Tarsal Coalition

Definition

  • Fibrous, cartilaginous or bony bridge between two or more tarsal bones
  • Failed mesenchymal segmentation
  • Often autosomal dominant

Epidemiology

  • Prevalence around 1%
  • Bilateral in up to half
  • Calcaneonavicular and talocalcaneal are the most common
  • Talonavicular and calcaneocuboid are rare
  • Associated with fibular hemimelia and Apert syndrome

Clinical Features

  • Symptoms start as the coalition ossifies
  • Calcaneonavicular presents around 8 to 12 years
  • Talocalcaneal, usually middle facet, presents around 12 to 16 years
  • Activity-related hindfoot or midfoot pain
  • Recurrent ankle sprains
  • Rigid flatfoot, with heel valgus not correcting on tiptoe
  • Restricted subtalar motion
  • Peroneal spastic flatfoot with painful peroneal spasm holding eversion

Investigations

Tarsal Coalition, radiograph of a calcaneonavicular coalition
Radiograph of a calcaneonavicular coalition. Image by Hellerhoff, Wikimedia Commons, CC BY-SA 3.0.
  • AP, lateral and 45° internal oblique foot views, plus Harris axial heel view
  • Calcaneonavicular coalition best seen on the oblique view
  • Anteater sign on the lateral is an elongated anterior calcaneal process
  • C sign, from medial talar dome and inferior sustentaculum, indicates talocalcaneal coalition
  • Talar beaking is a secondary sign of abnormal subtalar motion and does not indicate arthritis
  • Narrow posterior facet and absent middle facet suggest talocalcaneal coalition
  • CT defines bony coalitions, size relative to the posterior facet and multiple coalitions
  • MRI identifies fibrous and cartilaginous coalitions

Management

  • Activity modification, analgesia and orthoses first
  • Below knee walking cast for several weeks may give lasting relief
  • Calcaneonavicular, resection with EDB or fat interposition to reduce recurrence
  • Talocalcaneal, resection with fat interposition if small, without significant arthritis or severe valgus
  • Coalitions over half the posterior facet do poorly after resection
  • Calcaneal lengthening osteotomy for significant hindfoot valgus, with or without resection
  • Subtalar or triple arthrodesis for large coalitions, arthritis or failed resection

Complications

  • Recurrence
  • Persistent pain
  • Adjacent joint arthritis

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.