Juvenile Idiopathic Arthritis
By Dr. Ruth Renfrew (MBChB BSc DTM&H)
Juvenile Idiopathic Arthritis (JIA) affects between one and four in every 1000 children in Australia. It can start at any age up to 16. To understand what JIA is, it helps to know what the different words represent:
- Juvenile means young
- Arthritis means inflammation of the joints
- Idiopathic means that we don't know the cause
Joints are the places in your body where bones meet other bones, like your knees, wrists and elbows. Inflammation can make your joints sore, hot, swollen and stiff. So, altogether, JIA is a condition that affects young people, which makes their joints sore, and we don't know what causes it.
What happens in JIA?
Normally your joints move smoothly allowing you to walk and run, throw a ball, write with a pencil, and all the other movements that you do every day. There are three main parts in each joint that allow this to happen: the joint capsule, the synovial membrane and cartilage. The capsule keeps your bones in the right place within the joint. The synovial membrane produces a small amount of synovial fluid that keeps your joints well-oiled so they can move freely. Cartilage is a smooth material that covers the ends of your bones and cushions them like a shock absorber.
The body's immune system is made up of different cells and chemical messengers. Usually it fights infection, but in JIA the immune system gets confused and thinks that the synovial membrane is a threat to the body. As a result, it attacks the synovial membrane, which becomes thicker than normal and starts to produce too much fluid. Over time, the cartilage can be worn away by the thick synovial membrane, which allows the bones to rub against each other. This is what makes the joints sore, hot, swollen and stiff.
JIA can affect different joints in different people. Sometimes JIA can cause problems in other parts of the body too, for example the eyes. When this happens it is called uveitis and can make vision blurry.
With all types of JIA, it can feel better or worse at different times. When it's bad, it's called a flare. In between times, it's called remission.
How do you know if you have JIA?
Joint pain, swelling and stiffness are the main problems associated with JIA. There might be problems too with fevers, skin rash and dry eyes. Feeling more tired than normal or losing weight are also clues that someone might have JIA. The doctors do some tests to check, for example blood tests and different scans of the joints including bone scans, X-rays, MRI and ultrasound scans. With the results of all these tests, the doctor will know whether it's JIA and if treatment is needed.
What causes JIA?
We know that JIA is a problem with the immune system attacking joints. However, do you remember that word 'idiopathic'? It means that we still don't know for sure why some people get JIA and others don't. Doctors and scientists all over the world are working hard to try and find the answers.
How can JIA be treated?
There are three main types of medicine to treat JIA: NSAIDs, corticosteroids and DMARDS.
NSAIDs is short for Non-Steroidal Anti-Inflammatory Drugs, which means that this medicine fights inflammation. They work quickly to ease swelling and reduce pain but they don't fix the underlying mechanism. The most common side effect is an upset stomach.
Corticosteroids ease swelling and pain but they also relax the immune system, which helps to stop it from attacking the joints. They can be given locally or systemically. Local corticosteroids are injected directly into one joint. Systemic steroids are given as pills or on a drip and treat the whole body.
DMARDs, or Disease Modifying Anti-Rheumatic Drugs, work by stopping the signal that tells the immune system to attack in the first place. They can be given as tablets or injections. They stop lots of the attacks but not all of them. As both corticosteroids and DMARDs act by stopping the immune system from working properly, children who take them can be more likely to get infections.
As well as medicines, physiotherapy is a really good treatment for JIA. Physiotherapists can show us exercises to keep the joints working without hurting them.
Occasionally an operation is needed to replace joints that have had a lot of damage from repeated attacks and inflammation.
Having JIA can be tough. It can make children feel tired and they can struggle to keep up with their friends. It's important to remember that lots of children have JIA and are facing the same problems. Talking to friends and family about it can really help.
- In JIA, the body's own immune system attacks the joints
- This makes joints hot, swollen,
stiff & sore
- The doctor will arrange blood tests & scans to check if it's JIA
- The main treatments are medicines & physiotherapy
Living with JIA can be hard, but there are lots of people who can help.
About Dr. Ruth Renfrew
Dr. Ruth Renfrew is a medical writer at Medikidz, an organisation that provides children with informative, accessible and fun comics to help them understand health and illness.