Usefulness of magnetic resonance imaging for detection of asymptomatic osteonecrosis of the femoral head in patients with inflammatory bowel disease on long-term corticosteroid treatment

Objective. Osteonecrosis of the femoral head is one of the serious side effects of corticosteroid therapy. Early-stage osteonecrosis can now be diagnosed by magnetic resonance imaging even in asymptomatic patients. The aim of this study was to assess the usefulness of magnetic resonance imaging in diagnosing early osteonecrotic change and to determine whether corticosteroid administration is related to the development of osteonecrosis. Material and methods. We examined the relationship between osteonecrosis and corticosteroid administration, including maximum dosage, cumulative lifetime dose, duration, and bone mineral density in 20 patients with refractory inflammatory bowel disease requiring long-term corticosteroid treatment. Osteonecrosis of the femoral head was assessed by magnetic resonance imaging, and bone mineral density by osteodensitometry of the lumbar spine. Results. Osteonecrosis was diagnosed in 5 male patients including 4 in the asymptomatic stage. Cumulative lifetime dose of corticosteroid, duration of corticosteroid treatment, and steroid pulse therapy did not appear to be associated with the development of osteonecrosis. Maximum daily corticosteroid dose was significantly higher for patients with osteonecrosis than for those without it. Administration of 50 mg prednisolone for at least 14 days was a risk factor for osteonecrosis. Development of osteoporosis appeared not to be related to osteonecrosis. Conclusions. We conclude that high-dose corticosteroid treatment increases the risk of osteonecrosis, which may be due to different mechanisms from those responsible for osteoporosis. Magnetic resonance imaging is essential for diagnosis of asymptomatic osteonecrosis in patients receiving high-dose corticosteroids.