The enigma of stress fractures in the pediatric age: clarification or confusion through the new imaging modalities.

Cortical thickening and/or periosteal reaction in long bones of children and adolescents continue to present a diagnostic difficulty for the pediatric radiologist. A history of physical activity points to the possibility of stress fracture, nevertheless bone malignancy or chronic inflammatory changes have to be excluded. The MRI findings in recent cases of stress fractures were confusing. An extensive metadiaphyseal abnormal signal from the medullary cavity was observed. Only the meticulous correlation between the various imaging modalities established the correct diagnosis. Stress fractures can occur in a normal bone that is subjected to repeated trauma, with the strain being less than that which causes an acute fracture. Localized pain is the presenting symptom. This kind of fracture is encountered in adolescents who are often involved in competitive physical exercise. The conventional radiographic examination shows the evidence of the fracture repair rather than the fracture itself: localized periosteal reaction and endosteal thickening. A radiolucent cortical fracture-line is usually not demonstrated. The radiologic appearance can be problematic in the pediatric age and necessitates differentiation from osteomyelitis or bone malignancy. The diagnostic investigation includes multidirectional bone radiographs. Tcm99 polyphosphate bone scintigraphy and computerized tomography. Recently MRI has been added to the diagnostic armamentarium. This paper presents the experience gained in the diagnosis of pediatric stress fractures which were investigated and followed up by MRI. It was found that this modality did not contribute to the establishment of the final diagnosis of stress fracture.