In spite of being very common, arthritis is a condition not well understood. The term ‘arthritis’ is actually an informal term for joint pain or disease, and it does not refer to a single disease. More than 100 types of arthritis exist and they all have similar symptoms. Arthritis can affect people of all ages, sexes and races, and it is a leading cause of disability in the U.S. An estimated 50 million adults and 300,000 children have arthritic conditions. Women are more prone to this condition and it occurs more frequently with age.