Background. Congenital radial club hand is characterized by the underdevelopment of all forearm structures. Ulnar bone shortening ranges from 24.7% to 50.0% compared to the intact limb. The aim of the study was to evaluate the outcomes of ulnar lengthening by distraction osteogenesis in patients with congenital radial club hand type IV who underwent osteotomy with the formation of a bone-periosteal-muscle flap, and to compare these results with the treatment outcomes of the patients who had standard (oblique) ulnar osteotomy. Methods. The main group consisted of 20 patients who underwent osteotomy with the formation of a bone-periosteal-muscle flap during ulnar lengthening between 2019 and 2022. The control group included 19 patients (22 forearms) who underwent oblique ulnar osteotomy between 1998 and 2018. The following indicators were evaluated: length of the regenerate, distraction time, correction period, fixation index, osteosynthesis index, and complications. Results. A lengthening of 4.1 cm was achieved (30.7% of the initial ulnar bone length). The correction of angular deformity was 71.4%. Greater correction was achieved with osteotomy in the proximal ulna. In the subgroup with proximal segment osteotomy, the distraction and osteosynthesis indices were 25.6 and 25.7 days/cm, respectively. In the mid-third osteotomy group, these indices were 42.3 and 42.6 days/cm, respectively. Complications were limited to inflammatory phenomena in 30% of cases. All patients in the main group exhibited successful regenerate formation. Thus, the bone fragment with a periosteal-muscle pedicle serves as an additional source of osteogenesis during distraction. Conclusions. This study demonstrates the appropriateness of osteotomy with the formation of a bone-periosteal-muscle flap in children with congenital radial club hand. This technique allows for greater deformity correction, a shortened regenerate formation period, and a reduction in complications.