Juvenile Idiopathic Arthritis Center
Juvenile Idiopathic Arthritis Is Not a Child-size Type of Adult Rheumatoid Arthritis
The most common type of arthritis in children and adolescents is juvenile idiopathic arthritis (JIA) (idiopathic means that no cause has been determined). This umbrella term includes several arthritic conditions previously labeled juvenile rheumatoid arthritis (JRA). However, since researchers now have a better understanding of the different types of arthritis, the terminology has been updated. JIA isn’t just a “kid-sized” version of adult rheumatoid arthritis (RA): only about 10% of children have a condition that is close to adult RA, and the medical community has expanded the category to include related conditions. Thus, the new term is now widely accepted.
Arthritis literally means “joint inflammation.” The arthritides (that’s the plural of arthritis) encompasses a group of disease that cause pain, swelling, stiffness, and loss of motion in the joints. The medical community has identified more than 100 different rheumatic diseases have, all of which may affect the joints but can also cause pain, swelling, and stiffness in other structures, such as ligaments, tendons, bones, and muscles, and may even affect other organs or systems.
In the spine, the joints are called Facet Joints.
Arthritis Affects Young People Too
Arthritis is not “for old people.” Children and adolescents get arthritis too—not only most of the types that adults can suffer from, but also certain specific types. The number of children afflicted by arthritis or other rheumatic disease varies depending on the statistics used, but nearly 300,000 children from infancy to 16 years have one of these conditions.
JIA occurs in children aged 16 years or younger. Symptoms include joint pain and swelling, stiffness, tenderness, and warmth that have been present for at least 6 weeks. Other symptoms may include tightening of the muscles and soft tissues, erosion of the bone, misalignment of the joints, and alterations in growth patterns. As with other types of arthritis in adults, JIA can affect the spine.
Diagnosis May Be Challenging
Diagnosis is not always straightforward, and there are certain criteria for diagnosing JIA. The doctor will perform a physical exam and order laboratory tests. He or she will need to monitor your child’s symptoms for at least 6 weeks initially, and then for 6 months after the onset of the disease, because during this time, the number of joints involved will help determine the diagnosis (joint involvement varies by type of arthritis, and symptoms can change daily).
JIA can attack the joints of the spine, particularly in the neck. However, with certain types of spondyloarthropathy (see below), the lower back can be involved.
Types of JIA
Juvenile idiopathic arthritis is a spectrum of joint disorders. However, not every type of JIA affects all children or adolescents. The types include:
- Systemic arthritis. This condition (formerly known as systemic JRA) comprises about 10% of cases of JIA. In addition to joint involvement, the patient also has general body symptoms and may develop serious complications.
- Oligoarthritis (oligoarticular JIA; inflammation of a few joints). From 1 to 4 joints are affected during the first 6 months (persistent oligoarthritis); in some cases, more joints are involved after 6 months (extended oligoarthritis). The larger joints (eg, knees, ankles) are usually affected. Oligoarthritis accounts for about 40% of new cases of JIA.
- Polyarthritis (polyarticular JIA; inflammation of many joints). At least 5 joints are involved during the first 6 months. Polyarthritis tends to involve the small joints (eg, fingers, wrists), although the weight-bearing joints can be affected. About 25% of patients have polyarthritis. According to one source, teenagers diagnosed with polyarthritis may have early-onset adult rheumatoid arthritis. Some patients have high blood levels (are seropositive) of rheumatoid factor; a group of antibodies that accumulate in the joint lining; others are seronegative (not having a rheumatoid factor).
There are 2 separate types of polyarthritis.
- Psoriatic JIA. This type of arthritis usually occurs along with the skin disease, psoriasis (skin condition; dry, scaly skin), but it also may occur in the presence of a few other factors.
- Enthesitis-related JIA. This group of conditions, which includes spondyloarthropathy (inflammation of the joints of the spine), affects the soft tissues around the joints (ligaments, tendons, or joint capsules). It can affect the sacroiliac joints, which are located at the base of the back, as well as the knee and the Achilles tendon. Children with a certain genetic marker are more prone to this type of arthritis.
- Undifferentiated JIA. If the child’s signs and symptoms do not meet the criteria for any of these specific categories, or if they meet the criteria for more than one category, they are diagnosed as having undifferentiated JIA.
Juvenile idiopathic arthritis requires careful diagnosis and treatment, usually by a pediatric rheumatologist.
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