Painful accessory bones of the foot.

Sesamoid bones and secondary centers of ossification account for the accessory bones of the foot, and there is a wide range of frequency with which these different ossicles appear. They are usually incidental asymptomatic findings on imaging studies, and their clinical importance lies in not mistaking them for fractures. Occasionally these ossicles can become painful due to fracture, degenerative changes, avascular necrosis, and irritation or impingement of adjacent soft tissue.