Discography combined with methylene blue injection for the treatment of lumbar discogenic lower back pain. I. Indications 1. chronic persistent low back pain for more than six months, with varying degrees of low back pain centered on the spinal region, some patients with radiating pain in the hip, groin area or inner and outer thighs, and symptoms can be aggravated by prolonged standing or sitting; 2. poor effect of non-surgical treatment such as rest, exercise, oral anti-inflammatory and analgesic drugs and physical therapy; 3. normal neurological function examination; 4. negative straight leg raising test; 5. imaging CT and MRI did not show lumbar disc protrusion, spinal canal and nerve root canal stenosis, no vertebral endplate signal changes; MRI showed no significant compression of the dural sac and nerve roots, more than one disc in the MRIT2-weighted image showed low signal shadow, and some patients had high signal area behind the fibrous ring. 6. exclude other diseases such as rheumatoid arthritis; 7. no previous history of lumbar spine surgery; 8. loss of intervertebral space height less than 30% of the adjacent segment. Exclusion criteria 1.Patients whose pain symptoms can be relieved by conservative treatment; 2.Patients with intermittent claudication or nerve root radiological pain or numbness; 3.Patients with disc herniation, spinal stenosis, nerve root compression, segmental instability and other soft tissue strain diseases that clearly cause lumbar pain on imaging examination; 4.Patients with history of lumbar fracture or surgery are also excluded.