The clinical advantages of posterior microendoscopic discectomy in the knee-thoracic position under local anesthesia are discussed. Posterior microendoscopic discectomy in the knee-thoracic position under local anesthesia not only reduces incisional bleeding in many ways, increases the clarity of the operative field, improves the safety of the operation, but also maximizes the protection of the stability of the crest. It is considered to have obvious superiority over other anesthesia and surgery under body position and is worth advocating. Microendoscopic discectomy in the posterior knee-thoracic position under local anesthesia is often performed in the prone position under epidural anesthesia, and a total of 46 cases of lumbar disc herniation were treated with this surgical method from June 2001 to March 2004, with a superiority rate of 32 cases and an excellent rate of about 98%. I. Surgical method Take L4~5 left herniated disc surgery as an example. Patients first lie on the operating table, the axilla and hip transversely put a cushion, requiring the thickness of the hip cushion than the axilla cushion 2 ~ 3 times higher, and then put down the rear half of the operating table so that the lower limbs suspended, both knees flexed on the surface of the high bench with cushion, at this time the patient is in a flexed waist flexed hip flexed knee state, extremely similar to the knee-thorax position. After routine disinfection and towel laying, local anesthesia with 2% lidocaine, a positioning needle was inserted into the spinous process, and after the C-arm X-ray machine fluoroscopy was used to determine the correct vertebral space, a longitudinal incision of about 1.5~1.8 cm in length was made with the guide needle as the center, and the surgical working channel was placed after replacing the expansion cannula along the guide needle step by step, which was connected to the free arm and fixed, and the microendoscope system was inserted into the working tube, and the focal length was adjusted until the operative field was clear. The muscles and other soft tissues on the surface of the vertebral plate and the interlaminar space are removed with a medullary forceps to reveal the interlaminar space and the ligamentum flavum. A small amount of the lower edge of the lamina and the ligamentum flavum is removed with a gun-type bite forceps to reveal the dural sac and the L5 nerve root. If the nerve roots are not tolerated by individual patients, the nerve roots can be closed, the herniated disc can be exposed, the posterior longitudinal ligament and the fibrous ring can be cut with a miniature sharp knife, and the degenerated disc tissue can be removed with a medullary forceps. If there is narrowing of the nerve root canal, the lateral saphenous fossa is enlarged subconsciously along the nerve root so that the nerve root is completely decompressed. The wound was irrigated and hemostatic, the working channel was removed, the incision was sutured, antibiotics were applied 1 d before surgery and 0.5 h before surgery, and antibiotics continued to be applied 3~5 d after surgery. straight leg raising exercise was started the next day after surgery, and the lumbar circumference could be worn to move on the ground 3 d after surgery, and functional exercise of the lumbar back muscle was performed one week later, and no heavy work or bending and heavy lifting was performed for 3 months. Among the 46 patients who underwent posterior microendoscopic discectomy in knee-thoracic position under local anesthesia, 32 patients’ symptoms completely disappeared, 13 patients felt significantly better than before surgery, but there was still lumbar pain but it did not affect normal work, and there were no patients with aggravated postoperative symptoms. There was one case of intraoperative dural rupture, and there were no complications such as intervertebral space infection and nerve root injury. III. Discussion Posterior microendoscopic discectomy in knee-thoracic position under local anesthesia is a new technique for the treatment of lumbar disc herniation in recent years and is the development direction of modern minimally invasive surgery. It perfectly combines traditional open surgery with endoscopic technology, which largely overcomes both the shortcomings of traditional open surgery and the blindness of percutaneous percutaneous discectomy and aspiration. The main advantages are: small incision, less bleeding, no extensive stripping of the paravertebral muscles, only a small amount of the lower edge of the vertebral plate or part of the small joints need to be bitten off, which does not affect the stability of the crest, avoiding postoperative lumbar instability and reducing the incidence of lower back pain; high clarity of the field of view under the microscope, reducing the chance of damaging the dura and nerve roots; little pain for the patient, fast recovery and easy acceptance by the patient. Our department uses local anesthesia under knee-thoracic position surgery has the following advantages: 1. Local anesthesia plus epinephrine can reduce the bleeding of the incision, less intraoperative bleeding, clear visual field, intraoperative generally do not need to flush the field of view with saline, reducing the blood contamination of the microscopic endoscope camera and light source, can shorten the operating time; 2. High intraoperative nerve sensitivity, such as touching the nerve root, the patient immediately complains of pain, can avoid damage to the nerve 3.Low abdominal pressure in the knee-thorax position, expanding the volume of the spinal canal, while the lower extremities are in the flexed hip and knee position, relatively more blood is pooled in the lower extremities and the volume of blood in the body circulation is reduced, thus reducing the venous pressure in the spinal canal and reducing intraoperative bleeding; 4.The effect of lumbar flexion can be achieved in the knee-thorax position and the tension of the ligamentum flavum between the vertebral plates, which is conducive to the reduction of ligamentum flavum folds. 5.The intervertebral space is opened in the knee-thoracic position, so that 95% of patients can complete the operation of microscopic disc surgery through the intervertebral space, avoiding excessive occlusion of the lamina and small joints, which can reveal the nerve roots and intervertebral discs, especially for patients with a significantly narrowed intervertebral space and a stacked tile-shaped lamina, the advantages appear more prominent; 6.The intervertebral disc and the intervertebral space are The disc can be removed without biting the lower edge of the plate; 7. The disc surgery through the plate gap can reduce the biting of bone, reduce blood leakage from the bone surface, and maintain a clear view; 8. In conclusion, posterior microendoscopic discectomy in the knee-thoracic position under local anesthesia requires the operator to have skilled open surgical skills, be familiar with the anatomical relationship of the tissues around the disc, and achieve hand-eye coordination. Because the operative field is small and deep, a small amount of bleeding can cause unclear operative field, and it is very important to control bleeding from the perineural plexus under endoscopy. Posterior microendoscopic discectomy in the knee-thoracic position under local anesthesia not only reduces bleeding from the incision in many ways, increases the clarity of the operative field, and improves the safety of the procedure, but also maximizes the protection of the stability of the crest. The authors believe that it has obvious superiority over other anesthesia and surgery under body position and is worth advocating.