Radioulnar synostosis is the presence of a bony connection between the radius and ulna. I have previously blogged a few times on it HERE. While a synostosis can develop after a trauma, we typically discuss it when present from birth. The synostosis prevents forearm rotation but does not affect elbow or wrist motion (these are typically normal). There have been many attempts to ‘cure’ radioulnar synostosis to restore forearm rotation, all without full success. In 2018, we typically treat radioulnar synostosis if the forearm is stuck in a position of significant palm down (pronation) or palm up (supination). We also tend to consider surgery more frequently when both arms are involved.
Surgery for radioulnar synostosis tends to be an osteotomy or a cutting of the bone and rotating the forearm to a more functional position, close to the clapping position (‘neutral’). Usually positioned in slightly palm down position due to the importance of keyboarding and tabletop activities. I like this surgery as patients and families are happy with it. BUT, surgery is not always necessary because patients have a great ability to compensate. This video is a great demonstration of a patient with radioulnar synostosis who appears to be rotating the forearms but really is just rotating through the wrist joints.
Charles A. Goldfarb, MD
My Bio at Washington University