Joint Program in Nuclear Medicine

Acute Osteomyelitis in Pediatrics

Jan Stauss
S. Ted Treves, MD

July 25, 2002

Presentation

An otherwise healthy 11 year-old boy with increasing right knee pain and persistent fever for 8-9 days presents to the ER. Plain films of the right knee were negative.

Imaging Findings

A three phase bone scan was performed. The radionuclide angiogram of the region of the knees demonstrates increased blood flow to the region of the right upper tibia (shown by arrow). The tissue phase image reveals increased tracer concentration in the same region (shown by arrow). A whole body bone scan confirms the abnormal tracer uptake in the right proximal tibia, just below the epiphyseal growth plate (show by arrow). No other skeletal abnormalities are detected on the bone scan.

Differential Diagnosis

Diagnosis

Osteomyelitis of the right proximal tibia

Discussion

Osteomyelitis is a rather common diagnosis in pediatric patients, mostly due to hematogenous spread of staphylococci (>90%) or rarely streptococci, salmonella, proteus, klebsiella, or pseudomonas. Other rare infectious causes include tuberculosis, syphilis, fungal disease, and brucellosis. Classic signs and symptoms are fever, limping, refusal to bear weight, swelling, and pain that might be only diffusely localized. Because of its high vascularity the metaphyses of the long bones or metaphyseal-equivalent locations e.g. symphysis pubis, ischiopubic synchondroses, or triradiate cartilages are typically affected (1). The most sensitive, but nonspecific laboratory study to determine is the erythrocyte sedimentation rate. The white blood cell count is surprisingly normal in the majority of cases. Radiographic studies are often negative in acute osteomyelitis, because radiolucencies and periosteal new bone formation is normally seen only after more than a week post infection. The three phase bone scan typically shows increased tracer delivery and localization on radionuclide angiographic and tissue-phase images and increased uptake on skeletal-phase images as in the case presented.

So, what is the role of skeletal scintigraphy in managing children with suspected osteomyelitis? Its sensitivity has been reported to be as high as 94% and its specificity as high as 95% (2). At the Children's Hospital Boston bone scan is normally performed for initial evaluation of suspected osteomyelitis, if the radiographs are normal or equivocal (3). If clinical suspicion confidently has been limited to the spine or pelvis, MRI is valuable because of the provided anatomic detail (3). MRI is also helpful, when acute osteomyelitis does not respond to antibiotic therapy and localized abscess is suspected (3). When scintigraphy is normal but symptoms persist, the study should be repeated after 2 to 3 days (4).

References

1. Nixon GW: Hematogenous osteomyelitis of metaphyseal-equivalent locations. Am J Roentgenol 130: 123-129, 1978

2. Schauwecker DS: The scintigraphic diagnosis of osteomyelitis. AJR 158: 9-18, 1992

3. Connolly LP, Treves ST: Assessing the limping child with skeletal scintigraphy. J Nucl Med 39: 1056-1061, 1998

4. Treves ST, Connolly LP, Kirkpatrick JA, Packard AB, Roach P, Jaramillo D: Bone. In: Treves ST (ed): Pediatric nuclear medicine, second edition. New York, Springer-Verlag, 1995, pp 233-301.

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J. Anthony Parker, MD PhD, Tony_Parker@CareGroup.Harvard.edu