Arthritis in Children: Who Gets It and Why?


Most people think of arthritis as something older adults often suffer from. But juvenile idiopathic arthritis (JIA) affecting children is not uncommon. This condition used to be called juvenile rheumatoid arthritis (JRA) but new findings have shifted the name to reflect numerous subtypes of the disease.

Two pediatric rheumatologists from Children’s Hospital of Philadelphia wrote this article on juvenile idiopathic arthritis (JIA) to give us a better understanding of the condition. The information is also intended to help physicians treating children and teens with JIA make informed decisions about treatment.

First of all, who is affected by this potentially disabling disease? It first appears in children at a very young age (between one and three years old). It can develop later but rarely presents in babies before age six months. Early diagnosis and treatment can help prevent long-term complications but there is no cure. In some children, it disappears as mysteriously as it came. In others, active disease accompanies them right into adulthood.

What causes juvenile idiopathic arthritis (JIA)? No one knows for sure. There are probably multiple factors including genetics, confusion within the immune system, environmental agents, bacteria or viruses, trauma, and irregular hormone function. JIA is considered an autoimmune because the immune system fails to recognize self from nonself, identifies the joint as a foreign substance, and attacks itself.

How is it diagnosed? There isn’t one single individual lab test that can be relied upon to identify JIA as the underlying problem for all affected patients. That’s why doctors have to depend on the child’s symptoms, history (including family history), X-rays, and other imaging studies to make the diagnosis. There are a couple of blood tests that can help (e.g., presence of antinuclear antibodies or ANAs and rheumatoid factor (RF), but they aren’t positive in everyone.

How can you tell if your child has juvenile idiopathic arthritis? The first symptom is morning stiffness or joint stiffness after any prolonged period of rest or inactivity. Getting out of bed in the morning is a real chore. Te child may walk funny or with an odd gait. Getting the child moving or ready for daycare, school, or daily activities can be difficult. Young children don’t always complain of pain or say they feel stiff but they clearly feel better as the day goes on.

Since any joint can be affected, some odd symptoms might pop up — like difficulty chewing when the jaw is involved, an inability to turn the head when the neck is inflamed, or problems lying flat or leaning the chest against something when the sternum (breastbone) is affected.

Juvenile idiopathic arthritis is a systemic disease meaning it can affect the whole body and not just the joints. Besides joint swelling, pain, and loss of motion, the physician may notice changes in the eyes, swollen glands, an enlarged spleen or liver, and changes in heart and lung sounds.

The authors provide a detailed explanation of the seven subtypes of JIA. These include oligoarticular JIA, polyarticular RF-positive JIA, polyarticular RF-negative JIA, systemic JIA, psoriatic JIA, enthesitis-related or ERA arthritis, and finally, undifferentiated arthritis. These are listed in descending order of frequency. Oligoarticular JIA (affecting more than one joint) is the most common subtype. ERA and undifferentiated arthritis are much more rare.

The physician must know the various components and characteristics of each of these subtypes. This knowledge aids the physician in recognizing, diagnosing, and then treating the problem. For example, polyarticular arthritis affects girls more often than boys — usually in the teen years. It may be easy to think the multiple joints that hurt are linked with her menstrual cycle because that’s a new and different event in their lives. But a blood test will show whether this is an RF-positive or RF-negative form of JIA.

Enthesitis-related arthritis creates inflammation where the tendons attach to the bones. Boys are affected most often and present with back or sacroiliac pain and stiffness. This subtype is often accompanied by inflammatory bowel disease so there can be nausea, abdominal pain and/or bloating, and diarrhea. It’s important that these symptoms aren’t attributed to growing pains or stress. Again a blood test often reveals the presence of HLA-B27, a marker that helps make the diagnosis.

As the name suggests, systemic JIA comes with symptoms that affect the whole body: fever, skin rash, swollen glands. The children (boys and girls equally) are very sick but it can look so much like the flu or a virus that nothing is said or done until months go by and the symptoms keep coming back. Eventually the diagnosis is made but by that time, damage can be done to the joints.

The physician does have a few tools in the medical bag that can help figure out what’s going on. We’ve mentioned blood tests and X-rays. These aren’t always good screening tests but they do provide a place to start and sometimes reveal significant findings. When X-rays are negative, ultrasound, bone scans, and MRIs may be more helpful. Each one contributes something different, so the physician orders them based on the clinical presentation and history.

For children with swollen joints, a small bit of the fluid within the joint called synovial fluid can be withdrawn and tested. Signs of infection or inflammation can be seen when the fluid is examined under a microscope.

Throughout the search to find out what’s wrong, the goal is to treat early and quickly in order to reduce pain, minimize joint damage, and help the child maintain a normal lifestyle. Adequate management over the course of the disease process is important in order to improve quality of life measures as well.

In summary, this was the first of a two-part series reviewing the condition known as juvenile idiopathic arthritis. The focus of this first article was the recognition and diagnosis of the problem with an understanding of the causes and subtypes of JIA. The second article will be coming out with an update on the treatment and management of JIA for all seven subtypes.