Morphometric Analysis Of The Ventral Nerve Roots And Retroperitoneal Vessels With Respect To The XLIF In The Spines Of Degenerative Lumbar Scoliosis

Study Design:A morphometric analysis, using magnetic resonance imaging (MRI) studies of the lumbar spine at the patients with degenerative lumbar scoliosis.objective:To determine the variable location of the anterior vascular and nerves anatomy in the L1/2, L2/3, L3/4, L4/5lumbar distribution in the patients with degenerative lumbar scoliosis．To assess the reliability and the safety of the operation of lower lumbar spine at the patients with degenerative lumbar scoliosis interbody fusion through the extreme lateral interbody fusion(XLIF)．While‐time by observing the form of lower lumbar spinal vessels,nerves and their surrounding structures,to find out their anatomy relationships,and to reduce the mini‐operative surgical injury and complication of the extreme lateral interbody fusion(XLIF)of lower lumbar spine at the patients with degenerative lumbar scoliosis．Methods:consisted of segments from spines with degenerative lumbar scoliosis(n=60) and without degenerative lumbar scoliosis(n=15). The scoliosis group both right convexities with the lumbar Cobb angle<20°(n=15),>20°(n=15) and left convexities with the lumbar Cobb angle<20°(n=15),>20°(n=15) were included. They were divided into A, B, C, D, E five groups.Axial MR images were used to measure: the vertebral endplate anterior posterior (AP) diameter, the overlap between the ventral root and the posterior margin of the vertebra, and the overlap between the retroperitoneal large vessels and the anterior edge of the vertebra.Thus obtaining the corresponding security zone for the extreme lateral interbody fusion(XLIF).Results:The operation windows from L1/2to L4/5gradually decrease and the left ones are bigger than the right ones.Take the95%confidence interval, The left security zone in L1/2segment of the A, B, C, D, E five groups is (85.2%,83.1%,87.7%,84.5%,83.1%), L2/3segment is (79.0%,72.1%,73.2%,77.0%,74.7%), L3/4segment is (69.1%,65.7%,67.1%,70.1%,67.1%), L4/5segment is (55.7%,50.3%,51.4%,59.7%,57.8%).Conclusion:The extreme lateral interbody fusion of L1‐5at the patients with degenerative lumbar scoliosis is safe,reliable and practical. Because the variable location of the neurovascular structures was mostly dependent on the degree of rotatory deformity, The safe corridor for performing the discectomy and fusion should be a little backward in the dextroscoliotic spines, and be slightly forward in the levoscoliotic spines. So it is recommended to take preoperative MRI to assess the relative position of the adjacent neurovascular structures in relation to the lower vertebra's endplate at each level.