Juvenile idiopathic arthritis, formerly known as juvenile rheumatoid arthritis, is the most common type of arthritis in children under the age of 16.Juvenile idiopathic arthritis can cause persistent joint pain, swelling and stiffness. Some children may experience symptoms for only a few months, while others have symptoms for the rest of their lives.Some types of juvenile idiopathic arthritis can cause serious complications, such as growth problems, joint damage and eye inflammation. Treatment focuses on controlling pain and inflammation, improving function, and preventing joint damage.