Oligoarticular

Oligoarticular means "few joints." In this type, only a few joints are affected. About 50% of children with JIA have this type. It is more common in girls younger than age 8.

In half of children with oligoarticular JIA, only one joint is involved. This is most often a knee or ankle. This form is called monoarticular juvenile arthritis. In some cases, it needs only mild care.

In other children, the arthritis affects four or fewer large joints. The knees and ankles are common sites. The fingers and toes are rarely involved.

Oligoarticular JIA can also cause eye inflammation. Your child will need regular eye exams to prevent blindness. A doctor who treats eye disease (ophthalmologist) should do these exams. Eye problems may last into adult life. 

Polyarticular

About 30% of children with JIA have the polyarticular type. It is more common in girls than in boys.

Polyarticular juvenile arthritis affects five or more joints. These may include large joints, such as the knees and ankles. They may also include small joints in the hands and feet. The disease often affects both sides of the body.

Some children have a blood marker, or antibody, called IgM rheumatoid factor (RF). They often have a more severe form of the disease.

Antibodies are proteins in the blood. The body usually uses them to fight infection through an immune response. In this form of arthritis, the IgM RF antibody attacks the body's own tissues. Doctors believe this is the same type of arthritis as adult rheumatoid arthritis. It may need more significant treatment.

Psoriatic

Children with psoriatic arthritis have arthritis and one of the following:

• A skin disease called psoriasis
• A parent or sibling with psoriasis

These children may also have nail changes. They may have diffuse swelling of a finger or toe, called dactylitis. Some have only a few affected joints. Others have several affected joints, both small and large.

In juvenile arthritis, swelling in of some of the fingers and toes may be significant.

Courtesy of Texas Scottish Rite Hospital for Children

Enthesitis-related Arthritis

Enthesitis-related arthritis is a type of JIA. It often inflames tendons, ligaments, and joints. It may also affect the spine.

Children with this type may have joint pain with no clear swelling; they may also have back pain. Back inflammation often starts later in life.

Enthesitis-related arthritis most often affects boys older than age 6.

Systemic

About 20% of kids with JIA have the systemic type.

Systemic juvenile arthritis causes swelling, pain, and limited motion in at least one joint. Other symptoms include a rash and inflammation of internal organs. These organs may include the heart, liver, spleen, and lymph nodes. A fever of at least 102° each day for 2 weeks or longer suggests this diagnosis.

Without enough treatment, kids with systemic JIA can develop macrophage activation syndrome. This severe problem causes multi-organ dysfunction. It can be fatal if not treated.

Medical History

Your child's doctor will review your child's full medical history and ask:

• How long your child has had joint pain and swelling
• Whether the symptoms have improved or become worse
• Whether your child feels stiff when getting up after rest

The doctor will look for other causes of the symptoms, such as:

• An injury
• Another illness, such as an infection, cancer, or other autoimmune disease
• A family history of autoimmune disease

Physical Examination

Your child's doctor will examine your child's joints and check for:

• Swelling
• Warmth
• Decreased range of motion
• Muscle loss (atrophy) near the affected joints

Laboratory Tests

Tests of blood, joints, and tissue fluids can rule out other causes of the same symptoms. They may also help classify the type of JIA.

X-Rays

X-rays provide clear images of bone. The doctor may use them to look for bone injuries or unusual bone growth.

Ultrasound

Doctors often use ultrasound to look at the joint. It shows how much inflammation there is.

Magnetic Resonance Imaging (MRI) Scans

The doctor may order an MRI to look for inflammation in or near joints and tendons. An MRI is often the best test to show its degree. It can also show changes in the joint's structure and any injuries.

A young child may need medicine called sedation to stay still for the test.

Nonsurgical Treatment

Medications. Medicine is the most important part of any treatment plan for JIA. Your child may need some drugs for several years, until the disease is no longer active. The doctor will decide when it is safe to stop them. This may be after joint pain, swelling, and warmth are gone.

• Nonsteroidal anti-inflammatory drugs (NSAIDs) are often the first medicines used. Common examples are ibuprofen and naproxen. NSAIDs mainly reduce inflammation and relieve pain and stiffness. They help calm the disease.
• Disease-modifying anti-rheumatic drugs (DMARDs) are the next step if NSAIDs do not ease symptoms. DMARDs slow or stop the course of JIA. But they may take weeks or months to work. Methotrexate is the drug used most often. The doctor may prescribe a DMARD with an NSAID.
• Biologic agents are a class of drugs that also slow or stop the disease. Doctors often use them when DMARDs do not work well enough. They may be the first treatment when the disease is severe.
• Corticosteroids are stronger medicines. They may be used to treat severe juvenile arthritis quickly. They can be given by mouth (orally), injected into a vein (intravenously), or injected into a joint. However, corticosteroids can slow a child's growth. They can also cause weight gain, weak bones, and a higher risk of infections. It is important to follow the doctor's instructions exactly when taking them.

Additional options. Warm baths may also help soothe sore joints. 

Surgical Treatment

Surgery is rarely needed to treat JIA. It may be needed for very severe disease or complications. Surgery can improve the position of a joint that has become deformed.

Joint replacement is often used for adults with arthritis. But it has almost no role in treating kids. Adequate treatment of JIA will protect the joint. It can prevent long-term harm that might later require joint replacement.