Juvenile idiopathic arthritis (JIA) may either speed or slow the natural growth process of the bones on either side of the
affected joint, causing uneven bone growth. Children who have JIA may not grow as
tall as they would have if they did not have the condition. The growth
differences depend on the child's age when the disease started and the number
of joints affected. The more joints involved in the disease, the more severe
Leg length: Different leg
lengths are a possible complication if arthritis affects only one knee. The leg
that is affected by arthritis may not grow at the same rate as the other leg. So it may be shorter or longer than the unaffected leg.
Jaw development: If JIA affects the jaw (temporomandibular)
joint, it may cause one or both sides of the lower jawbone to grow more slowly
than normal. If the lower jaw does not develop normally, it can lead to
difficulty eating. In some cases surgery is needed to restore a more normal jaw
function and appearance.
The closer to puberty a child is when symptoms begin, the more likely
the child's height will be affected. JIA may also temporarily delay the
development of breasts and the growth of body hair.