A Case of Shortening and Deformity of the Ulna with Dislocation of the Radial Head Caused by Enchondroma

We report a case of shortening and deformity of the ulna with dislocation of the radial head caused by enchondroma in the ulna.The patient was a 4-year-old girl with shortening of 3cm and varus deformity of the left forearm. Extension and internal rotation were limited in her left elbow joint. Radiographic findings showed an enchondroma at the distal of the ulna, shortening and varus deformity of the ulna, and a dislocation of the radial head. Because the displacement of the radial head increased with growth, we treated the dislocation by ulnar lengthening using callotasis. As length increased the displaced radial head gradually moved in the distal direction by traction of the interosseous menbrane. When there was 30% lengthening of the ulna, its dislocation were completely repositioned. Due to concern about the recurrence of the radial head-dislocation in the future, the ulna was lengthened by 42% of its original length. The limited motion in the elbow joint was improved and the length in the forearm was almost equalized. No neurological disturbance was seen. In such cases with ulnar shortening and dislocation of the radial head, ulnar lengthening with callotasis may be a more safe and accessible treatment compared with previous therapeutic methods.