Accessory tarsal navicular subtypes

An accessory navicular is best seen on a lateral (nonstandard) oblique plain radiograph, as in images A and B above. Image A shows a Type I accessory navicular (arrow), image B a Type II accessory navicular (dashed arrow), and image C a Type III accessory navicular (small arrow). The size of the ossicle and extent of its connection to the navicular increase with each type. The dashed line indicates the site of resection of the accessory navicular and enlarged medial body of the navicular proper.