This adolescent girl attended orthopedic outpatients clinic complaining of flat feet and right midfoot pain, worse on walking.
Tarsal coalition occurs in approximately 1%. It typically presents in adolescence. 50% are bilateral (even if symptomatic on only one side). Frequently pes planus (flat foot) is a feature. Coalition may be: bony, fibrous (this case) or cartilaginous.

The commonest coalition is calcaneonavicular. This is best seen on an oblique projection.

In a bony coalition a ‘bony bar’ is observed. In a fibrous coalition irregularity and narrowing of the bony interfaces with sclerosis is identified (this case). If further imaging is required CT if the investigation of choice.

1. Tarsal Coalition. Wang. Emedicine
2. Wheeless’ Textbook of Orthopaedics Online

Credit: Dr Ian Bickle