Fever and Refusal to Walk in a 4-Year Old
Radiology Cases in Pediatric Emergency Medicine
Volume 4, Case 17
Myron H. Rosen, MD
Children's Medical Center of Dallas
University of Texas Southwestern School of Medicine
This is a previously healthy 4-year old female who is
brought to the ED by her mother because of fever and
right leg pain since the previous night. The patient
stated that she had been swimming the previous day,
and had slipped in the pool, twisting her right leg.
Immediately after that, however, she was able to walk
around easily without pain. Later that night she
developed a fever (temperature not measured), and her
right leg began to hurt. She was taken to an ED
because she had difficulty walking. She was diagnosed
with a hip sprain and was sent home on ibuprofen. Her
fever and leg pain worsened to the point that she was
no longer able to ambulate, prompting a return to the
Exam VS: T40.7, P164, R40, BP 139/84. She is
anxious and in obvious discomfort, although she
appears alert and non-toxic. She prefers to keep her
right hip abducted and externally rotated, with the right
knee flexed. She refuses to bear any weight on the
right leg. Range of motion of the right hip is severely
limited, especially internal rotation, adduction, and
extension. The overlying skin is warm but not
erythematous. Examination of the remainder of the right
lower extremity, the left lower extremity, and spine are
within normal limits.
View the patient's general appearance.
Laboratory Results: CBC WBC 31,700 with 4%
bands, 85% segs, 6% monos, and 5% lymphs. Hgb
12.4, Hct 35.4. Platelet count 394,000. CRP 8.2. ESR
39. Hip radiographs were obtained.
View hip radiographs.
Think about the most likely diagnosis at this time.
The photo of her general appearance shows her
preferred position of comfort with her hip in external
rotation. What radiographic abnormalities would you
expect to see?
Her hip radiographs show a widened joint space in
her right hip. Compare the joint space to the left hip
and it is rather obvious here. [Use the "tear drop"
distance method as described in Case 15 of Volume 4
(Osteoid Osteoma), to measure the joint space.] This
finding is seen in the minority of patients with septic
arthritis; thus, the absence of joint space widening
cannot be relied upon to rule out septic arthritis.
An orthopedic consultation is obtained. Under
fluoroscopic guidance, the right hip is needle-aspirated,
revealing grossly purulent fluid. Laboratory analysis:
80,000 WBC's with 88% segs, 1% monos, and 11%
lymphs. 16,000 RBC's. Gram stain shows many gram
positive cocci in chains.
What organisms are the most common causes of
septic arthritis ? Given the laboratory results, what
organism is likely in our patient ? What antibiotic
regimen would be appropriate for patients with septic
The patient is placed on IV cefuroxime and
hospitalized for operative drainage of the right hip.
Cultures of the aspirate grow out group A
Teaching Points and Discussion:
1. Early diagnosis and treatment of septic arthritis of
the hip cannot be overemphasized. Fibrous deposition
and lysosomal enzymes from polymorphonuclear
leukocytes in synovial fluid can rapidly damage
cartilage. Permanent damage will occur in only a few
days if the diagnosis and treatment are delayed.
View later changes.
This radiograph of a different patient at follow-up
shows the result of a poorly treated septic hip. The
patient's right hip shows degenerative changes. There
is flattening of the femoral epiphysis with an irregular
articular surface. Early effective treatment can
minimize such subsequent complications.
2. The diagnosis is particularly difficult to make in
infants, who cannot voice their complaints, and
especially in neonates who may not have the typical
findings of fever, chills and leukocytosis. Don't be
fooled by a history of trauma. Parents of toddlers will
almost always recall a recent "injury" prior to the onset
of symptoms. Such a history is not sufficient to rule out
3. The affected extremity will typically be held in a
position of slight flexion, abduction and external
rotation. This maximizes the intraarticular space, thus
decreasing the tension of the joint exudate. Refer to
the photo of our patient in this position of comfort. Click
4. Laboratory findings include an elevated
erythrocyte sedimentation rate and/or C-reactive
protein, as well as a leukocytosis, often with a "left
shift". The left shift (a high percentage of immature
granulocytes) is not reliable and is noticeably absent in
our patient. Blood cultures may be positive in up to
50% of cases. The most important procedure in
making the diagnosis, however, is hip aspiration
(arthrocentesis). If the aspirated synovial fluid contains
more than 20,000 white blood cells and has greater
than 75% polymorphonuclear leukocytes, infection
should be strongly suspected. Synovial glucose
content less than 1/2 of serum and/or protein greater
than 1/3 of serum are suggestive of septic arthritis.
Positive results of direct smear and cultures of synovial
fluid are diagnostic. Joint fluid cultures are positive in
about 60-80% of cases.
5. Don't expect plain radiographs to establish the
early diagnosis of septic arthritis. Plain films may
demonstrate a widened hip space, but the absence of
this does not rule out septic arthritis. Lateral
displacement of the proximal femur due to synovial
exudate and inflammation can also be seen in the early
stages. Late findings include periostitis, periarticular
osteoporosis, and dislocation of the femoral head.
Ultrasound is the most effective study in demonstrating
the presence of a joint effusion acutely. Radionuclide
bone scanning can be helpful in the early stages, but
the definitive diagnostic tool remains isolation and
identification of the organism by hip aspiration.
1. The most common etiologic organism is
Staphylococcus aureus. Other organisms include
Haemophilus influenzae type B (more common in
younger patients), Streptococcus pyogenes (group A
beta-hemolytic strep), Neisseria gonorrhea (more
common in young adults), pneumococcus, and
2. The infection may reach the hip joint by either
hematogenous spread, or from a focus of osteomyelitis
in the femoral neck or (less commonly) the ilium.
Hematogenous spread is more common in children
than in adults.
1. The treatment for septic arthritis of the hip
includes intravenous antibiotics and immediate surgical
incision and drainage of the hip, followed by a period of
immobilization. Antibiotics should be continued for at
least 4-6 weeks, depending on the sensitivities of the
organism and the patient's clinical status.
2. The initial choice of antibiotics should take into
account the most common etiologies of septic arthritis.
In the case presented above, cefuroxime was used to
cover streptococci and staph aureus. Cefuroxime
(similarly cefotaxime and ceftriaxone) would also cover
H. influenzae type B. An anti-staphyloccocal penicillin
(nafcillin, oxacillin) could also have been selected to
cover streptococci and staph aureus. However, given
the growing frequency of methicillin resistant staph
aureus, empirically starting vancomycin pending culture
results and antibiotic sensitivities may be justified as
1. Transient ("toxic") synovitis can present with
intense pain, refusal to walk, and limited and/or painful
range of motion. A bone scan may help to rule out a
septic hip, but if septic arthritis is suspected, the hip
should be tapped and the patient should be given IV
antibiotics. A brief period of observation can also be
helpful. If there is dramatic improvement in 24 hours,
the diagnosis is most likely to be transient synovitis.
2. Osteomyelitis can sometimes cause a
sympathetic effusion of the joint, without an actual
infection of the joint itself.
3. Acute rheumatic fever can also present with
acute arthritis of the hip. However, there is usually a
migrating pattern to the arthritis. Other findings
consistent with rheumatic fever may be present, such
as a heart murmur suggestive of acute carditis,
subcutaneous nodules, erythema marginatum, or
chorea. The Jones' criteria may be helpful in making
4. Hemophilia with bleeding into the joint space may
be difficult to distinguish from septic arthritis. However,
the patient is usually a known hemophiliac. This
condition requires urgent decompression of the joint
space to prevent permanent damage to the femoral
5. Other causes of refusal to walk associated with
fever include diskitis, new-onset leukemia, peri-rectal
abscess, and osteomyelitis.
1. Salvati E. Neonatal and Infantile Septic Arthritis.
In: Tronzo R (ed). Surgery of the Hip Joint. New York,
Springer-Verlag, 1984, pp. 387-403.
2. Simon RR, Koenigsknecht SJ (eds). Emergency
Orthopedics, third edition. Norwalk, CN, Appleton &
Lange, 1995, pp. 421-423.
3. Sponseller PD. Bone, Joint and Muscle
Problems. In: Oski F, et al (eds). Principles and
Practice of Pediatrics. Philadelphia, PA, Lippincott,
4. Paterson D. Septic arthritis of the hip joint.
Orthopedic Clinics of North America 1978;9(1):135.
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