Low back pain is one of the common clinical symptoms. Many diseases can cause low back pain, with localized lesions accounting for most of them, probably related to the long-term weight bearing of the low back and its easy structural damage. It is also extremely common to have lesions in adjacent organs or radiating low back pain. The following is a brief description of the common diseases causing low back pain and their clinical characteristics: 1. Spinal lesions (1) herniated disc: common in young adults, prone to lumbar 4-sacral 1. It often has a history of heavy lifting or sprain, and can occur suddenly or slowly. The main manifestations are lumbago and sciatica, which can occur simultaneously or separately. Sometimes the pain is severe and worsens when coughing or sneezing, and is relieved when resting in bed. There may be numbness and coldness in the lower limbs or intermittent claudication. (2) Proliferative spondylitis: also known as degenerative spondylitis, mostly seen in patients over 50 years of age, who feel lumbar pain, soreness, stiffness and difficulty moving in the morning, and the pain improves after moving the lumbar area, but it worsens after too much activity. The pain is obvious in the evening. It can be relieved by lying down, the pain is not severe, there is a comfortable feeling when tapping the lumbar area, and there is no obvious pressure pain in the lumbar spine. (3) Ankylosing spondylitis: Early symptoms often manifest as lower back pain with morning stiffness, which is heavier at night when resting or being sedentary. It usually lasts for more than 3 months and is often accompanied by sacroiliac joint pain, limited forward flexion, back extension, lateral bending and rotation of the spine. It responds well to nonsteroidal anti-inflammatory drugs. (4) Tuberculous spondylitis: It is the most common form of infectious spondylitis, with the lumbar spine being the most susceptible, followed by the thoracic spine. Back pain is often the first symptom of tuberculous spondylitis. The pain is confined to the site of the lesion. It is vague, dull or aching, pronounced at night and intensifies with activity, accompanied by hypothermia, night sweats, weakness and lack of appetite. Late stage may have spinal deformity, cold abscess and spinal cord compression symptoms. (5) Spinal tumors: There are many pieces of metastatic malignant tumors, such as metastases of prostate cancer, thyroid cancer and breast cancer or multiple myeloma accumulated in the spine. It manifests as intractable low back pain, which is severe and persistent, difficult to be relieved by rest and medication, and radiating nerve root pain. (6) Septic spondylitis: This disease is uncommon and often results from sepsis, trauma, lumbar spine surgery, lumbar puncture and discography infection. Patients feel severe low back pain, with significant pressure pain, percussion pain, with chills and high fever and other symptoms of systemic toxicity. (7) Spinal fracture has a clear history of trauma and is mostly due to a fall from a height, landing on the foot or hip first, with pressure pain and percussion pain at the fracture site, and the spine may have a kyphosis or lateral convexity deformity with impaired movement. (Such mostly acute pain) 2, paraspinal tissue lesions (1) lumbar muscle strain: often due to incomplete treatment of lumbar sprains or cumulative injury, patients feel lumbosacral pain, dull pain, relieved at rest and aggravated after exertion. Especially, the pain is obvious when working bent over, while the pain can be relieved when stretching or tapping the lumbar region. (2) Lumbar muscle fibrous tissue inflammation: Often caused by cold, humidity, chronic strain caused by low back fascia and muscle tissue edema, fibrous degeneration. Most patients feel diffuse pain in the lumbar back, mainly in the muscles on both sides of the lumbar spine and above the iliac crest, which is worse in the morning and improves after a few minutes of activity, but the pain increases again after too much activity. The pain is relieved by tapping on the lumbar region. 3, spinal nerve root lesions (1) spinal cord compression: seen in disc herniation, primary or metastatic tumors in the spinal canal, epidural abscesses, etc.. The main manifestation is the nerve root provocation sign. Patients often feel pain in the back of the neck or lumbar pain, which radiates along the posterior root distribution area of one or more spinal nerves, and the pain is intense, burning-like or cramp-like pain, which is aggravated by spinal activities, coughing and sneezing. There is some localized pain and there may be sensory impairment. (2) Lumbosacral radiculitis: mainly pain in the lower back and lumbosacral region with stiffness, pain radiating to the buttocks and lower extremities, obvious pressure pain in the lumbosacral region, segmental sensory disorders in severe cases, weakness of the lower extremities, muscle atrophy, and hypotonic reflexes. (3) Subarachnoid hemorrhage: The blood from the subarachnoid space can cause severe low back pain when it stimulates the spinal membrane and the posterior roots of the spinal nerve. 4. Low back pain caused by internal diseases (1) Diseases of the urinary system: urinary tract stones, nephritis, pyelonephritis, tuberculosis, tumors, etc. In the case of kidney stones, the pain is mostly colic and intense percussion pain; in the case of pyelonephritis, the pain is distinct and obvious percussion pain; in the case of kidney tumors, the pain is mostly dull or swelling pain, sometimes colic. (2) Pelvic organ diseases: male prostatitis and prostate cancer often cause lower lumbosacral pain, accompanied by urinary frequency, urinary urgency and difficulty in urination; female chronic adnexitis, cervicitis, uterine prolapse and pelvic inflammatory disease can cause lumbosacral pain, accompanied by a feeling of lower abdominal cramping and pelvic pressure pain. 5, digestive system diseases The afferent fibers of digestive tract and organs enter the same spinal cord segment as the afferent fibers of certain skin area, so the visceral afferent pain sensation excites the afferent fibers of skin area, causing inductive pain. In gastric and duodenal ulcers, chronic perforation of the posterior wall directly accumulates the peri-spinal tissues, causing painful muscle spasms in the low back, often accompanied by epigastric pain. In addition, acute pancreatitis often has left-sided lumbar back radiating pain. 6, respiratory system diseases Pleurisy, tuberculosis and lung cancer can cause pain in the posterior chest and lateral thoracic scapular area. Back pain is often accompanied by pain in the lower lumbar region.