Forearm deformity in multiple hereditary exostosis. Radiologic predictors of radial head dislocation

Introduction: Radial head dislocation in patients with multiple hereditary exostosis (MHE) can lead to functional deficit. We investigated whether the location of the exostosis and certain radiological criteria predict risk of radial head dislocation/subluxation.

Hypothesis: We hypothesized that the radiological criteria differentiate between patients who need closer follow-up of the forearm and others for whom multiple radiographs are superfluous.

Patients and methods: We retrospectively reviewed the demographics of patients with MHE in our hospital, and radiographic measurements were made on forearm radiographs: radial length, ulnar length, ulnar variance, radial articular angle, and radial bowing.

Results: Forty-nine forearms were analyzed in 30 patients. Mean age was 9.5 years at first evaluation and 11.8 years at last evaluation. Radial head dislocation or subluxation was found in 6 forearms (12%). Risk factors comprised isolated exostosis in the distal portion of the ulna or exostosis in the distal part of both the ulna and radius, radial or ulnar shortening>4.6cm, radial bowing>8.1%, radial articular angle>35°, and≥3 exostoses in the forearm.

Discussion: In patients with MHE with risk factors for radial head dislocation, close follow- up with regular radiography is indicated and early surgery should be performed before the radial head dislocates.

Level of evidence: IV; retrospective study.