Introduction Surgical treatment is mandatory for spinal pseudarthrosis in advanced ankylosing spondylitis (AS) patients with painful sagittal deformity and/or neurological deficits.However, the most effective and safe surgical procedure for AS-related symptomatic thoracolumbar pseudarthrosis is still controversial.The purpose of this study is to explore the outcomes of pedicle subtraction osteotomy (PSO) at the level of pseudarthrotic lesion combined with supplemental anterior fusion for patients suffering from kyphotic pseudarthrosis in AS.Materials and methods Seven AS patients with thoracolumbar pseudarthrosis and kyphotic deformity were reviewed.There were 6 males and 1 female with a mean age of 41.7 years.All patients had back pain.Imaging findings demonstrated 3-column extensive discovertebral destruction in all patients.The preoperative global kyphosis averaged 75° (range, 37°-114°) with the apex at the level of pseudarthrosis.Three patients had incomplete neurological deficits (Frankel D) preoperatively.All patients underwent PSO at the level of pseudarthrosis in the first stage followed by supplemental anterior fusion in the second stage.Radiographic and clinical outcomes were assessed with an average follow-up of 38 months (range, 24-59 months).The visual analogue scale (VAS) was compared before surgery and at the final follow-up.Results All patients showed significant pain relief postoperatively and were satisfied with the kyphosis correction as well.Solid bony fusion was shown at the final follow-up.Three patients with neurological deficits had complete recovery of neurological function.The global kyphosis was corrected from 75° to 30°, with a mean correction of 45°.The VAS showed significant improvement.No surgical complication was observed.Conclusion PSO can be safely performed through the site of pseudarthrotic lesion in AS patients with pseudarthrosis and kyphotic deformity.After PSO, supplemental anterior fusion is sometimes necessary to support the anterior and middle column in a second stage if there is a bone defect in the osteotomy site.