What do you suggest if my left hand does not turn palms-up. it's called radioulnar synostosis?

Radio ulnar motion: known as pronation and supination is absent in a complete ru synodtosis. Other reasons for me just Supination or placing the palm up our previous fracture elbow problems or wrist issues the diagnosis of synosgosis where there is either a bone or fibrous Union is made with x-rays of the forearm. Unless extreme position these don't typically need any rx and there is no disability