Objective To analyze the relationship of the lateral angulation with the incision level after anterior approach operation for thoracolumbar fractures by evaluating the Cobb' s angle at different approach levels.Methods A retrospective study was done on 154 patients with thoracolumbar fractures treated consecutively with anterior operation from May 2004 to January 2008.The preoperative,postoperative and follow-up angle of coronal Cobb and the postoperative angle between screws and endplates on the anteroposterior radiograph were measured.According to the relationship between the injury vertebrae and the incision level,the patients were divided into two groups,ie,incision level ≥2 vertebrae group and incision level ≤ 1 vertebra group.Results All patients were followed up for 6-47 months(mean 37 months),which showed significant postoperative lateral angulation(P ＜ 0.01)especially at follow-up (P ＞ 0.05).The coronal Cobb' s angle showed insignificant difference before operation between two groups but it was increased after operation and during the follow-up(P ＜0.01).The screws A or B were more parallel to the endplate in two groups(P ＜ 0.01),while the parallel of the screws C or D to the endplate showed no statistical difference(P ＞ 0.05).Conclusions Compared with the operation with incision level ≥2 vertebrae,the operation with incision level ≤ 1 vertebra can more easily induce postoperative lateral angulation and exert a significant impact on implantation orientation of the vertebral screws A and B,which may indirectly lead to postoperative lateral angulation.