中文摘要：

目的：通过影像学测量观察,探讨经皮椎间孔内镜手术入路与椎间孔、神经根及邻近组织的解剖学关系,为临床应用提供参考。方法回顾性分析2011年1月—2015年1月在天津市天津医院行腰椎影像学检查的患者影像资料,按脊柱序列正常、无畸形、无移行椎的要求共纳入100例正常腰椎的横断面 MRI 资料和100例正常腰椎正侧位 X 线图像资料。选取 L2/3~ L5/ S1节段椎间盘上下缘两个层面的 MRI 横断面图像的,分别测量椎间盘上、下缘的椎间孔宽度最小值（Gs、Gi）、神经根-椎间盘距离（Hs、Hi）、神经根-关节突距离（Is、Ii）和入路靶角（Js°、Ji°）。选取 L4/5和 L5/ S1节段正侧位 X 线图像,分别从正位和侧位测量分析髂脊-椎间盘距离（Qa、Qb）和入路靶角（Ra°、Rb°）。结果 MRI 横断面图像资料分析显示 Gs 均〉 Gi,其中 L4/5节段 Gi 最小[（2.72±1.40） mm],L2/3节段 Gs 最大[（5.16±1.53） mm]。神经根-椎间盘距离从头端向尾端逐渐减小,并且在椎间盘下缘层面距离最近。 L2/3和 L3/4节段神经根位于椎间盘的背侧；而在 L4/5和 L5/ S1节段,神经根位于椎间盘的腹侧。 Is 〈 Ii,其中 L4/5节段 Is 最近[（-2.55±4.94） mm], L5/ S1节段 Ii 最远[（-8.23±11.11） mm]。椎间盘上、下缘横断面入路靶角从头端向尾端逐渐减小。 L2/3和 L3/4节段 Js°〉 Ji°；L4/5和 L5/ S1节段Js°〈 Ji°。正侧位 X 线图像分析显示 L4/5节段位置与髂脊约处于同一高度,L5/ S1节段靶角明显大于 L4/5节段。结论下腰椎（L4/5和 L5/ S1）椎间孔变小、神经根与椎间盘更近、入路靶角变大变陡,手术入路更复杂、难度更大；行经皮椎间孔镜手术时需采用环锯扩大椎间孔,使工作通道充分进入椎管内,减小神经根损伤的风险。

英文摘要：

Objective To radiographically analyze the relationships of the nerve root and the safe trajectory in lumbar using percutaneous transforaminal endoscopic discectomy （PTED） approach. Methods A retrospective study from January 2011 to January 2015 in Tianjin Hospital was carried out. One hundred MRIs of transverse views and 100 X-rays were used for image analysis, those with previous spinal surgery, trauma or gross deformity were omitted from the study. The MRI study was done bilaterally from L2 / 3 to L5 / S1 . On transverse MRI, the foraminal width （G）, the nerve root-disc distance （H）, nerve root-facet distance （I） and the target angle （J°） were analyzed at the superior （s） and inferior （i） margin of the disc. The X-ray study was done from L4 / 5 to L5 / S1 in two planes AP （a） and Lateral （b）. The crest height （Q） and target angle （R°） were measured on both planes. Results On transverse MRIs, the foraminal width was larger at superior margin of the disc. The smallest Gi was measured at the inferior margin of L4 / 5 [（2. 72 ± 1. 40） mm] and the largest Gs was measured at the superior margin of L2 / 3 [（ 5. 16 ± 1. 53） mm]. The nerve root-disc distance decreased caudally and was measured closer at the inferior margin of the disc. The nerve root lay dorsal to the disc at L2 / 3 and at L3 / 4 , whereas the nerve root lay ventral to the disc at L4 / 5 and L5 / S1 . The nerve root-facet distance was measured shortest at the superior margin than at the inferior margin of the disc. The shortest Is of superior margin was at L4 / 5 [（ - 2. 55 ± 4. 94） mm] and the longest Ii of inferior margin at L5 / S1 [（ - 8. 23 ± 11. 11） mm]. The target angles （ Js, Ji） decreased caudally. The target angles at L2 / 3 and L3 / 4 were wider at their superior margin than their inferior margin. In＆nbsp;contrast, the angles at the lower lumbar levels, L4 / 5 and L5 / S1 , were smaller at their superior margin than those at their inferior margin. On X-rays, L4 / 5 lied a