We report the results of performing a pronating osteotomy of the radius, coupled with other soft-tissue procedures, as part of an upper limb functional surgery programme in tetraplegic patients with supination contractures. In total 12 patients were reviewed with a mean follow-up period of 60 months (12 to 109). Pre-operatively, passive movement ranged from a mean of 19.2° pronation (−70° to 80°) to 95.8° supination (80° to 140°). A pronating osteotomy of the radius was then performed with release of the interosseous membrane. Extension of the elbow was restored postoperatively in 11 patients, with key-pinch reconstruction in nine. At the final follow-up every patient could stabilise their hand in pronation, with a mean active range of movement of 79.6° (60° to 90°) in pronation and 50.4° (0° to 90°) in supination. No complications were observed. The mean strength of extension of the elbow was 2.7 (2 to 3) MRC grading. Pronating osteotomy stabilises the hand in pronation while preserving supination, if a complete release of the interosseous membrane is also performed. This technique fits well into surgical programmes for enhancing upper limb function.