Abstract：
BACKGROUND: Oblique lumbar interbody fusion (OLIF) can provide an ideal minimally invasive solution for achieving spinal fusion in an older, more frail population where decreased bone quality can be a limiting factor. Stabilization can be achieved with bilateral pedicle screws (BPS), which require additional incisions and longer operative time. Alternatively, a novel self-anchoring stand-alone lateral plate system (SSA) can be used, where no additional incisions are required. Based on the relevant literature, BPS constructs provide greater primary biomechanical stability compared to lateral plate constructs, including SSA. This difference is further increased by osteoporosis. Screw augmentation in spinal fusion surgeries is commonly used; however, in the case of OLIF, it is a fairly new concept, lacking a consensus-based guideline.
OBJECTIVE: This comparative finite element (FE) study aimed to investigate the effect of PMMA screw augmentation on the primary stability of a stand-alone implant construct versus posterior stabilization in OLIF with osteoporotic bone quality.
METHODS: The biomechanical effect of screw augmentation was studied inside an in-silico environment using computer-aided FE analysis.
METHODS: A previously validated and published L2-L4 FE model with normal and osteoporotic bone material properties was used. Geometries based on the OLIF implants (BPS, SSA) were created and placed inside the L3-L4 motion segment with increasing volumes (1-6 cm3) of PMMA augmentation. A follower load of 400 N and 10 Nm bending moment (in the three anatomical planes) were applied to the surgical FE models with different bone material properties. The operated L3-L4 segmental range of motion (ROM), the inserted cage\'s maximal caudal displacements, and L4 cranial bony endplate principal stress values were measured.
RESULTS: The nonaugmented values for the BPS construct were generally lower compared to SSA, and the difference was increased by osteoporosis. In osteoporotic bone, PMMA augmentation gradually decreased the investigated parameters and the difference between the two constructs as well. Between 3 cm3 and 4 cm3 of injected PMMA volume per screw, the difference between augmented SSA and standard BPS became comparable.
CONCLUSIONS: Based on this study, augmentation can enhance the primary stability of the constructs and decrease the difference between them. Considering leakage as a possible complication, between 3 cm3 and 4 cm3 of injected PMMA per screw can be an adequate amount for SSA augmentation. However, further in silico, and possibly in vitro and clinical testing is required to thoroughly understand the investigated biomechanical aspects.
CONCLUSIONS: This study sheds light on the possible biomechanical advantage offered by augmented OLIF implants and provides a theoretical augmentation amount for the SSA construct. Based on the findings, the concept of an SSA device with PMMA augmentation capability is desirable.
OBJECTIVE: This comparative finite element (FE) study aimed to investigate the effect of PMMA screw augmentation on the primary stability of a stand-alone implant construct versus posterior stabilization in OLIF with osteoporotic bone quality.
METHODS: The biomechanical effect of screw augmentation was studied inside an in-silico environment using computer-aided FE analysis.
METHODS: A previously validated and published L2-L4 FE model with normal and osteoporotic bone material properties was used. Geometries based on the OLIF implants (BPS, SSA) were created and placed inside the L3-L4 motion segment with increasing volumes (1-6 cm3) of PMMA augmentation. A follower load of 400 N and 10 Nm bending moment (in the three anatomical planes) were applied to the surgical FE models with different bone material properties. The operated L3-L4 segmental range of motion (ROM), the inserted cage\'s maximal caudal displacements, and L4 cranial bony endplate principal stress values were measured.
RESULTS: The nonaugmented values for the BPS construct were generally lower compared to SSA, and the difference was increased by osteoporosis. In osteoporotic bone, PMMA augmentation gradually decreased the investigated parameters and the difference between the two constructs as well. Between 3 cm3 and 4 cm3 of injected PMMA volume per screw, the difference between augmented SSA and standard BPS became comparable.
CONCLUSIONS: Based on this study, augmentation can enhance the primary stability of the constructs and decrease the difference between them. Considering leakage as a possible complication, between 3 cm3 and 4 cm3 of injected PMMA per screw can be an adequate amount for SSA augmentation. However, further in silico, and possibly in vitro and clinical testing is required to thoroughly understand the investigated biomechanical aspects.
CONCLUSIONS: This study sheds light on the possible biomechanical advantage offered by augmented OLIF implants and provides a theoretical augmentation amount for the SSA construct. Based on the findings, the concept of an SSA device with PMMA augmentation capability is desirable.
摘要：
背景：斜腰椎椎间融合术（OLIF）可以为老年人实现脊柱融合提供理想的微创解决方案，更脆弱的人群，骨骼质量下降可能是一个限制因素。稳定可以通过双侧椎弓根螺钉（BPS）实现，这需要额外的切口和更长的手术时间。或者，可以使用一种新颖的自锚固独立侧板系统(SSA)，不需要额外的切口。基于相关文献，与外侧板构造相比，BPS构造提供了更大的主要生物力学稳定性，包括SSA。骨质疏松症进一步增加了这种差异。脊柱融合手术中通常使用螺钉增强；然而，在OLIF的情况下，这是一个相当新的概念，缺乏基于共识的指导方针。
目的：这项比较研究旨在研究PMMA螺钉增强对具有骨质疏松性骨质量的斜腰椎椎间融合术中独立植入物结构与后路稳定性的主要稳定性的影响。
方法：使用计算机辅助有限元分析在计算机环境中研究了螺钉增强的生物力学效应。
方法：使用了先前验证和发布的具有正常和骨质疏松骨材料特性的L2-L4有限元模型。基于OLIF植入物的几何形状(BPS，SSA）被创建并放置在L3-L4运动段内，增加了PMMA增强量（1cm3-6cm3）。将400N的从动件载荷和10Nm的弯矩（在三个解剖平面中）应用于具有不同骨骼材料特性的手术有限元模型。操作的L3-L4分段运动范围(ROM)，插入的笼子的最大尾端位移，测量和L4颅骨终板主应力值。
结果：与SSA相比，BPS构建体的非增强值通常较低，这种差异因骨质疏松症而增加。在骨质疏松的骨骼中，PMMA增强逐渐降低了所研究的值以及两种构建体之间的差异。每个螺杆注射的PMMA体积在3cm3和4cm3之间，增强SSA和标准BPS之间的差异变得相当。
结论：基于这项研究，增强可以增强构建体的主要稳定性并减少它们之间的差异。考虑到泄漏是一种可能的并发症，每个螺杆注射3cm3至4cm3之间的PMMA可以是SSA增加的足够量。然而,进一步在硅，并且可能需要体外和临床测试才能彻底了解所研究的生物力学方面。
结论：这项研究揭示了增强OLIF植入物可能提供的生物力学优势，并为SSA构建体提供了理论上的增强量。根据调查结果,具有PMMA增强能力的SSA装置的概念是合乎需要的。
目的：这项比较研究旨在研究PMMA螺钉增强对具有骨质疏松性骨质量的斜腰椎椎间融合术中独立植入物结构与后路稳定性的主要稳定性的影响。
方法：使用计算机辅助有限元分析在计算机环境中研究了螺钉增强的生物力学效应。
方法：使用了先前验证和发布的具有正常和骨质疏松骨材料特性的L2-L4有限元模型。基于OLIF植入物的几何形状(BPS，SSA）被创建并放置在L3-L4运动段内，增加了PMMA增强量（1cm3-6cm3）。将400N的从动件载荷和10Nm的弯矩（在三个解剖平面中）应用于具有不同骨骼材料特性的手术有限元模型。操作的L3-L4分段运动范围(ROM)，插入的笼子的最大尾端位移，测量和L4颅骨终板主应力值。
结果：与SSA相比，BPS构建体的非增强值通常较低，这种差异因骨质疏松症而增加。在骨质疏松的骨骼中，PMMA增强逐渐降低了所研究的值以及两种构建体之间的差异。每个螺杆注射的PMMA体积在3cm3和4cm3之间，增强SSA和标准BPS之间的差异变得相当。
结论：基于这项研究，增强可以增强构建体的主要稳定性并减少它们之间的差异。考虑到泄漏是一种可能的并发症，每个螺杆注射3cm3至4cm3之间的PMMA可以是SSA增加的足够量。然而,进一步在硅，并且可能需要体外和临床测试才能彻底了解所研究的生物力学方面。
结论：这项研究揭示了增强OLIF植入物可能提供的生物力学优势，并为SSA构建体提供了理论上的增强量。根据调查结果,具有PMMA增强能力的SSA装置的概念是合乎需要的。
