Essentially, arthritis is a pain or swelling in a joint, caused by some toxin or injury. Arthritis is a symptomatic feature of many types of related diseases and, as a general term, can refer to approximately 100 different conditions that cause pain, stiffness, and swelling in joints and other connective tissues (muscles, tendons and ligaments).
There are three basic categories of arthritis:
Chronic arthritis (the latter two categories) does not go away, unlike a temporary inflammation caused by a localized infection of a joint. Usually the cause is not curable and treatment aims at reducing pain and discomfort and preventing further disability.
Arthritis is common (one in seven individuals suffer from arthritis), can occur in males and females of all ages and is not limited to the very old (36% are under 40 years of age, 79% are under 60). Millions of dollars are spent on research each year.
Nearly 43 million people in the USA have arthritis. As reported in the U.S. National Health Interview Survey (2015), the rate of arthritis symptomology was 29.9 percent in men under 65 and 31.2 percent in women under 65. Of course, this jumped sharply with age. The prevalence in men 65 and older was 55.8 percent, and 68.7 percent among their female peers. Undiagnosed arthritis was more common than previously thought: in subjects between the ages of 18 and 64, 19.3 percent of men and 16.7 percent of women had chronic joint pain but no diagnosis of arthritis; among those 65 or older, nearly 16 percent of men and just under 14 percent of women reported suffering from joint pain without an official arthritis diagnosis.