Module 71, Pediatric Orthopaedist Level
This 9 year old female presented to the emergency room with a four
day history of mild right knee pain. She limps on the affected extremity
when ambulating but has minimal to no pain at rest. There is no history
to suggest trauma. She apparently has had mildly elevated temperatures
over the last several days according to the mother. There is no history
of joint stiffness or chronic fatigue. No other joints are involved. There
is no history of tick exposure. She has been otherwise healthy in the past.
On physical examination of the right knee there is no limitation in flexion
or extension. There is mild diffuse tenderness that is poorly localized
over the medial femoral condyle. There is no soft tissue swelling or joint
effusion noted. No pain is elicited with ROM of the knee. The remaining
extremities are without tenderness or swelling. Temperature was 38.3 C.
An xray of the knee was found to be normal. The laboratory test included,
WBC 13400, Differential: 73% polys, 8% lymphs, 1% bands, and Sedimentation
rate 41mm/hr. A Bone scan was obtained and revealed increased uptake in
the region of the distal femur with a predominant epiphyseal location and
slight uptake in the metaphysis on the flow and pool images. Delayed images
showed focally increased uptake in the epiphysis of the distal right femur.
Next a CT scan was obtained which showed no subperiosteal fluid collections.
There was an area in the region of the distal femoral epiphysis that contained
a difference in density from the surrounding bone. Also an Ultrasound demonstrated
soft tissue swelling in the region of the distal femur.
Question 71A
Aspiration of the femoral epiphysis is indicated based on this data.
Question 71B
The
above is consistent with osteoid osteoma.
Question 71C
An
aspiration of the distal femoral epiphysis yielded bloody fluid, but 24
hours later was growing staph aureus. Open debridement of the lesion is
now indicated.
Question 71D
Following
the above imaging studies, the blood cultures from the time when she first
presented to the emergency room grew staph aureus. Further work-up is not
needed and she should be started on IV antibiotics.
Question 71E
There
are venous sinsoids in the epiphysis with blind loops which can cause blood
sludging and be the site of hematogenous osteomyelitis.
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