The human intervertebral disc is located between two adjacent vertebrae, or the intervertebral space, and consists of three parts: the microscopic ring, the nucleus pulposus, and the cartilage plate (end plate). The nucleus pulposus is the central part, the fibrous ring surrounds it, and the cartilage plate seals the upper and lower sides like a lid. Previously, doctors believed that a herniated disc was somehow caused by increased pressure within the disc, causing the nucleus pulveris to be pushed out of the fibrous annulus fissure. Therefore, several treatments were designed to remove the nucleus pulposus tissue from the central portion of the disc. These techniques have evolved from the 1960s to the present, and there are quite a few types, but the philosophy of treatment is the same: remove the nucleus pulposus tissue and hollow out the disc so that the amount of tissue in the central portion is reduced and the internal pressure is lowered, thus reducing herniation and irritation to the surrounding tissues. This type of surgery is also known as a myelotomy. Nowadays, there is a better understanding of the mechanism and pathology of herniated discs. A herniated disc is not entirely due to the protrusion of the nucleus pulposus as a result of increased internal pressure, and it is not all the nucleus pulposus tissue that is herniated. The herniated tissue may be the nucleus pulposus, the torn annulus fibrosus, or even the ruptured cartilage plate. Moreover, the disc is not an elastomer and will not retract on its own like a balloon, with the protruding fragments retracting after lowering the internal pressure. Nucleus pulposus resection, a treatment designed according to earlier theories, has significant limitations and is currently suitable for only a small number of patients. The results of practical application show that some patients do get pain relief for a certain period of time. Moreover, this type of surgery is performed by percutaneous puncture into the disc, which is very popular among patients because it causes minimal damage. Therefore, there are still many doctors who still use these techniques to treat patients with herniated discs. The percutaneous puncture approach uses a puncture needle about 2 to 6 mm in diameter that penetrates the skin, passes through the muscle, and enters the disc at the intervertebral foramen in the lumbar spine (foramen, refer to my article: What You Know About Minimally Invasive Spine Surgery Techniques – Endoscopic Lumbar Discectomy). This route is minimally invasive as there are no bony structures to obscure it and no bone needs to be removed. Through the hollow needle path, the surgeon uses a variety of means to remove the nucleus pulposus tissue within the disc. These include: disc lysis, vaporization, aspiration, shaving, ablation, and clamping. The following are a few commonly used in China: percutaneous puncture access I. Nucleus pulposus resection As early as the 1960s, American doctors used a biological preparation of papaya rennet, injected into the middle of the nucleus pulposus through a puncture needle, and dissolved the nucleus pulposus tissue through a biochemical reaction. This process is very similar to the use of meat tenderizing powder in the kitchen to soften beef. The human body can have a serious allergic reaction to papaya rennet, and nowadays, collagenase is used instead, which is slightly less effective in dissolving the nucleus pulposus. Radiofrequency ablation Anyone who knows the principles of physics knows that radiofrequency has energy and will destroy tissue cells when it reaches a certain amount. The radiofrequency device used for myelomeningocele removal uses bipolar, and the energy generated between the two poles will smash the myelomeningocele cells. The temperature generated by this process is not very high and generally does not affect the nearby nerve tissue. This is different from ablation devices used in tumor treatment, which can produce temperatures higher than 100 degrees, enough to cook tissue cells. Automatic percutaneous medullary nucleus excision The device used by the surgeon during the operation is actually a kind of rotating planer, which chips down the nucleus bit by bit and removes it along the device. IV. Clamping The clamp for clamping the nucleus pulposus is arguably one of the most primitive tools, but the clamp used in the percutaneous approach is very finely made. The surgeon uses this tool to clamp the nucleus pulposus tissue out with quite a lot of effort. The first generation of intervertebral foraminoscopic techniques used the forceps. V. Laser vaporization As the name implies, the energy of the laser is used to destroy the nucleus pulposus tissue cells and turn them into gas to be extracted. The device that emits the laser is placed into the nucleus pulposus through the hollow orifice of the puncture needle. In all of these procedures, the surgeon cannot directly see the nucleus pulposus intraoperatively, nor can he or she directly see if the surgical tool has been placed in its intended location. In fact, the only way to determine the position of the surgical tool is to use X-ray equipment. The tools are made of metal and are not X-ray transparent. Therefore, the fluoroscopy will show up in the image. Likewise, the vertebrae are impervious to X-rays and are visible in the image. Based on the interrelationship between the two images, the doctor can ultimately determine whether the tool is in the proper position. In other words, the X-ray fluoroscopy machine is an indispensable piece of equipment for percutaneous puncture surgery. The patient’s surgical procedure kind of has to consider the radiological damage caused by too much fluoroscopy in addition to the trauma of the procedure itself; the therapeutic effect is definitely temporary.