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Extremity complaints are common
in children; they are estimated to account for up to 10% of
nonwell child visits to pediatricians’ offices.1 Conversely,
rheumatologic conditions, are rare, affecting fewer than 200,000 children
in the United States. Thus, clinicians caring for children need
an efficient and effective means of distinguishing arthritis, lupus,
and other autoimmune conditions from injuries, infections, tumors,
and noninflammatory causes of extremity complaints. This chapter
will discuss the key components of a focused history and physical
examination useful for rapidly narrowing down the possible explanations
of a child’s musculoskeletal ailment. The next chapter
discusses laboratory and imaging studies that may be used to confirm
the caregiver’s clinical suspicions.
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The reported incidence and prevalence of musculoskeletal diseases
in children worldwide vary significantly. For example, among more than
30 epidemiological studies of juvenile arthritis, new cases are
reported to arise at a rate of 0.008 to 0.226 per 1,000 children,
yielding a reported prevalence of 0.07 to 4.01 per 1,000 children.2,3 Although
there are likely geographic, genetic, and environmental factors
that result in true variations in the likelihood of developing rheumatologic
conditions, several additional factors also contribute to reported differences.
First among these is the fact that most pediatric rheumatologic
conditions are diagnosed on the basis of clinical criteria rather than
definitive laboratory or imaging findings. New signs may develop
over time, leading to reclassification of conditions. Thus, children treated
for ankylosing spondylitis may later develop colitis, thereupon
qualifying for a diagnosis of Crohn disease. Arthritis that resolves
after one year may be called monocyclic juvenile arthritis by some
caregivers, transient or postinfectious arthritis by others. Despite
these uncertainties, outcomes in virtually all autoimmune conditions
are optimized by expeditious diagnosis and early initiation of effective
therapy. Recognition of signs and symptoms suggestive of rheumatologic
conditions is thus essential for everyone who provides healthcare to
children.
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The presenting symptoms of musculoskeletal conditions are more
dependent upon the location of the abnormality than upon the specific
diagnosis. Thus, fractures, tumors, and osteomyelitis all present
with pain that may awaken the patient from sleep because of the
constant stimulation of sensory nerves by lesions within bone. Conversely,
for unknown reasons, children with arthritis seldom complain of
pain; more than 90% of children with joint or extremity
pain do not have arthritis, and more than 90% of those
with arthritis do not complain of pain.4 Inflammatory arthritis
may cause children to limp or lose milestones because joint effusions
cause distension of the joint capsule and discomfort with motion. Pain,
however, is generally absent. Thus, differences in the location,
timing, and characteristics of a child’s symptoms enable
a pediatrician to rapidly narrow the potential causes of musculoskeletal
complaints. Confirmation of the suspected diagnosis may then be
obtained from physical exam findings, often without need for further
investigations.
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When a child presents with a musculoskeletal complaint, it is
helpful to categorize the symptoms according to the nature of onset ...