Posttraumatic radioulnar synostosis is a rare complication following fracture of the forearm and elbow. Risk factors for synostosis are related to the initial injury and surgical management of the fracture. Typically, patients present with complete loss of active and passive forearm pronation and supination. Evidence of bridging heterotopic bone between the radius and ulna can be seen on plain radiographs. Although nonsurgical management is sufficient in some cases, surgical excision is typically required. The timing of surgical intervention remains controversial. However, early resection between 6 and 12 months after the initial injury can be performed safely in patients with radiographic evidence of bony maturation. Surgical management consists of complete resection of the synostosis with optional interposition of biologic or synthetic materials to restore forearm rotation. A low recurrence rate can be achieved following primary radioulnar synostosis excision without the need for routine adjuvant prophylaxis.