Departments of1Orthopedic Surgery and.
2Department of Bioengineering, Imperial College, London, United Kingdom; and.
J Neurosurg Spine. 2024 Jul 5;41(4):463-472. doi: 10.3171/2024.4.SPINE231007. Print 2024 Oct 1.
The aims of this study were to 1) define the incidence of transforaminal lumbar interbody fusion (TLIF) interbody subsidence; 2) determine the relative importance of preoperative and intraoperative patient- and instrumentation-specific risk factors predictive of postoperative subsidence using CT-based assessment; and 3) determine the impact of TLIF subsidence on postoperative complications and fusion rates.
All adult patients who underwent one- or two-level TLIF for lumbar degenerative conditions at a multi-institutional academic center between 2017 and 2019 were retrospectively identified. Patients with traumatic injury, infection, malignancy, previous fusion at the index level, combined anterior-posterior procedures, surgery with greater than two TLIF levels, or incomplete follow-up were excluded. Interbody subsidence at the superior and inferior endplates of each TLIF level was directly measured on the endplate-facing surface of both coronal and sagittal CT scans obtained greater than 6 months postoperatively. Patients were grouped based on the maximum subsidence at each operative level classified as mild, moderate, or severe based on previously documented < 2-mm, 2- to 4-mm, and ≥ 4-mm thresholds, respectively. Univariate and regression analyses compared patient demographics, medical comorbidities, preoperative bone quality, surgical factors including interbody cage parameters, and fusion and complication rates across subsidence groups.
A total of 67 patients with 85 unique fusion levels met the inclusion and exclusion criteria. Overall, 28% of levels exhibited moderate subsidence and 35% showed severe subsidence after TLIF with no significant difference in the superior and inferior endplate subsidence. Moderate (≥ 2-mm) and severe (≥ 4-mm) subsidence were significantly associated with decreases in cage surface area and Taillard index as well as interbody cages with polyetheretherketone (PEEK) material and sawtooth surface geometry. Severe subsidence was also significantly associated with taller preoperative disc spaces, decreased vertebral Hounsfield units (HU), the absence of bone morphogenetic protein (BMP) use, and smooth cage surfaces. Regression analysis revealed decreases in Taillard index, cage surface area, and HU, and the absence of BMP use predicted subsidence. Severe subsidence was found to be a predictor of pseudarthrosis but was not significantly associated with revision surgery.
Patient-level risk factors for TLIF subsidence included decreased HU and increased preoperative disc height. Intraoperative risk factors for TLIF subsidence were decreased cage surface area, PEEK cage material, bullet cages, posterior cage positioning, smooth cage surfaces, and sawtooth surface designs. Severe subsidence predicted TLIF pseudarthrosis; however, the causality of this relationship remains unclear.
本研究旨在：1）确定经椎间孔腰椎体间融合术（TLIF）椎间融合器下沉的发生率；2）通过 CT 评估，确定与术前和术中患者及器械相关的预测术后下沉的重要危险因素；3）确定 TLIF 下沉对术后并发症和融合率的影响。
回顾性分析 2017 年至 2019 年在多机构学术中心接受单节段或双节段 TLIF 治疗腰椎退行性疾病的所有成年患者。排除外伤性损伤、感染、恶性肿瘤、指数水平的既往融合、前后联合手术、手术中融合超过 2 个 TLIF 水平或随访不完整的患者。在术后 6 个月以上获得的冠状位和矢状位 CT 扫描的椎体面对表面直接测量每个 TLIF 水平的上终板和下终板的椎间融合器下沉。根据最大下沉程度将患者分为三组：轻度、中度和重度，分别为先前记录的<2mm、2-4mm 和≥4mm。在下沉组之间比较患者的人口统计学资料、合并症、术前骨质量、手术因素，包括椎间融合器参数和融合率及并发症发生率。
共有 67 例患者 85 个融合节段符合纳入和排除标准。总体而言，28%的节段出现中度下沉，35%的节段出现严重下沉，TLIF 后上终板和下终板下沉无显著差异。中重度（≥2mm）和重度（≥4mm）下沉与 Cage 表面积和 Taillard 指数减小以及聚醚醚酮（PEEK）材料和锯齿状表面几何形状的椎间融合器显著相关。严重下沉还与术前椎间盘间隙较高、椎体 Hounsfield 单位（HU）降低、未使用骨形态发生蛋白（BMP）和 Cage 表面光滑显著相关。回归分析显示 Taillard 指数、Cage 表面积和 HU 降低以及未使用 BMP 预测下沉。严重下沉被认为是假关节的预测因素，但与翻修手术无显著相关性。
TLIF 下沉的患者水平危险因素包括 HU 降低和术前椎间盘高度增加。TLIF 下沉的手术危险因素包括 Cage 表面积减小、PEEK 笼材料、子弹笼、后笼定位、Cage 表面光滑和锯齿状表面设计。严重下沉预测 TLIF 假关节；然而，这种关系的因果关系尚不清楚。
