gms | German Medical Science

Objectives/Interrogation: We would like to report on a 31-year-old otherwise healthy male with a limitation of rotation to the left forearm. He complained of increasing pain at night and progressively decreasing range of motion for one year. There was no previous trauma to the limb. Radiographs showed bridging bone formation. Contralateral radiographs were obtained and showed a similar process, although less pronounced. A resection of the bony mass without interposition of soft tissues was performed. Histological examination confirmed the resected specimen to be made up of bony tissue without cellular abnormalities.

Methods: A resection of the bony mass without interposition of soft tissues was performed. Histological examination confirmed the resected specimen to be made up of bony tissue without cellular abnormalities. Postoperatively there was a restored range of motion, which remained stable 6 months later. Preoperative pain also disappeared.

Results and Conclusions: Radioulnar synostosis has traditionally been classified into 2 groups: congenital and post-traumatic. The congenital form is thought to be a developmental error occurring in utero, when the proximal ends of the radius and ulna are covered by a common perichondrium. Only proximal congenital fusions have been reported. The diagnosis is usually made between 2.5 and 6 years of age, as patients usually have little complaints. Secondly, posttraumatic radioulnar synostosis is described as a complication occurring following osteosynthesis of fractures of one or both forearm bones. It has also been reported after stab wounds and other soft-tissue injuries. The synostosis may develop anywhere along the intraosseous membrane.

This case does not seem to fit in to either of these categories. The patient presented because of progressively decreasing pro-supination, previously having symmetrical motion. Also, the location of the synostosis was not proximal. Both arguments favour against a congenital synostosis. On the other hand, there is no recollection of any trauma, and the contralateral forearm showed a similar problem, excluding a posttraumatic synostosis.

Review of the literature yielded one case report documenting an 18-year-old man with progressively decreasing motion, without previous trauma. Radiographs showed a distal synostosis, which was resected with good results. The authors termed this condition 'idiopathic radioulnar synostosis'. This is, to the best of our knowledge, the first report of a diaphyseal, bilateral idiopathic radioulnar synostosis.