Osteochondral Lesion of the Talus

An osteochondral lesion of the talus (OLT) is a defect involving the articular cartilage and the underlying subchondral bone of the talar dome. The terms osteochondral lesion, osteochondral defect, osteochondritis dissecans and transchondral fracture overlap and are often used interchangeably; "osteochondral lesion of the talus" is the preferred modern umbrella term because it does not assume a single cause.

Definition

Osteochondral lesion of the talus (OLT): an injury or defect of the talar dome that affects both:

• The articular cartilage (the smooth bearing surface), and
• The subchondral bone beneath it (which can develop oedema, cysts or a detached fragment).

Epidemiology and aetiology

• Most lesions are post-traumatic. According to PubMed, OLTs typically occur after a traumatic injury - classically an inversion ankle sprain or an ankle fracture - and are best diagnosed on MRI (Anastasio 2023).
• A minority are atraumatic (idiopathic), where repetitive microtrauma with local vascular impairment is thought to play a role.
• Common in young, active patients - the same population that sustains ankle sprains and sports injuries.
• Frequently missed early - because plain radiographs often look normal, an OLT is a classic cause of an "ankle sprain that will not settle."
• Associated with chronic ankle instability - recurrent inversion injuries expose the talar dome to repeated shear.

Talar dome and cartilage

The talus is largely covered by articular cartilage and has no muscular attachments, so it relies on a precarious blood supply that enters around its neck. The talar dome articulates with the tibial plafond and the medial and lateral malleoli to form the ankle (tibiotalar) joint.

The cartilage of the talar dome is relatively thin, and like all hyaline cartilage it has poor intrinsic healing capacity because it is avascular. Once the cartilage and subchondral plate are breached, repair depends on cells reaching the defect - which is the rationale behind bone marrow stimulation.

Why location matters

Pathophysiology

1. Initial injury - shear or compression across the talar dome (during a sprain or fracture) damages cartilage and the subchondral plate.
2. Subchondral response - oedema develops; the fragment may stay in place (stable) or partially separate.
3. Cyst formation - synovial fluid is driven into the subchondral bone through the cartilage breach, forming subchondral cysts over time.
4. Progression - a stable lesion may remain quiet, while an unstable or cystic lesion causes mechanical symptoms and, if untreated, can lead to ankle osteoarthritis.

History

• Deep, poorly localised ankle pain - typically worse with weight-bearing and activity.
• Antecedent trauma - a previous ankle sprain or fracture in most cases. Ask specifically about a sprain that never fully recovered.
• Mechanical symptoms - catching, locking, clicking or a sense of giving way, suggesting an unstable fragment or loose body.
• Recurrent swelling after activity.
• Chronic ankle instability - recurrent inversion injuries point to both the cause and a target for treatment.

Examination

• Tenderness over the anteromedial or anterolateral talar dome, palpated with the ankle plantar/dorsiflexed to bring the dome forward.
• Effusion / swelling of the ankle.
• Range of motion - often preserved; pain at extremes.
• Ligament assessment - test for lateral ligament laxity (anterior drawer, talar tilt) because instability frequently coexists and may need addressing.
• Alignment - assess hindfoot and ankle alignment (varus/valgus) on standing, as malalignment changes management.

Complications of OLT and its treatment

• Persistent or recurrent pain - the commonest reason for revision; often due to an undersized procedure, a large/cystic lesion, or uncorrected malalignment.
• Nerve injury - the most frequently reported complication after OLT surgery (e.g. injury to cutaneous nerves around portals or approaches).
• Failure / need for revision surgery - higher with larger lesions and with biologics added to bone marrow stimulation in some series.
• Donor-site morbidity - knee pain after harvesting OAT plugs.
• Malleolar osteotomy problems - nonunion, malunion or hardware irritation when an osteotomy is used for access.
• Subchondral cyst formation / progression - especially if the lesion is incompletely treated.
• Ankle osteoarthritis - the long-term consequence of an untreated or failed lesion.

Principles

• Protected weight-bearing - a period of non- or partial weight-bearing protects the repair while it matures; the duration depends on the procedure (longer for grafting/osteotomy than for simple debridement).
• Early range of motion - controlled ankle motion encourages cartilage health and prevents stiffness.
• Progressive loading - gradually advance to full weight-bearing as pain and healing allow.
• Physiotherapy - regain strength, proprioception and balance; address any ankle instability that contributed to the lesion.
• Graded return to sport - typically several months; return is guided by symptoms, strength and imaging when needed.

What to quote

• Bone marrow stimulation gives good short-term results for small, stable lesions, but outcomes are strongly size-dependent - smaller lesions (around under 10mm) do significantly better than larger ones (Guo 2010).
• Osteochondral autograft (OAT) produces good long-term clinical and MRI outcomes, with significant improvements in pain and function maintained at long follow-up; results are worse when OAT is used as a salvage after previous failed surgery (Imhoff 2011).
• Patient and lesion factors affect outcome - higher age, BMI and larger lesion size are associated with poorer results and higher failure rates (Anastasio 2023; Dekker 2017).
• Surgery is generally safe - no life-threatening complications are reported, and the overall complication rate is around 5% (Hollander/Dahmen 2023).

Global epidemiology. Osteochondral lesions of the talus are most common in young, active patients and are usually post-traumatic, classically following an inversion ankle sprain or an ankle fracture. They are a leading cause of persistent ankle pain after a sprain worldwide. There is no implant registry for OLT - the evidence is pooled case series, systematic reviews and consensus statements, so practice is consensus-driven globally.

Side-by-side guidance

High- vs limited-resource practice