[A Prospective Study of Steroid-induced Osteonecrosis by MRI Screening]

The first aim of this study was to investigate the efficacy of magnetic resonance imaging (MRI) for detecting multiple osteonecrosis, and the second aim was to determine the onset and early development of the osteonecrotic lesions by the MRI. MRI was employed to examine for osteonecrosis in the hip, knee, ankle and shoulder in 140 patients who received high-dosage corticosteroids (over 30 mg of prednisolone per day) for their condition. Osteonecrosis was indicated by the presence of band-like lesions on the MRI. In 33 hips of 20 patients, hip prostheses had already been performed because of osteonecrosis in the femoral head. One hundred and twenty (86%) of the 140 patients had affected joints. MRI showed osteonecrotic lesions in 176 hips of 99 patients, in 143 knees of 77 patients, in 46 ankles of 30 patients and in 44 shoulders of 25 patients. Osteonecrosis in the knee occurred very frequently, so MRI was useful to examine the knee to detect multiple osteonecrosis. When there was no osteonecrosis in either the hip or the knee, then osteonecrosis in the ankle or shoulder was rare. We concluded that MRI screening of both the hip and knee was sufficient to detect multiple osteonecrosis. A prospective study of osteonecrosis was carried out. A total of 35 patients who had undergone a first MRI examination within 6 months from high-dosage corticosteroid administration were followed up by MRI. Characteristic MRI findings of osteonecrosis were present in 13 patients (37%) involving 11 hips (16%) and 18 knees (26%). In the remaining 22 patients, MRI showed no abnormal findings. The appearance of band-like lesions on MRI occurred at approximately 3 months from the corticosteroid administration. In 4 hips of 2 patients and in 12 knees of 7 patients, the observed band-like lesions gradually diminished until approximately 1 year from the administration, but since then the band-like lesions showed no further reduction on MRI.