A 10-year-old child has painful flat foot that is rigid and does not correct on tiptoeing. X-ray of the ankle shows an oblique bony bar between the calcaneus and navicular. The diagnosis is:

• A Idiopathic flexible flatfoot
• B Tarsal coalition (calcaneonavicular coalition) ✓
• C Congenital vertical talus (rocker-bottom foot)
• D Peroneal spastic flat foot due to tibialis posterior tendon dysfunction

Explanation

Tarsal coalition is an abnormal fibrous, cartilaginous, or bony union between tarsal bones that causes peroneal spasm and rigid flatfoot. Calcaneonavicular (C-N) coalition is the most common type; it is visible on oblique X-ray as a bony bar or 'anteater sign' (elongated anterior process of calcaneus). Talocalcaneal coalition (middle facet) is the second most common and best seen on CT. Resection of the bar is curative in younger patients; subtalar or triple arthrodesis is reserved for advanced cases.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.