Three-dimensional, analysis of deformities of the radius and ulna in congenital proximal radioulnar synostosis

We reconstructed three-dimensional images of radius and ulna in 38 forearms of 25 patients with congenital proximal radioulnar synostosis from their computed tomographic studies. We also analysed correlations between the deformities of radius and ulna and degrees of fixed pronation of these forearms. The average ulnar deviation, flexion and internal rotation deformities of the radius were 6 degrees, 3 degrees and 18 degrees, respectively. The average radial deviation, extension and internal rotation deformities of the ulna were 3 degrees, 4 degrees and 30 degrees, respectively. The flexion deformity of the radius and the internal rotation deformity of the radius and ulna were correlated significantly with degree of fixed pronation. We conclude that the patients with congenital proximal radioulnar synostosis have remarkable flexion deformity of the radius and internal rotation deformity of the radius and ulna, which might impede forearm rotation after corrective surgery in the proximal part of the forearm.