This painful health condition is the number one cause of disability in the country. Arthritis is an umbrella term referring to more than 100 types of joint diseases that affect over 50 million adults in the U.S. It can affect your neck, knees, ankles, toes, wrists, hands, hips, elbows, shoulders, and back. The most common type of arthritis is osteoarthritis, which affects an estimated 31 million Americans. The medical community estimates that the number of people expected to have professionally diagnosed arthritis by the year 2040 is more than 78 million. Arthritis is much more common among people who have other chronic conditions, particularly amongst people who have heart disease, diabetes, or high blood pressure. A doctor might recommend treatment in the form of medications, dietary changes, surgery, or alternative therapies.