【Objective】 To compare the clinical efficacy of percutaneous transforaminal endoscopic decompression （PEID） and percutaneous interlaminar endoscopic decompression （PETD） in the treatment of L5-S1 lateral recess stenosis. 【Methods】 We selected the patients in our center diagnosed with L5-S1 lateral recess stenosis from March 2018 to October 2019 and divided them into Group A and Group B according to the principle of prospective， single-blind， and randomized control （A： PETD； B： PEID）. The operation was performed by the same senior surgeon with mature spinal endoscopy technology. We recorded the basic information， operation duration， usage count of C-arm， hospital stay， VAS score and ODI index of lower back and lower limbs before operation and 3 days， 1 month， 1 year and the last follow-up after the operation， and the operative excellent and good rates （the last follow-up）. The angle of bony lateral recess was measured during pre- and postoperative CT. 【Results】 A total of 95 patients （A： n=48； B： n=47） successfully completed the operation and were followed up for at least 1 year. The two groups did not significantly differ in age， gender， hospital stay， or complication by lumbar intervertebral disc herniation， but PEID group had significantly shorter operation duration and fewer usage counts of C-arm （P<0.001）. VAS score of lower back and lower limbs， and ODI index were significantly reduced at 3 days，1 month， 1 year and the last follow-up after the operation， with no significant difference between the two groups at the same time； no statistical difference was found between the two groups in operative excellent and good rates at the last follow-up （P>0.05）. The postoperative bony side recess angle was significantly improved （P<0.05）， while there was no significant difference in either pre- or postoperative bony side recess angle between the two groups （P>0.05）. 【Conclusion】 Both PEID and PETD are effective strategies in the treatment of L5-S1 lateral recess stenosis and can achieve good clinical outcomes.

【Objective】 To investigate the effect of decompression technique with bone-chisel under percutaneous spinal endoscopy through transforaminal approach in elderly patients with unilateral lateral recess stenosis （ULLRS）. 【Methods】 We enrolled 46 old patients with ULLRS who underwent percutaneous spinal endoscopy through transforaminal approach assisted with bone-chisel technique from March 2017 to July 2019. The visual analogue scale （VAS） score of low back pain and leg pain， the Oswestry dysfunction index （ODI）， and the modified MacNab score before and after operation were obtained. We also recorded preoperative and postoperative sagittal diameter measured by computer tomography （CT） to evaluate decompression of the lateral recess. All the patients were followed up for at least 1 year for complications. 【Results】 All the 46 patients were followed up for 17 to 42 months. Dural tear occurred in one case， transient nerve root irritation in two cases， and there were no other complications. The low back pain VAS score， lower limb pain VAS score， and ODI index of all the patients were significantly improved in the last follow-up （P<0.05）. The results of the modified MacNab efficacy evaluation at the last follow-up revealed that the excellent and good rate was 91.3% （excellent in 38， good in 4， and fair in 4）. The sagittal diameter （mm） of the bony lateral recess 1 year after surgery increased by an average of 55.8%， which was significantly better than that before surgery （t=6.354， 4.22±1.25 vs. 2.71±0.57， P<0.001）. 【Conclusion】 Percutaneous spinal endoscopy through transforaminal foramen approach combined with bone-chisel technique is effective in treating ULLRS in elderly patients.