Rheumatoid arthritis (RA) is a long-term, or chronic, disease that leads to inflammation of the joints and surrounding tissues, and occasionally even other organs. It is considered to be an autoimmune disease, meaning that the immune system confuses healthy tissue for foreign bodies and begins attacking itself. RA may ultimately destroy joint cartilage.
RA can occur at any age but it is typically more common in middle age and in women. RA usually affects both sides and may begin with only minor pain, stiffness and fatigue. Early intervention with the right medications, physical therapy, exercise and information may help delay joint deterioration.
Because RA is chronic, without medical treatment your symptoms may worsen leading to more intense pain, loss of mobility and potential deformation of the joint. Your knee may start to become swollen, and feel warm and spongy to the touch.
Learn basics of knee anatomy »
Explore potential treatment options for rheumatoid arthritis of the knee »