ObjectiveTo investigate the safety and effectiveness of debridement and interbody fusion via posterior pedicle lateral approach in treatment of ankylosing spondylitis with thoracolumbar Andersson lesion (AL).MethodsBetween October 2011 and January 2017, 10 patients of ankylosing spondylitis with thoracolumbar AL were treated with debridement via posterior pedicle lateral approach and interbody fusion with bone grafting. There were 8 males and 2 females with an average age of 48.8 years (range, 31-79 years). The disease duration was 1.5-48.0 months (mean, 10.6 months). All patients were single-segment lesion, including 3 cases of T10, 11, 4 cases of T11, 12, and 3 cases of T12, L1. The preoperative visual analogue scale (VAS) score was 8.0±0.8, the Oswestry disability index (ODI) was 68.8%±5.5%, and the Cobb angle of local kyphosis was (26.3±7.1)°. According to American Spinal Injury Association (ASIA) scoring system, neurological impairment was assessed in 1 case of grade C, 4 cases of grade D, and 5 cases of grade E.ResultsAll the operations of 10 patients completed successfully. The operation time was 120-185 minutes (mean, 151.5 minutes), and the intraoperative blood loss was 300-750 mL (mean, 450.0 mL). Dural sac tear occurred in 1 case during operation and was repaired, with no cerebrospinal fluid leakage after operation. All patients were followed up 24-50 months (mean, 31.2 months). At last follow-up, the VAS score was 1.9±0.9 and ODI was 13.0%±3.0%, showing significant differences when compared with preoperative ones (t=17.530, P=0.000; t=31.890, P=0.000). Neurological function was improved significantly at 24 months after operation, and rated as ASIA grade E. The Cobb angles were (12.6±4.6)° at 3 days and (13.6±4.6)° at 24 months after operation, which were significantly different from those before operation (P<0.05); there was no significant difference between 3 days and 24 months after operation (P>0.05). At 24 months after operation, the grafted bone obtained good fusion at AL segment. During the follow-up, there was no failure of internal fixation such as nail withdrawal, broken nail, and broken rod.ConclusionDebridement and interbody fusion via posterior pedicle lateral approach for the ankylosing spondylitis with thoracolumbar AL can achieve satisfactory effectiveness, good fusion, and a certain correction of local kyphosis.