Symptomatic case of type 1 accessory navicular bone: A case report

Abstract

Accessory Navicular Bone (ANB) (os navicularum or os tibiale externum) is a common variant of secondary ossification present in 5 to 10 % of the population. Due to its unique anatomical location in foot and associated relation with tibialis posterior tendon, these are usually symptomatic in type 2 ANB or type 3 ANB stages. Often patients with ANB can develop plantar fascitis or bunions or calcaneal spur.Case Report: A 20 year old female had a history of pain over the medial aspect of midfoot for 1 year. She had consulted many centers with midfoot pain. Patient had a history of twist injury to the same foot 1 year back and has been diagnosed and treated for the same. Pain subsided for 2 months and again she had similar pain in midfoot for which she was diagnosed as a case of plantar fascitis and treated conservatively. Later radiographs showed type 1 ANB, but she was treated conservatively with analgesics and sole raise which failed. Finally surgical excision and tibialis posterior advancement done for flat foot and symptomatic relief was achieved.Discussion: Most of type 1 ANB are asymptomatic, and patients with type 1 ANB are usually incidental finding mostly not requiring any surgical intervention. Cause of midfoot pain in this patient was misdiagnosed as sprained foot initially and lateral attributed to plantar fasciitis, even after radiography showed type 1 ANB.Conclusion: In case of type 2 or type 3 ANB, that can be a cause of pain in the midfoot due to local mechanical factors. But type 1 ANB can also cause severe midfoot pain, which can be easily missed or misdiagnosed as sprained foot or plantar fascitis. This case required surgical excision and tibialis posterior advancement for symptomatic relief.