Department of Spinal Surgery, Shandong Province Hospital Affiliated to Shandong University, Jinan, China.
Department of Spinal surgery, Armed Police Hospital of Shandong Province, Jinan, China.
Orthop Surg. 2020 Feb;12(1):262-268. doi: 10.1111/os.12624.
We create a new S1 cortical screw trajectory technique using 3D reconstruction and the finite element (FE) method to provide a more reliable theoretical basis for clinical practices and to advance internal fixation technology for treatment of lumbosacral degenerative diseases.
This retrospective study included patients (aged from 40 to 70 years) who needed intervertebral fusion surgery between August 2016 and August 2017. Data of patients with lumbosacral lesions was scanned and measured by 64-row spiral CT, and were then transmitted to the GE-AW4.3 post-processing system for 3D reconstruction. The trajectories of the three different screws were simulated by FE software and processed by mimics software to simulate the screw path: traditional PS fixation (Model A); traditional cortical screw (Model B); and new cortical screw (Model C). The CT value of the bone around the screw canal was recorded. Biomechanical effects of the three screws were analyzed and compared.
The displacement of flexion and extension, the vertebral body stress of right torsion, and the cage stress of flexion showed no significant differences among the three models (P > 0.05). The results demonstrated that cortical screws exceeded pedicle screws in stability and pullout force. Models B and C showed higher vertebral displacement in left bending (0.41 and 0.31 mm) and right bending (0.58 and 0.40 mm), lower vertebral body stress on extension (48.37 and 38.92 MPa), left bending (0.76 and 0.74 mm) and right bending (0.50 and 0.53 mm), and higher cage stress on left bending (162.19 and 160.63 MPa), right bending (150.02 and 150.05 MPa), left torsion (158.45 and 146.27 MPa) and right torsion (167.33 and 171.15 MPa) (all P < 0.05) compared to model A. Compared to Model B, Model C had higher displacement of left and right torsion, lower pressure in extension and flexion, and lower stress on cages in extension (P < 0.05).
The new cortical screw insertion method has similar effects to traditional cortical screw fixation. However, it demonstrated advantages in promoting lumbosacral interbody fusion, which protects vessels and nerves.
我们使用三维重建和有限元（FE）方法创建了一种新的 S1 皮质螺钉轨迹技术，为临床实践提供了更可靠的理论依据，并推进了治疗腰骶部退行性疾病的内固定技术。
这项回顾性研究纳入了 2016 年 8 月至 2017 年 8 月期间需要进行椎间融合手术的患者（年龄 40 至 70 岁）。通过 64 排螺旋 CT 对患者腰骶病变部位进行扫描和测量，并将数据传输至 GE-AW4.3 后处理系统进行三维重建。通过 FE 软件模拟三种不同螺钉的轨迹，并通过 mimics 软件处理，以模拟螺钉路径：传统 PS 固定（模型 A）；传统皮质螺钉（模型 B）；和新皮质螺钉（模型 C）。记录螺钉通道周围骨的 CT 值。分析和比较三种螺钉的生物力学效应。
三种模型在屈伸位的位移、右侧扭转的椎体应力和屈伸位的 cage 应力方面无显著差异（P > 0.05）。结果表明，皮质螺钉在稳定性和拔出力方面超过了椎弓根螺钉。模型 B 和 C 在左侧弯曲（0.41 和 0.31mm）和右侧弯曲（0.58 和 0.40mm）时椎体位移更高，伸展时椎体应力更低（48.37 和 38.92MPa），左侧弯曲（0.76 和 0.74mm）和右侧弯曲（0.50 和 0.53mm），左侧弯曲时 cage 应力更高（162.19 和 160.63MPa），右侧弯曲（150.02 和 150.05MPa），左侧扭转（158.45 和 146.27MPa）和右侧扭转（167.33 和 171.15MPa）（均 P < 0.05）。与模型 A 相比，模型 B 和 C 在左侧和右侧扭转时的位移更高，伸展和屈曲时的压力更低，伸展时 cage 的应力更低（P < 0.05）。
新型皮质螺钉插入方法与传统皮质螺钉固定具有相似的效果，但在促进腰骶椎间融合方面具有优势，可保护血管和神经。
