Evaluation of transient osteoporosis of the hip in magnetic resonance imaging

Transient osteoporosis is a relatively rare condition of unknown etiology that causes temporary bone loss. The syndrome is characterized by self-limited course and spontaneous resolution after 6 to 12 months. The pathogenesis of transient osteoporosis is not fully understood but several hypotheses that have been proposed include trauma, neurovascular dysfunction and transient hyperemia. Clinical manifestations include sudden onset of pain in the hip that usually worsens with weight bearing and leads to functional disability involving the affected extremity. Radiographs are frequently unremarkable, but may reveal periarticular osteopenia 3–6 weeks after the onset of clinical symptoms. There is no radiographic evidence of demineralization during the early phase of syndrome, as a result advanced imaging is required. Magnetic resonance imaging is the most sensitive and predictable test for an early diagnosis and monitoring of disease progression.