Background

The number of oblique lumbar interbody fusion (OLIF) procedures has continued to rise over recent years. Adjacent segment degeneration (ASD) is a common complication following vertebral body fusion. Although the precise mechanism remains uncertain, ASD has gradually become more common in OLIF. Therefore, the present study analyzed the association between disc degeneration and OLIF to explore whether adjacent degeneration was promoted by OLIF in degenerative disc disease.

Methods

A three-dimensional nonlinear finite element (FE) model of the L3-S1 lumbar spine was developed and validated. Three lumbar spine degeneration models with different degrees of degeneration (mild, moderate and severe) and a model of OLIF surgery were constructed at the L4-L5 level. When subjected to a follower compressive load (500 N), hybrid moment loading was applied to all models of the lumbar spine and the range of motion (ROM), intradiscal pressure (IDP), facet joint force (FJF), average mises stress in the annulus (AMSA), average tresca stress in the annulus (ATSA) and average endplate stress (AES) were measured.

Results

Compared with the healthy lumbar spine model, the ROM, IDP, FJF, AMSA, ATSA and AES of the segments adjacent to the degenerated segment increased in each posture as the degree of disc degeneration increased. In different directions of motion, the ROM, IDP, FJF, AMSA, ATSA and AES in the OLIF model in the L3-L4 and L5-S1 segments were higher than those of the healthy model and each degenerated model. Compared with the healthy model, the largest relative increase in biomechanical parameters above (ROM, IDP, FJF, AMSA, ATSA or AES) was observed in the L3-L4 segment in the OLIF model, of 77.13%, 32.63%, 237.19%, 45.36%, 110.92% and 80.28%, respectively. In the L5-S1 segment the corresponding values were 68.88%, 36.12%, 147.24%, 46.00%, 45.88% and 51.29%, respectively.

Conclusions

Both degenerated discs and OLIF surgery modified the pattern of motion and load distribution of adjacent segments (L3-L4 and L5-S1 segments). The increases in the biomechanical parameters of segments adjacent to the surgical segment in the OLIF model were more apparent than those of the degenerated models. In summary, OLIF risked accelerating the degeneration of segments adjacent to those of a surgical segment.

中文翻译：

---

斜腰椎间融合术是否能促进变性椎间盘疾病的邻近变性：有限元分析

背景

近年来，倾斜腰椎椎间融合术（OLIF）的数量一直在增加。椎体融合术后，邻近节段变性（ASD）是一种常见的并发症。尽管确切的机制仍不确定，但ASD在OLIF中已逐渐变得越来越普遍。因此，本研究分析了椎间盘退变与OLIF之间的关系，以探讨OLIF是否在变性椎间盘疾病中促进了邻近的退行性变。

方法

建立并验证了L3-S1腰椎的三维非线性有限元（FE）模型。在L4-L5水平上构建了三种不同程度的变性（轻度，中度和重度）腰椎变性模型和OLIF手术模型。当受到跟随者压缩载荷（500 N）时，混合力矩载荷被应用于所有腰椎模型，并且运动范围（ROM），椎间盘内压力（IDP），小关节力（FJF），测量环面（AMSA），环面平均Tresca应力（ATSA）和平均端板应力（AES）。

结果

与健康的腰椎模型相比，随着椎间盘退变程度的增加，与退变节段相邻的节段的ROM，IDP，FJF，AMSA，ATSA和AES在每个姿势中均增加。在不同的运动方向上，L3-L4和L5-S1段的OLIF模型中的ROM，IDP，FJF，AMSA，ATSA和AES高于健康模型和每个退化模型的ROM，IDP，FJF，AMSA，ATSA和AES。与健康模型相比，在OLIF模型中，L3-L4段的上述生物力学参数（ROM，IDP，FJF，AMSA，ATSA或AES）最大相对增加，分别为77.13％，32.63％，237.19％，分别为45.36％，110.92％和80.28％。在L5-S1段中，相应的值分别为68.88％，36.12％，147.24％，46.00％，45.88％和51.29％。

结论

退化的椎间盘和OLIF手术均改变了相邻节段（L3-L4和L5-S1节段）的运动和负荷分布模式。与简并模型相比，OLIF模型中与手术节段相邻的节段的生物力学参数的增加更为明显。总之，OLIF有加速与手术段相邻的段退化的风险。