Hip Pain in an 11-Year-Old Male
Radiology Cases in Pediatric Emergency Medicine
Volume 5, Case 11
Rodney B. Boychuk, MD
Kapiolani Medical Center For Women And Children
University of Hawaii John A. Burns School of Medicine
This 11 year old male was in good health until 6
days ago when he began to have right hip pain at rest,
which worsened with walking. The pain was described
as intermittent in nature. It did not radiate to the back
or down the leg. It was described initially as being of
medium severity, worsening when moving from side to
side and with walking. The pain progressively
increased in intensity. Five days ago, the patient was
seen by a pediatrician and an orthopedic surgeon.
Pelvic radiographs were done (including hips). These
were interpreted as normal. WBC was elevated at
25,600 and his ESR was elevated at 88. A UA was
normal. The patient was observed and treated with
acetaminophen for pain, which appeared to help
somewhat. Yesterday when the patient awoke, he was
unable to bear any weight on his right leg and could not
walk. There was no past history of significant trauma,
unusual physical activity, or definite fever. He did have
a history of a sore throat, with fever up to 39.5 degrees,
vomiting x1 with diarrhea x1 three days prior to the
onset of this hip pain.
Exam: VS T38, P102, RR 20, BP 126/89. Weight
54 kg (greater than 95th percentile), height 138 cm
(25th percentile). He is lying down eating a cookie in no
distress. There are no mouth lesions or palatal
petechiae. The posterior pharynx is non-erythematous;
however, the tonsils are slightly enlarged, without any
exudates. Heart regular without murmurs. Lungs clear.
Abdomen is soft and somewhat obese. There is
definite right lower quadrant tenderness with palpation.
There is no rebound tenderness. Bowel sounds are
active. Definite right-sided pelvic pain is elicited with
attempts to rotate the pelvis; however, there was no
pain with either internal or external rotation of the hip
joint. Hip flexion and extension do not elicit any
significant pain; however, straight leg raising elicits
pain. There appears to be some tenderness along the
right lumbar area just lateral to the lumbar spine
(paraspinal area) and over the posterior region of the
iliac crest with palpation. He is unable to bear weight
on the right leg. The left hip appears totally normal.
His neurologic exam is unremarkable.
A repeat sed rate is 62, and the following
radiographs are ordered: 1) pelvis including hips, 2)
abdomen, and 3) lumbar spine.
Only the flat plate of the abdomen is shown here.
All of these radiographs are initially interpreted as
normal (note that retrospectively, there is a scoliosis to
the right in the abdominal films and one might consider
that there is a right lower quadrant sentinel loop
Because of persistence of these physical findings, a
CT scan of the abdomen is done with both oral and IV
View abdominal CT scan.
The CT scan extends from the lower level of the
kidneys down through the pelvis. There is enlargement
of the right psoas muscle (left side of the image).
There is a septated 2.0 cm hypodense area with an
enhancing margin in the medial aspect of the right
psoas muscle (arrow). This finding is consistent with a
psoas abscess. There is a small amount of edema of
the adjacent retroperitoneal fat. The appendix is filled
with barium and appears normal. No other
abnormalities are seen.
Overall impression: An abscess in the medial
aspect of the right psoas muscle with diffuse
enlargement of the muscle. The abscess is situated
just inferior to the lower pole of the right kidney.
Findings at surgery: The psoas muscle was
diffusely edematous, but only a small amount of fluid
was obtained. No well-established abscess was found.
Culture of the fluid from the psoas muscle was positive
for group A beta-hemolytic streptococcus.
Post-operatively, the patient developed persistent
fevers, with chills and a temperature greater than 40
degrees. Initially, he was treated with vancomyin;
however, because of the above, switched to penicillin
and clindamycin. Clindamycin is of value in severe
streptococcal and staphylococcal infections for two
reasons: 1) It acts on bacterial cells at a different site
than penicillin. If the bacterial cells are not actively
dividing, they will not be killed by penicillin. In certain
abscesses where organisms are present in high
quantities, active division is not occurring for many of
the organisms. 2) It has an effect of depressing
harmful toxin production that may be produced by this
invasive group A beta-hemolytic streptococcus.
Discussion of psoas muscle abscess in children:
Although primary psoas abscess is very rare in
children of "developed" countries, it is not rare in tropic
and sub-tropical "third world" countries with poor
socioeconomic conditions. Staphylococcus aureus is
the most frequent type of infection seen in these
environments, with almost all children presenting with
the triad of pyrexia, flank pain and hip symptoms.
Psoas abscess can be a secondary problem associated
with tuberculous spondylitis or in relation to
inflammatory bowel disease (1). More recently, in the
United States, psoas abscesses have been seen
secondary to transperitoneal low-velocity gunshot
wounds to the spine (3), or gastrointestinal or
genitourinary trauma (2). Primary psoas abscess can
be seen in patients with sickle cell disease, intravenous
drug users, immunocompromised individuals or
individuals positive for HIV.
Bacterial infections of muscle also known as
pyomyositis or tropical pyomyositis occur more
commonly in tropical regions. Pyomyositis should be
considered in the differential diagnosis of
septic-appearing children, as well as children
complaining of joint pain or muscle aches (7). Recent
imaging techniques are important in diagnosis. Plain
radiographs occasionally show a blurring or
indistinctness of the lateral margins of the psoas
muscle but, in general, are not as helpful as other
techniques. Ultrasonography is useful in showing
enlarged psoas muscle with hypoechogenic masses,
however it is not as accurate as a CT scan in showing
the abscess (5). Drainage of the abscess by CT-guided
percutaneous catheter has been recommended by
some (4), while surgical drainage is recommended by
others, especially when percutaneous catheter drainage
is not successful. MRI is advantageous because
multiple processes can be evaluated (6). If the patient
does not respond quickly to antibiotics and surgical
intervention, either there is a recurrence of the
previously debrided abscess, or there is an
unrecognized secondary abscess. Multiple abscess
sites should be considered prior to initial debridement.
1. Sadat-Ali M, al-Habdan I, Ahlberg A.
Retrofascial nontuberculous psoas abscess. Int Orthop
2. Santaella RO, Fishman EK, Lipsett PA. Primary
vs. secondary iliopsoas abscess. Arch Surg
3. Lin SS, Vaccaro AR, Reich SM. Low-velocity
gunshot wounds to the spine with an associated
transperitoneal injury. J Spinal Disord
4. Golli M, Hoeffel C, Belguith M. Primary psoas
abscess in children--6 cases. Arch Pediatr
5. Royston DD, Cremin BJ. The ultrasonic
evaluation of psoas abscess (tropical pyomyositis) in
chilren. Pediatr Radiol 1994;24(7):481-3.
6. Roe JB, Yalcin S. Magnetic-resonance-imaging
scans in discitis. Sequential studies in a child who
needed operative drainage: a case report. J Bone Joint
Surg Am 1995;77(2):329.
7. Renwick SE, Ritterbusch JF. Pyomyositis in
children. J Pediatr Orthop 1993;13(6):769-72.
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