[Diagnosis of bone necrosis by magnetic resonance tomography. The potentials for early diagnosis].

Twenty-eight patients with necrosis in the hip joint, the femoral condyles and the talus were examined by MR tomography. This revealed various features whose frequency depended upon the various stages of the necrosis. Three patients who showed no, or only indefinite, changes on radiographs, displayed clear evidence of necrosis on MR. Staging of femoral head necrosis on the basis of MR criteria is suggested, as well as a suitable procedure for early diagnosis. Accurate localisation and knowledge of the extent of the necrosis by means of MR makes it possible to plan an osteotomy accurately.