[Legg-Calve-Perthes disease in the MRI: possibilities and limits].

Magnetic resonance imaging (MRI) was performed on the hips of 32 children with Legg-Calve-Perthes disease. Each patient had between 2 and 6 MR-tomographies in the course of the disease. We found that MR-tomography is superior to plain radiography in the early diagnosis of the avascular femoral necrosis. In addition it is also advantageous because it does not involve the use of ionizing radiation. MR-tomography is more accurate in defining the extent of capital femoral epiphyseal necrosis and metaphyseal involvement and in showing the contours of the femoral head. The characteristics of MR images in the 4 radiographic stages were analysed. For better distinction the radiographic stages I and II could be subdivided into the MR stages Ia and Ib and IIa and IIb. According to our experience it is now possible to replace plain radiographs by MR images.