Knee pain in the elderly is mainly caused by osteoarthritis, a chronic disease characterized by degeneration of articular cartilage and bone hyperplasia. Patients often experience pain and stiffness in the knee joint, which is especially worse when going up and down stairs or walking for a long time, and is relieved by rest. As the disease progresses, the joints become deformed and the range of motion is reduced, which has a significant impact on the quality of life.