Clinical and Functional Outcomes of Ulnar Lengthening in the Treatment of Masada Type I Forearm Deformities in Hereditary Multiple Osteochondromas.

PURPOSE: Forearm deformity is common in hereditary multiple osteochondromas (HMO). The results of ulnar lengthening and osteochondroma excision are generally favorable, both clinically and radiographically. This study aimed to assess the clinical, radiographic, and functional results of forearm reconstruction in patients with Masada type I deformity (osteochondroma in the distal ulna with radial bowing, without radial head dislocation). METHODS: A retrospective review was performed on patients with HMO who underwent surgical reconstruction for a Masada type I forearm deformity over a 10-year period. Eleven forearms in 10 patients underwent gradual ulnar lengthening with an external fixator. Age at the time of surgery was 5 to 12 years. Radiographic evaluation included ulnar shortening, radial articular angle, and carpal slip. Clinical evaluation included range of motion of the elbow and wrist. Functional outcomes were evaluated with the Disabilities of the Arm, Shoulder, and Hand questionnaire and the Short Form-36 survey. RESULTS: At an average follow-up of 37.5 months, significant improvement was observed in ulnar shortening, the radial articular angle, and carpal slip. Preoperative average Disabilities of the Arm, Shoulder, and Hand score of 24.2 improved to 17.3. Significant improvement was observed in 3 measures of the Short Form-36 survey: general health, social functioning, and health change. CONCLUSIONS: In agreement with the literature, surgical reconstruction yielded favorable clinical and radiographic results in Masada type I forearm deformities. The main functional improvement was observed in scales of mental health. The baseline physical impairment was minimal in the absence of radial head dislocation, but although it improved with treatment, it was not necessarily clinically relevant. This study can assist surgeons and families in setting realistic goals and expectations for surgery. There may also be additional long-term benefits to forearm lengthening in HMO, including prevention of radial head dislocation, improved range of motion, and better cosmesis, which future research may help to clarify. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.