arthritis

Inflammatory arthritis, JIA

Inflammatory arthritis in childhood (differentiated from that caused by infection) affects more than 300,000 children in the United States alone. It is more common than childhood diabetes. Past terminology included juvenile rheumatoid arthritis (JRA) or juvenile chronic arthritis, but the new international terminology is juvenile idiopathic arthritis (JIA). This is arthritis caused by auto-immune factors.

The classifications of inflammatory arthritis can be confusing, even to physicians. The new classification terminology clarifies and defines the subtypes along the lines of this schema:

oligoarthritis - few joints involved
polyarthritis - many joints involved
systemic arthritis
"enthesopathy associated" - that is, inflammation of the points of attachment of ligaments and muscles to bone
psoriatic - associated with psoriasis
undifferentiated - poorly classified arthritic conditions

The oligoarticular subtype¹ affects 4 or fewer joints, generally knees, ankles, wrists and elbows. It typically strikes girls less than 7 years old. A very serious inflammation of the eye known as uveitis is present in about a third of cases - sometimes before the onset of joint symptoms². The hallmark of inflammatory arthritis is morning stiffness. The child who won't walk in the morning but runs around in the afternoon should arouse suspicions of inflammatory arthritis. Late complications of oligoarticular JIA can be vision loss due to uveitis, leg length inequality, and progression to polyarticular disease. Remission will occur in 30-40 percent of cases, with progression to polyarticular disease in the rest of the cases.

The polyarticular subtype of juvenile inflammatory arthritis affects 5 or more joints. It tends to be much more destructive of joints than oligoarthritis. Girls are more often affected than boys if the rheumatoid factor test is negative. A fourth or more of affected children will remit by the teenage years. If the rheumatoid factor is positive, girls greatly predominate over boys. This group of children has a more serious prognosis, with more late complications such as undergrown jaw and serious neck or hip disease.

Systemic subtype juvenile arthritis was once called Still's disease. It involves at least one joint but usually more, and is characterized by daily high, spiking fevers in the 102-105° range, and a pinkish-tinged rash. A potentially life-threatening complication called macrophage activation syndrome can be triggered by viral infections or certain drugs such as NSAIDs and sulfa drugs. Sulfa drugs especially should be avoided by systemic juvenile arthritis patients.

Treatment of juvenile inflammatory arthritis has come a long way in recent years. NSAIDs such as naproxen and ibuprofen are a mainstay of treatment. Indomethacin, meloxicam (Mobic®) and refecoxib (Vioxx®) are approved in childhood as well. The immunosuppressant methotrexate is used as well, and newer "biologics" are now being used in childhood arthritis treatment.

Spondyloarthropathies

The spondyloarthropathies are a broad group of related disorders that have a common but variable association with a genetic marker known as HLA B27. They have a tendency to involve

ligament to bone joints (enthesitis)
the spine
the sacroiliac joints.

and may have other organ involvement, including the eyes, skin, or mucous membranes.

Enthesitis can involve

the point where the Achilles tendon attaches to the heel
where the patellar tendon attaches to the tibia (shin) just below the kneecap
tendon connections to the kneecap (patella) itself
spinal ligaments on the vertebral discs
elbow joints
hip joints
and many others

Enthesitis can be associated with ankylosing spondylitis (below) as well. The spondyloarthropathies per se include

Ankylosing spondylitis
Reactive arthritis (Reiter syndrome)
Enteropathic arthritis - associated with inflammatory bowel disease
Psoriatic - associated with psoriasis

Ankylosing spondylitis is typically a male disease, by a 3:1 margin. It often begins gradually in the mid teens with morning back stiffness. The sacroiliac joints (joining sacrum to pelvis) are often tender. It can be associated with uveitis, and may even affect the heart in 5% of cases. It is destructive, and can lead to severe stiffening of the spine.

Reactive arthritis arises as a reaction to a bacterial gastrointestinal or urinary tract infection. There is a triad of symptoms: urethral inflammation, conjunctivitis, and arthritis. It has a 9:1 male predominance. Systemic symptoms of fever and weight loss are seen in about a third of cases.

Enteropathic arthritis arises as a part of inflammatory bowel disease, either in the individual, or sometimes in a child with a family history of inflammatory bowel disease. It tends to flare with exacerbations of the colitis. Systemic complications include iritis (a destructive inflammation of the iris of the eye), skin lesions (pyoderma gangrenosum), and mouth ulcers.

Psoriatic arthritis is very common in the general population (1-2%). It will develop in 10-30% of persons with psoriasis. It would be suspected in a child with psoriasis or even a family history of psoriasis who had joint inflammation of greater tha 6 weeks duration. Nail abnormalities, especially pitting, are very common in psoriatic arthritis. A "fungal infection" of the fingernails may actually be psoriatic nail disease - fungal infection of fingernails is very unusual.

1. The old "pauciarticular" classification.
2. Young girls under 7 years of age with positive ANA test (antinuclear antibody) are at high risk for uveitis.

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