Tarsal Coalition


  • A tarsal coalition is a condition where one or more of the bones of the hindfoot (talus, calcaneus, and navicular) do not fully separate during development.
  • The coalition holding the bones together can range from flexible fibrous tissue, cartilage, or a rigid bridge of solid bone. The effect of a tarsal coalition is that the position of the hindfoot tends to be fixed.
  • The most common tarsal coalitions are:
  • Talo-calcaneal coalition: In this case the talus and the calcaneus have not fully separated.
  • Calcaneo-navicular coalition: In this case the beak of the calcaneus is attached to the lateral part of the navicular.
  • Talo-navicular coalition: This coalition is less common and results when the talar head and the navicular do not fully separate.

Diagnostic tips

  1. Pain (which can occur in various areas of the foot)
  2. A fixed foot deformity (symptoms will occur is during adolescence)
  3. As patients get older they may develop painful arthritis in one or more of their hindfoot joints (e.g. Subtalar arthritis or talonavicular arthritis)

Tests and Imaging

  1. Plain x-ray of the ankle or the foot reveals “C-Sign” (seen in talo-calcaneal coalition in which the
    bony contour of the coalition between the talus and the calcaneus form a smooth C-shape line) and “Ant eater sign” (seen in a calcaneo-navicular coalition).

Immediate Treatment

  1. Eliminating precipitating activities (e.g. Walking on uneven terrain) or limiting activities in the short-term can be helpful in decreasing symptoms.
  2. Anti-inflammatory medication may be helpful in controlling the symptoms associated with a tarsal coalition.
  3. Corticosteroid injection may be used to provide to some temporary relief of symptoms.

Possible Referral

  1. Podiatry for supportive orthoses to limit stress on affected joints, footwear advice/modification, ankle bracing.
  2. Orthopedic surgeon for surgical management (Subtalar Fusion or Resection of the Coalition) when symptoms become too severe despite adequate non-surgical management.