下颈椎经关节螺钉和Magerl侧块螺钉与脊神经关系的解剖学比较

Transarticular screws versus Magerl lateral mass screws:an anatomic comparison of their possible effects on injury to spinal nerve roots

目的对比下颈椎经关节螺钉和Magerl侧块螺钉固定技术神经根(前支和后支)损伤的潜在风险。方法应用经关节螺钉和Magerl侧块螺钉两种固定技术,固定C_(3-7)节段,每种技术使用2具标本和20枚螺钉。使用直径为3．5mm、长度为20mm的螺钉进行过度穿透侧块腹侧皮质固定。仔细解剖颈部的前侧方,观察螺钉与脊神经前、后支的关系。结果下颈椎经关节螺钉固定技术总体神经损伤比例(45%)明显低于Magerl侧块螺钉固定技术(90%),两者差异有显著性意义(P＜0．05)。经关节螺钉和Magerl侧块螺钉固定技术引起的神经损伤均最多见于脊神经后支,分别为25%和45%。结论经关节螺钉固定技术神经根损伤的风险低于Magerl侧块螺钉固定技术。

Objective To compare anatomically the potential incidences of injury to the nerve roots of ventral and dorsal rami caused by the transarticular screws and Magerl lateral mass screws in the fixation of subaxial cervical spine. Methods Fixations with the transarticular screws and Magerl lateral mass screws were performed in this study. For each kind of fixation, 20 screws were inserted from C3 to C7 in two specimens. A 20-mm long screw was used to over-penetrate the ventral cortex. The anterolateral aspect of the cervical spine was carefully dissected to allow ob- servation of the screw-ramus relationship. Results The overall percentage of nerve violation was significantly lower in the transarticular screw fixation （45%） than in the Magerl lateral mass screw fixation （90%）. The difference was statistically significant between the two fixation methods （ P 〈 0.05）. The greatest percentages of nerve violation caused by the transarticular screws and lateral mass screws were found at the dorsal ramus, 25% and 45%, respectively. Conclusion The potential risk of nerve root violation caused by the transarticular screw technique is lower than that by the Magerl lateral mass screw technique in the lower cervical spine.