Department of Orthopaedics, Centro Hospitalar Universitário do Porto, Largo Prof. Abel Salazar, 4099-001, Porto, Portugal.
Eur J Orthop Surg Traumatol. 2022 Oct;32(7):1291-1299. doi: 10.1007/s00590-021-03103-z. Epub 2021 Aug 31.
Cage subsidence is a very common complication after lumbar interbody fusion. It may compromise vertebral interbody fusion through progressive spinal deformity and consequently cause compression of neural elements. Clinical relevance remains, however, unclear, with few studies on this subject and even less information regarding its correlation with clinical findings. The aim of this study was to identify risk factors for cage subsidence and clinical evaluation after transforaminal (TLIF) and posterior (PLIF) lumbar interbody fusion.
A retrospective study in patients submitted to TLIF and PLIF between 2008 and 2017 was conducted.
A total of 165 patients were included (123 TLIF and 42 PLIF). Univariate analysis showed an increased risk of cage subsidence in spondylolisthesis comparing with degenerative disk disease (p = 0.007). A higher preoperative lumbar lordosis angle (p = 0.014) and cage placement in L2-L3 (p = 0.012) were associated with higher risk of subsidence. The posterior cage positioning on vertebral endplate was associated with a higher risk of subsidence (p = 0.028) and significant subsidence (p = 0.005), defined as cage migration > 50% of cage height. PLIF presented a higher risk when comparing with TLIF (p = 0.024). Hounsfield unit (HU) values < 135 (OR6; 95% CI [1.95-34]) and posterior positioning (OR7; 95% CI [1.7-27.3]) were independent risk factors for cage subsidence and significant subsidence, respectively, in multivariate analysis. There was a tendency for significant subsidence in degrees ≥ 2 of Meyerding spondylolisthesis (OR4; 95% CI [0.85-21.5]). Significant cage subsidence was not associated with worse clinical results. Other analyzed factors, such as age (p = 0.008), low bone mineral density (BMD) (p = 0.029) and type of surgery (TLIF) (p = 0.004), were associated with worse results.
The present study shows that lower BMD and posterior cage positioning are relevant risk factors for lumbar cage subsidence. Low BMD is also a predictor of poor clinical results, so it must be properly evaluated and considered, through HU values measurement in CT scan, a feasible and reliable tool in perioperative planning.
腰椎体间融合术后， cage 沉降是一种非常常见的并发症。它可能通过进行性脊柱畸形而损害椎体间融合，并因此导致神经元素受压。然而，临床相关性仍不清楚，关于这个主题的研究很少，关于其与临床发现的相关性的信息更少。本研究旨在确定经椎间孔（TLIF）和后路（PLIF）腰椎体间融合术后 cage 沉降的危险因素和临床评估。
对 2008 年至 2017 年间接受 TLIF 和 PLIF 的患者进行回顾性研究。
共纳入 165 例患者（TLIF 123 例，PLIF 42 例）。单因素分析显示，与退行性椎间盘疾病相比，脊椎滑脱症患者 cage 沉降的风险增加（p=0.007）。术前腰椎前凸角较高（p=0.014）和 cage 置于 L2-L3（p=0.012）与沉降风险增加相关。椎体终板后路 cage 定位与沉降风险较高相关（p=0.028）和明显沉降（p=0.005），定义为 cage 迁移> cage 高度的 50%。与 TLIF 相比，PLIF 风险更高（p=0.024）。HU 值<135（OR6；95%CI[1.95-34]）和后路定位（OR7；95%CI[1.7-27.3]）是多因素分析中 cage 沉降和明显沉降的独立危险因素。Meyerding 脊椎滑脱程度≥2 度时，明显沉降的趋势（OR4；95%CI[0.85-21.5]）。明显的 cage 沉降与较差的临床结果无关。其他分析因素，如年龄（p=0.008）、低骨密度（BMD）（p=0.029）和手术类型（TLIF）（p=0.004），与较差的结果相关。
本研究表明，较低的 BMD 和后路 cage 定位是腰椎 cage 沉降的相关危险因素。低 BMD 也是临床结果不佳的预测因素，因此必须通过 CT 扫描的 HU 值测量进行适当评估和考虑，这是围手术期计划中一种可行且可靠的工具。
