Short-term outcomes of gradual ulnar lengthening in multiple hereditary osteochondromas of the forearm with monolateral external fixator

Hereditary multiple exostoses is an autosomal dominant genetic condition primarily affecting long bones. Forearm deformities, including wrist ulnar deviation, ulnar shortening, radial or ulnar bowing, and radial head dislocation, are common manifestations. Gradual ulnar lengthening is suggested as a viable treatment option for managing these deformities. This retrospective single-center study included 15 forearms treated with gradual ulnar lengthening using a monolateral external fixator by a single surgeon. Clinical and radiological characteristics were recorded preoperatively and during follow-ups. The Wilcoxon signed-rank test compared preoperative and postoperative radiological and clinical parameters, while McNemar's test assessed changes in radial head dislocation or subluxation. Significant radiological improvements were observed post-treatment. Proportional ulnar length increased from a mean of 0.85 ± 0.10 preoperatively to 1.11 ± 0.03 at the last follow-up ( P < 0.001). Ulnar variance decreased from a mean of 17.6 ± 5.58 mm preoperatively to 0.13 ± 1.81 mm at the last follow-up ( P < 0.001), while radial bowing decreased from a mean of 0.06 ± 0.02 to 0.05 ± 0.01 at the last follow-up ( P < 0.001). In addition, the radioarticular angle decreased significantly from a mean of 29.93 ± 7.34 to 20.20 ± 5.71° ( P < 0.001). The incidence of radial head dislocation or subluxation decreased significantly, from 11 patients preoperatively to only one at the last follow-up. These findings demonstrate the effectiveness of gradual ulnar lengthening with a monolateral external fixator in correcting forearm deformities and reducing the incidence of radial head dislocation or subluxation.