Radiographic Anatomy and Clinical Value of Modified Corner Approach in Interlaminar Endoscopic Lumbar Discectomy

Objective To explore the imaging anatomical characteristics and clinical value of the modified corner approach targeting the intersection of S1 superior endplate and facet joint. Method The CT and MRI data of 100 patients were used to measure the distance between the target and the dura sac, pedicle, L5 nerve and S1 nerve. The learning curve of IELD surgery based on modified corner approach was determined by prospectively collecting data from 80 patients with IELD. Results The average distance between the target and the dura sac was 4.59 ± 1.74mm. The average distance between the target and the inferior border of the L5 nerve was 10.14 ± 1.72mm, rang from 7.52–13.54 mm. The average distance between the target and the outer edge of the S1 nerve was 0.51 ± 0.91mm, rang from − 0.12 ~ 2mm. The average distance between the target and the inner edge of S1 pedicle was 3.77 ± 1.04mm. The distance between the target and the dura sac and the inner edge of the pedicle is mainly affected by the age of the patient. Conclusion The modified corner approach is a simple, safe and repeatable surgical approach with the intersection of the superior endplate and facet joint as the puncture target. For patients without or with mild facet joint degeneration, the puncture target can be appropriately moved inward by 2mm.