Talar coalition.
This is a rare condition. Many times may remain undiagnosed until it becomes symptomatic.
Tarsal Coalition is a fibrous, fibro-cartilaginous or ossified abnormal union of two bones, resulting from non-segmentation of primitive mesenchyme cells. The reported incidence is 1to 5.6% of general population. CN – Calcaneo-Navicular (44%) and TC - Talo-Calcaneal (48%) are the most common. With Talo-Navicular and Calcaneo-Cuboid also being seen less commonly. Bilaterality is seen in up to 50-60% of the occurrences.