The posterior longitudinal ligament has no interruption in the whole length of the spine, but since the first lumbar vertebra, the posterior longitudinal ligament gradually narrows to the 5th lumbar vertebra and the 1st sacral vertebra, the width is only equal to half of the original, the lumbosacral part is the part that bears the greatest dynamic and static forces, so the narrowing of the posterior longitudinal ligament has caused a natural structural weakness, and the nucleus pulposus tends to protrude to the posterior sides. The causes of this disease are both endogenous and exogenous. The endogenous cause is degeneration of the intervertebral disc itself or developmental defects of the intervertebral disc; the exogenous cause is injury, strain and cold. Lack of blood supply to the intervertebral disc, the repair capacity is weak, and in daily life and labor, due to weight bearing and spinal movement, the intervertebral disc is often subject to extrusion, pulling and twisting from all sides, so it is easy to atrophy, elasticity weakening and other degenerative changes, which is the main factor of the nature of the occurrence. (1) Trauma, especially accumulated strain injury, is an important cause of rupture of the annulus fibrosus. Because the lumbar vertebrae are arranged in a physiological anterior convexity, the intervertebral disc is thin in the back and thick in the front, when people bend forward, the pulp school moves backward, and due to the influence of weight, muscle and ligament and other tension, the nucleus pulposus produces a strong resistive elasticity, the size of this resistive elasticity is proportional to the size of the weight-bearing pressure. In this case. If this force is excessive, or if the disc annulus fibrosus itself is defective, the nucleus pulposus may break through the annulus fibrosus and bulge or protrude laterally and posteriorly, causing compression of the nerve root, cauda equina, or spinal cord. Generally, between the ages of 20 and 30, the annulus fibrosus begins to degenerate and its elasticity decreases, and stress added to these degenerated or decompensated annulus fibrosus, such as after a lumbar sprain, can easily cause rupture of the annulus fibrosus. At this age, the nucleus pulposus can still maintain its gelatinous state and expansion, because of which the nucleus must be squeezed between the fissure, thus affecting the healing of the fissure, even if the trapped fissure is small and the nucleus pulposus does not break through the fibrous ring for a while, but because the fissure continues to exist, it may also develop in the future in the continuous activity and extrusion. If the fracture of the fibrous ring caused by the sprain is large, the protruding nucleus pulposus can cause acute sciatica. Between the ages of 30 and 40, if the fibrous tissue in the nucleus pulposus increases but does not yet cause the disc to narrow, the resistance of the nucleus pulposus to degeneration becomes greater than in the semi-liquid period, and the possibility of nucleus pulposus protrusion becomes relatively small. After the age of 40-50, if the degeneration of the nucleus pulposus, the fibrous ring and the cartilage plate are obvious and the disc atrophy is extensive, the rupture and protrusion are mostly small after the injury, and it is not easy to cause the typical sciatica. Unless the fractured annulus fibrosus is squeezed into the spinal canal, it will not cause acute symptoms. If the nucleus pulposus degeneration has reached an advanced stage and the fibrous ring is still intact, there is significant narrowing of the intervertebral space so that bone spurs or labral changes occur at the edge of the vertebral body. (2) Cold Many patients with lumbar disc herniation have no history of trauma or strain, only cold and exposure to cold. The reason for this may be due to the developmental defects of the intervertebral discs, and the cold flow makes the muscles of the lumbar back spasm and small blood vessels contract, affecting the local blood circulation, which in turn affects the nutrition of the intervertebral discs, and at the same time, the muscle tension spasm can increase the pressure on the intervertebral discs, especially for the degenerated intervertebral discs, which can cause further damage, resulting in the protrusion of the nucleus pulposus. According to Chinese medicine, the causes of this disease are mainly the following three: acute flash and contusion, blood stagnation; external wind, cold and dampness, meridian occlusion; long-term disease and strain, kidney deficiency type.