Kim Tae Hoon, Lee Suk Ha, Yang Jae Hyuk, Hong Jae Young, Suh Seung Woo
Department of Orthopedic Surgery, Konkuk University Medical Center, Konkuk University School of Medicine Scoliosis Research Institute, Department of Orthopedics, Korea University, Guro Hospital Department of Orthopedics, Korea University, Ansan Hospital, Korea.
Medicine (Baltimore). 2018 Feb;97(7):e9907. doi: 10.1097/MD.0000000000009907.
The trajectory of the pedicle screw perpendicular to the SAP (superior articular process) is consistent with the universal trajectory presented in the previous study of the entry point using computed tomography. The ideal entry point and trajectory of pedicle screw insertion have been a matter of considerable debate. We attempted to find the relationship between SAP and entry point and trajectory of the pedicle screw.Thoracic spine CT (computed tomography) scans of 9 volunteers were studied. A safe zone for the trajectory of the screw in the axial (MarginAx) and sagittal (MarginSag) was defined as the zone between lines perpendicular to the SAP along the medial and lateral cortex of the pedicle in the axial section, and the superior and inferior cortex in the sagittal section without violation of the pedicle walls. The midline of MarginAx and MarginSag was defined as the safe entry point of the trajectory in the axial and sagittal planes (TrajectoryAx and TrajectorySag), respectively.MarginAx and MarginSag were 4.14 ± 0.99 and 9.03 ± 2.01 mm, respectively. There was a statistically significant difference in TrajectoryAx between the upper and middle, and between the upper and lower (P = .0076 in both cases), but not between the middle and lower thoracic spine (P = .066). TrajectorySag was within 1 mm at the levels of T4, T8, T11 vertebrae and at 0 mm at the other levels. Thus, the midpoint of MarginSag was within 1 mm from the SAP base.There was a constant angular relationship with the SAP and the pedicle axis; the line perpendicular to the SAP can act as a trajectory. Therefore, we suggest that the SAP might be the only accurate and safe reference for pedicle screw insertion in the thoracic spine perpendicular to the SAP using freehand technique.
椎弓根螺钉垂直于上关节突（SAP）的轨迹与先前使用计算机断层扫描研究进针点时提出的通用轨迹一致。椎弓根螺钉置入的理想进针点和轨迹一直是相当有争议的问题。我们试图找出上关节突与椎弓根螺钉进针点和轨迹之间的关系。对9名志愿者的胸椎计算机断层扫描（CT）图像进行了研究。将轴向（MarginAx）和矢状面（MarginSag）上螺钉轨迹的安全区定义为轴向截面中沿椎弓根内侧和外侧皮质垂直于上关节突的线之间的区域，以及矢状截面中垂直于上关节突的上、下皮质之间的区域，且不侵犯椎弓根壁。MarginAx和MarginSag的中线分别定义为轴向和矢状面（TrajectoryAx和TrajectorySag）上轨迹的安全进针点。MarginAx和MarginSag分别为4.14±0.99和9.03±2.01毫米。胸椎上段与中段、上段与下段之间的TrajectoryAx存在统计学显著差异（两种情况均为P = 0.0076），但胸椎中段与下段之间无差异（P = 0.066）。在T4、T8、T11椎体水平，TrajectorySag在1毫米以内，在其他水平为0毫米。因此，MarginSag的中点距离上关节突基部在1毫米以内。上关节突与椎弓根轴线存在恒定的角度关系；垂直于上关节突的线可作为轨迹。因此，我们建议，在上胸椎使用徒手技术垂直于上关节突进行椎弓根螺钉置入时，上关节突可能是唯一准确且安全的参考标志。
