The anatomical observation of L_5～S_1 intervertebral foramen associated with TESSYS' approach

Objective Provide objective anatomical basis for postolateral percutaneous L5~S1transforaminal endoscopic discectomy. Method To the adjacent relationship among the needle, the iliac crest, the superior S1 articular process, the L5 efferent roots, the dura, and the vertebral vessels were observed and measured; various types of protrusion of puncture angle range in 10 adult spinal specimens(20 sides) were also measured when TESSYS was placed into the L5~S1foramen. Results All data have not shown statistical difference by paired t test(P0.05). There were L5 posterior medial nerve branches, descending branches of dorsal branches of L5 segmental arteries and veins going around the roots of S1 superior facet. The vertical distance from highest point of iliac crests to the midline of spine was(9.25 ± 0.47) cm, the angle between highest point of iliac crests and leading edge of superior facets on the coronal plane was(11.10±1.17) °, the distance between L5 transverse processes and iliac crests on the coronal plane was(10.78±0.81) mm, central protrusion angle of the needle was(83.00±1.92) °, lateral protrusion angle of the needle was(32.15±1.63) °~(62.60±1.70) °, extreme lateral protrusion angle of the needle was(11.75±1.16) °, the anchor points of superior facets to L5 exiting roots and the dura was(8.30±0.87) mm and(17.29±1.06) mm, respectively, inferior margin of L5 exiting roots to lower edge of foramen was(5.84±0.67) mm, the height of superior facets was(11.31±0.96) mm, the length of S1 superior facets was( 17.41±0.98) mm. Conclusions The puncture and location of postolateral percutaneous L5~S1transforaminal approach is complex than other lumbar segments, which requires that physicians have a solid knowledge of anatomy and excellent spatial visualization.