Congenital Radioulnar Synostosis

Synostosis, or osseous union represents a failure of differentiation of parts of any two adjacent bones and can involve any part of the upper extremity. Synostosis between the radius and ulna can take two forms: congenital and post-traumatic.Congenital radioulnar synostosis is defined as fusion of the proximal ends of the radius and ulna. There is no rotational motion of the radius around the ulna. A patient with congenital radioulnar synostosis in midprone or pronation has severe disabilities in activities of daily living.Sandifort described the first case of congenital radio-ulnar synostosis in 1793. A developmental defect results in fusion of the proximal radio-ulnar joint of the forearm. The forearm is usually fixed in pronation, often with diminished function.The disorder is often familial, most cases being diagnosed before 5 years of age.