This retrospective study includes 6 patients (average age, 8.7 years) with a dislocation of the radial head and ulnar plastic deformation. All were Monteggia fractures, Bado type I equivalents. The maximum ulnar bow was near the midulna. Five patients underwent an ulnar osteotomy, with elongation and reduction of the angulation within the middle third of the ulna, and open reduction of the radial head. One patient underwent an ulnar osteotomy with only elongation. The osteotomy sites were stabilized by a plate and screws or Kirschner wires. Mean follow-up was 3.4 years. Postoperatively, the average elbow range of motion was extension to 0 degrees, flexion to 138 degrees, forearm supination to 90 degrees, and forearm pronation to 88 degrees. Results in all patients were rated as excellent. One nonunion occurred. An osteotomy performed within the middle third of the ulna, combined with open reduction of the radial head, resulted in excellent clinical outcomes.