Transient osteoporosis of the hip, complete resolution after treatment with alendronate as observed by MRI description of eight cases and review of the literature.

Transient osteoporosis of the hip (TOH), also referred to as transient bone marrow edema syndrome, is most common in middle-aged men and often after trivial trauma or sport-related injuries. Diagnosis is usually made by eliminating other possible causes of hip pain. Magnetic resonance imaging (MRI) plays an important role in diagnosis and demonstrates a typical pattern of bone marrow edema (BME) in the form of diffuse low signal on T1-weighted images and high signal on T2 fat-suppressed or short T1 inversion recovery images. No consensus exists about the management of TOH, as it may progress to avascular necrosis. We describe eight cases of TOH treated with alendronate resulting in improvement of pain and function and complete resolution of BME on MRI. The literature is reviewed regarding TOH and the relationship with bone marrow edema syndrome, avascular necrosis of the hip, and regional migratory osteoporosis. To our knowledge, this is the first report describing the improvement of this condition after of alendronate with documented radiological improvement on follow-up MRI.