LAUSR

BACKGROUND Percutaneous endoscopic interlaminar discectomy (PEID) is widely used as a minimally invasive procedure that shows satisfying outcomes for the treatment of L5/S1 and even L4/5 disc herniation. PEID can be divided into direct and indirect approaches according to the established method of the working channel. The direct approach mainly utilizes the puncture needle directly through the intervertebral space into the intervertebral disc under non-direct vision and insertion of the guidewire into the puncture needle to guide the dilator and working channel to retract the ligamentum flavum, dural sac and nerve roots. This approach requires a skilled puncture technique, as damage to the nerve roots and dural sac can easily occur. Therefore, we improved this interlaminar access procedure; we placed the puncture target at the inferior endplate and performed preoperative epidurography to expose the spinal nerve roots and dural sac after the puncture needle was passed through the ligamentum flavum. Then, we positioned the puncture needle at the posterior edge of the superior centrum. Finally, we inserted the working sleeve for the operation. This approach is convenient and effectively reduces the learning curve and intraoperative complications. The aim of this study was to introduce the procedure and investigate the safety and efficacy of full-endoscopic interlaminar discectomy via an inferior endplate approach for the treatment of lumbar disc herniation. METHODS We performed full-endoscopic interlaminar discectomy via the inferior endplate approach in 321 patients who satisfied our inclusion criteria during the period from May 2014 to May 2017. All operations were completed under local anaesthesia. Under fluoroscopic guidance, we performed epidurography to expose the spinal nerve roots and dural sac. The working sleeve and endoscope were then introduced into the inferior endplate of the superior centrum. Herniated disc material was removed using forceps and a laser under clear endoscopic visualization. We retrospectively evaluated the 321 patients with more than 30 (range 12-48) months of follow-up. The therapeutic effects were assessed using scores of the visual analogue scale (VAS), Oswestry disability index (ODI), Macnab standard and infrared thermal imaging. RESULTS The mean VAS score for radicular pain improved from 6.3 ± 1.01 preoperatively to 1.01 ± 0.35 at the final follow-up (P < 0.01). The mean ODI score improved from 85.5 ± 12 preoperatively to 12.4 ± 3.7 at the final follow-up (P < 0.01). According to the Macnab standard, the excellent and good outcome scores were 96.5%. The infrared thermal imaging scores indicated that the skin temperature of both lower extremities significantly improved 1 week after surgery compared with the preoperation temperature (P < 0.01). CONCLUSION The inferior endplate approach for percutaneous endoscopic interlaminar discectomy provides a safe and very effective alternative for the treatment of lumbar disc herniation.