Objective:To investigate the imaging features and surgical strategies of late-onset spinal deformity after myelomeningocele (MMC) repair.Methods:A total of 23 patients with late-onset spinal deformity after MMC repair from January 2006 to December 2019 were retrospectively analyzed, including 16 males and 7 females, aged 15.4±5.9 years (range, 6-28 years). All patients underwent MMC resection and repair in infancy (0-4 years). The complications of MMC, imaging characteristics of spinal deformity (Cobb angle of scoliosis, coronal balance, regional kyphosis), surgical methods, clinical outcomes and incidence of complications were analyzed. The Scoliosis Research Society-22 (SRS-22) score and Oswestry disability index (ODI) were used to evaluate the quality of life.Results:All patients were followed up for 2.4±0.8 years (range, 1-4 years). Among 23 patients, MMC occurred in the upper thoracic segment in 3 cases, thoracic segment in 1 case, thoracolumbar segment in 13 cases, and lumbosacral segment in 6 cases. 16 patients had scoliosis or kyphosis with the apex of the spine in the same segment as the MMC lesion. Among 13 patients with MMC located in thoracolumbar segment, 12 patients had scoliosis and 9 patients had kyphosis. Among 6 patients with MMC located in lumbosacral segment, 3 patients had pelvic tilt. Vertebral deformities included widening of pedicle space in 21 cases, enlargement of spinal canal in 19 cases, absence of spinous process in 17 cases, malsegmentation in 17 cases, and hemivertebra deformity in 9 cases. Intramedullary lesions included split cord in 6 cases and tethered cord in 9 cases. The overall implant density was 57.2%±17% (range, 16.6%-100%). At the last follow-up, the Cobb angle of scoliosis was 40.9°±19.1°, which was significantly smaller than 71.5°±28.2° before operation ( P<0.001). The local kyphosis angle was 26.7°±12.9°, which was significantly lower than that before operation (40.4°±21.5°), the difference was statistically significant ( P<0.001).The coronal balance was 16.1±13.6 mm, which was smaller than that before operation 28.5± 23.7 mm, the difference was statistically significant ( P<0.001). The total score of SRS-22 was 18.7±0.7, which was higher than that before operation 17.7±0.9, and the difference was statistically significant ( t=-9.74, P<0.001); ODI was 25.5%±6.2% after operation, which was significantly lower than that before operation (44.8%±10.1%), the difference was statistically significant ( t=13.66, P<0.001). Dural rupture occurred in 4 patients, including postoperative cerebrospinal fluid leakage in 2 cases; postoperative pleural effusion in 1 patient; and screw malposition in 2 patients. Three patients had broken rods and one had deep infection at final follow-up. Conclusion:About 70% of MMC patients who underwent resection and repair in early childhood developed late-onset spinal deformity in adulthood with the lesion at the parietal vertebrae. Posterior correction can obtain satisfactory clinical results. If the posterior element of the apical vertebral body is hypoplastic, the implant density can be increased by anterior vertebral screw, lamina hook fixation, and S 2 sacroiliac screw.