In old age, people often suffer from stiff and inflamed joints due to an autoimmune disease known as rheumatoid arthritis, which occurs due to the immune system attacking the cells of its own body. The cells lined in the synovial membrane of the synovial joints are attacked, which causes inflammation and stiffness in the joints.

•Thus, the reasons for these symptoms are the inflammation in the synovial joints due to the immune system attacking its own synovial cells.

•The trigger behind the immune system attacking itself is still unknown, but possible reasons are smoking, genetic factors, and vitamin D deficiency.