Fatigue fracture of the sacrum in a child.

The authors describe a 9-year-old girl with stress fracture of the sacrum. Such fractures can cause low-back or hip pain in children but may not be evident on plain films. The appearance on scintigraphy is not diagnostic. Likewise, the findings on magnetic resonance imaging may be nonspecific or confusing, because changes in signal intensity in the marrow may not be sufficient to distinguish infection or malignancy from healing of the fracture. Computed tomography can be more specific in delineating a sclerotic fracture oriented parallel to the sacroiliac joint. Recognition of the characteristic radiographic findings in sacral fatigue fractures can prevent incorrect diagnosis and unnecessary diagnostic procedures or treatments.