Applied Anatomy For Transforaminal Endoscopic Lumbar Surgery

Background&Objectivelumbar intervertebral disc herniation is a common and frequently-occurring disease,and the treatment of lumbar intervertebral disc herniation are more minimally invasive,as the most potential and most minimally invasive spinal surgery,percutaneous transforaminal endoscopic discectomy(PTED)are widely application in clinical,however,the anatomic study about the applied anatomy for transforaminal endoscopic lumbar surgery,especially the domestic,are fall behind.The purpose of this study is to improve the Chinese data about spinal anatomy at L1/2?L5/S1,and we hope this study can help to choice a suitable working cannula when transforaminal endoscopic lumbar surgery.MethodsAnatomic structures,including the high of intervertebral foramens,the high of nerve root foramens,the sagittal diameter of foramens,the nerve root/ganglion sagittal diameter,the vertical dimension between the intersection of a horizontal line drawn through the middle of disc space and the posterrior border of intervertebral foramen and the exiting nreve root,the morphology safety triangle of spinal canal,the distence between the intersection and the exiting nreve root,the distence between the intersection and the thecal sac/traversing nreve root on 10 adult cadaver spine specimens(L1?S1)were observed and measured,and all the specimens were taken from healthy adult and been preserved by formalin,of course,all specimens have no obvious degeneration,have no spinal deformity.Results?The high of intervertebral foramens at L1/2?L5/S1 were(16.06±3.18)?(19.30±2.20)?(19.02±2.37)?(16.45±1.82)?(10.77±1.77)mm;?the vertical dimension between the intersection of a horizontal line drawn through the middle of disc space and the posterrior border of intervertebral foramen and the exiting nreve root at L1/2?L5/S1 were(4.75±0.80)?(6.42±0.44)?(7.30±0.82)?(7.74±0.52)?(4.68±1.27)mm;?The length of the base of safety triangle of spinal canal at L1/2?L5/S1 were(9.33±1.67)?(10.73±1.51)?(12.60±2.43)?(16.20±2.64)?(14.91±2.88)mm;?The high of safety triangle of spinal canal at L1/2?L5/S1 were(14.32±1.65)?(16.94±3.12)?(19.96±2.46)?(20.87±2.08)?(20.75±2.47)mm;? The distence between the intersection of a horizontal line drawn through the middle of posterior margin of disc and the vertical line drawn through the middle of the pedicle and the exiting nreve root at L1/2?L5/S1 were(3.65±0.73)?(4.14±0.71)?(4.56±0.88)?(5.40±0.67)?(4.49±0.59)mm;?The distence between the intersection of a horizontal line drawn through the middle of posterior margin of disc and the vertical line drawn through the middle of the pedicle and the thecal sac/traversing nreve root at L1/2?L5/S1 were(4.49±0.63)?(5.23±0.70)?(6.18±0.93)?(7.73±0.60)?(7.67±1.00)mm;?The distence between the intersection of a horizontal line drawn through the middle of posterior margin of disc and the vertical line drawn through the midial one third of the pedicle and the exiting nreve root at L1/2?L5/S1 were(4.02±0.78)?(4.67±0.65)?(5.17±0.91)?(6.16±0.74)?(5.48±0.61)mm;?The distence between the intersection of a horizontal line drawn through the middle of posterior margin of disc and the vertical line drawn through the midial one third of the pedicle and the thecal sac/traversing nreve root at L1/2?L5/S1 were(3.89±0.61)?(4.39±0.71)?(5.17±0.97)?(6.58±0.70)?(6.22±1.20)mm.ConclusionsThe upper is bigger than the lower like a inverted pear-shaped at normal intervertebral foramens;Ligaments at the intervertebral foramen area made the high of nerve root foraminals significantly smaller than the high of intervertebral foramens;"Safety triangle of lumbar" can be divided into two triangles,one is"safety triangle of intervertebral foramen" and another one is "safety triangle of spinal canal";Safety triangle of intervertebral foramen can admit the size of working cannula is 4.0?5.0?6.0?7.5?4.5mm at L1/2?L5/S1;Safety triangle of spinal canal can admit the size of working cannula is 5.0?6.0?7.0?7.5?7.5mm at L1/2?L5/S1;In safety triangle of intervertebral foramen,it is likely to damage to the dorsal branches of lumbar arteries,or damage to the branches of dorsal branches;the intersection of a horizontal line drawn through the middle of posterior margin of disc and the vertical line drawn through the midial one third of the pedicle can be used as a most suitable puncture point.