Transient osteoporosis of the hip misdiagnosed as osteonecrosis on magnetic resonance imaging.

A 34-year-old man developed idiopathic, bilateral, asynchronous transient osteoporosis of the hip. The symptoms included hip pain with activity, and roentgenography revealed osteoporosis of the femoral head and neck. Radionuclide bone scans showed increased uptake of the involved femoral head. Magnetic resonance imaging (MRI) early after the onset of right-side symptoms was characterized by decreased signal intensity on T1-weighted images and patchy areas of increased and decreased signal intensity on T2-weighted images; this was initially interpreted as being consistent with osteonecrosis. Despite evaluation by multiple physicians and imaging methods, including MRI, the correct diagnosis of transient osteoporosis of the hip was delayed until after resolution of the syndrome. Transient osteoporosis of the hip should be included in the differential diagnosis of hip pain.