Indirect reduction of the radial head using an external fixator to treat chronic radial head dislocations.

OBJECTIVES We evaluated the results of indirect reduction of the radial head via a circular external fixator in pediatric patients with unilateral chronic radial head dislocation. METHODS Three male patients (mean age 6.3 years; range 5 to 8 years) with chronic radial head dislocation underwent ulnar lengthening using a circular external fixator for indirect reduction of the radial head. None of the patients had radiographic evidence for deformity of the radial head, dysplasia of the capitellum, or osteoarthritic changes. The etiologic factors were ulnar hemimelia, brachial plexus injury, and congenital radial head dislocation, respectively. Pre- and postoperative assessment of the patients included measurements of the carrying angle, flexion-extension of the elbow, and pronation-supination of the forearm, and anteroposterior and lateral radiographs, on which the congruency of the radiocapitellar joint, the orientation and length of the ulna and radius were assessed. The mean relative shortening of the ulna was 3.2 cm (range 2.5 to 4 cm) preoperatively. Distraction was begun on the seventh postoperative day at a rate of 3x0.25 mm per day and was continued until the achievement of reduction. Upon completion of the consolidation of the distraction callus, the fixator was removed and a brace was applied for three months to prevent fracture of the regenerated bone. The patients were followed-up for a mean of 62 months (range 42 to 98 months). RESULTS Complete reduction of the radial head was achieved in all the patients within a mean of six weeks, without any loss in position and recurrence of dislocation during the follow-up period. None of the patients exhibited dysplastic or arthritic signs in the radial head at final examinations. All three patients showed improvement in the carrying angle and were satisfied with the cosmetic appearance of the elbow and the length of the upper extremity. The mean flexion-extension improved by 28.3 degrees and the mean supination-pronation improved by 31.7 degrees. The external fixators were removed within a mean of 110 days (range 90 to 135 days). The mean bone healing index was 36 days/cm (range 30 to 42 days/cm). The mean ulnar lengthening was 3.2 cm (range 2.5 to 4.5 cm). Before reconstruction, the patient with congenital radial head dislocation also had a bowing deformity of the ulna and, during lengthening, this deformity was corrected gradually through additional hinges to the Ilizarov frame. The patient with ulnar hemimelia had a history of shish-kabab osteotomy at another center for ulnar bowing. Considering his young age (5 years), after achievement of radial head reduction, the proximal radius was fixed to the frame and the lengthening of the ulna was continued for an additional 7 mm to prevent future redislocation of the radial head due to asymmetric growth. There were no serious complications. Two patients had minor pin track infections that resolved completely by local wound care and oral antibiotics. CONCLUSION Albeit technically demanding, chronic radial head dislocations in children can be treated by indirect reduction of the radial head through ulnar lengthening with the use of a circular external fixator. This technique has a very low complication rate.