Three-dimensional Deformity Analysis of the Forearm Bones in Congenital Proximal Radioulnar Synostosis

Congenital proximal radioulnar synostosis (PRUS) is a rare congenital anomaly where the radius and ulna are fused at the proximal portion which can cause the rotation of the forearm to be restricted (Fig.1). Bilateral pronation ankylosis over sixty degrees can restrict the patient’s daily activities. According to the position of the radius head in x-ray, PRUS is classified into three types, posterior dislocation type, anterior dislocation type and non-dislocation type. We performed Kanaya’s mobilization procedure using a free vascularized fascio-fat graft and correction osteotomy of the radius (Kanaya 1998). Most patients gained satisfactory range of motion (ROM) after surgery. However, unsatisfactory forearm rotation can be seen in some cases. It considered that sever bone bowing of radius in the post-dislocation type might be the cause of unsatisfactory result.