FATIGUE FRACTURES OF THE SACRUM IN CHILDREN - 2 CASE-REPORTS AND A REVIEW OF THE LITERATURE

We present the clinical and radiological features of two children with fatigue fractures of the sacrum. Both patients were active, had no un derlying bone disease and presented with insidious onset of low back p ain. Plain radiography was non-contributory to the diagnosis. In both patients a focal area of increased activity was present in the lateral aspect of the sacrum on bone scintigraphy, which corresponded to line ar medullary sclerosis in the sacral ala demonstrated by computed tomo graphy. Magnetic resonance imaging in one patient revealed a linear si gnal void in the sacral ala on Tl- and T2-weighted images. This was su rrounded by diffuse low marrow signal on TI-weighted images, and incre ased marrow signal on T2-weighted images. Fatigue fractures of the sac rum should be considered in the differential diagnosis of low back pai n in children. An awareness of their appearance on magnetic resonance imaging is important as this modality is increasingly utilised, partic ularly in children.