MRI evaluation of steroid- or alcohol-related osteonecrosis of the femoralcondyle

We reviewed 30 patients (46 knees) with steroid- or alcohol-related osteone crosis of the femoral condyle. Their average age was 35 (14-61) years and t he mean observation time was 7 (3-16) years. The medic-lateral extent and t he anterior-posterior (AP) location of the necrotic lesion were evaluated o n T1-weighted MRI and related to the collapse of the condyle. The size of t he lesion was classified into three categories on the mid-coronal MRI of th e femoral condyle: there were 44 small, 20 medium, and 9 large lesions. The condyle was divided into 3 zones: anterior, middle, and posterior. The loc ation of the lesion was evaluated on the mid-sagittal image. There were 7 a nterior, 9 middle, 29 posterior, 14 middle and posterior and, in 14 cases, all 3 zones were involved. 44 small lesions did not collapse, while 6/ 20 m edium lesions and 5/9 large lesions collapsed. No lesion involving only one zone collapsed, while 4/ 14 lesions involving the middle and posterior zon es and 7/14 lesions involving all three zones progressed to collapse. 4/6 c ondyles with large necrotic lesions involving all three zones collapsed. We conclude that the extent of the necrotic lesion on both the mid-coronal an d mid-sagittal planes is of importance for the prognosis of osteonecrosis o f the femoral condyle.