Evaluation and Management of Common Accessory Ossicles of the Foot and Ankle in Children and Adolescents

Robert F. Murphy, MD; Sara S. Van Nortwick, MD; Richard Jones, MD; James F. Mooney III, MD


J Am Acad Orthop Surg. 2021;29(7):e312-e321. 

In This Article

Abstract and Introduction


Accessory ossicles are a common radiographic finding about the foot and ankle in children and adolescents. They are often noted incidentally during evaluation of foot and ankle injuries, and most can be managed nonsurgically. Although over 20 accessory ossicles have been described around the foot and ankle, five specific structures generate the most concern in pediatric patients. An accessory navicular presents commonly with medial midfoot pain and may require surgical intervention after failure of nonsurgical treatment. Although an accessory navicular can be treated surgically with simple excision, there is some recent evidence that supports concomitant reconstruction of associated flatfoot deformities. Os trigonum, an ossicle posterior to the talus, is also commonly asymptomatic. However, os trigonum may be associated with persistent posterior ankle pain, and open and endoscopic resection techniques are successful. Os subfibulare is an uncommon ossicle that may be associated with recurrent ankle sprains. Recent literature reports successful return to activities after ossicle excision and ligament reconstruction. Os subtibiale may be confused with a medial malleolar fracture in skeletally immature patients. Os peroneum may contribute to lateral midfoot pain.


Accessory ossicles have been described adjacent to multiple bones of the foot and ankle. Most of these structures represent incidental findings; however, some may be associated with acute injury, instability, or persistent pain, which may require more extensive evaluation and treatment. Because many of the ossicles are of limited concern in skeletally immature patients, a comprehensive discussion of all accessory bony structures of the foot and ankle is beyond the scope of this review. Those most likely to be problematic in the pediatric cohort include the accessory navicular, os trigonum, os subfibulare (OSF), os subtibiale (OST), and os peroneum (OP).