Summary
- 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
- Pain (which can occur in various areas of the foot)
- A fixed foot deformity (symptoms will occur is during adolescence)
- 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
- 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
- Eliminating precipitating activities (e.g. Walking on uneven terrain) or limiting activities in the short-term can be helpful in decreasing symptoms.
- Anti-inflammatory medication may be helpful in controlling the symptoms associated with a tarsal coalition.
- Corticosteroid injection may be used to provide to some temporary relief of symptoms.
Possible Referral
- Podiatry for supportive orthoses to limit stress on affected joints, footwear advice/modification, ankle bracing.
- Orthopedic surgeon for surgical management (Subtalar Fusion or Resection of the Coalition) when symptoms become too severe despite adequate non-surgical management.
