Background:According to the current literature, the recommended surgical treatment is circumferential spinal fusion, including both anterior and posterior procedures, for progressive thoracolumbar kyphosis in mucopolysaccharidosis (MPS). The purpose of this study was to report our experience with the posterior-only approach and instrumented fusion for MPS kyphosis.Methods:Six consecutive patients with MPS and thoracolumbar junctional kyphosis managed with the posterior-only approach were included. Demographic data, the type of MPS, medical comorbidities, and accompanying clinical manifestations were recorded. Measurements recorded on radiographs for the study included the presence of any coronal-plane deformity, fusion levels, changes in the local kyphosis angle (LKA), proximal and distal junctional kyphosis angles, and the apical vertebral wedge angle.Results:The average age at the time of surgery was 6.6 (range, 4 to 12) years. The average follow-up duration was 52.6 (range, 44 to 64) months. The mean preoperative LKA of 63.115.8 (range, 48 to 92) degrees decreased to a mean of 16.68.4 (range, 5 to 30) degrees immediately after surgery. At the latest follow-up, the mean LKA was 19.6 +/- 8.8 (range, 8 to 34) degrees. Apical vertebral listhesis was reduced in all patients with surgical correction. The average apical vertebral wedge angle of 15 (range, 11 to 19) degrees at the early postoperative period decreased to 4.6 (range, 2 to 7) degrees at the latest follow-up. Adjacent-segment problems occurred in 2 patients. There were no neurological complications or implant failures in any of the patients.Conclusions:Posterior-only corrective techniques and instrumented fusion with pedicle screws for progressive thoracolumbar junctional kyphosis in MPS patients are safe and effective methods. Its results are comparable to those achieved with conventional circumferential fusion. However, patients should be monitored closely for adjacent-segment problems.Level of Evidence:Level IVretrospective case series.