Chua Min Jia, Siddiqui Shiblee, Yu Chun Sing, Nolan Colum Patrick, Oh Jacob Yoong-Leong
Department of Orthopaedic Surgery, Tan Tock Seng Hospital, Singapore.
Department of Orthopedics, Wockhardt Hospital, Mumbai, India.
Asian Spine J. 2019 Dec;13(6):936-941. doi: 10.31616/asj.2018.0276. Epub 2019 Jul 17.
A retrospective study of radiographic parameters of patients who underwent lumbar spinal pedicle screw insertion.
The optimal length of pedicle screws is often determined by the lateral radiograph during minimally invasive surgery (MIS). Compared with open techniques, measuring the precise length of screws or assessing the cortical breach is challenging. This study aims to ascertain the optimal pedicle screw lengths on intraoperative lateral radiographs for L1-L5.
Research has revealed that optimal pedicle screw length is essential to optimize fixation, especially in osteoporotic patients; however, it must be balanced against unintentional breach of the anterior cortex, risking injury to adjacent neurovascular structures as demonstrated by case reports.
We reviewed intra- and postoperative computed tomography scans of 225 patients who underwent lumbar pedicle screw insertion to ascertain which of the inserted screws were 'optimal screws.' The corresponding lengths of these screws were analyzed on postoperative lateral radiographs to ascertain the ideal position that a screw should attain (expressed as a percentage of the entire vertebral body length).
We reviewed 880 screws of which 771 were optimal screws. We noted a decreasing trend in average optimal percentages of insertion into the vertebral body for pedicle screws going from L1 (average=87.60%) to L5 (average=78.87%). The subgroup analysis revealed that there was an increasing percentage of screws directed in a straight trajectory from L1 to L5, compared to a medially directed trajectory.
During MIS pedicle screw fixation, this study recommends that pedicle screws should not exceed 85% of the vertebral body length on the lateral view for L1, 80% for L2-L4, and 75% for L5; this will minimize the risk of anterior cortical breach yet maximize pedicle screw purchase for fixation stability.
对接受腰椎椎弓根螺钉植入术患者的影像学参数进行回顾性研究。
在微创手术（MIS）中，椎弓根螺钉的最佳长度通常由侧位X线片确定。与开放技术相比，测量螺钉的精确长度或评估皮质骨破裂具有挑战性。本研究旨在确定L1-L5在术中侧位X线片上的最佳椎弓根螺钉长度。
研究表明，最佳椎弓根螺钉长度对于优化固定至关重要，尤其是在骨质疏松患者中；然而，如病例报告所示，必须在避免无意穿透前皮质骨（从而有损伤相邻神经血管结构的风险）之间取得平衡。
我们回顾了225例接受腰椎椎弓根螺钉植入术患者的术中和术后计算机断层扫描，以确定哪些植入的螺钉是“最佳螺钉”。在术后侧位X线片上分析这些螺钉的相应长度，以确定螺钉应达到的理想位置（表示为整个椎体长度的百分比）。
我们回顾了880枚螺钉，其中771枚为最佳螺钉。我们注意到，从L1（平均=87.60%）到L5（平均=78.87%），椎弓根螺钉植入椎体的平均最佳百分比呈下降趋势。亚组分析显示，与向内方向的轨迹相比，从L1到L5，沿直线轨迹的螺钉百分比在增加。
在MIS椎弓根螺钉固定术中，本研究建议，在侧位片上，L1的椎弓根螺钉长度不应超过椎体长度的85%，L2-L4为80%，L5为75%；这将使前皮质骨破裂的风险降至最低，同时最大限度地增加椎弓根螺钉的把持力以确保固定稳定性。
