Lesson

Talar dome injury

Injuries to the talar dome should be suspected when an athlete presents with chronic ankle pain following an injury to the ankle.11 Chondral injuries generally occur to either the anterolateral or posteromedial ankle. The incidence is similar, but lateral talar dome injuries are more likely to be associated with direct trauma.

 

History

Patients will generally present with persisting symptoms following an ankle injury. Symptoms which are associated with talar dome injuries include recurrent swelling, a locking or catching sensation and recurrent instability.

 

Examination

The examination findings are often quite non-specific. The patient may have a swollen ankle with localised joint line tenderness. It is usually possible to directly palpate the talar dome with the ankle in plantar flexion. They may also present with signs that are suggestive of impingement.

 

Investigations

Anterolateral injuries are generally better seen on XR, are generally wider and shallower and result from a dorsiflexion and inversion mechanism. Posteromedial injuries typically result from plantar flexion and inversion, are deep and cup-shaped and are less likely to be associated with identifiable trauma.

MRI can be used to grade the injury.

  • Grade one injuries display an increased signal in the subchondral bone with no clear defect in the overlying articular cartilage.
  • Grade two injuries involve a visible fracture line with no breach of the overlying articular cartilage.
  • Grade three injuries have a fracture line with a breach in the overlying cartilage, but no displacement.
  • Grade four injuries involve a displaced osteochondral fragment.
  • Lateral talar dome injury

    A relatively acute (note the sharp edges) lateral talar dome injury.

  • Medial talar dome injury

    Note the old (rounded and well corticated) medial talar dome injury.

  • Lateral talar dome injury

    Note the very subtle lateral talar dome injury – which was confirmed on MRI.

  • Low grade injury

    Coronal MRI of subtle lateral talar dome injury. Note the increased uptake.

  • High grade injury

    Large high grade lateral talar dome injury on a coronal fat-sat image.

Treatment

Low-grade injuries are initially managed conservatively with limited weight-bearing and a cycling programme for a minimum of three months; there is some capacity for the articular cartilage to heal. Higher-grade posteromedial injuries may also be better managed conservatively initially as they do less well with surgical management. High-grade injuries or injuries which fail to improve are managed arthroscopically. The best predictor of outcome is the size and location of the lesion. Lesions which are located anteriorly and are less than 150mm2 do better than larger, more posterior lesions. Options include excision and drilling as well as open reduction and internal fixation if the defect is large (especially in young patients). A variety of cartilage restoration procedures have also been described such as autologous chondrocyte implantation and osteochondral allograft transfer.11

To learn more about osteochondral lesions in the ankle consider reading the following article.