The Oxford dictionary defines it as “inflammation of a joint or joints”. It comes from the root “arthro” which means joint and “itis” which means inflammation of. A common sense definition of arthritis is the condition of chronic pain and stiffness that occurs secondary to deterioration of a joint. It can occur in any joint such as the finger, the back, the shoulder, or as we are concentrating on here, the hip and knee. It is associated with aging.