[Perthes disease].

The Legg-Calve-Perthes disease is an idiopathic avascular necrosis of the hip during early childhood. It is characterized by different stages with the main risk of persisting hip deformation, dysfunction of the joint movement, and the potential for early osteoarthritis. For the evaluation of prognosis and therapy planning patients age and extent of the necrotic area of the epiphysis are important factors. For an early diagnosis and sufficient therapy all radiological efforts have to be performed. MR imaging is an ideal method for the assessment of osteonecrotic changes of the Morbus Perthes. Compared to plain radiography by MR imaging pathologic alterations can be detected earlier and with higher specificity. However, conventional radiograms have to be still used as basic imaging modality. Nowadays x-rays and MR imaging should be the main methods for the evaluation of children suffering from Perthes disease.