Forearm lengthening by distraction osteogenesis: A report on 5 limbs in 3 cases.

Radioulnar length discrepancy causes pain and decreases function of the wrist, forearm, and elbow. Limb lengthening, which has been used in the treatment of various deformities of the forearm, is necessary to restore balance between the ulna and radius. We treated 5 limbs in 3 patients (2 boys, 1 girl; mean age 9.3 years old) with radioulnar length discrepancy by distraction osteogenesis of either the ulna or radius using external fixators. We dissected the interosseous membrane between the ulna and radius in 3 limbs in 2 cases and did not do so in 2 limbs of 1 case. These cases include 2 cases with hereditary multiple exostoses, and 1 case with multiple epiphyseal dysplasia. The results were investigated and evaluated in this study, using appropriate clinical and radiographic parameters, noting the state of the interosseous membrane, which has an important role in forearm stability. The mean fixation period was 113 days. The mean distraction distance was 22.8 mm. The mean follow-up period was 637.7 days. The mean ulnar shortening and radial articular angle respectively improved from 7.4 mm and 30.2° preoperatively to -0.1 mm and 34.8° postoperatively. Balance between the ulna and radius was restored, and the results showed significant improvements in range of motion of the joints. However, 2 unintended radial head subluxations occurred in 2 limbs without dissection of the interosseous membrane. In addition, a keloid remained in 1 limb due to pin site infection. Forearm lengthening by distraction osteogenesis was useful in our cases. It is important to recognize the function of the interosseous membrane when lengthening is performed by osteotomy of the proximal ulna by gradual distraction with an external fixator.