Today’s development of surgical technology is oriented towards minimally invasive and intelligent, and it has become a new trend to minimize surgical trauma under the premise of achieving the same or better surgical results than traditional open surgery. With the development and advancement of basic spine theories, biomechanical research, spine surgical techniques and instruments, the indications for minimally invasive spine surgery are gradually expanding, and endoscopic technology is promoting the development of minimally invasive spine surgery. Lumbar disc herniation is a common disease in spinal surgery, and the mechanism of pain mainly includes mechanical compression, inflammation and chemical stimulation, and autoimmune reaction. Although most patients can be cured by conservative treatment, 10%-20% of patients still need surgery. For a long time, most patients have been treated with open surgery, which is more traumatic, destroys more bony structures, affects the stability of the spine, causes recurrence of low back pain due to serious postoperative scar adhesion, and takes a long time for patients to recover, etc. With minimally invasive spine surgery techniques, patients can be treated with surgery. With the continuous improvement and development of minimally invasive spine surgery techniques, as well as the clinical application of advanced surgical equipment such as lasers, radiofrequency and navigation technology, more and more minimally invasive techniques are applied to the treatment of lumbar disc herniation. Compared with traditional open surgery, minimally invasive treatment has the advantages of less trauma, precise efficacy, fewer complications, no damage to spinal stability, less pain and faster recovery, etc., which is welcomed by both doctors and patients and has become a new trend in the treatment of lumbar intervertebral disc herniation. Some minimally invasive methods, such as ozone, collagenase injection, percutaneous laser nucleus pulposus ablation, etc., use the nucleus pulposus center to decompress the herniated material, causing the herniated material to retract, and ultimately indirectly decompressing the compressed area, which makes the symptomatic relief, but the herniated compressed area can not be completely eliminated, and sometimes the imaging test shows that the herniated material still exists, and the possibility of recurrence increases. Therefore, it is difficult for these techniques to prevent recurrence of the disease and maintain the long-term therapeutic effect. Zeng Xianlin, Department of Orthopedics, Wuhan Union Medical College Hospital, Wuhan, China In the 1880s, Parviz Kambin and Hijikata first began applying working tubes for discectomy, and then in 1996, the U.S. Food and Drug Administration (FDA) approved the use of spinal endoscopic systems. Subsequently, the use of spinal endoscopic technology for the treatment of lumbar disc herniation was gradually carried out. In 1998, Yeung proposed the inside-out intradiscal technique (the inside-out intradiscal technique), in which the disc tissue is firstly removed by entering the disc tissue through the posterior-lateral “safety triangle” approach. The inside-out intradiscal tissue (the inside-out intradiscal technique) is firstly seen in the endoscopic field of view, and the posterior longitudinal ligament is seen at the top of the surgical field of view in the decompression process, therefore, the surgical operation is relatively simple, and it is not easy to injure the nerve roots, the dural sac and the blood vessels in the spinal canal. The indications are: herniated disc, herniated disc under the posterior longitudinal ligament, extreme lateral herniated disc in the intervertebral foramen and outside the intervertebral foramen, and in the case of combined foraminal stenosis, foraminoplasty can be performed first, and then discectomy can be performed further. In 2003, Hooglang used an intervertebral foraminal approach to remove herniated disc tissue “from the outside in” under direct endoscopic visualization, while at the same time exploring the epidural space, the lateral socket, the exit nerve root of the foramen, and the travelling nerve root of the spinal canal, which is known as the TESSYS technique. The technique is designed to enlarge the intervertebral foramina by removing a portion of the bony structure at the anterior inferior margin of the superior articular process in a stepwise fashion with a set of reamers of different diameters. After enlargement and shaping of the intervertebral foramen, the surgical working catheter is placed directly into the spinal canal, and the prolapsed or free lumbar disc tissue is removed directly through the anterior dural space under the direct view of the intervertebral foramenoscope. This technique can deal with any protruding or prolapsed nucleus pulposus tissue in the spinal canal, and decompression of the nerve roots can be carried out under the direct view without destroying the structural integrity of the spinal column in the posterior part of the spine, preserving the ligamentum flavum, and reducing the postoperative hemorrhage, adhesion, and scar formation caused by the surgery, This reduces the clinical symptoms caused by postoperative bleeding, adhesion, scar formation, etc. The TESSYS technique clearly identifies protruding and degenerated nucleus pulposus tissue, ruptured fibrous rings, compressed and edematous nerve roots, and the dural sac that fluctuates with respiration. The removal of the diseased nucleus pulposus and decompression of the nerve root can be easily performed with the use of the associated surgical instruments, with a clear view of the surgical field. The application of flexable radiofrequency electrodes can not only ablate the protruding and prolapsed nucleus pulposus tissue, but also thermocoagulate the degenerated nucleus pulposus tissue in the disc and repair the ruptured annulus fibrosus, which not only preserves the physiological function of the intervertebral discs, but also reduces the recurrence of the discs after the operation. Especially for patients who have had one surgery and need revision, due to the adhesion of scar, the posterior surgery is more difficult and bleeding is more, the transverse intervertebral foramenoscopic technique can avoid the posterior adhesion and scar, and decompress the periphery of the nerve root. The YESSTM system has some advantages of its own when compared with the MED system, which is commonly used in clinical practice. Firstly, the MED system adopts the endoscopic technique via the posterior approach. During the process of inserting the endoscope, it is necessary to pass through the paraspinal muscles of the spine, mainly the multifidus muscle, which will cause damage to the multifidus and other paravertebral muscles, whereas the YESSTM system adopts the approach via the foramen ovale system, which avoids the damage to the paravertebral muscles. Secondly, the decompression effect of different approaches on the foramen magnum varies, and Osman SG et al. showed that decompression of the foramen magnum by the posterior approach could only enlarge the foramen magnum by 34.2%, whereas that by the transforaminal approach could reach 45.5%, and the transforaminal approach was able to achieve a better decompression effect. Third, posterior decompression may increase the mobility of the upper and lower segments due to the destruction of the posterior lamina and commissure, which may potentially lead to lumbar instability, whereas transforaminal approach does not. Finally, the transforaminal approach allows direct visualization of the foramina for decompression, thus effectively ensuring complete decompression. Because TESSYS is less invasive, it can be performed under local anesthesia while the patient is awake, reducing the risk of nerve root injury. Smaller incisions, less destruction of posterior structures, and less intra-operative bleeding allow the patient to get out of bed earlier and shorten the recovery time.