Although the word arthritis means joint inflammation, the term is used to describe around 200 rheumatic diseases and conditions that affect joints, the tissues that surround the joint, and other connective tissue.5. The most common form of arthritis is osteoarthritis.he term arthritis is used to describe numerous rheumatic diseases and conditions that affect joints. Some forms of arthritis, such as rheumatoid arthritis and lupus, can affect multiple organs and cause widespread symptoms.