PROGNOSTICATION OF OSTEONECROSIS OF THE FEMORAL-HEAD IN PATIENTS WITHSYSTEMIC LUPUS-ERYTHEMATOSUS BY MAGNETIC-RESONANCE-IMAGING

To detect and prognosticate osteonecrosis of the femoral head in the p reradiographic stage, 60 patients with systemic lupus erythematosus wh o had normal hip radiology were followed prospectively for a mean peri od of 5 years (range, 3-7 years) using magnetic resonance imaging (MRI ). The first MRI scans showed a low intensity band in the femoral head of normal fat intensity on T1 weighted images in 16 hips of 9 patient s. The MRI findings were used to classify the lesions into three categ ories. Type A (six hips): the lesions occupied the medial one third or less of the weight bearing portion. Type B (two hips): the lesions oc cupied the medial two thirds or less of the weight bearing portion. Ty pe C (eight hips): the lesions occupied more than the medial two third s of the weight bearing portion. At the final followup, all of the Typ e A and one of the Type B hips were classified as being in Stage 1, an d one Type B and two Type C hips had progressed to Stage 2. The MRI ap pearance of six Type C hips had changed from a band to an inhomogeneou s pattern with the femoral head progressing to collapse on radiographs 2-5 years after the diagnosis of systemic lupus erythematosus. The re maining hips, which had been classified as normal at the first MRI, ma intained a normal appearance, except for one hip that developed a Type A lesion. The presence of a low intensity band on T1 weighted images was an early specific finding of osteonecrosis of the femoral head, an d extensive lesions demarcated by band images signified a poorer progn osis in systemic lupus erythematosus patients. If no MRI abnormalities appeared after I gear of the startup treatment for systemic lupus ery thematosus, there was little risk of femoral head collapse based on th e subsequent clinical course of the patients followed in the current s tudy.