Background

Proximal junction kyphosis is a common clinical complication of posterior long-segment spinal fusion and vertebral body augmentation method is one of the effective approaches to prevent it. The purpose of this study was to explore the biomechanical effect of proximal junction kyphosis after posterior long-segment thoracolumbar fusion with different vertebral augmentation schemes using finite element analysis.

Methods

3D nonlinear finite element models of T1-L5 spine posterior long-segment T8-L5 thoracolumbar fusion combined with T7, T8 and T7&T8 vertebral bone cement augmentation were constructed from human spine CT data and clinical surgical operation scheme to analyze the von Mises stress in the vertebrae, intervertebral discs pressure and pedicle screws system loads under the flexion, extension, lateral bending and axial rotation motion.

Findings

Compared with thoracolumbar posterior long-segment fusion model, T7 maximum stress in T7, T8 and T7&T8 vertebrae augmentation models were reduced by 8.64%, 7.17%, 8.51%;0.79%, −3.88%,1.67%;4.02%, 5.30%, 4.27% and 3.18%, 3.06%, −6.38% under the flexion, extension, lateral bending and axial rotation motion. T7/T8 intervertebral disc pressure in T7, T8, T7&T8 vertebral augmentation models were 36.71Mpa,29.78Mpa,36.47Mpa;22.25Mpa,18.35Mpa,22.06Mpa;84.27Mpa,68.17Mpa, 83.89Mpa and 52.23Mpa, 38.78Mpa,52.10Mpa under the same condition. The maximum stress 178.2Mpa of pedicle screws is mainly distributed at the root of screw.

Interpretation

Thoracolumbar posterior long-segment fusion with proximal double-segment vertebral augmentation should be recommended to prevent proximal junction kyphosis than single-segment augmentation. Simulation results can provide theoretical foundations and assist surgeons in selecting the appropriate operation scheme.

背景

近端关节后凸是后路长节段脊柱融合术常见的临床并发症，椎体增强术是预防它的有效方法之一。本研究的目的是利用有限元分析探讨不同椎体增强方案的后路长节段胸腰椎融合术后近端关节后凸畸形的生物力学效应。

方法

T1-L5脊柱后路长节段T8-L5胸腰椎融合术结合T7、T8和T7&T8椎体骨水泥增强的3D非线性有限元模型，根据人体脊柱CT数据和临床手术方案构建，分析椎体中的von Mises应力。椎骨、椎间盘压力和椎弓根螺钉系统在屈曲、伸展、侧弯和轴向旋转运动下的载荷。

发现

与胸腰椎后路长节段融合模型相比，T7、T8和T7&T8椎体增强模型中T7最大应力分别降低了8.64%、7.17%、8.51%；0.79%、-3.88%、1.67%；4.02%、5.30%、 4.27% 和 3.18%、3.06%、-6.38% 在屈曲、伸展、侧弯和轴向旋转运动下。T7/T8椎间盘压力在T7、T8、T7&T8椎体增强模型中分别为36.71Mpa、29.78Mpa、36.47Mpa；22.25Mpa、18.35Mpa、22.06Mpa；84.27Mpa、68.17Mpa、82Mpa、82Mpa、82Mpa.82.83同等条件下Mpa。椎弓根螺钉最大应力178.2Mpa主要分布在螺钉根部。

解释

与单节段椎体增强相比，应推荐胸腰椎后路长节段融合术与近端双节段椎体增强术预防近端关节后凸畸形。仿真结果可为外科医生选择合适的手术方案提供理论依据。