Juvenile Idiopathic Arthritis

Authored by , Reviewed by Dr John Cox on | Certified by The Information Standard

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.

The place where two bones meet is called a joint. 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.

Normal joint

Normal joint

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.

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:

Oligoarticular JIA (50% of all cases 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 for more details.

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.

Polyarticular JIA - rheumatoid factor negative (25% of all cases of JIA)

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.

Polyarticular JIA - RF positive (5% of all cases of JIA)

Arthritis affects five or more joints in the first six months. A blood test for RF in the blood is positive.

Systemic-onset JIA (5-10% of all cases of JIA)

Arthritis develops with at least two weeks of daily high temperature (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:

  1. A rash which quickly fades and changes.
  2. Increased size of lymph glands (nodes).
  3. Increased size of the liver and/or spleen.
  4. Inflammation of the lining of the heart (pericarditis), lungs (pleuritis) or the abdomen (peritonitis).

Juvenile psoriatic arthritis (2-15% of all cases of JIA)

Arthritis occurs with psoriasis or arthritis plus at least two of:

  1. Inflammation of a finger or toe, causing pain and swelling.
  2. Abnormality of one or more fingernails.
  3. Psoriasis in a close relative.

Enthesitis-related arthritis (2-10% of all cases of JIA)

Arthritis occurs with inflammation at the site of attachment of a tendon or ligament to a bone (called enthesitis), plus any two of:

  1. Pain in the joints of the lower back (lumbosacral spine) and/or the pelvis (sacroiliac joints).
  2. A blood test for a chemical marker of certain diseases - called HLA B27 - is positive in 90% of people who have enthesitis-related JIA.
  3. A family history of illnesses associated with being HLA B27-positive, including ankylosing spondylitis, inflammation affecting the eye (uveitis), psoriatic arthritis and ulcerative colitis.
  4. The child affected with enthesitis-related arthritis also has other illnesses associated with being positive for HLA B27.
  5. The arthritis affects a boy and starts when the boy is over the age of 6.

Undifferentiated arthritis (1-10% of all cases of JIA)

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 (uveitis) and inflammation of the lining of the heart (pericarditis), lungs (pleuritis) or abdomen (peritonitis). JIA may also be associated with high temperature (fever) or symptoms of anaemia (such as feeling tired all the time).

Oligoarticular JIA

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.

Polyarticular JIA (RF negative)

This most often presents in preschool children and in children aged 10-13 years. It is more common in girls.

Polyarticular JIA (RF positive)

  • This affects small joints, especially the joints of both hands and wrists, with swelling and stiffness.
  • Rheumatoid nodules may develop. These are small painless lumps which occur on the skin over the elbows and forearms but usually do no harm.
  • There may also be fever, an increase in the size of the liver, spleen and glands, and inflammation of the lining of the heart, lungs or abdomen.

Systemic JIA

  • This usually starts before the age of 5 years.
  • A high fever often occurs, most often in the afternoon or evening, with a rapid return of the temperature to normal.
  • A rash often appears with the fever. The rash is usually a light pink colour and quickly disappears.
  • Arthritis only occurs at the start of the disease in about one third of children but usually develops within a few months. The arthritis usually affects several joints.

Juvenile psoriatic arthritis

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.

Enthesitis-related JIA

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. They help to:

  • Find out what type of arthritis it is.
  • Make sure there are no other causes for the symptoms, such as bone infection or a break (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:

  • X-rays, which are normal in the early stages of JIA but help to check for any other bone or joint problems such as infection or injury.
  • Ultrasound scans to see if there is any fluid in the joint and the extent of arthritis of the joint.
  • MRI scans to show details of the damage to the joint and any changes of the bones surrounding the joints.
  • If there is any possibility of an infection in a joint then some fluid may be taken from the joint and sent to the laboratory for testing.

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:

Disease-modifying antirheumatic drugs (DMARDs) may be used to help reduce the effects of the disease. These medicines can be very effective but also need very close supervision by your doctor. DMARDs used for JIA include methotrexate, sulfasalazine, 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 inflammation affecting the eye (uveitis) may have long-term reduced vision. They also have an increased risk of later developing cataracts or increased pressure in the eye (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 juvenile idiopathic arthritis (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.

Further reading and references

I'm a 20 year old and for the past few months (maybe a year, I forgot how long it's been happening) I've been experiencing hip popping whenever I get up from my chair or start moving after sitting at...

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