This article does not deal with the more general topic of childhood arthritis. Juvenile idiopathic arthritis (JIA) is the most common form of persistent arthritis in children. (Juvenile in this context refers to an onset before age 16, idiopathic refers to a condition with no defined cause, and arthritis is the inflammation of the synovium of a joint. ) JIA is a subset of arthritis seen in childhood, which may be transient and self-limited or chronic. It differs significantly from arthritis commonly seen in adults, and other types of arthritis that can present in childhood which are chronic conditions...