Among the causes of gait abnormality in childhood, those that
should be kept in mind in acute settings include infection, trauma,
and malignancy. Children who develop a limp acutely should be evaluated
carefully with a detailed history and physical examination, appropriate
radiographs and laboratory studies, and timely referral for subspecialty
evaluation in order to exclude these potentially worrisome causes.
When necessary, the lower extremity should be carefully immobilized
and protected from weight bearing until a definitive diagnosis can
be achieved. When infection is suspected, the workup should be conducted
in either an observation or inpatient status until the diagnosis
is confirmed or excluded. This ensures that appropriate diagnostic
and therapeutic resources can be brought to bear in a timely manner
before the infection worsens without a correct diagnosis. Regardless
of the underlying cause of the limp, vigilance is necessary in order
to make an accurate diagnosis in a timely manner to ensure the best
Infections of bone and joint are discussed in Chapter 234.
From an epidemiological perspective, the most common cause of
an unexplained limp in childhood is infection. Whereas injury generally
occurs as a discretely observed event and results in a sudden onset
of limited mobility, infection often has a more insidious onset. Following
trauma, radiographs usually reveal the alteration in skeletal anatomy
which makes the diagnosis clear. Although exceptions may exist,
such as Salter Harris type 1 physeal injuries or occult elbow fractures
with positive fat pad signs, the ability to distinguish fractures
with plain radiographs is usually straightforward. However, with
infection, plain radiographic findings may be subtle, with deep soft
tissue swelling being the first identifiable sign in many cases.
Trauma may be reported as an antecedent event in approximately
35% of children with infection.1 In these
circumstances, the physician should be mindful of subtle details
in the history and physical examination. One should ask about the
timing of the injury with respect to the onset of symptoms, the
mechanism of injury, and the presence of fever. One should also
inspect the area of concern for signs of erythema, warmth, and swelling
that may not be consistent with injury, based on the reported timing
or mechanism of the injury.
Whenever infection is suspected, laboratory studies should be
obtained to assess for a systemic response to the infection. These
should include a complete blood count (CBC) with differential, C-reactive
protein (CRP), and the erythrocyte sedimentation rate (ESR). Among
these studies, the most sensitive test for identifying the inflammation
associated with acute musculoskeletal infection is the CRP.2 Abnormalities
of the infectious indices should raise the level of concern and
motivate the physician to perform more dedicated imaging to help
define the nature and extent of the problem.
If a precise location can be determined from physical examination,
then magnetic resonance imaging (MRI) with and without intravenous contrast
is the most sensitive and specific study to evaluate ...