Juvenile idiopathic arthritis (JIA) is a condition in which joint inflammation occurs in children under the age of 16 years. It lasts for at least six weeks. Arthritis causes inflammation, pain and swelling of the affected joints. The severity can vary from mild to severe.
Treatment includes medicines called disease-modifying antirheumatic drugs (DMARDs), which can prevent or delay the arthritis from getting worse, and also medication to ease the pain and stiffness of the affected joints. The earlier the treatment is started, the less joint damage is likely to occur. Surgery is needed in some cases if a joint becomes badly damaged.
A joint is where two bones meet. Joints allow movement and flexibility of various parts of the body. The movement of the bones is caused by muscles which pull on tendons that are attached to bone. Cartilage covers the end of bones. Between the cartilage of two bones that form a joint there is a small amount of thick fluid called synovial fluid. This lubricates the joint, which allows smooth movement between the bones.
The synovium is the tissue that surrounds a joint. Synovial fluid is made by cells of the synovium. The outer part of the synovium is called the capsule. This is tough, gives the joint stability, and stops the bones from moving out of joint. Surrounding ligaments and muscles also help to give support and stability to joints.
Arthritis means inflammation of one or more joints.The common main symptoms of arthritis are pain and stiffness of affected joints. The stiffness is usually worse first thing in the morning, or after resting. The inflammation causes swelling around the affected joints.
Juvenile idiopathic arthritis (JIA) is a condition in which inflammation of one or more joints occurs in children under the age of 16 years. It lasts for at least six weeks. There are seven different types of JIA:
Arthritis affects between 1 and 4 joints during the first six months after the arthritis begins. One of the blood tests taken may show a positive result for antinuclear antibodies. Antinuclear antibodies are a type of protein in the blood called auto-antibodies. These proteins occur in people with some conditions and can be measured in the blood. See the separate leaflet called Antibody and Antigen Tests.
If more than six joints are affected after six months, it is called extended oligoarthritis. If no more than four joints are affected after six months then it is called persistent oligoarthritis.
Arthritis affects five or more joints in the first six months. A blood test for a chemical called rheumatoid factor (RF) in the blood is negative.
Arthritis affects five or more joints in the first six months. A blood test for RF in the blood is positive.
Arthritis develops with at least two weeks of daily fever. The fever must be greater than 39ºC and return to less than 37ºC between the episodes of fever. There must be one or more of:
Arthritis occurs with psoriasis or arthritis plus at least two of:
Arthritis occurs with inflammation at the site of attachment of a tendon or ligament to a bone (called enthesitis), plus any two of:
Undifferentiated JIA is used to describe arthritis that doesn’t fit into any of the other different groups of JIA.
JIA is uncommon. Between 1 and 2 in every 1,000 children are affected at any one time. Between 1 and 2 in every 10,000 children develop JIA each year.
JIA presents with arthritis and, sometimes, other symptoms outside of joints (known as extra-articular symptoms). These include conditions causing eye inflammation and inflammation of the lining of the heart, lungs or abdomen. JIA may also be associated with fever or symptoms of anaemia (such as feeling tired all the time).
This usually presents in children under 6 years old and is more common in girls. It often starts with one or two swollen joints causing stiffness and reduced movement but often not much pain. The knees and ankles are most often affected.
This most often presents in preschool children and in children aged 10-13 years. It is more common in girls.
This affects girls twice as often as boys and tends to start at about 6 years of age. The arthritis affects both small and large joints. In over half of affected children, the arthritis starts before the psoriasis.
This affects boys much more often than girls and usually starts after 10 years of age. It often affects the legs and may cause pain in the heel. There is often swelling of a knee or foot. Psoriasis, eye inflammation and bowel inflammation may also occur with enthesitis-related JIA.
The diagnosis of JIA is based on the symptoms and an examination by your doctor. Tests are important to help find out what type of arthritis it is, and to make sure there are no other causes for the symptoms, such as bone infection or a fracture of a bone.
Blood tests include a test for anaemia (which may occur with JIA) and tests for inflammation (called ESR and CRP, which are often raised with JIA). Blood tests may also be useful to see whether any infection (virus or bacteria) has caused the arthritis and not JIA.
Other blood tests are used to see if there is a positive test for chemicals which are markers for different types of inflammation. Examples of these markers are called antinuclear antibodies, RF and HLA B27.
Other tests include the following:
Physiotherapy and occupational therapy are used to help keep the affected joints working as normally as possible. They also reduce the risk of any permanent damage to the joints. Hydrotherapy (which involves different methods of treatment using water) can also be very helpful. Children should be encouraged to participate in as much physical activity as possible, including most sports and dancing.
Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to help reduce pain and stiffness in the joints.
Steroids may be used in different ways:
Medicines to help reduce the affects of the disease may be used disease-modifying antirheumatic drugs (DMARDs). These medicines can be very effective but also need very close supervision by your doctor. DMARDs used for JIA include methotrexate, sulphasalazine, leflunomide, etanercept and tocilizumab.
Surgery may be needed, including joint replacement operations.
Without treatment, JIA can lead to problems with growth, weakness of bones (osteoporosis) and a delay of puberty.
There may be long-term problems with the affected joints.
Some children who develop uveitis may have long-term reduced vision. They also have an increased risk of later developing cataracts or glaucoma.
Because they are unable to participate in all the usual physical activities with friends and at school, children with JIA may have emotional and behavioural difficulties and problems at school. This can be made worse because of having to deal with pain and the amount of time taken away from school in order to attend hospital appointments and admissions. Therefore children with JIA and their families often need a lot of support.
With modern treatments, the outlook for most children with JIA is now very good. However, the outlook is variable depending on the type and the severity of JIA. It is therefore essential for the diagnosis to be made early and treatment to be started early.