Department of Orthopaedic Surgery, National Defense Medical College, Tokorozawa, Saitama; and.
J Neurosurg Spine. 2014 Aug;21(2):203-9. doi: 10.3171/2014.3.SPINE13665. Epub 2014 Apr 25.
A cortical bone trajectory (CBT) is a new pedicle screw trajectory that maximizes the thread contact with cortical bone surface, providing enhanced screw purchase. Despite the increased use of the CBT in the lumbar spine, little is known about the insertion technique for the sacral CBT. The aim of this study was to introduce a novel sacral pedicle screw trajectory. This trajectory engages with denser bone maximally by the screw penetrating the S-1 superior endplate through a more medial entry point than the traditional technique, and also has safety advantages, with the protrusion of the screw tip into the intervertebral disc space carrying no risk of neurovascular injury.
In this study, the CT scans of 50 adults were studied for morphometric measurement of the new trajectory. The entry point was supposed to be the junction of the center of the superior articular process of S-1 and approximately 3 mm inferior to the most inferior border of the inferior articular process of L-5. The direction was straight forward in the axial plane without convergence, angulated cranially in the sagittal plane penetrating the middle of the sacral endplate. The cephalad angle to the sacral endplate, length of trajectory, and safety of the trajectory were investigated. Next, the insertional torque of pedicle screws using this technique was measured intraoperatively in 19 patients and compared with the traditional technique.
The mean cephalad angle in these 50 patients was 30.7° ± 5.1°, and the mean length of trajectory was 31.5 ± 3.5 mm. The CT analysis revealed that the penetrating S-1 endplate technique did not cause any neurovascular injury anteriorly in any case. The new technique demonstrated an average of 141% higher insertional torque than the traditional monocortical technique.
The penetrating S-1 endplate technique through the medial entry point is suitable for the connection of lumbar CBT, has revealed favorable stability for lumbosacral fixation, and has reduced the potential risk of neurovascular injuries.
皮质骨轨道（CBT）是一种新的椎弓根螺钉轨迹，最大限度地增加了与皮质骨表面的螺纹接触，从而增强了螺钉的固定力。尽管在腰椎中越来越多地使用 CBT，但对于骶骨 CBT 的插入技术知之甚少。本研究旨在介绍一种新的骶骨椎弓根螺钉轨迹。该轨迹通过从更内侧的入点穿过 S-1 上终板来与最密集的骨最大程度地接触，从而使螺钉穿透，与传统技术相比，这具有更大的安全性优势，螺钉尖端突出到椎间盘间隙不会带来神经血管损伤的风险。
本研究对 50 名成年人的 CT 扫描进行了形态测量，以测量新轨迹的形态。入点应位于 S-1 上关节突的中心与 L-5 下关节突最下边缘下方约 3 毫米处的交点。在轴平面中方向是笔直向前的，没有会聚，在矢状平面中向头侧倾斜，穿透骶骨终板的中间。研究了与骶骨终板的头侧角度、轨迹的长度和轨迹的安全性。然后，在 19 名患者中测量了使用该技术的椎弓根螺钉的插入扭矩，并与传统技术进行了比较。
这 50 名患者的平均头侧角度为 30.7°±5.1°，平均轨迹长度为 31.5±3.5 毫米。CT 分析显示，在任何情况下，穿透 S-1 终板的技术都不会导致任何前方的神经血管损伤。新技术比传统的单皮质技术平均显示出 141%更高的插入扭矩。
通过内侧入点穿透 S-1 终板的技术适用于腰椎 CBT 的连接，对腰骶固定具有良好的稳定性，并降低了神经血管损伤的潜在风险。
