Joint pain is a common problem in childhood but arthritis is fortunately rare. Benign limb pain in childhood is sometimes called ‘growing pain’ and, though meaningless, this is probably a convenient term that parents readily accept.
JUVENILE CHRONIC ARTHRITIS
Juvenile chronic arthritis is a general term used to cover a group of diseases in which an exact diagnosis is not always possible. There are three main types: Still’s disease, juvenile RA and juvenile ankylosing spondylitis.
This is the commonest type of juvenile chronic arthritis, accounting for about 70% of cases. It is entirely distinct from RA, being distinguished by a number of clinical features and negative tests for rheumatoid factor. There are two peaks in the age of onset: the first and largest is between the ages of 2 and 5 years, and the second between the ages of 10 and 15 years. Still’s disease occasionally begins after the age of 16 years, and rarely in the twenties. The disease is often episodic, with bouts of fever and arthritis. It can be divided into three subtypes:
1 The systemic type is usually seen in children under the age of 5 years. They present with a high fever, a characteristic rash and various other features, including lymphadenopathy, splenomegaly and pericarditis. The rash is characterized by patches of erythema on the trunk or limbs, often appearing in the evening and brought out by warmth. Arthritis or arthralgia are minor features of the illness and may be absent. Arthritis may, however, develop later in the course of the disease.
2 The pauciarticular or oligoarticular type of Still’s disease affects up to four of the large joints such as the hips, knees or ankles. These patients are particularly liable to chronic iritis, which may lead to blindness without any preceding symptoms. Antinuclear antibodies are often positive and provide a useful warning that iritis may develop. Slit-lamp examination should be performed at regular intervals in these patients. 3 Polyarticular Still’s disease presents with a bilateral symmetrical polyarthritis not unlike that of RA, but with less prominent and less frequent involvement of the small joints of the hands and feet. The characteristic systemic features described above may be associated with arthritis, whether polyarticular or pauciarticular.
The non-articular features of Still’s disease are often helpful in making a diagnosis. A high swinging fever is also characteristic. This can be misleading to the unwary, as it suggests the possibility of infection. The joints themselves are swollen, but pain and tenderness are much less prominent than in adult RA. The ESR is usually raised and there is frequently an anaemia.
Treatment is with NSAIDs as in RA. Gold and penicillamine are effective but probably in a smaller proportion of cases than in RA. Corticosteroids should be avoided because of their effect on growth. It is important to protect the joints and prevent deformity during relapses, particularly as spontaneous remissions occur in 85% of patients before the age of 20 years. Long periods of rest and splinting of joints may be necessary. The patient’s education and normal life-style should be continued if possible.
Juvenile rheumatoid arthritis
RA may begin before 16 years of age. The clinical features re identical to those of adults and tests for rheumatoid factor are usually positive. However, the prognosis is much worse than in adults. Juvenile RA accounts for about 15% of cases of juvenile chronic arthritis. Juvenile ankylosing spondylitisThis accounts for the remaining 15% of cases of juvenile chronic arthritis. It is the most benign of the subtypes and usually presents between the ages of 10 and 15 years. A peripheral arthritis occurs, with the lower limb joints being particularly affected. Joints are swollen and painful in the acute stage, but often respond well to antiinflammatory drugs and usually settle within a few years. These patients may develop iritis and there may be other features of HLA-B27-associated diseases . Back pain is not a prominent feature at this age. A family history of ankylosing spondylitis or related diseases is sometimes helpful in the diagnosis. Tests for rheumatoid factor are negative. Although the arthritis usually resolves, 50% of these patients go on to develop ankylosing spondylitis in adult life.
Other types of arthritis that are seen in childhood are summarized.
Some soft tissue syndromes particularly affect childrenincluding Osgood-Schlatter disease, which is characterized by localized pain over the tibial tubercle and is usually seen in athletic teenagers. A mysterious condition called transient synovitis of the hip, which causes hip pain, may give rise to concern because of the possibility of tuberculosis or other serious conditions. It presents as painful limitation of movement of one hip, and usually resolves within a few weeks or months.