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.
Case Tarsal coalition - calacneonavicular courtesy of Dr Ian Bickle, radiopaedia.org