Cause of Osteochondral Lesions of the Medial Talar Dome
Trauma is the primary cause of osteochondral lesions of the medial talar dome, accounting for up to 75% of cases, with medial lesions typically located posteriorly on the talar dome and resulting from inversion injuries with plantarflexion. 1, 2
Primary Traumatic Etiology
The overwhelming majority of medial talar dome osteochondral lesions result from traumatic mechanisms 1, 2:
- Single acute trauma is the most common cause, particularly ankle sprains and fractures that create shearing forces on the posterior-medial talar dome 1, 3, 4
- Repetitive microtrauma from less intense but repeated loading events can also produce these lesions over time 5
- Mechanism of injury: Medial lesions specifically occur with ankle inversion combined with plantarflexion, which drives the posterior-medial talus against the tibial plafond 1
Location Pattern
Medial osteochondral lesions have a characteristic anatomic distribution 1:
- Posterior location on the medial talar dome is typical (in contrast to lateral lesions which occur anteriorly) 1
- This posterior-medial location correlates with the biomechanical forces during the causative inversion-plantarflexion injury 1
Secondary Non-Traumatic Causes
While trauma dominates, other etiologies contribute in a minority of cases 1:
- Ischemic necrosis of the subchondral bone may cause or contribute to lesion development 1
- Endocrine disorders have been implicated as potential causative factors 1
- Genetic predisposition may play a role in susceptibility to these lesions 1
Pathophysiology of Progression
Once initiated, the lesion can progress through a characteristic pathway 5:
- Subchondral microfracture occurs at the time of injury, disrupting the bone plate beneath the cartilage 5
- Fluid pressurization during weight-bearing forces water into the fractured subchondral bone, creating repetitive high-pressure episodes 5
- Osteolysis and cyst formation develop from this increased fluid flow and pressure, with osteoclast activity lowering pH and sensitizing the innervated subchondral bone 5
- Pain generation arises not from the cartilage defect itself but from the repetitive high fluid pressure and pH changes in the highly innervated subchondral bone 5
Clinical Pitfall
Do not assume all medial talar dome lesions are traumatic—while trauma accounts for 75% of cases, up to 25% may have non-traumatic etiologies including vascular or metabolic causes that require different management considerations 2.