下端融合椎的选择对强直性脊柱炎胸腰椎后凸畸形椎弓根截骨矫形术后骨盆投射角的影响

目的:探讨经椎弓根椎体截骨矫形术（PSO）中选择不同的下端融合椎（LIV）对强直性脊柱炎（AS）胸腰椎后凸畸形患者术后骨盆投射角（PI）的影响。方法:回顾性队列研究。纳入2006年3月—2014年9月南京大学医学院附属鼓楼医院94例AS胸腰椎后凸畸形患者的临床资料，其中男83例、女11例，年龄19～59（34.7±8....

Effect of lowest instrumented vertebra selection on pelvic incidence in ankylosing spondylitis patients with thoracolumbar kyphosis who underwent pedicle subtraction osteotomy

Objective To investigate the effect of different lowest instrumented vertebra (LIV) on pelvic incidence (PI) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis after pedicle subtraction osteotomy (PSO). Methods This study was a retrospective cohort study. Ninety-four AS patients (83 males and 11 females) with thoracolumbar kyphosis treated in the Affiliated Hospital of Nanjing University Medical School from March 2006 to September 2014 were included. The patients' age ranged from 19 to 59 (34.7±8.5) years. All patients underwent PSO. The patients were divided into two groups on the basis of the choice of LIV. Sixty-nine patients were included in group A whose LIV was L₄ or L₅, including 20 cases with distal fixation to L₄ and 49 cases to L₅. By contrast, 25 patients were included in group B whose LIV was S₁. The changes of global kyphosis (GK), sagittal vertical axis (SVA), PI, pelvic tilt (PT), and sacral slope (SS) were compared between the two groups before, 10 days after, and 2 years after surgery. Results (1) No significant differences were observed in sex, age, body mass index, and other baseline data between the two groups (all P values >0.05). All patients received surgical treatment successfully and recovered well after operation, and no surgery-related complications occurred. (2) Comparison of data between the two groups: Statistically significant differences were observed in SVA before surgery (t=3.46, P=0.001), and no significant differences were found in GK, PI, PT, and SS (all P values >0.05). However, no significant differences were found in GK, SVA, PI, PT, and SS between the two groups on the 10th day after surgery (all P values >0.05). At 2 years after surgery, the PT in group A was lower than that in group B, whereas the SS was higher than that in group B. The differences of PT and SS were statistically significant between the two groups (t=2.81, 0.01, all P values <0.05), whereas GK, SVA, and PI showed no significant difference (all P values >0.05). (3) Comparison of data within the group: No significant difference was observed in PI at different time points in both groups (all P values >0.05), whereas statistically significant differences were found in GK, SVA, PT, and SS (all P values <0.05). The GK, SVA, and PT in groups A and B decreased at 10 days and 2 years after the operation, whereas SS increased, with statistical significance compared with before surgery (all P values <0.05). Compared with the 10th day after surgery, the PT increased, whereas the SS decreased in groups A and B at 2 years after surgery, with statistical significance (all P values <0.05); however, the GK and SVA showed no statistical significance (all P values >0.05). Conclusion For AS patients with thoracolumbar kyphosis who underwent PSO, no significant change was observed in PI regardless of whether or not the LIV was S₁. Moreover, no significant effect on PI was found after surgery.