Derotational Osteotomy Through the Synostosis for Functionally Limiting Congenital Radioulnar Synostosis

Congenital radioulnar synostosis fixes the forearm in a variable degree of pronation. While many children compensate sufficiently and do not require surgery, severe fixed pronation that interferes with activities of daily living may warrant derotational osteotomy. We describe a single-level derotational osteotomy performed through the synostosis using an intramedullary ulnar pin as the rotational axis. The technique incorporates strict subperiosteal exposure to protect the posterior interosseous nerve, controlled shortening when necessary, stable percutaneous fixation, and prophylactic compartment release. The goal is to reposition the forearm into a more functional resting position that takes advantage of compensatory radiocarpal and shoulder motion, rather than to restore active pronosupination, which requires resection of the synostosis with an interposition flap. Fifteen consecutive patients underwent derotational osteotomy using this technique. All osteotomies achieved union, with no cases of compartment syndrome, loss of correction, or unplanned return to the operating room. Two patients developed transient posterior interosseous nerve palsies following 65- and 70-degree corrections; both resolved completely. Derotational osteotomy using this technique through the radioulnar synostosis site provides controlled repositioning of the fixed forearm into a more functional position, with reliable union rates and a low complication profile.