Surgical Treatment of the Accessory Navicular (Os Tibiale Externum) in Dancers: A Retrospective Case Series.

This study is to draw attention to a relatively common anatomical anomaly and its possible operative treatment in dancers. The accessory navicular, or os tibiale externum, is an accessory bone on the medial side of the navicular of the foot at the insertion of the posterior tibial tendon (PTT). It can cause obvious hyperpronation, medial foot pain, and a limited and painful relevé in dancers. To the best of our knowledge, this is the first report on the operative treatment of the accessory navicular exclusively in dancers. Six dancers (10 feet) were treated in our clinic for a symptomatic accessory navicular Type II. Five of them (eight feet) underwent surgery, two unilaterally and three bilaterally (at the same time). All five had an excellent result at mean follow-up of 4.7 years, given that they fully resumed their professional dance activities without restriction, discomfort, or residual symptoms. One patient stopped dancing for unrelated reasons and became symptom free without further (surgical) treatment. Although no conclusions can be drawn from a retrospective case series and other treatment modalities were not considered, simple excision of a symptomatic accessory navicular Type II seems to be a good choice in dancers.