Lumbar disc herniation can be divided into 4 stages according to the way of protrusion: 1, bulge: the nucleus pulposus is displaced posteriorly in the fibrous ring, and the whole disc also protrudes posteriorly, but it is smooth and symmetrical posterior convexity, which generally does not cause or only causes mild symptoms. 2.Protrusion: The disc protrudes significantly posteriorly, but the nucleus pulposus is still in the annulus fibrosus, and the protrusion is asymmetric, which can cause obvious symptoms by compressing the nerve roots. 3.Prolapse: The nucleus pulposus in the disc breaks through the fibrous ring and enters the spinal canal, causing severe compression on the nerve, but it has not been completely detached from the fibrous ring. 4.Free: The nucleus pulposus in the disc is completely detached from the fibrous ring and can move freely in the spinal canal, often with adhesions between the nerve. The degree of disc herniation is sometimes not parallel to the symptoms, that is, not necessarily the symptoms caused by a severely herniated disc are also heavy.