School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China.
School of Mechanical Engineering and Automation, Northeastern University, Shenyang, China.
Comput Biol Med. 2023 Sep;164:107357. doi: 10.1016/j.compbiomed.2023.107357. Epub 2023 Aug 13.
Lumbar/lumbosacral fusion supplemented with topping-off devices has been proposed with the aim of avoiding adjacent segment degeneration proximal to the fusion construct. However, it remains unclear how the biomechanics of the sacroiliac joint (SIJ) are altered after topping-off surgery. The objective of this study was to investigate the biomechanical effects of topping-off instrumentation on SIJ after lumbosacral fusion.
The validated finite element model of an intact lumbar spine-pelvis segment was modified to simulate L5-S1 interbody fusion fixed with a pedicle screw system. An interspinous spacer, Device for Intervertebral Assisted Motion (DIAM), was used as a topping-off device and placed between interspinous processes of the L4 and L5 segments. Range of motion (ROM), von-Mises stress distribution, and ligament strain at SIJ were compared between fusion (without DIAM) and topping-off (fusion with DIAM) models under moments of four physiological motions.
ROM at the left and right SIJs in the topping-off model was higher by 26.9% and 27.5% in flexion, 16.8% and 16.1% in extension, 18.8% and 15.8% in lateral bending, and 3.7% and 7.4% in axial rotation, respectively, compared to those in the fusion model. The predicted stress and strain data showed that under all physiological loads, the topping-off model exhibited higher stress and ligament strain at the SIJs than the fusion model.
Motion, stress, and ligament strain at SIJ increase when supplementing lumbosacral fusion with topping-off devices, suggesting that topping-off surgery may be associated with higher risks of SIJ degeneration and pain than fusion alone.
为了避免融合结构近端的相邻节段退变，人们提出了在腰椎/腰骶融合的基础上补充顶置装置的方法。然而，顶置手术后骶髂关节（SIJ）的生物力学如何改变仍不清楚。本研究的目的是研究腰骶融合后路顶置器械对 SIJ 的生物力学影响。
对完整的腰椎-骨盆节段的验证有限元模型进行了修改，以模拟 L5-S1 椎间融合固定的椎弓根螺钉系统。使用棘突间间隔器（DIAM）作为顶置装置，放置在 L4 和 L5 节段的棘突间。在四个生理运动的力矩下，比较融合（无 DIAM）和顶置（融合加 DIAM）模型之间 SIJ 的运动范围（ROM）、von-Mises 应力分布和韧带应变。
顶置模型中左右 SIJ 的 ROM 在屈伸时分别增加了 26.9%和 27.5%，在伸展时分别增加了 16.8%和 16.1%，在侧屈时分别增加了 18.8%和 15.8%，在轴向旋转时分别增加了 3.7%和 7.4%，与融合模型相比。预测的应力和应变数据表明，在所有生理负荷下，顶置模型的 SIJ 处的应力和韧带应变均高于融合模型。
在腰骶融合的基础上补充顶置装置会增加 SIJ 的运动、应力和韧带应变，提示顶置手术可能比单纯融合更容易导致 SIJ 退变和疼痛。
