Juvenile idiopathic arthritis describes inflammation of the synovial lining of the joints that occurs before 16 years of age. The word idiopathic means the cause of the disease is unknown; however, the condition is likely due to a combination of genetic factors and environmental triggers, such as bacterial infection or trauma. Treatment involves the use of medications to relieve pain and stiffness and slow the disease process, as well as physical therapy to maintain range of motion and help with everyday activities.