Agarwal Nitin, White Michael D, Zhang Xiaoran, Alan Nima, Ozpinar Alp, Salvetti David J, Tempel Zachary J, Okonkwo David O, Kanter Adam S, Hamilton D Kojo
J Neurosurg Spine. 2020 Mar 6;33(1):12-16. doi: 10.3171/2020.1.SPINE19776. Print 2020 Jul 1.
Stand-alone lateral lumbar interbody fusion (LLIF) is a useful minimally invasive approach for select spinal disorders, but implant subsidence may occur in up to 30% of patients. Previous studies have suggested that wider implants reduce the subsidence rate. This study aimed to evaluate whether a mismatch of the endplate and implant area can predict the rate and grade of implant subsidence.
The authors conducted a retrospective review of prospectively collected data on consecutive patients who underwent stand-alone LLIF between July 2008 and June 2015; 297 patients (623 surgical levels) met inclusion criteria. Imaging studies were examined to grade graft subsidence according to Marchi criteria. Thirty patients had radiographic evidence of implant subsidence. The endplates above and below the implant were measured.
A total of 30 patients with implant subsidence were identified. Of these patients, 6 had Marchi grade 0, 4 had grade I, 12 had grade II, and 8 had grade III implant subsidence. There was no statistically significant correlation between the endplate-implant area mismatch and subsidence grade or incidence. There was also no correlation between endplate-implant width and length mismatch and subsidence grade or incidence. However, there was a strong correlation between the usage of the 18-mm-wide implants and the development of higher-grade subsidence (p = 0.002) necessitating surgery. There was no significant association between the degree of mismatch or Marchi subsidence grade and the presence of postoperative radiculopathy. Of the 8 patients with 18-mm implants demonstrating radiographic subsidence, 5 (62.5%) required reoperation. Of the 22 patients with 22-mm implants demonstrating radiographic subsidence, 13 (59.1%) required reoperation.
There was no correlation between endplate-implant area, width, or length mismatch and Marchi subsidence grade for stand-alone LLIF. There was also no correlation between either endplate-implant mismatch or Marchi subsidence grade and postoperative radiculopathy. The data do suggest that the use of 18-mm-wide implants in stand-alone LLIF may increase the risk of developing high-grade subsidence necessitating reoperation compared to the use of 22-mm-wide implants.
独立式腰椎椎间融合术（LLIF）是治疗特定脊柱疾病的一种有用的微创方法，但高达30%的患者可能会发生植入物下沉。先前的研究表明，更宽的植入物可降低下沉率。本研究旨在评估终板与植入物面积不匹配是否能预测植入物下沉的速率和分级。
作者对2008年7月至2015年6月期间连续接受独立式LLIF手术的患者的前瞻性收集数据进行了回顾性分析；297例患者（623个手术节段）符合纳入标准。根据马尔基标准对影像学研究进行检查，以对移植物下沉进行分级。30例患者有植入物下沉的影像学证据。测量植入物上方和下方的终板。
共识别出30例有植入物下沉的患者。在这些患者中，6例马尔基分级为0级，4例为I级，12例为II级，8例为III级植入物下沉。终板与植入物面积不匹配与下沉分级或发生率之间无统计学显著相关性。终板与植入物宽度和长度不匹配与下沉分级或发生率之间也无相关性。然而，使用18毫米宽的植入物与更高级别下沉（p = 0.002）的发生之间存在强相关性，这需要进行手术。不匹配程度或马尔基下沉分级与术后神经根病的存在之间无显著关联。在8例显示影像学下沉的18毫米植入物患者中，5例（62.5%）需要再次手术。在22例显示影像学下沉的22毫米植入物患者中，13例（59.1%）需要再次手术。
对于独立式LLIF，终板与植入物面积、宽度或长度不匹配与马尔基下沉分级之间无相关性。终板与植入物不匹配或马尔基下沉分级与术后神经根病之间也无相关性。数据确实表明，与使用较宽的22毫米植入物相比，在独立式LLIF中使用18毫米宽的植入物可能会增加发生需要再次手术的高级别下沉的风险。
