Causes of sciatica are primary and secondary, such as cold, flu, trauma, lumbar disc herniation, spinal diseases, hip arthritis and so on. 1. Primary sciatica: the etiology is unknown, but it is closely related to interstitial neuritis invaded by cold, flu, tonsil infection, etc., and it can co-exist with fibrositis and myositis. 2. Secondary sciatica: it is related to the damage of sciatic nerve pathway, and can be divided into two categories of radicular and dry according to the site of injury, and a small part of it can be secondary to systemic diseases. (1) Radicular sciatica: it is often caused by intravertebral diseases and spinal diseases. Trauma, vascular malformation, inflammation of spinal cord and cauda equina, lumbosacral and intravertebral tumors are all intravertebral diseases, and lumbar intervertebral disc herniation, spinal stenosis, spinal tuberculosis are all spinal diseases. (2) Dry sciatica: Hip arthritis, sacroiliac arthropathy, pelvic tumor, lumbar large muscle abscess, uterine compression during pregnancy, uterine adnexitis, and inappropriate injection site of the gluteal muscle can cause dry sciatica. Sciatica may also have other causes, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.