Synostosis is an immobile joint formed when the gap between two bones ossifies and become a single bone. Bony joints can form by ossification of either fibrous or cartilaginous joints. The First sternocostal joint is an unusual variety of synarthrosis inaccurately called as synchondrosis. The attachment of the first rib to the sternum also becomes a synostosis with age. This rare synostosis of manubriocostal (sternocostal) joint was found incidentally during routine osteology classes for undergraduate MBBS students at Department of Anatomy, Sri Devaraj Urs Medical college,Kolar, Karnataka, India. We observed that the specimen showed the rarest bilateral synostosis of first rib with the sternum .The synostosis was examined and relevant measurements were taken in detail using vernier calipers.Synostosis leads to compression of neurovascular bundle causing thoracic outlet syndrome. It may be associated with clavicular hyperostosis and is considered a part of SAPHO syndrome (Synovitis, Acne, Pustulosis, Hyperostosis and Osteitis).We have hardly few literatures reporting this rare bilateral anubriocostal synostosis and knowledge of such rare synostosis is thereby of utmost importance to thoracic surgeons,orthopedicians, radiologists, dermatotologists dealing with this region.
