The causes of knee pain are diverse and can be categorized into physiological and pathological. Physiological includes after excessive exercise; pathological causes include orthopedic diseases and rheumatic immune diseases, which are mostly unrelated to nephritis. 1. Physiological: if you walk for too long a distance, or just after climbing stairs and other exercises that require knee pain, it is a normal physiological phenomenon, and it can be relieved after reducing walking or resting. 2. Pathological: the most common diseases that cause knee pain are orthopedic diseases, such as knee osteoarthritis, knee tuberculosis, bone tumors, bone fracture and ligament injuries, etc., which will cause symptoms in the knee; and rheumatoid immune diseases, such as rheumatoid arthritis, etc., which may cause knee pain if it affects the knee joints, synovium, etc., and are mostly unrelated to nephritis. When knee pain occurs, it is recommended to go to the hospital in time to identify the cause and standardize the treatment under the guidance of professional physicians.