To measure the volume of osteonecrosis in 30 patients with disease in both hips (one side with collapse and the other without at Ficat stage I).
The volume of the osteonecrosis was measured by magnetic resonance imaging.
The progression to collapse was influenced by the size of the lesion in each patient. The first collapsed hip was that with the largest volume of osteonecrosis.
The volume of the osteonecrotic lesion on the second hip (stage I without collapse) is a good predictor of the time to collapse of this second hip.