Palepu Vivek, Helgeson Melvin D, Molyneaux-Francis Michael, Nagaraja Srinidhi
U.S. Food and Drug Administration,Center for Devices and Radiological Health,Office of Science and Engineering Laboratories,Division of Applied Mechanics,Silver Spring, MD 20993.
Walter Reed National Military Medical Center,Department of Orthopaedics,Bethesda, MD 20889.
J Biomech Eng. 2019 Mar 1;141(3). doi: 10.1115/1.4042181.
Several approaches (anterior, posterior, lateral, and transforaminal) are used in lumbar fusion surgery. However, it is unclear whether one of these approaches has the greatest subsidence risk as published clinical rates of cage subsidence vary widely (7-70%). Specifically, there is limited data on how a patient's endplate morphometry and trabecular bone quality influences cage subsidence risk. Therefore, this study compared subsidence (stiffness, maximum force, and work) between anterior (ALIF), lateral (LLIF), posterior (PLIF), and transforaminal (TLIF) lumbar interbody fusion cage designs to understand the impact of endplate and trabecular bone quality on subsidence. Forty-eight lumbar vertebrae were imaged with micro-ct to assess trabecular microarchitecture. micro-ct images of each vertebra were then imported into image processing software to measure endplate thickness (ET) and maximum endplate concavity depth (ECD). Generic ALIF, LLIF, PLIF, and TLIF cages made of polyether ether ketone were implanted on the superior endplates of all vertebrae and subsidence testing was performed. The results indicated that TLIF cages had significantly lower (p < 0.01) subsidence stiffness and maximum subsidence force compared to ALIF and LLIF cages. For all cage groups, trabecular bone volume fraction was better correlated with maximum subsidence force compared to ET and concavity depth. These findings highlight the importance of cage design (e.g., surface area), placement on the endplate, and trabecular bone quality on subsidence. These results may help surgeons during cage selection for lumbar fusion procedures to mitigate adverse events such as cage subsidence.
腰椎融合手术中使用了几种方法（前路、后路、侧路和经椎间孔）。然而，由于已发表的椎间融合器下沉临床发生率差异很大（7%-70%），目前尚不清楚这些方法中是否有一种具有最大的下沉风险。具体而言，关于患者终板形态测量和小梁骨质量如何影响椎间融合器下沉风险的数据有限。因此，本研究比较了前路（ALIF）、侧路（LLIF）、后路（PLIF）和经椎间孔（TLIF）腰椎椎间融合器设计之间的下沉情况（刚度、最大力和功），以了解终板和小梁骨质量对下沉的影响。对48个腰椎椎体进行了显微CT成像，以评估小梁微结构。然后将每个椎体的显微CT图像导入图像处理软件，测量终板厚度（ET）和最大终板凹陷深度（ECD）。将由聚醚醚酮制成的通用ALIF、LLIF、PLIF和TLIF椎间融合器植入所有椎体的上终板，并进行下沉测试。结果表明，与ALIF和LLIF椎间融合器相比，TLIF椎间融合器的下沉刚度和最大下沉力显著更低（p<0.01）。对于所有椎间融合器组，与ET和凹陷深度相比，小梁骨体积分数与最大下沉力的相关性更好。这些发现突出了椎间融合器设计（如表面积）、在终板上的放置以及小梁骨质量对下沉的重要性。这些结果可能有助于外科医生在腰椎融合手术中选择椎间融合器时，减少诸如椎间融合器下沉等不良事件的发生。
