This article does not deal with the more general topic of childhood arthritis

Childhood arthritis

Childhood arthritis, also juvenile arthritis, is arthritis in a child.Childhood arthritis may be:* Transient & self-limited* ChronicChronic forms of arthritis seen in childhood are:* Ankylosing spondylitis* Psoriatic arthritis...

.

Juvenile idiopathic arthritis (JIA) (aka Juvenile Rheumatoid Arthritis JRA) is the most common form of persistent arthritis

Arthritis

Arthritis is a form of joint disorder that involves inflammation of one or more joints....

 in child

Child

Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...

ren. (Juvenile in this context refers to an onset before age 16, idiopathic

Idiopathic

Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...

 refers to a condition with no defined cause, and arthritis

Arthritis

Arthritis is a form of joint disorder that involves inflammation of one or more joints....

 is the inflammation

Inflammation

Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...

 of the synovium

Synovium

Synovial membrane is the soft tissue found between the articular capsule and the joint cavity of synovial joints....

 of a joint.)

JIA is a subset of arthritis seen in childhood, which may be transient and self-limited or chronic.