tries to catch you
Talar lesion questions test staging, location and the match between defect size and repair.
- Trap: attributing persistent ankle pain after a sprain to ligament injury alone Correct: talar osteochondral lesions are often missed, so pain beyond the expected recovery period warrants MRI.
- Trap: using microfracture for every lesion regardless of size Correct: microfracture suits small contained defects, while large defects need grafting because the fibrocartilage fill is weaker.
- Trap: treating posteromedial and anterolateral lesions as equivalent Correct: posteromedial lesions are commoner and harder to reach arthroscopically, so the approach and planning differ.
Frequently asked questions
Which classification grades osteochondral lesions of the talus?
The Berndt and Harty classification grades osteochondral lesions of the talus on radiographs into four stages. Stage I is compression, stage II is partial detachment, stage III is complete undisplaced detachment and stage IV is a displaced fragment.
Which talar lesion location is the most common?
Posteromedial osteochondral lesions of the talus are the most common location. Anterolateral lesions are less common and are more often linked to inversion injuries of the ankle.
What is the role of microfracture in talar osteochondral lesions?
Microfracture creates small holes in the subchondral bone to release marrow cells that form fibrocartilage within the defect. It suits small, contained lesions, while larger lesions usually need osteochondral autograft or allograft because fibrocartilage is weaker than hyaline cartilage.
Which imaging test is most sensitive for an osteochondral lesion of the talus?
MRI is the most sensitive imaging test for an osteochondral lesion of the talus, showing the cartilage defect and subchondral marrow oedema. Plain radiographs may appear normal, and CT is used mainly to assess loose or cystic fragments.