Diagnosis and treatment of focal fibrocartilaginous dysplasia of the distal ulna.

Focal fibrocartilaginous dysplasia (FFCD) of the distal ulna is a rare benign lesion resulting in progressive radiocapitellar dislocation, limb deformity and limitation in function. This study reported our experience with 10 cases and it aimed to determine a reasonable strategy for diagnosis and treatment. Ten cases treated from 2010 to 2018 in our department were retrospectively reviewed. The diagnosis was based on imaging features. All patients underwent lesion excision in the early stage and five patients required ulna lengthening in the second stage. The radiographic and functional outcomes were analyzed and reported. The median age at diagnosis was 32 months (range, 6-36 months). The median age at the time of surgery was 34 months (range, 10-40 months). The median clinical and radiographic follow-up period was 37 months (range, 24-50 months). The ulna was shortened by an average of 31 mm (range, 27-35 mm). There was no new radial head dislocation after lesion excision. For five cases of radial head dislocation, the median elbow varus angle before ulnar lengthening was 20° and it decreased to 5° after ulnar lengthening. Supination and pronation of the elbow increased from 50°-10° to 70°-30°. We believe that early excision of the lesion can prevent radiocapitellar joint dislocation in patients with FFCD of the ulna. Ulna lengthening can correct limb deformity and improve the range of motion.