Department of Spine Surgery, Drum Tower Hospital of Nanjing University Medical School, 321, Zhongshan Rd, Nanjing, 210008 China; Medical School of Nanjing University, 22, Hankou Rd, Nanjing, 210008 China.
Department of Spine Surgery, Drum Tower Hospital of Nanjing University Medical School, 321, Zhongshan Rd, Nanjing, 210008 China; Medical School of Nanjing University, 22, Hankou Rd, Nanjing, 210008 China.
Spine J. 2019 Jan;19(1):79-86. doi: 10.1016/j.spinee.2018.05.024. Epub 2018 May 21.
Rod fracture (RF) has a negative impact on the surgical outcome of patients with ankylosing spondylitis (AS) after lumbar pedicle subtraction osteotomy (PSO). However, there is a paucity of published studies analyzing the risk factors for RF in PSO-treated patients with AS with thoracolumbar kyphosis.
The objective of this study was to investigate the risk factors for RF after PSO for thoracolumbar kyphosis secondary to AS.
STUDY DESIGN/SETTING: This is a retrospective single-center study.
Patients with AS who underwent PSO for thoracolumbar kyphosis between January 2002 and December 2016 were included.
Demographic data, including age, sex, body mass index, and smoking status, were summarized. The surgical data analyzed included the levels of osteotomy, the fusion levels, the upper instrumented vertebra, the lower instrumented vertebra, the osteotomy site, the rod material, the rod diameter, and the rod contour angle (RCA). Radiographic parameters included the sagittal vertical axis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Radiographic parameters were measured at baseline, immediately after the operation, and at the final follow-up. Adequate ossification of the anterior longitudinal ligament (ALL) at the PSO level was defined by a total bony bridge. Adequate ossification of the ALL was also measured at baseline, immediately after the operation, and at the final follow-up.
Patients with a minimum of 2 years' follow-up or patients who developed RF were enrolled in the study. Recruited patients were divided into the RF group and the no-RF group based on whether they developed RF. Patient demographics, operative data, radiographic parameters, and adequate ossification of the ALL were analyzed to determine the risk factors for RF. For patients with RF, the fusion status at the PSO level, the time course to the development of RF, the site of RF, and the corresponding solution were also recorded.
Rod fracture occurred in 11 (8.9%) of the 123 recruited patients. Solid fusion at the PSO level was found in all patients in the RF group. The average duration to the onset of RF was 31.4 months (range, 12-68 months). All RFs occurred at or immediately adjacent to the PSO level. The RCA was greater in the RF group than in the no-RF group (27.8° vs 22.9°, p=.031). A greater proportion of patients with a rod diameter of 5.50 mm were found in the RF group than in the no-RF group (100.0% vs 68.8%, p=.033). There was a larger proportion of patients with adequate ossification of the ALL at the final follow-up visit in the no-RF group than in the RF group (67.0% vs 27.3%, p=.018). Multivariate analyses demonstrated that the RCA (odds ratio, 1.174; 95% confidence interval, 1.018-1.354; p=.028) and adequate ossification of the ALL at the final follow-up visit (odds ratio, 0.079; 95% confidence interval, 0.014-0.465; p=.005) were independent factors for RF. Notably, revision surgery was performed among six patients, whereas conservative treatment was used for the remaining five patients.
In patients with AS after PSO for thoracolumbar kyphosis with solid fusion at the PSO level, the incidence of RF was 8.9%. Rod diameter was identified as a risk factor for RF. Furthermore, the RCA was identified as an independent risk factor for RF. In contrast, adequate ossification of the ALL around the PSO level at the final follow-up visit was identified as an independent protective factor for RF.
脊柱骨折（RF）会对接受腰椎经椎弓根截骨术（PSO）治疗的强直性脊柱炎（AS）患者的手术结果产生负面影响。然而，目前关于胸腰椎后凸畸形的 AS 患者接受 PSO 治疗后 RF 风险因素的研究很少。
本研究旨在探讨胸腰椎后凸畸形继发 AS 患者接受 PSO 治疗后 RF 的风险因素。
研究设计/设置：这是一项回顾性单中心研究。
纳入 2002 年 1 月至 2016 年 12 月期间接受胸腰椎后凸畸形 PSO 的 AS 患者。
总结患者的人口统计学数据，包括年龄、性别、体重指数和吸烟状况。分析手术数据包括截骨水平、融合水平、上固定椎、下固定椎、截骨部位、棒材材料、棒材直径和棒材轮廓角度（RCA）。影像学参数包括矢状垂直轴、胸椎后凸、腰椎前凸、骶骨倾斜、骨盆倾斜和骨盆入射角。在基线、术后即刻和最终随访时测量影像学参数。PSO 水平的前纵韧带（ALL）完全骨化定义为完全骨性桥。在基线、术后即刻和最终随访时也测量 ALL 的完全骨化情况。
纳入至少随访 2 年或发生 RF 的患者进入研究。根据是否发生 RF，将招募的患者分为 RF 组和非-RF 组。分析患者的人口统计学、手术数据、影像学参数和 ALL 的充分骨化情况，以确定 RF 的风险因素。对于发生 RF 的患者，还记录了 PSO 水平的融合状态、RF 发生的时间、RF 的部位以及相应的解决方案。
在 123 名纳入的患者中，11 名（8.9%）发生了 RF。RF 组所有患者的 PSO 水平均实现了坚固融合。RF 发生的平均时间为 31.4 个月（范围，12-68 个月）。所有 RF 均发生在或紧邻 PSO 水平。RF 组的 RCA 大于非-RF 组（27.8°比 22.9°，p=.031）。RF 组中直径为 5.50mm 的棒材比例高于非-RF 组（100.0%比 68.8%，p=.033）。非-RF 组在最终随访时 ALL 充分骨化的比例高于 RF 组（67.0%比 27.3%，p=.018）。多变量分析表明，RCA（优势比，1.174；95%置信区间，1.018-1.354；p=.028）和最终随访时 ALL 的充分骨化（优势比，0.079；95%置信区间，0.014-0.465；p=.005）是 RF 的独立因素。值得注意的是，六名患者接受了翻修手术，而其余五名患者则采用了保守治疗。
在 PSO 治疗胸腰椎后凸畸形且 PSO 水平融合牢固的 AS 患者中，RF 的发生率为 8.9%。棒材直径被确定为 RF 的风险因素。此外，RCA 被确定为 RF 的独立危险因素。相比之下，在最终随访时 PSO 周围 ALL 的充分骨化被确定为 RF 的独立保护因素。
