骨质疏松对后路单节段腰椎融合术后融合器沉降程度的影响

Influence factors analysis of cage subsidence grading after posterior lumbar fusion in osteoporotic patients

目的:探讨单节段后路腰椎椎间融合术治疗合并骨质疏松的腰椎退变性疾病术后融合器沉降程度的相关影响因素,分析不同程度沉降与临床疗效的相关性。方法:回顾性分析2013年6月~2015年6月在我院行单节段后路腰椎融合手术治疗合并骨质疏松的腰椎退变性疾病患者的一般情况(年龄、性别、体重、病程)及手术相关资料[手术时间、出血量、单侧/双侧减压、传统/皮质骨螺钉(CBT)置钉、手术节段等],收集术前、术后各随访时间点的影像学资料,评估腰椎骨密度(BMD)、融合器沉降度、腰椎退变等级、终板改变Modic分型,测量手术节段椎间隙高度、节段性前凸角、腰椎前凸角和骶骨倾斜角等,并依据融合器沉降度分为轻度沉降组(沉降≤1mm)、中度沉降组(1mm<沉降<3mm)和重度沉降组(沉降≥3mm),采用日本骨科协会(Japanese Orthopaedic Association scores,JOA)评分改善率评价临床疗效。单因素及Logistic回归法统计分析融合器沉降度相关的影响因素;Pearson相关性分析融合器沉降程度与临床疗效的关系。结果:共纳入186例行单节段后路腰椎融合手术的腰椎退变性疾病合并骨质疏松的患者,其中162例获得随访,随访时间17~26个月(21.9±4.8个月),融合器重度、中度、轻度沉降分别为46例、64例、52例,三组术后腰椎JOA评分改善率差异无统计学意义[(64.38±18.20)%vs (63.74±22.76)%vs (59.90±25.01)%,P>0.05)]。单因素分析结果表明三组间腰椎BMD T值、Modic分型、椎间隙高度矫正值、手术节段前凸角矫正值、CBT置钉法为影响融合器沉降程度的相关因素(P<0.05),其余因素无统计学差异。Logistic回归分析显示手术节段椎间隙高度矫正值(OR=1.902,95%CI=1.323~2.509)、节段性前凸角矫正值(OR=1.605,95%CI=1.207~2.367)为融合器沉降程度的影响因素(P<0.05)。腰椎JOA评分改善率与融合器沉降程度无明显相关性(r=0.354,P=0.435);腰痛VAS评分与融合器沉降度呈弱相关(r=0.434,P<0.05)。结论:合并骨质疏松的腰椎退变性疾病患者行腰椎融合术后易发生融合器沉降,手术节段椎间隙高度矫正值和前凸角矫正值是融合器沉降程度的独立影响因素,过度撑开椎间隙、过度矫正节段性前凸会增加融合器沉降程度,融合器沉降程度与术后腰痛程度呈弱相关。

Objectives:To investigate the influence factors related to cage subsidence grading,and explore the association between cage subsidence grading and clinical outcomes after posterior lumbar interbody fusion in single level lumbar degenerative disease with osteoporosis.Methods:Data of 186 patients of lumbar degenerative disease with osteoporosis who underwent single level posterior decompression and interbody fusion from June 2013 to June 2015 were reviewed.The followings were recorded including general characteristics(age,sex,body weight,symptom duration),operation related information(operation time,blood loss,unilateral/bilateral decompression,tradition/cortical bone trajectory screw fixation,operated level) and radiological parameters(bone mineral density,cage subsidence grading,Modic changes,intervertebral space height,segmental lordosis,lumbar lordosis,sacral slope).All patients were divided into mild subsidence group(subsidence≤1 mm),moderate subsidence group(1 mm<subsidence<3 mm) and severe subsidence group(subsidence≥3 mm),basing on the loss of intervertebral space height.Lumbar Japanese Orthopaedic Association(JOA) score was used to evaluate the clinical outcomes.Influence factors analysis of cage subsidence grading was evaluated by using multiple logistic regression analysis.Relationship between cage subsidence grading and clinical outcomes was explored by using comparative statistics and Pearson correlation analysis.Results:162 out of the total 186 patients with an average of 21.9±4.8 months follow-up were finally reviewed in this study.46,64,and 52 patients were enrolled in three different subsidence subgroups respectively.No significant difference of the general characteristics was found among subgroups(P>0.05).The BMD value(T-score),Modic changes,adjusted intervertebral space height,adjusted segmental lordosis,CBT screw fixation were found as influence factors of cage subsidence grading in univariate analysis(P<0.05).Adjusted intervertebral space height rate(OR=1.902,95%CI=1.323-2.509) and adjusted segmental lordosis(OR=1.605,95%CI=1.207-2.367) were found as influence factors of cage subsidence in logistic regression(P<0.05).Weak Pearson relationship was found between cage subsidence grading and lumbar VAS improvement(r=0.434,P<0.05).Conclusions:Significant cage subsidence highly occurred in patients of lumbar degenerative disease with osteoporosis who underwent lumbar interbody fusion.However,only weak relation was found between cage subsidence grading and lumbar JOA scores.Cage subsidence grading is affected by many factors,and the adjusted intervertebral space height rate and the adjusted segmental lordosis were found as important and independent influence factors.