Knee pain in the elderly may be related to rheumatic immune diseases, osteoarthritis of the knee, meniscus injury of the knee and other causes. 1. Rheumatic immune diseases: rheumatoid arthritis develops in the knee joint, and untimely treatment may lead to knee pain. 2. Osteoarthritis of the knee joint: usually caused by osteophytes and degeneration of the knee joints of the elderly, osteoarthritis can lead to narrowing of the joint space, which will lead to knee pain when this kind of patients move their knee joints. 3. Knee meniscus injury: when the patient’s knee suffers trauma, if it leads to knee meniscus injury, so that the meniscus tear will also cause knee pain in the elderly. It is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, and then give standardized treatment.