Evaluation of femoral head necrosis using a volumetric method based on MRI

Most studies agree that the fate of femoral head osteonecrosis is associated with the size and location of the necrotic lesion. We present a volumetric method for assessment of osteonecrosis, based on magnetic resonance imaging. The method evaluates the percentage of the necrotic volume in the femoral head and in each of the head segments (octants). Along with the method, we present a classification system based on the geometrical features of the lesion. The system was used to classify 106 hips with osteonecrosis before treatment with vascularized fibular grafting. The hips were evaluated using the volumetric method. The follow up study indicates that the proposed method and the classification system can be reliable tools for the assessment of femoral head necrosis.