According to epidemiological surveys, 50-80% of people over 20 years of age, both men and women, have experienced low back pain. The duration of low back pain can be long or short, so low back pain is subdivided into acute, subacute and chronic low back pain. Generally speaking, if you have 6-12 weeks of continuous low back pain is called subacute low back pain, and if the pain lasts more than 3 months, it is called chronic low back pain. Low back pain arises from many causes. As the saying goes, “Patients have low back pain, doctors have headaches”. This is mainly because some patients with low back pain do not have any specific lesions, while others have low back pain that is associated with spinal lesions. This requires the physician to be able to differentiate the cause of low back pain by one or more diagnostic tools, so that the patient can be clearly diagnosed and treated for the purpose of pain relief. From the patient’s history, course, symptoms and imaging data such as X-rays, MRI films or CT films, the physician can make a general determination. That is, whether there is a diagnosis of lumbar disc herniation, lumbar spinal stenosis, fracture, inflammation, tumor, etc.. These diseases are directly related to low back pain, but there are still some cases where even after these examinations, the diagnosis of the disease cannot be made. This requires some special diagnostic methods in order to arrive at a diagnosis and thus a treatment. Doctors will propose functional tests as a special diagnostic method, which are used to determine the condition by means of imaging, excitation tests, etc. Here we introduce the diagnostic methods of discography and small joint block and related problems. One of the most common causes of low back pain is bulging, tearing or rupture of the lumbar intervertebral disc. When an intervertebral disc that has been damaged is destroyed, it cannot act as a shock cushion and absorb force, and pain is produced. However, the lumbar discs do not appear to be clearly herniated on a single MRI film, or multiple discs appear to be mildly degenerated. So which disc or discs are causing the back pain? This is often the case when a lumbar discography is performed. This involves injecting a contrast agent into the disc through a needle into the lumbar disc. If the patient’s previous manifestations of low back pain can be replicated, it will be possible to determine which disc is causing the problem. This will allow for targeted treatment. With this method of examination, it is equivalent to extending the doctor’s finger to point at the target to arrive at a scientific judgment. Then there are also some patients whose low back pain is caused by degeneration of the small joints of the lumbar spine, which can also create diffuse pain in the lumbar spine, and there are no characteristic changes on the imaging film. In this case, it is necessary to perform a small joint block for scientific diagnosis. This is done by injecting local anesthetic drugs into the small joints or near the nerve branches that innervate the small joints, and observing the patient for the onset of low back pain. If it is clear that the pain is caused by a small joint, the treatment will be easier. So, is there any danger in these diagnostics and is its safety guaranteed? The above two examination methods are performed under the guidance of X-ray or CT, which generally do not cause damage to nerve tissue or blood vessels. Therefore, the safety is guaranteed.