Fatigue fractures of the proximal tibia simulating malignancy.

The clinical and radiological features of nine fatigue fractures developing along the soleal line of the posteromedial cortex of the proximal tibia are described. Seven patients were referred with the diagnosis of a probable malignant sarcoma of bone. All nine patients were male and all but one were 18 years of age or less. Only two gave a history of a recent increase in physical activity. The plain radiographic findings consisted of an uninterrupted, lamellar, periosteal reaction arising medially and posteriorly in the proximal tibia with the fracture seen through the thickened posterior cortex. Bone scan revealed a fusiform focus of increased uptake in the posteromedial cortex of the tibia with varying degrees of activity in the adjacent metaphysis. Computed tomography, on a soft-tissue window, showed perifracture oedema and the absence of a soft-tissue mass. The attenuation of the underlying medulla was increased as a result of fibrosis and hyperaemia. On an extended window setting, both periosteal and endosteal callus was identified, maximal in the posteromedial tibia, and the fractures, multiple in two cases, were best demonstrated on a cortical window. Clinical and radiological features that differentiate a fatigue fracture of the tibia from a sarcoma are discussed.