[Syndrome of the painful external tibial bone]

The tuberosity ossis naviculare rises from a separate apophyseal nucleus normally fusing with the os naviculare. In 10% of the cases it remains autonomous during life as os tibiale external. This variance of evolution is dominantly inherited. By statically false position of the foot, but also by traumata the loosening of the synchondrosis may cause sharp pain of the os tibiale external. As to X-rays the accessory tarsal bone may be mistaken for fractures. Normally conservative treatment is successful; if not the operative removal is advisable.