What is the epidemiology of an accessory navicular?
An accessory navicular bone is present in 4-21% of the population. It first appears in adolescence and is more common in females. Reported prevalence of bilaterality varies from 50-90%.
There is an accessory bone located on patient's posteromedial tuberosity of the tarsal navicular bone. The accessory bone has a cartilaginous connection to the navicular best seen on T2 sequence which suggests it is a type II accessory navicular bone.