The role of carpal instability in scaphoid nonunion: casual or causal?

We studied twenty consecutive scaphoid nonunions in twenty patients between the ages of eighteen and thirty-eight years. There were nineteen males and one female. The mean age was 25.2 years. Factors evaluated were fracture displacement, delay in treatment, and carpal instability. Fracture displacement and carpal instability were documented in patients by abnormal x-rays showing fragment displacement, abnormal scapholunate and radiolunate angles, etc., or by fluoroscopically controlled arthrography. We concluded that intercarpal ligamentous instability is consistently present and, therefore, the critical factor in wrists with ununited scaphoid fractures. Thirteen patients have been treated surgically; ligamentous disruption was confirmed at surgical exploration. In twelve patients, treatment of the nonunion included intercarpal ligamentous reconstruction. A satisfactory outcome was achieved in all twelve of these patients. One patient's treatment did not include ligament reconstruction. Although the scaphoid fracture united after a Russe bone graft, he remains symptomatic with persistent intercarpal instability. The remaining seven patients are being evaluated or awaiting surgery. Since ligamentous injury is so common in nonunion, we believe it is causal and that surgical care of nonunion involves ligamentous repair or other stabilization procedure. Prevention of nonunion involves early attention to the therapy of carpal instability when associated with scaphoid fracture.