Background: Radial nerve palsy associated with fractures of the humeral shafts is the most common nerve lesion complicating fractures of long bones. Transverse fracture and fractures of the middle or middle-distal shaft had higher associations of radial nerve palsy. Most of the patients were recovered without surgery, but early exploration should be considered in some patients with long-segment nerve defect. We evaluated the correlation of distraction of fracture gap in humeral shaft fracture with long-segment injury of radial nerve. Method: We evaluated 10 patients of radial nerve palsy with transverse humeral shaft fractures, who showed the distraction gap at the fracture site on preoperative radiograph. The mean age was 31 years, and the mean follow-up period was 2.1 years. Most common mechanism of injury was a traffic accident. We evaluated the lengths of the nerve defect under microscope and the functional recovery at the time of final follow-up. Results: Long-segment injury was detected in 9 patients (90%), and mean size of nerve defect was 12 cm (range, 9-15 cm). All patients were treated with sural nerve grafting. Motor powers of wrist and finger extension were recovered more than grade IV in all patients at the final follow-up. One patient who showed no injury of radial nerve was recovered to normal in 6 months after trauma. Conclusion: In our study, the distraction of fracture gap in preoperative radiograph often correlates with long-segment radial nerve injury. Therefore, patients of radial nerve palsy with transverse humeral shaft fractures, and with the distraction gap at the fracture site on the preoperative radiograph, often need early exploration and preparation of nerve graft at the time of surgery.
