Free os cuboideum secundarium: a case report.

The free os cuboideum secundarium is one of the most rare accessory bones of the foot and is located proximal and plantar to the cuboid. In a 9-year-old boy, a free os cuboideum secundarium of the left foot was resected for persistent pain after trauma. Histologic examination showed degenerative changes of the hyaline cartilage that covered the entire bone. The central spongiosa appeared normal. The patient is free of pain and is still playing football 9.5 years after resection of the accessory bone. Follow-up examination showed no clinical sign of pathology except a soft scar with little discomfort when walking without shoes. Radiographs showed complete remodeling of left cuboid and calcaneus with normal bony configuration of both feet.