There are many reasons that cause patients to have leg pain all the time, and the most common ones are necrosis of the femoral head, nerve root compression and so on, which are as follows: First, necrosis of the femoral head: if there is necrosis of the femoral head, it will lead to leg pain all the time, and localized magnetic resonance examination is needed, which will lead to clear diagnosis. Nerve root compression: if the patient has lumbar spinal stenosis, disc herniation, vertebral body slippage, when compressed to the nerve root, it will also lead to the patient’s leg pain. Third, other factors: if the patient has knee osteoarthritis, synovitis, meniscus injury, rheumatism, rheumatoid arthritis, can also lead to old leg pain, need to carry out the blood routine, blood sedimentation, C-reactive protein, anti-O rheumatoid factor, renal function test, and localized ordinary X-ray film examination can be a clear diagnosis.