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Vol 9, No 2, March/April 2001
89
A limp is a common reason for a child
to present to the orthopaedist, often
after first being seen by a primary-
care physician or in an emergency
department. Most parents are keen
observers; they are quick to detect
even subtle gait abnormalities and
generally will not wait long to have
a limp evaluated. The orthopaedist
is expected to recognize the gait
abnormality, determine the proba-
ble site of origin, and then develop a
good working diagnosis before
ordering selective diagnostic tests.
These tests should provide the data
for confirming the diagnosis and
developing a treatment plan while
decreasing costs to the health-care
system, as well as minimizing pain
and anxiety for the child and parent.
Pain, weakness, and mechanical
factors are the primary causes of
limp in children. The etiology of a
limp ranges from benign, self-limited
conditions that call for only a diag-
nosis and reassurance (e.g., tran-
sient synovitis) to conditions in
which early diagnosis may be life-
saving (e.g., acute leukemia).

1
The
long differential diagnosis (Tables 1
and 2) may seem daunting, particu-
larly when the site of origin is un-
known. However, after obtaining a
thorough history and performing a
careful physical examination, the site
of origin can often be localized and
the differential diagnosis narrowed,
thus permitting a well-organized
approach to obtaining additional
data with selective diagnostic tests.
Appropriate treatment can then be
instituted.
Normal Gait
Normal gait is a smooth, rhythmic,
mechanical process that advances
the center of gravity with a mini-
mum expenditure of energy. Many
aspects of gait change with age.
2
When children begin to walk (typi-
cally between 12 and 16 months of
age), they have a short stride
length, a relatively fast cadence
and slow velocity, and a widened
base of support in double stance.
Their hips, knees, and ankles move
through a small arc of motion.

2
Until 30 to 36 months of age, chil-
dren have neither the balance nor
the abductor strength to maintain
single-limb stance for very long.
By 7 years of age, children exhibit a
mature gait.
2
The mature gait cycle is com-
posed of the stance phase (initial
contact, loading response, mid-
stance, terminal stance, preswing)
and the swing phase, during which
the limb is advanced in space to
position the foot for the next heel-
strike. The abductors stabilize the
pelvis during stance phase, pre-
venting significant side-to-side
motion as the opposite limb swings
Dr. Flynn is Assistant Professor of Orthopaedic
Surgery, Unviersity of Pennsylvania School of
Medicine, Philadelphia; and Attending
Surgeon, Division of Orthopaedic Surgery,
Children’s Hospital of Philadelphia. Dr.
Widmann is Assistant Professor of Orthopaedic
Surgery, Weill Medical College of Cornell
University, New York, NY; and Assistant
Attending Surgeon, Hospital for Special
Surgery, New York.
Reprint requests: Dr. Flynn, Division of

Orthopaedic Surgery, Children’s Hospital of
Philadelphia, 34th and Civic Center Blvd,
Philadelphia, PA 19104-4399.
Copyright 2001 by the American Academy of
Orthopaedic Surgeons.
Abstract
A limp is a common reason for a child to present to the orthopaedist. Because of
the long list of potential diagnoses, some of which demand urgent treatment, an
organized approach to evaluation is required. With an understanding of normal
and abnormal gait, a directed history and physical examination, and the devel-
opment of a differential diagnosis based on the type of limp, the patient’s age,
and the anatomic site that is most likely affected, the orthopaedist can take a
selective approach to diagnostic testing. Laboratory tests are indicated when
infection, inflammatory arthritis, or a malignant condition is in the differential
diagnosis. The C-reactive protein assay is the most sensitive early test for mus-
culoskeletal infections; an abnormal value rapidly returns to normal with effec-
tive treatment. Imaging should begin with plain radiography. Ultra-
sonography is particularly valuable in assessing the irritable hip and guiding
aspiration, if necessary.
J Am Acad Orthop Surg 2001;9:89-98
The Limping Child: Evaluation and Diagnosis
John M. Flynn, MD, and Roger F. Widmann, MD
through. During normal walking
motion, one foot is always on the
ground. The kinematics of normal
gait has been studied in detail,
2,3
establishing normal ranges of joint
motion during different phases of
the gait cycle. The ankle dorsiflexes

at heel-strike, then plantar-flexes to
foot-flat, and then dorsiflexes again
as the tibia moves forward. The
knee is flexed at heel-strike, extends
until toe-off, and then flexes during
swing, allowing clearance of the
foot as it positions for the next heel-
strike. The hip follows a similar
pattern, with slight flexion at heel-
strike, extension through stance,
and then flexion in swing.
Abnormal Gait
Normal gait can be altered by pain,
a mechanical problem, or a neuro-
muscular problem. A child will
adopt an antalgic gait in an effort to
prevent pain in the affected limb.
The single-limb-support phase of
stance is shortened on the painful
extremity, as is the stride length of
the normal opposite limb (to get
back to bearing weight on the well
leg as quickly as possible). A vari-
ant of the classic antalgic gait is the
“cautious” gait of a child with back
pain.
4
For example, a child with
diskitis will lose the normal rhyth-
mic flexion and extension of the

lumbar spine, as demonstrated
when bending to pick up objects off
the floor.
5
Another variant of the
antalgic gait is the complete refusal
to walk. This pattern is seen most
often in toddlers and may indicate
a condition causing pain that can-
not be avoided by any of the possi-
ble gait alterations.
Circumduction—excessive hip
abduction, pelvic rotation, and hik-
ing—functionally shortens a limb,
thus enhancing foot clearance dur-
ing swing when there is joint stiff-
ness, particularly in the ankle.
6
Children with a significant limb-
length inequality may “vault” with
the short leg (or toe-walk) to clear
The Limping Child
Journal of the American Academy of Orthopaedic Surgeons
90
Table 1
Differential Diagnosis of Antalgic Gait
<4 yr 4 to 10 yr >10 yr
Toddler’s fracture (tibia or foot) Fracture (especially physeal) Stress fracture (femur, tibia, foot, pars
Osteomyelitis, septic arthritis, Osteomyelitis, septic arthritis, diskitis intra-articularis)
diskitis Legg-Calvé-Perthes disease Osteomyelitis, septic arthritis, diskitis

Arthritis (juvenile rheumatoid Transient synovitis Slipped capital femoral epiphysis
arthritis, Lyme disease) Osteochondritis dissecans (knee or ankle) Osgood-Schlatter disease or Sindig-
Discoid lateral meniscus Discoid lateral meniscus Larsen-Johanssen syndrome
Foreign body in the foot Sever’s apophysitis Osteochondritis dissecans (knee or
Benign or malignant tumor Accessory tarsal navicular ankle)
Foreign body in the foot Chondromalacia patellae
Arthritis (juvenile rheumatoid arthritis, Arthritis (Lyme disease, gonococcal)
Lyme disease) Accessory tarsal navicular
Benign or malignant tumor Tarsal coalition
Benign or malignant tumor
Table 2
Differential Diagnosis of a Nonantalgic Limp
Circumduction Gait/
Equinus Gait (Toe-Walking) Trendelenburg Gait Vaulting Gait Steppage Gait
Idiopathic tight Achilles tendon Legg-Calvé-Perthes disease Limb-length discrepancy Cerebral palsy
Clubfoot (residual or untreated) Developmental dysplasia of the hip Cerebral palsy Myelodysplasia
Cerebral palsy Slipped capital femoral epiphysis Any cause of ankle or Charcot-Marie-Tooth
Limb-length discrepancy Muscular dystrophy knee stiffness disease
Hemiplegic cerebral palsy Friedreich’s ataxia
the long leg, rather than circumduct
it. An equinus gait (toe-walking)
occurs when ankle dorsiflexion is
limited. This may result from gas-
trocnemius-soleus spasticity, short-
ening of the Achilles tendon, or
both. Thus, stance phase will be
initiated with toe-strike rather than
heel-strike.
Several abnormal gait patterns
result from muscle weakness or a

neurologic abnormality. A Trendel-
enburg gait results from altered
hip mechanics, particularly abduc-
tor weakness. During stance on the
involved side, the contralateral side
of the pelvis drops. To preserve
balance, the child may lean the
trunk toward the affected side. A
variation of the Trendelenburg gait
is the waddling gait of a child with
bilateral hip dislocation. A “step-
page gait” develops when the ankle
dorsiflexors are weak (e.g., as in
Charcot-Marie-Tooth disease). To
compensate for the weakness, the
child increases knee flexion in the
swing phase to clear the foot. The
foot will slap to the ground because
the ankle dorsiflexors are unable to
decelerate the foot between heel-
strike and foot-flat. An unsteady
gait may result from conditions that
affect balance, such as Friedreich’s
ataxia. Careful initial analysis of
the gait can enhance the specificity
of the remainder of the physical
examination and facilitate localiza-
tion of the origin of the limp.
History
An accurate history may be difficult

to obtain from a young child, and
some or all of the history must be ob-
tained from the parents or primary
caregivers. A brief discussion with
the child, followed by a parental
description of pain complaints and
changes in gait pattern, is invalu-
able in guiding the subsequent
physician-directed evaluation. In
certain circumstances, adolescents
and some children should be ques-
tioned privately, as they may pro-
vide important details regarding
exposure to sexually transmitted
diseases, such as gonococcal infec-
tion, which may not be obtained in
the presence of parents.
7
Once the
parent and patient have had an
opportunity to describe the pain
and/or limp in their own terms, the
physician is best prepared to com-
plete the history.
The history should focus on the
character of the limp: the presence
or absence of pain or other localiz-
ing symptoms, the frequency and
duration of symptoms, and the
mechanism of injury, when appro-

priate. A history of ceasing athletic
participation or social play with
friends should raise concern.
4
The
absence of pain suggests either neu-
romuscular or metabolic disease or
a congenital or developmental ab-
normality, such as hip dysplasia or
limb-length discrepancy. In a tod-
dler, the absence of pain complaints
may not be particularly helpful,
and the physical examination takes
on greater importance.
The pattern, onset, and duration
of pain may suggest the origin.
4
Acute onset of severe pain over a
few days focuses the evaluation on
trauma, infection, or malignancy,
whereas gradual worsening over
months suggests inflammatory or
mechanical symptoms.
8
It is helpful
to characterize the quality of the
pain as constant, intermittent, or
transient. Constant pain is of partic-
ular concern, suggesting an intra-
medullary process, such as expand-

ing tumor or infection. A history of
trauma is readily established in most
circumstances, with some notable
exceptions: pathologic fracture and
child abuse.
It is important to characterize the
timing of pain (e.g., morning pain,
pain after activity, or pain that wakes
the child from sleep). Morning pain
or pain and stiffness after inactivity
are more characteristic of inflamma-
tory joint disorders.
8
Pain after activ-
ity may suggest an overuse injury,
such as a stress fracture, or an inter-
nal articular derangement, such as
an osteochondral lesion, a meniscal
tear, or an anterior cruciate ligament
tear. Night pain that wakes a child
from sleep may represent benign
“growing pains,” but the concern is
that it may derive from osteoid oste-
oma or a malignant condition.
Pain relief with nonsteroidal anti-
inflammatory medications may be
characteristic of osteoid osteoma but
is not diagnostic. Referred pain must
also be considered, particularly thigh
or medial knee pain referred from

painful conditions of the hip (e.g.,
slipped capital femoral epiphysis).
Buttock or lateral thigh pain may be
referred from the back. Pain in multi-
ple joints suggests an arthritic process.
A past medical history including
recent trauma or exposure to infec-
tious diseases and use of antibiotics
is helpful in diagnosis. Recent vari-
cella infection may lower systemic
immunity, rendering the child sus-
ceptible to opportunistic bone or
joint infections.
9
Failure to achieve
appropriate developmental mile-
stones or, more ominously, deterio-
ration of motor ability warrants fur-
ther neuromuscular or metabolic
evaluation. The review of systems
should seek a history of recent fever,
weight loss, or malaise suggestive of
infection or malignancy. A history
of prior medical evaluation for the
same problem should be sought, and
the pertinent records should be ob-
tained when possible. A complete
history should include questioning
about the family history of neuro-
muscular disease, metabolic disease,

inflammatory arthritis, or infectious
disease exposure.
Physical Examination
The physical examination of the
limping child has three essential
components: the gait exam, the
John M. Flynn, MD, and Roger F. Widmann, MD
Vol 9, No 2, March/April 2001
91
standing/floor exam, and the table-
top exam. The child should be
dressed in as little clothing as is prac-
tical; gym shorts and bare feet are
ideal. Much can be missed watching
a small child walk in an oversized
gown that extends to the floor.
Gait Examination
The examination area should
offer sufficient space to see multiple
gait cycles. It is important not to be
fooled by an artificial “doctor walk”;
the best chance to see the true limp
is by observing gait when the child
does not know she is being watched,
such as when the child is walking to
the examination room.
10
Running
may accentuate the limp or abnor-
mal gait. Subtle weakness or the

upper-extremity posturing of cere-
bral palsy might not be seen until
the child runs. Shoes may provide
valuable clues to gait problems; for
example, a child having trouble
clearing his foot in swing phase may
have excessive toe wear.
It is best to adopt a systematic
approach to the gait examination,
working from the ground up and
watching each limb segment and
joint through several gait cycles.
Trying to simultaneously analyze
every facet of gait is difficult for
even the most experienced clinician,
considering that a typical toddler
takes 180 steps per minute. Note
how the foot strikes the floor—is
there heel-strike, foot-flat, or toe-
strike? A child may walk on the
medial or lateral border of the foot
to protect a sore bone or the site of a
puncture wound or foreign body.
Abnormal limb rotation may be
observed. Metatarsus adductus,
internal tibial torsion, or femoral
anteversion will result in an internal
foot-progression angle. An adoles-
cent with a slipped capital femoral
epiphysis or a young child with an

occult fracture may walk with an
external foot-progression angle.
The next feature to consider is
the symmetry of the stance phase.
A unilateral shortened stance phase
is characteristic of an antalgic gait.
The range of motion of each joint
should also be evaluated. Limited
ankle dorsiflexion is seen in chil-
dren with a short Achilles tendon
or a spastic gastrocnemius-soleus.
At the knee, motion should be ob-
served through several gait cycles.
Contracture or spasticity in the
quadriceps or hamstrings or intra-
articular derangement will limit
knee motion. Any frontal-plane ab-
normalities should be noted as well
(e.g., a varus thrust of the proximal
tibia in Blount’s disease). Hip mo-
tion may be abnormal, exhibiting
circumduction, persistent flexion,
or excessive pelvic or trunk motion.
Upper-extremity posturing as well
as difficulty with balance and coor-
dination may suggest a neurovas-
cular origin of the limp.
Standing/Floor Examination
After the history and vital signs
have been taken and the physician

has thoroughly studied the child’s
gait, there are several tests to con-
sider before the tabletop examina-
tion. The spine should be examined
with the child standing, taking care
to note balance in the coronal and
sagittal planes, scoliosis, lumbo-
sacral step-off, pelvic obliquity, and
any cutaneous findings (e.g., café-
au-lait spots, hairy patches, or sacral
dimples). On the forward bend, the
examiner should note a thoracic or
lumbar prominence due to scoliosis.
The Trendelenburg test is per-
formed by having the child stand
on the affected leg with the knee
flexed and the hip extended. The
child may need to rest his hands
against the wall for balance. If the
Trendelenburg test is performed
with hip flexion, the hip flexors can
elevate the pelvis and mask a mild
deficiency of the gluteus medius.
4
It may take 20 seconds or more of
continuous testing on the affected
limb before abductor weakness
causes the opposite pelvis to drop.
If muscular dystrophy is a possi-
bility, a Gower test is performed by

having the child sit on the floor and
then rise quickly, observing to see if
he uses his hands to substitute for
weak hip extensor muscles. Repeti-
tive single-leg heel raises and toe
raises can be utilized to accentuate
subtle weakness in the foot plantar-
flexors or dorsiflexors.
Tabletop Examination
With the child on the examining
table, one should thoroughly in-
spect for asymmetry, deformity,
erythema, rashes, and swelling.
Puncture wounds or foreign bodies
should be sought on the plantar
surface of the foot in walkers and
on the anterior aspect of the knee in
crawlers. The resting position of
the limb should be noted; for exam-
ple, a child with septic arthritis of
the hip will hold the hip flexed and
externally rotated. Note also any
muscle hypertrophy (e.g., calf hy-
pertrophy in muscular dystrophy)
or atrophy (e.g., global unilateral
atrophy in hemiplegia or quadri-
ceps atrophy in a child with a pain-
ful hip or knee).
Palpation of the lower extremity
to find the point of maximum ten-

derness is often the most valuable
part of the physical examination of a
limping child. Knowing the exact
site of pain dramatically limits the
differential diagnosis and may elim-
inate the need for a bone scan or
other diagnostic test (Fig. 1). Every
joint of the lower extremity should
be taken through its range of mo-
tion, noting pain, contractures, or
muscle spasticity. The patellofemo-
ral joint, a common source of pain
in adolescents, should be tested for
signs of apprehension or pain with
patellar compression during flexion
and extension. The sacroiliac joint is
tested by direct percussion posteri-
orly and by stressing the joint with
the hip positioned in flexion, abduc-
tion, and external rotation (FABER
test). The rotational profile should
The Limping Child
Journal of the American Academy of Orthopaedic Surgeons
92
be documented in children with in-
toeing or out-toeing.
11
Appropriate
neurologic testing should also be
performed.

Limb lengths should be assessed.
If an inequality is noted, the differ-
ence is most accurately determined
by leveling the pelvis with blocks
under the short leg. Although a sig-
nificant limb-length inequality may
itself alter gait, it also suggests other
potential causes of limping, such as
hemiplegia and developmental dis-
location of the hip.
Radiographic Evaluation
Although the various imaging
modalities may each have a role in
the assessment of the child with a
limp, plain radiography should
always be performed first, because
radiographs are inexpensive, can be
easily obtained at any hour, and are
both sensitive and specific for a
wide variety of disorders.
12
In chil-
dren who can localize tenderness,
initial plain radiographs should
include orthogonal images of the
affected limb that visualize the joint
both above and below the point of
maximum tenderness. A third ob-
lique view is included when imag-
ing the ankle or foot if an area of

suspected pathologic change may
be obscured by bone overlap, mini-
mal displacement of fracture frag-
ments, or minimal physeal widen-
ing.
12
If the patient can localize
pain but the initial radiographs of
the long bones are negative, addi-
tional oblique views may reveal
more subtle osseous changes, such
as a minimally displaced tibial frac-
ture (toddler’s fracture) or the peri-
osteal elevation of a stress fracture.
In children who present with a limp
or refusal to bear weight but are too
young to localize pain, plain radio-
graphs of the entire lower extremity
should be obtained (Fig. 2).
Plain radiographs are not particu-
larly helpful in identifying early
bone or joint infections. The early ra-
diographic findings of acute hema-
togenous osteomyelitis include a nor-
mal osseous appearance with subtle
displacement and swelling of the soft
tissues.
13
Comparison views may
depict subtle soft-tissue swelling, but

radiographic sensitivity for the early
changes of osteomyelitis is less than
50%.
14
The radiographic appearance
of early soft-tissue changes due to
septic arthritis is difficult to interpret
and unreliable.
15
Early bone or joint
changes are not typically seen radio-
graphically until 10 to 12 days after
the onset of bone or joint infection,
13
and the presence of these changes
suggests a significant delay in diag-
nosis.
The triphasic technetium-99m
bone scan is an excellent test for
evaluating a limping child when
the history and physical examina-
tion fail to localize the anatomic site
of pathologic changes (Fig. 3). Bone
scanning has been demonstrated to
be superior to the other standard
screening tests for infection (tem-
perature, white blood cell [WBC]
count, erythrocyte sedimentation
rate [ESR], and plain radiography)
in the limping toddler.

14
The tech-
netium accumulates at the site of in-
creased blood flow and osteoblastic
activity in osteomyelitis, stress frac-
tures, occult fractures, neoplasm,
and metastases. In suspected early
bone infection, bone scans have high
sensitivity (84% to 100%) and speci-
ficity (70% to 96%).
12,14,16
Although the diagnosis of many
long-bone infections can be made
John M. Flynn, MD, and Roger F. Widmann, MD
Vol 9, No 2, March/April 2001
93
A B
Figure 1 A, A healthy limping toddler presented with reproducible tenderness to palpa-
tion over the midportion of the tibia. Rotational stress to the tibia was also painful.
Although the radiographs were read as normal, an occult fracture was suspected. B, At 4
weeks, radiographs showed periosteal elevation along the medial cortex of the tibia
(arrows), confirming the clinical suspicion of a toddler’s fracture. The child’s symptoms
resolved after 4 weeks in a cast.
without scintigraphy, bone scans
are particularly helpful in localiz-
ing sepsis around the pelvis and
the spine—areas that are difficult
to examine and where soft-tissue
changes are difficult to identify.
17

Prior bone drilling and periosteal
elevation have been demonstrated
experimentally to have no effect on
a subsequent bone scan performed
within 24 hours,
18
and prior aspira-
tion has not interfered with results
in clinical practice.
17
Other advan-
tages of bone scanning over cross-
sectional imaging modalities include
decreased expense, less need for se-
dation, and the ability to image the
whole body.
Limitations of bone scintigraphy
include difficulty in distinguishing
between bone infarct and osteomy-
elitis in hemoglobinopathies and the
occurrence of false-negative bone
scans in cases of Langerhans cell his-
tiocytosis and some other aggressive
tumors in children.
17
Bone scanning
has low sensitivity for septic arthri-
tis, especially when there is adjacent
osteomyelitis, and is therefore not
indicated in this circumstance.

Leukemia may result in increased,
decreased, or no change in tech-
netium uptake.
14
A “cold” scan (i.e.,
one showing low uptake) in the set-
ting of suspected osteomyelitis is
not necessarily negative; instead, it
may represent bone rendered avas-
cular due to a subperiosteal or end-
osteal abscess. A study of cold bone
scans in pediatric patients with
osteomyelitis revealed that they had
more severe bone infections requir-
ing more aggressive medical and
surgical treatment compared with
control children with “hot” bone
scans and osteomyelitis.
19
The Limping Child
Journal of the American Academy of Orthopaedic Surgeons
94
A B
Figure 2 A, Anteroposterior (AP) radiograph of the hips and pelvis of a 2-year-old girl
with a 2-week history of limping, fever, malaise, and difficulty sleeping through the night.
Periosteal changes (arrow) were noted in the right femur. B, A full-length AP radiograph
of the femur demonstrates the extent of periosteal elevation and geographic medullary
canal erosion of the lesion, which on biopsy proved to be eosinophilic granuloma.
Figure 3 A, AP radiograph of an 8-year-old girl who presented with a limp and the sudden, nontraumatic onset of severe left groin and
thigh pain. The film was read as normal. B, The history, physical examination, and plain radiographs did not allow precise localization of

the process. A bone scan showed decreased uptake in the left femoral head, suggesting Legg-Calvé-Perthes disease.
A B
Ultrasonography is a valuable
diagnostic tool in the evaluation of
a limping child with an irritable hip
(Fig. 4). Ultrasonography is nonin-
vasive, requires no sedation, and is
typically more accessible and less
expensive than other secondary
radiologic tests.
20
However, if
infection is highly probable, ultra-
sonography should not delay urgent
operative irrigation and debride-
ment. If a hip effusion is noted, the
ultrasonographer can assist with a
guided aspiration and can docu-
ment the intra-articular positioning
of the needle. If ultrasonography is
not available, a possibly infected
hip can be aspirated with fluoro-
scopic guidance.
In one series of 44 patients with
a limp or hip pain and negative
plain radiographs, ultrasonog-
raphy was 100% accurate in pre-
dicting the presence of aspiration-
documented hip effusion.
21

Another
larger prospective study of 111 chil-
dren with irritable hips confirmed
that the plain radiograph was of lit-
tle value in the detection of early
hip effusion; in that study, there
was radiographic evidence of effu-
sion in 15% of hips, compared with
sonographic evidence of effusion in
71% of hips.
15
Furthermore, Zawin
et al
22
showed that ultrasound-
guided hip aspiration in the radiol-
ogy suite decreased the subsequent
operative time for septic hips by
50%. However, a large prospective
study of 500 painful hips in chil-
dren demonstrated that ultrasound
cannot effectively differentiate
among sterile, purulent, and hem-
orrhagic effusions.
23
The authors of
that study concluded that ultra-
sonography of the hip should be
reserved for select cases in which
sepsis is suspected.

Ultrasound evaluation of the irri-
table hip is performed with the
transducer oriented in an oblique
sagittal plane parallel to the long
axis of the femoral neck with the hip
in extension.
12
An effusion causes
bulging of the iliofemoral ligament,
so that the joint capsule appears
convex; the normal opposite capsule
will be concave.
22
Ultrasonography can help con-
firm the diagnosis of osteomyelitis
on the basis of characteristic early
and late ultrasonographic clinical
features.
24
Early changes, such as
deep soft-tissue swelling, are fol-
lowed by periosteal thickening.
Subperiosteal fluid or abscess is seen
as a later finding 1 to 2 weeks after
the onset of symptoms. The main
value of ultrasound imaging of the
extremity in cases of suspected in-
fection is to rule out subperiosteal
abscess.
20

Cross-sectional imaging, includ-
ing computed tomography (CT) and
magnetic resonance (MR) imaging,
is rarely necessary as an initial
study in the evaluation of a limping
child. Computed tomography is in-
dicated specifically for imaging of
suspected localized abnormalities of
cortical bone (Fig. 5). It may also
confirm the presence of either a cen-
tral nidus in cases of osteoid osteoma
or the occurrence of a tarsal coalition.
Magnetic resonance imaging has
proved to be the most effective im-
aging modality for bone marrow,
joints, cartilage, and soft tissues
(Fig. 6, C). It is extremely useful in
cases of suspected tumor and stress
fractures.
Laboratory Testing
Infection, inflammatory disease, and
malignancy all demand rapid diag-
nosis and treatment, and laboratory
testing may assist both in making
the appropriate diagnosis and in
monitoring the efficacy of treatment.
Laboratory testing is indicated when
a child presents with an acute non-
traumatic limp and signs and symp-
toms of fever, malaise, night pain, or

localized complaints. Appropriate
tests include a complete blood cell
count with differential and determi-
nation of the ESR, the C-reactive
protein (CRP) and antinuclear anti-
body levels, and the rheumatoid fac-
tor and Lyme titers.
In the setting of bone or joint
infection, the WBC count is neither
sensitive nor specific. Although the
WBC count is elevated in 25% to
John M. Flynn, MD, and Roger F. Widmann, MD
Vol 9, No 2, March/April 2001
95
A B
Figure 4 A, A 12-year-old girl presented with an antalgic limp on the right and thigh
pain. She had pain with internal rotation of the hip, suggesting an effusion. The plain radio-
graph was normal. B, Sonogram of the right hip shows an effusion. Ultrasound-guided
aspiration yielded purulent fluid. Drainage of the septic hip was performed immediately.
Femoral
head
Hip capsule
Effusion
31% of children with osteomyeli-
tis,
25
normal values for the WBC
count are seen frequently in osteo-
myelitis.
26

The differential is more
sensitive and may be abnormal in as
many as 65% of children with osteo-
myelitis and 70% with septic arthri-
tis. The complete blood cell count
may reveal moderate to severe ane-
mia in cases of systemic juvenile
rheumatoid arthritis (JRA), as well
as leukocytosis with active disease.
8
Patients with systemic-onset JRA
may present with WBC counts in the
range of 30,000 to 50,000/mm
3
. The
platelet count may rise considerably
as well.
The ESR is a sensitive indicator
of inflammation and is most helpful
in the diagnosis and follow-up of
bone or joint infection. The ESR
reflects changes in the concentration
of fibrinogen synthesized by the
liver, which increases after 24 to 48
hours and may not return to normal
for 3 weeks with appropriate treat-
ment.
27
In one study of previously
well children with new-onset limp,

an ESR elevated to over 50 mm/hr
was associated with a clinically im-
portant diagnosis in 77% of cases.
28
The ESR is also a sensitive indicator
of infection and is elevated in 90%
of patients with osteomyelitis.
16,25
However, early in the course of in-
fection, the ESR may be normal. Ex-
treme elevation of ESR in what ap-
pears to be isolated osteomyelitis
should raise the question of associ-
ated septic arthritis.
C-reactive protein is an acute-
phase protein synthesized by the
liver in response to inflammation.
Unlike the ESR, the CRP level rises
within 6 hours of onset of symp-
toms and returns to normal within 6
to 10 days with appropriate treat-
ment. The CRP level is more sensi-
tive than the WBC count or the ESR
in assessing the effectiveness of
therapy and predicting recovery
from osteomyelitis and septic arthri-
tis.
27,29
The CRP value is not influ-
enced by prior aspiration or drilling

of the cortex, and a secondary rise
suggests relapse.
29
The CRP level
should be determined on the initial
screening examination if musculo-
skeletal infection is in the differen-
tial diagnosis.
Aspiration and evaluation of joint
fluid should be performed when
joint sepsis is considered in the dif-
ferential diagnosis. Of the large
joints, the hip is the most technically
difficult to aspirate. Sedation and
local anesthesia are helpful, and
aspiration under fluoroscopic guid-
ance with arthrography at the com-
pletion of the procedure is recom-
mended to confirm appropriate
spinal needle placement within the
joint.
30
Ultrasound-guided aspira-
tion provides similar confirmation of
needle placement. Culture and cell
counts should be obtained in all
cases. A WBC count greater than
80,000/mm
3
with a percentage of

polymorphonuclear cells greater
than 75% is highly suggestive of
joint sepsis, although early sepsis
may present with a much lower cell
count.
30
The rheumatoid factor and anti-
nuclear antibody levels are deter-
mined when inflammatory arthritis
is a possibility. In practice, JRA is
the most frequently diagnosed pedi-
atric arthritis.
31
It must be noted
that the rheumatoid factor test is
positive in only 15% to 20% of chil-
dren with JRA, and is more fre-
quently positive in older children
and children in a poor functional
class.
8
The finding of a positive
antinuclear antibody test is impor-
tant in the identification of children
most at risk for the development of
chronic uveitis, which may result in
blindness if untreated.
Testing for Lyme disease should
be performed on any patient who
presents with acute arthritis and

who lives in or has recently traveled
to an endemic area.
32
The presenta-
tion of acute Lyme arthritis may
have considerable overlap with that
of septic arthritis, including fever,
local swelling, pain with range of
joint motion, and an elevated WBC
count in joint aspirate. Serologic
confirmation of Lyme disease is
based on a two-test approach con-
sisting of a preliminary enzyme-
linked immunosorbent assay and a
confirmatory Western immunoblot
assay, which specifically examines
the reactivity of antibodies.
32
The Limping Child
Journal of the American Academy of Orthopaedic Surgeons
96
A B
Figure 5 A, A 10-year-old soccer player presented with a limp and thigh pain of 4 weeks’
duration. AP radiograph shows a radiodense area in the medial subtrochanteric region.
B, CT scan obtained to better characterize the sclerotic area shows a pattern typical of a
femoral-neck stress fracture. A biopsy was avoided. The pain and limp resolved after 2
months of protected weight bearing.
Making the Diagnosis
When a limping child is brought for
musculoskeletal evaluation, some

potential diagnoses require urgent
treatment to ensure the best possible
outcome. Some conditions affect all
age groups, but many conditions
have a peak age of onset. Although
there is increasing interest in prac-
tice standardization with use of
algorithms for many musculoskele-
tal conditions, there are so many
exceptions in the evaluation of the
limping child that any single algo-
rithm will be unreliable for all pre-
sentations. Despite this complexity,
there are five essential questions
that the orthopaedist must answer
to direct the evaluation of a limping
child: (1) Is the limp due to pain?
(2) Did the limp develop suddenly
or gradually, or has it always been
there? (3) Is the child systemically
ill? (4) What type of limp does the
child exhibit? (5) Can the problem
be localized (specifically, is there a
point of maximum tenderness)?
The answers to these questions will
narrow the differential diagnosis
and establish the pace of evalua-
tion.
33
Determining whether the

gait is antalgic is the first step in
developing a differential diagnosis
(Tables 1 and 2).
The answers to these five essen-
tial questions direct the evaluation
of different clinical scenarios. For
example, a healthy 4-year-old pre-
sents with the gradual onset of a
painless Trendelenburg gait. Exami-
nation shows that there is unilateral
limitation of hip motion. The work-
up of this limp requires only a plain
radiograph to establish the diagnosis
of Legg-Calvé-Perthes disease or de-
velopmental dysplasia of the hip.
In a very different scenario, an ill
child presents with the sudden
onset of an antalgic gait. Samples
for screening laboratory studies
should be drawn, and plain radio-
graphs should be obtained for ana-
tomic localization. If the site cannot
be localized, a bone scan is valu-
able. An MR imaging study may
add important information, espe-
cially if a malignant condition is
suspected. If septic arthritis of the
hip is a possibility, ultrasound-
guided aspiration may be indicated.
Unfortunately, the presentations

are usually not this straightforward.
The most common challenge is de-
termining whether an acute limp is
due to trauma. A typical case is illus-
trated in Figure 6. The 11-year-old
patient had ankle pain after falling.
Her pain persisted after casting of a
suspected fibular physeal fracture.
The plain-radiographic appearance
remained normal. Her limp was
clearly due to pain, which was wors-
ening with time. Because this was un-
characteristic for trauma, laboratory
tests were obtained, which revealed
an ESR of 35 mm/hr. Because the
process could be localized by pain
and swelling around the distal fibula,
a bone scan was not needed. An MR
imaging study obtained to simultane-
ously evaluate the soft tissues, the
bone, and the ankle joint revealed
osteomyelitis with a soft-tissue ab-
scess. The patient was successfully
treated with surgical drainage and
antibiotics.
John M. Flynn, MD, and Roger F. Widmann, MD
Vol 9, No 2, March/April 2001
97
A B C
Figure 6 An 11-year-old girl sustained a suspected distal fibular physeal fracture. AP (A) and lateral (B) plain radiographs of the ankle

taken 10 days after the injury. C, Because of persistent pain and an ESR of 35 mm/hr, an MR imaging study of the distal portion of the leg
was obtained. The appearance of this transverse section at the distal fibula is consistent with fibular osteomyelitis and soft-tissue swelling
with an abscess, which were successfully treated with surgical drainage and antibiotic therapy. Cultures grew Staphylococcus aureus.
Summary
Limping children commonly present
to the orthopaedic surgeon, who is
expected to recognize the gait abnor-
mality, determine the probable
anatomic origin, and develop a good
working diagnosis on which to base
a cost-effective strategy for ordering
diagnostic tests. Armed with the
results of an appropriate history and
physical examination and an under-
standing of normal and abnormal
gait, the orthopaedist can use the
child’s age and the answers to five
essential questions to develop a dif-
ferential diagnosis and plan a selec-
tive approach to diagnostic testing.
The Limping Child
Journal of the American Academy of Orthopaedic Surgeons
98
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