Imaging study on the mode of development and changes in avascular necrosis of the femoral head in systemic lupus erythematosus: long-term observations.

To find out when and how avascular necrosis of the femoral head (ANFH) develops in patients with SLE who are receiving corticosteroids, we carried out a 3-yr prospective study using imaging methods. Twenty-three patients with SLE who were free of hip pain and radiographically negative were enrolled in the study. Initially, abnormal findings characteristic of ANFH were detected in eight (35%) and six (26%) patients on MRI and radionuclide uptake bone scanning, respectively. During a 3-yr observation period abnormalities on MRI, bone scanning and radiography were found in four, five and four patients, respectively and three patients developed hip pain. Analyses of imaging changes demonstrated that only a small proportion of patients (2/8, 25%) who initially showed abnormal MRI progressed to be radiographically positive for ANFH over the 3 years. High doses of corticosteroids over the 3-yr period were to be responsible for the emergence of change in MRI abnormalities. It is also suggested that abnormal MRI findings tend to develop either within a relatively short interval after the start of corticosteroid treatment or are associated with the exacerbation of SLE.