BACKGROUND:One-hole split endoscope technique has been widely used in the treatment of lumbar degenerative diseases,but there is no relevant literature on the safety analysis of this technique in the treatment of upper lumbar disc herniation. OBJECTIVE:To observe the position relationship of nerve roots,intervertebral space and bone landmarks in the upper lumbar spine by three-dimensional lumbar CT reconstruction technology,and to provide a basis for the clinical operation of one-hole split endoscope surgery. METHODS:Twenty-six patients with upper lumbar disc herniation underwent a lumbar CT scan.Mimics 17.0 software was imported to measure the related imaging parameters of L1/2 to L3/4 segments:(1)Measurement of vertical distance:In coronal view,the distance(a)from the intersection point of the medial facet of the superior articular process and the superior endplate(N)to the apex of the articular process(S);in the coronal view,the distance(b)from the sagittal intersection(M)of N and the inferior endplate to the apex of the inferior articular process(X).(2)Measured horizontal distance:the distance(c)between the cross-section of N and the lower edge of the outlet nerve root(N2);distance(d)between the cross-section of N and the intersection point of neural tissue(N1);N1 to N2 distance(e);distance(f)between the cross-section of M and the lateral edge of the nerve tissue(M1);M to M cross-section and exit nerve root intersection(M2)distance(g);distance(h)from M1 to M2;distance(i)from M2 to N1;distance(j)from the posterior edge of the articular surface(R)to M2 in sagittal view of the superior articular process. RESULTS AND CONCLUSION:(1)With the decrease of the segment,the distances a and b gradually increased,and the distance j gradually decreased.There was no significant difference between L1/2 and L2/3 segments(P>0.05).(2)With the decrease of the segment,distance d first decreased and then increased;distance f gradually decreased;distances c,e,g,h and i gradually increased;and there was no significant difference between L2/3 and L3/4 segments(P>0.05).(3)Distance i was the shortest distance without pulling nerve roots in the natural state,and the area of the safety zone was between four points M1,M2,N1,and N2.The bone was removed to the upper and lower endplates by biting the bone downward and upward through S and X,respectively,to expose the intervertebral space,and the window of distance g to M2 could be opened outward to avoid injury of the outlet nerve roots.(4)In conclusion,the upper lumbar vertebrae have unique anatomical characteristics.Based on the relevant measurements of nerve roots,spinal dura and intervertebral space,the parameters of the one-hole split endoscope technique are more accurate and safe during operation.

BACKGROUND:One-hole split endoscope as a new type of endoscopic technique is suitable for the treatment of far lateral lumbar disc disease.However,there are few research data on L5/S1,which has a very low incidence of far lateral lumbar disc herniation at home and abroad,and there is no detailed image anatomical data describing the one-hole split endoscope treatment of L5/S1 far lateral lumbar disc herniation. OBJECTIVE:Through the three-dimensional image reconstruction,the bony landmarks were determined to accurately locate the positional relationship between the L5 outlet nerve root,the L5/S1 intervertebral space and other structures.One-hole split endoscope via posterolateral approach was used to accurately,safely and effectively decompress the L5 outlet nerve root and treat the L5/S1 far lateral lumbar disc herniation. METHODS:Twenty-nine patients with L5/S1 unilateral far lateral lumbar disc herniation who met the inclusion and exclusion criteria were selected,including 12 males and 17 females at the age of 48-74 years.The lumbar CT data of the patients were imported into Mimics 21.0 software to reconstruct the three-dimensional lumbar model.Measurement of L5/S1 related parameters:(1)Measurement on the sagittal plane at the intersection(H)of the lower edge of the transverse process and the lateral edge of the isthmus:The vertical distance between H and the upper and lower edges of L5 outlet nerve root(a1,a2);the vertical distance between H and the lower endplate of L5 and the upper endplate of S1(b1,b2);vertical distance from the lower edge of the pedicle from H to L5(c).(2)Horizontal distance between the left and right sides of the sagittal surface where the medial wall of the pedicle was located from H to L5(d).(3)The horizontal distance from H to the left and right side of the sagittal plane where the lateral margin of the dura was located(e).(4)Horizontal distance(f)between the left and right sides of the sagittal plane at the outermost edge of the lower endplate from H to L5.(5)Measurements were made on the sagittal plane where the outermost edge of the lower endplate of L5:The vertical distance between the cross section of H and the upper and lower edges of L5 outlet nerve root(g1,g2);vertical distance(h1,h2)between the transverse section of H and the lower endplate of L5 and the upper endplate of S1,respectively;(6)anteroposterior horizontal distance from H to L5 in the coronal plane where the last edge of the nerve root exits(i);(7)anteroposterior horizontal distance from the highest point of the posterior margin of the sacral wing to the last margin of the inferior endplate of L5 in the coronal plane(j). RESULTS AND CONCLUSION:(1)There was no significant difference in the relevant measurement parameters between men and women(P>0.05).(2)a1,a2,b1,b2,c,d,e,f,h1,h2,g1,g2,i,and j on the affected side were not significantly different from the healthy side(P>0.05).(3)There was no significant difference between a1 and c(P>0.05),indicating that the lower edge of the pedicle was the upper edge of the L5 outlet nerve root;the L5 outlet nerve root was close to the lower edge of the pedicle and ran anterolateral behind the L5 vertebral body,and H was located above the L5 outlet nerve root.(4)With H as the bony marker point,it was not necessary to probe upward or to remove the isthmus,but only to grind part of the bone downward and laterally to reveal the L5 outlet nerve root and vertebral space,and to have enough safe distance to avoid damage to the dural membrane to complete exploration and decompression of the lateral recess and foraminal region.(5)The surgeon could operate in the sagittal plane where the most lateral edge of the L5 inferior endplate was located,and in the"rectangular area"formed by the L5 transverse process and the sacral wing.The closer to the medial and inferior area(Kambin triangle),the safer the operation was.(6)It is suggested that using H as the bony landmark point to locate the L5 outlet nerve root and intervertebral space through one-hole split endoscope via posterolateral approach can achieve accurate,safe and effective decompression of L5/S1 far lateral lumbar disc herniation.