Sacral ribs. A case report.

Supernumerary ribs are a rare anatomic curiosity usually discovered as an incidental finding on routine radiographs. The occurrence of sacrococcygeal ribs are extremely rare. Sacral ribs develop as a consequence of the failure of the rib anlage to fuse with the vertebral centers. The present case is unique from previous reports because of the associated scoliosis and hypoplasia of the ipsilateral gluteal musculature and foramina within the accessory rib.