[The limping child. Differential radiologic diagnosis of acute gait disorder in childhood and adolescence].

Limping is a common and often challenging problem in children and adolescents. A limp is defined as asymetric deviation from a normal gait pattern. A systematic approach is necessary to determine the cause of the limp, so the radiologist should combine a thorough history, clinical information and pertinent radiologic testing. The possible differential diagnosis is extensive and includes many pathologies of the lower extremity and spine like trauma, infection, neoplasia, furthermore inflammatory, developmental and congenital disorders. In cases with knee or tight pain, an underlying hip condition should be considered. The childs age can narrow the possible differential diagnoses, because certain entities are age-related. Despite this wide bandwidth of entities, potential catastrophic causes like septic arthritis and malignant disease should be excluded first. Plain radiographs are often diagnostic. The choice of further imaging modalities like ultrasonography, magnetic resonance imaging, computed tomography and bone scan should be guided by the history and clinical findings.