Arthritis that occurs in children is classified as Juvenile Idiopathic Arthritis (JIA). Juvenile means that the arthritis began before 16 years of age, idiopathic means that the cause is not known and arthritis means that one or more joints are inflamed – that is, they are swollen, painful, stiff and you may not be able to move them as far as normal.
There are different terms when referring to arthritis in children. These include Juvenile Arthritis, Juvenile Chronic Arthritis, Juvenile Rheumatoid Arthritis, Still’s Disease, Juvenile Idiopathic Arthritis. In general, there are five main types of JIA, these are systemic onset, oligoarthritis or pauciarticular, polyarticular, enthesitis related arthritis, and psoriatic arthritis.
The causes of arthritis in children are unknown. Research suggests that for some types of JIA, genetics may be involved. However, these conditions are not regarded as hereditary.
What are the main symptoms?
Your child may have experienced one or more of these symptoms:
- joint pain, swelling, tenderness, stiffness, redness and warmth
- fatigue (tiredness and lack of energy), fevers, loss of appetite or weight, and generally feeling unwell
- skin rashes
- inflammation of the eyes (uveitis) and other organs of the body in some forms of the disease.
Any joint in the body may become inflamed but the joints most commonly affected are the knees, hips, hands and feet. Any number of joints might be affected from just one to several.
JIA symptoms can fluctuate – meaning they may vary from day to day, week to week. There will be times when symptoms are worse – these are called ‘flares’ – and then times when they are in remission.
The outlook for children with JIA is usually very positive. The good news is that most children with JIA will not have active symptoms by the time they become adults.
What causes it?
The causes of arthritis in children are not yet fully understood.
We do know that JIA is an autoimmune condition. This means the body’s immune system (its protective mechanism against infection) starts to mistakenly attack healthy cells of the body. This happens for reasons we don’t yet understand, possibly after being triggered by a virus or bacterial infection. The immune system fails to ‘turn off’ when the infection has been cleared producing ongoing joint inflammation called JIA. The immune system mistakenly attacks cells in the connective tissues, including the lining of the joints (synovium). JIA can also affect connective tissues in other parts of the body.
JIA is not an infectious condition so it cannot be spread from one child to another.
How is it diagnosed?
There is no single test to diagnose JIA. Instead, it involves a number of steps. These may include:
- detailed health and medical histories of your child and their biologically related family members (where known)
- physical examination of affected joint/s
- laboratory tests e.g. blood tests
- other tests such as X-rays, ultrasound and/or scans of the joints
- eye tests.
The results of these tests will help in confirming a diagnosis of JIA, or rule out any other possible causes for the symptoms your child is experiencing.
Sometimes all of the test results will be normal. This does not necessarily mean your child does not have JIA – it just means that the tests will need to be repeated, possibly when your child has symptoms.
If your doctor suspects JIA, your child should be referred to a rheumatologist (ideally a paediatric rheumatologist who specialises in children with arthritis) who would confirm the diagnosis and start treatment.
Reaching a diagnosis can take time due to the fluctuating nature of the condition. The ‘waiting period’ can be a very anxious and frustrating time. These feelings are understandable, but it is important to keep on with the process until the diagnosis is made. Once JIA is diagnosed, your child can be started on treatment to manage symptoms and to reduce potential damage.
What are the main types of juvenile idiopathic arthritis?
There are five main types of JIA each with its own specific set of symptoms. These main types are :
- Oligoarthritis (from ‘oligo’ meaning few). This is the most common type of JIA and occurs when up to four joints are affected, usually the large joints such as the knees and ankles. Children with oligoarthritis may develop uveitits (inflammation of the eye).
- Polyarticular (from ‘poly’ meaning many). This type involves five or more joints, with the same joints on each side of the body affected, including fingers, toes, wrists, ankles, hips, knees, neck and jaw.
- Systemic onset JIA. (Also known as ‘Still’s disease’) This is the least common type of JIA. It not only affects the joints, but causes widespread inflammation with high fevers, rashes, swollen glands, aching limbs and fatigue. It can be difficult to diagnose because early symptoms can be confused with other childhood diseases such as measles or glandular fever.
- Enthesitis-related arthritis (ERA). Enthesitis refers to inflammation of the ligaments and tendons which are attached to bones. This type of JIA causes pain and inflammation in the tendons and tissues around the joints rather than the joints themselves. It most commonly affects the spine, heel, hips, knees and ankles.
- Psoriatic arthritis. This type of JIA can affect any number of joints and is usually associated with the scaly skin rash of psoriasis. Like other forms of JIA there is a risk of developing uveitis (eye inflammation).