经椎间孔腰椎椎体间融合联合单侧椎弓根钉棒固定术后融合器沉降及其对临床疗效的影响

Radiological and clinical evaluation of cage subsidence after transforaminal lumbar interbody fusion with unilateral pedicle screw fixation

中文关键词:  经椎间孔腰椎椎体间融合术  单侧固定  融合器  沉降

英文关键词:Transforaminal lumbar interbody fusion  Unilateral pedicle screw fixation  Cage  Subsidence

中文摘要:

  【摘要】 目的：观察经椎间孔腰椎椎体间融合（transforaminal lumbar interbody fusion，TLIF）联合单侧椎弓根钉棒内固定术后融合器沉降情况及其与临床疗效的相关性。方法：回顾分析2014年1月~2015年1月行TLIF+单侧椎弓根钉棒内固定术的43例退变性腰椎疾病患者，融合节段数51个。随访时间23.8±3.7个月（19~28个月）。通过腰椎CT测量并比较患者术前及术后融合节段椎间高度的变化，测量时间点分别为术前、术后即刻、术后半年、术后1年及末次随访时。根据椎间高度丢失的程度将融合器沉降分为0级（0~24%）、Ⅰ级（25%~49%）、Ⅱ级（50%~74%）和Ⅲ级（75%~100%）。统计、分析总体融合器沉降度在术后半年、1年及末次随访时的变化情况。根据融合器前后径及融合节段的长度，分别将患者分为32mm组（n=15）、36mm组（n=28）及单节段组（n=35）、双节段组（n=8），分析各组间术后半年、术后1年及末次随访时融合器沉降度是否存在统计学差异。统计43例患者术前和术后半年、1年及末次随访时的VAS评分及Oswestry功能障碍指数（Oswestry disability index，ODI），采用Pearson系数分析末次随访时融合器沉降与VAS评分、ODI的相关性。结果：末次随访时88.2%（45/51）的融合节段融合器沉降等级为0级，11.8%（6/51）的融合节段沉降等级为Ⅰ级，无Ⅱ级或Ⅲ级沉降的患者。术后半年融合器沉降程度[（9.6±3.4）%]与术后1年融合器沉降程度[（14.2±5.6）%]比较有统计学差异（P<0.05），而术后1年与末次随访时的融合器沉降程度无统计学差异（P>0.05）。术后1年及末次随访时32mm组患者的融合器沉降程度大于36mm组（P<0.05），单节段组和双节段组的融合器沉降程度无统计学差异（P>0.05）。术后半年、1年及末次随访时腰腿痛VAS评分与术前比较显著降低（P<0.05），ODI明显改善（P<0.05）。末次随访时的腰痛VAS评分与融合器的沉降程度呈弱相关性（Pearson相关系数为0.334，P＜0.05），而腿痛VAS评分及ODI与融合器沉降无明显相关性（P>0.05）。结论：TLIF联合单侧椎弓根钉棒内固定术后融合器沉降的程度低，且多数发生在术后1年内。在条件允许的情况下尽量选择前后径大的融合器以降低融合器沉降度，而手术节段的长短（单节段或双节段）对融合器沉降无明显影响。腰痛VAS评分与融合器沉降度存在弱相关性。

英文摘要:

  【Abstract】 Objectives: To assess the radiographic and clinical characteristics of cage subsidence in transforaminal lumbar interbody fusion(TLIF) with unilateral pedicle screw fixation. Methods: A total of 43 patients who underwent unilateral instrumented TLIF from January 2014 to January 2015 was included in this retrospective study. The total number of fusion segment was 51. The duration of follow-up was 23.8±3.7 months(19-28 months). Intervertebral height of fusion segment was measured by comtupter tomography. The time points of measurement were preoperation, immediate, half a year, 1 year and the final follow-up after operation. Subsidence was classified by using the following scale: Grade 0, 0-24% loss of postoperative disc height; Grade Ⅰ, 25%-49%; Grade Ⅱ, 50%-74%; and Grade Ⅲ, 75%-100%. Changes of overall cage subsidence were analyzed at different follow-up time point(6 months, 1 year and the final follow-up after operation). According to the cage anteroposterior diameter and fusion length, patients were divided into 32mm(n=15) and 36mm group(n=28), 1-level(n=35) and 2-level(n=8) group, respectively. Statistical difference of cage subsidence degree between groups at different follow-up time point was analyzed. Visual analogue scale(VAS) and the Oswestry disability index(ODI) were recorded, changes of VAS and ODI were analyzed at different follow-up time point(6 months, 1 year and the final follow-up after operation). The correlation between cage subsidence degree and VAS and ODI at the final follow-up was tested by Pearson correlation coefficient. Results: At the final follow-up after operation, most fusion levels were classified as Grade 0(45/51, 88.2%), and 6 fusion levels with Grade Ⅰ subsidence (6/51, 11.8%). No Grade Ⅱ or Grade Ⅲ subsidence was found. The subsidence degree showed significant difference between 6 months follow-up[(9.6±3.4)%] and 1 year follow-up[(14.2±5.6)%](P<0.05), while no significant difference between 1 year and the final follow-up(P>0.05). Cage subsidence degree in 32mm group was higher than that in 36mm group at the final follow-up(P<0.05), while there was no difference between 1-level and 2-level group at the final follow-up(P>0.05). Both VAS and ODI improved after operation(6 months, 1 year and the final follow-up)(P<0.05), and it showed low correlation between VAS of low back pain and cage subsidence(Pearson coefficient: 0.334, P＜0.05), while no significant relationship between ODI, VAS of leg pain and cage subsidence(P<0.05). Conclusions: Cage subsidence degree in TLIF with unilateral pedicle screw fixation is relatively low, and most of the cage subsidence occurrs within 1 year after operation. The anteroposterior diameter of the cage will affect the cage subsidence. If conditions permit, the cage with large anteroposterior diameter should be selected as far as possible to reduce the cage subsidence degree, while no relationship between fusion length and cage subsidence. The VAS score of lumbar pain is weakly correlated with the cage subsidence.