后路L4/5融合术后邻椎病发生的危险因素

Risk factors of adjacent segment disease after posterior L4/5 fusion

中文关键词:  腰椎融合术  邻椎病  节段性前凸  椎间隙相对高度

英文关键词:Lumbar fusion surgery  Adjacent segment disease  Segmental lordosis  Relative height of intervertebral space

中文摘要:

  【摘要】 目的：探讨后路L4/5融合术后邻椎病（adjacent segment disease，ASD）发生的危险因素。方法：回顾性分析2012年9月~2021年9月因后路L4/5融合术后ASD于我院接受翻修手术的26例患者，纳入ASD组；采用1∶2匹配的方法，从同期接受腰椎后路融合手术且末次随访时未发生ASD的患者中，按性别、手术时年龄、手术节段、随访时间匹配52例患者作为对照组。收集两组患者术前、术后3d、末次随访时的影像学资料，在腰椎侧位X线片上测量：腰椎前凸角（lumbar lordosis，LL）、节段性前凸（segmental lordosis，SL）、骶骨倾斜角（sacral slope，SS）和L3/4、L4/5、L5/S1的椎间隙相对高度；在初次术前MRI上，采用Pfirrmann分级对融合节段邻近节段椎间盘退变情况进行评估。将两组患者术前基线资料，术前、术后3d、末次随访时的腰椎影像学资料（包括腰椎矢状位参数和初次术后腰椎矢状位参数矫正值）进行比较，将有差异的参数进行多因素Logistic回归分析，通过受试者工作特征（receiver operating characteristic，ROC）曲线确定独立危险因素对ASD的最佳预测阈值。结果：ASD组与对照组在术前第一诊断、术前邻近节段椎间盘的Pfirrmann分级、合并症情况均无统计学差异（P>0.05）。ASD组患者初次接受手术后5.4±2.3年行二次手术，二次手术融合节段L3/4 16例，L5/S1 10例。两组术前SL、SS以及L4/5、L3/4和L5/S1椎间隙相对高度均无显著性差异（P＞0.05），ASD组患者初次术前LL显著性小于对照组（P=0.031）。初次融合术后3d，ASD组SL和LL显著性小于对照组（P＜0.05）。末次随访时，ASD组SL和LL均显著小于对照组（P<0.001）；ASD组的L3/4椎间隙相对高度明显小于对照组（P=0.002）。两组初次手术各参数的矫正值相比，ASD组的SL相对差值（relative △SL，r△SL）显著性小于对照组（P<0.001），两组间LL相对差值（relative △LL，r△LL）、L4/5椎间隙高度相对差值（relative △disc height，r△DH）、L3/4 r△DH、L5/S1 r△DH均无显著性差异（P>0.05）。以ASD为因变量的多元回归分析结果显示较小的初次r△SL是发生ASD的独立危险因素（OR=0.031，95%置信区间0.005~0.209），其曲线下面积（area under curve，AUC）为0.731（95%置信区间0.615~0.848），最佳预测阈值为-10.5%。结论：后路L4/5融合术中局部曲度纠正不足可能会导致远期邻近节段高度的丢失，是融合术后发生ASD的独立危险因素。

英文摘要:

  【Abstract】 Objectives: To explore the risk factors of adjacent segment disease(ASD) after posterior L4/5 fusion. Methods: A total of 26 patients who underwent revision surgery for ASD after posterior L4/5 fusion in our hospital between September 2012 and September 2021 were retrospectively analyzed and included in the ASD group. Another 52 patients were matched in 1∶2 as the control group by gender, age at surgery, surgical segment, and follow-up time from those patients who underwent posterior lumbar fusion during the same period and without ASD at the final follow-up. The imaging data before operation, at postoperative 3d and final follow-up were collected of both groups of patients, and parameters were measured on lateral lumbar X-ray films such as lumbar lordosis(LL), segmental lordosis(SL), sacral slope(SS), and the relative height of the intervertebral space at L3/4, L4/5, and L5/S1. Disc degeneration in the adjacent segments of the fused one was assessed using the Pfirrmann classification on the first preoperative MRI images. Preoperative baseline data, lumbar sagittal alignment parameters at preoperation, postoperative 3d and final follow-up, and relative correction values of initial postoperative/preoperative lumbar sagittal parameters were compared between the two groups, and parameters with significant difference were incorporated in multivariate logistic regression analysis. The optimal predictive thresholds for ASD of the independent risk factors were determined by receiver operating characteristic(ROC) curves. Results: There was no significant difference between the ASD group and the control group in the first preoperative diagnosis, preoperative Pfirrmann grading of adjacent segmental discs, or comorbidities(P>0.05). The patients in the ASD group received a second surgery 5.4±2.3 years after the initial operation, and the fusion segments of the second surgery were L3/4 in 16 patients and L5/S1 in 10 patients. The preoperative SL, SS, and relative height of L3/4, L4/5 and L5/S1 intervertebral space between the two groups were of no significant difference, respectively(P>0.05). The patients in the ASD group had significantly smaller preoperative LL than those in the control group(P=0.031). After the initial fusion, both SL and LL were significantly smaller in the ASD group than those in the control group(P<0.05). At the final follow-up, both SL and LL were significantly smaller in the ASD group than those in the control group(P<0.001); also, the relative height of L3/4 intervertebral space was significantly smaller in the ASD group(P=0.002). When comparing the relative correction values of the parameters of the initial surgery between the two groups, the relative difference in SL(r△SL) was significantly smaller in the ASD group than in the control group(P<0.001), while the relative difference in LL(r△LL), L4/5 relative difference in disc height(r△DH), L3/4 r△DH, and L5/S1 r△DH were not significantly different between the two groups(P>0.05). In the multiple regression analysis of the occurrence of ASD, a smaller initial postoperative/preoperative r△SL was an independent risk factor(OR=0.031, 95%CI 0.005-0.209). The ROC curve suggested an area under curve(AUC) of 0.731 (95%CI 0.615-0.848) for r△SL. The best predictor of the occurrence of ASD for r△SL threshold was -10.5%. Conclusions: Inadequate local curvature correction during posterior L4/5 fusion may lead to long-term loss of adjacent segment height, which is an independent risk factor for the development of ASD after fusion.