Many people start to feel pain and stiffness in their bodies over time. Sometimes their hands or knees or shoulders get sore and are hard to move and may become swollen. These people may have arthritis (ar-THRY-tis). Arthritis may be caused by inflammation (in-flah-MAY-shun) of the tissue lining the joints. Some signs of inflammation include redness, heat, pain, and swelling. These problems are telling you that something is wrong.