A 23-year-old man presents with right forearm stiffness for several weeks. Twelve months ago, he had an open reduction and internal fixation of his right radius and ulnar diaphyseal fractures. Anteroposterior radiograph of the forearm shows that the patient has developed a synostosis between the radius and ulna.
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A synostosis is a fusion of two bones. A radioulnar synostosis occurs when a bony bridge forms between the radius and the ulna. Bone formation between the radius and ulnar occurs after the bone has been disrupted either by fracture or iotrogenic trauma that causes heterotopic ossification. One such iotrogenic cause can be a distal biceps repair. Patients with a radioulnar synostosis generally present with decreasing forearm rotation. A decrease in supination and pronation can be disabling with activities that require forearm rotation such as twisting or lifting objects. As the synostosis develops, forearm motion can be painful, but often the pain subsides with complete bridging of the synostosis.1,2
Surgical resection of the synostosis is recommended for patients who cannot tolerate restricted forearm motion. The goal of surgery is to remove the bridging bone and improve forearm motion. Surgical resection comes with risks, however, as the neurovascular structures of the forearm run along the synostosis. Surgical resection is usually performed between 1 and 2 years after the original injury. Once the synostosis is resected, a barrier such as bone wax or silicone is generally used between the radius and ulnar to help prevent recurrence. Although the postoperative use of radiation therapy and NSAIDS have failed to show a decrease in postoperative heterotopic ossification, these treatments are often used to help prevent recurrence. Recurrence rates can range from 6% to 35%.1,2
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Jupiter JB, Ring D. Operative treatment of post-traumatic proximal radioulnar synostosis. J Bone Joint Surg Am. 1998;80:248-257.
- Kamineni S, Maritz NG, Morrey BF. Proximal radial resection for posttraumatic radioulnar synostosis: a new technique to improve forearm rotation. J Bone Joint Surg Am. 2002;84-A(5):745-751.