| Background: Percutaneous endoscopic foraminal discectomy(PETD),as a minimally invasive surgical method,is one of the preferred treatments for the treatment of lumbar disc herniation(LDH),it has the advantages of short operation time,less blood loss,less paravertebral muscle damage,quick functional recovery,satisfactory clinical efficacy,and less postoperative complications,but it has a steep learning curve and a greater risk of nerve root injury than traditional open surgery.The surgical basis of PETD is Kambin triangle,which is an anatomical channel with no important blood vessels and nerve structures,and is a safe working area;Kambin triangle is worth further study,study and obtaining anatomical data related to PETD,the deformation of soft tissue and nerve can change the size of the Kambin triangle.Using the closer imaging techniques can reduce the error and ensure the reliability of the data.Objective: Through imaging studies,the anatomical relationship between percutaneous endoscopic surgical approach of each lumbar foramina and intervertebral foramina,nerve roots and adjacent tissues was explored to provide reference for clinical application.Methods: The imaging data of patients who underwent lumbar CT and MRI in Qingdao Third People’s Hospital from May 2020 to July 2022 were analyzed.A total of100 normal lumbar CT images and 100 normal lumbar MRI images were included,with the age range from 20 to 40 years.Selected bilateral foramina from L1-2 to L 5-S1,the minimum pore width was measured at the lower rim level of the CT transverse axial,sagittal pore height,sagittal pore width,approach target angle were measured in the CT sagittal position,the approach target Angle and the iliac crest-disc distance between the L4 and S1 segments were measured in the CT coronal position;the nerve root-disc distance,nerve root-facet distance,approach target angle were measured at the lower edge level of the MRI transverse axial,the nerve root-pedicle distance was measured in the sagittal position of the MRI site.Results: Comparisons of CT and MRI measurements on the left and right sides of the foramina in each segment of the lumbar spine were analyzed using an independent sample t-test.The minimum pore width in the transverse axial position of L1 to S1 foraminal CT was 8.33±0.65 mm,7.69±0.79 mm,7.07±0.83 mm,6.08±0.85 mm,6.44±0.71 mm,respectively,the sagittal pore height were 18.45±1.36 mm,19.03±1.44 mm,17.49±2.06 mm,16.63±1.84 mm,15.86±1.17 mm,the sagittal pore width were8.79±0.83 mm,8.32±0.82 mm,7.65±0.81 mm,6.57±0.73 mm,6.83±0.67 mm,CT transverse axial minimum hole width,sagittal hole width in L4-5 segment minimum,sagittal hole height in L2-3 segment maximum;CT coronal iliac crest-disc distance at L4-5 and L5-S1 were 1.83±9.07 mm,-33.04±7.27 mm,while L4-5 discs were approximately the same height as the iliac crest,and L5-S1 discs were below the iliac crest level.CT sagittal target angles L1 to S1 are 19.73 ± 4.62°,24.62 ± 4.43°,31.02 ± 5.66°,39.16 ± 5.63°,49.24 ± 5.26°,CT coronal target angles L1 to S1 are 13.30 ± 3.58°,17.52 ± 3.47°,21.64 ±3.18°,27.63 ± 3.88°,34.91 ± 4.99°,L1 to S1 CT sagittal and coronal target angles gradually increase from top to bottom.The nerve root-disc distance between the L 1 to S1 segments at the lower margin of the MRI disc is 3.99±1.07 mm,3.49±1.06 mm,2.74±0.82 mm,-2.18±1.17 mm,-1.90±0.78 mm,respectively,the nerve root-facet distance is 3.28±0.72 mm,4.27±0.86 mm,5.11±0.99 mm,-5.55±3.39 mm,-8.73±2.51 mm,respectively.Sagittal nerve root-pedicle distance of 12.04±0.83 mm,11.68±3.17 mm,10.80±0.71 mm,10.13±0.78 mm,9.21±0.97 mm,the nerve root-disc distance,nerve root-pedicle distance gradually decreased from top to bottom;the nerve root-facet distance gradually increased from top to bottom,in L1-2,L2-3,L3-4 segment,the nerve root is located in the dorsal lumbar disc,while in L4-5,L5-S1 segment,the nerve root is located in the ventral lumbar disc;the MRI transverse approach target angles L1 to S1 were 24.22 ± 5.28°,19.26 ± 4.22°,14.64 ± 4.59°,8.75 ± 3.68° and 5.14 ± 3.21°,which gradually decreased from top to bottom.Conclusion: The lower lumbar spine(L4-5 and L5-S1)has smaller foramen,the target angle of sagittal and coronal approach is increased,the nerve root-disc distance and nerve root-pedicle distance are decreased,and the percutaneous endoscopic foraminal surgical approach is more complicated and difficult.Especially when the orifice width is less than the casing diameter,and percutaneous endoscopic foramen discectomy requires expansion of the foramen to reduce the risk of nerve root injury.If the L5-S1 segment is affected by the excessive ilium crest bone,the percutaneous endoscopic interlaminar approach or other surgical methods should be selected. |
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