ObjectivTo evaluate the effectiveness of Cross-Union surgery for the treatment of pseudarthrosis of the tibia (PT) with neurofibromatosis type 1 (NF1). MethodsThe clinical data of 8 NF1 children with PT who met the selection criteria between January 2018 and December 2023 were retrospectively analyzed. There were 5 males and 3 females, and the operative age ranged from 1.8 to 13.3 years with a median age of 3.5 years. According to Paley classification, there were 2 cases of type 2a, 2 cases of type 3, 2 cases of type 4a, and 2 cases of type 4c. There were 5 cases of first operation and 3 cases of refracture due to previous operation history. Six cases had leg length discrepancy before operation, and 2 of them had shortening over 2.00 cm. Except for 1 case of ankle fusion, the other 7 cases had ankle valgus. Preoperative coronal/sagittal angulation was recorded. Postoperative pseudarthrosis healing and refracture were observed. Leg length discrepancy and tibiotalar angle were measured and recorded before operation and at last follow-up. Inan method was used to evaluate the imaging effect. ResultsAll patients were followed up 12-37 months (mean, 23.5 months). One pseudarthrosis failed to heal at 12 months after operation and healed at 3 months after reoperation, while the other pseudarthrosis healed with a healing rate of 87.5% and a healing time of 4-8 months (mean, 5.3 months). No refracture occurred during the follow-up. At last follow-up, there were 2 new cases with leg length discrepancy, which were 0.66 cm and 1.33 cm, respectively. In 2 cases, the leg length discrepancy was more than 2.00 cm before operation, which was 2.14 cm and 9.00 cm respectively. There was no significant difference in leg length discrepancy between pre- and post-operation in 8 cases (P>0.05). At last follow-up, 6 patients still had ankle valgus, and there was no significant difference in the tibiotalar angle between pre- and post-operation (P>0.05); the tibial coronal/sagittal angulation significantly improved when compared with that before operation (P<0.05). According to Inan imaging evaluation criteria, 1 case was good, 6 cases were fair, and 1 case was poor. Conclusion Cross-Union surgery is an effective method for the treatment of PT with NF1 in children, can achieve good bone healing results with a low risk of re-fracture. The procedure may not have significant effects on leg length discrepancy and ankle valgus, and further treatment may be required.