Knee pain is usually an orthopedic condition, the most common being osteoarthritis, others also include meniscal damage, chondromalacia of the patella, etc., which can usually be clarified by MRI examination. In addition, there are also cases of rheumatic or rheumatoid arthritis, especially in patients with a long course of disease, further improvement of joint MRI, ultrasound or X-ray, rheumatoid factor, blood sedimentation and other tests are required under the guidance of a doctor to clarify the diagnosis and take targeted treatment according to the cause, which is beneficial to the prognosis of the disease.