[Transient osteoporosis especially with transient demineralization of the hip]

Transient osteoporosis is observed regionally in several disorders including demineralization of femoral head, migratory osteolysis, and sympathetic osteodystrophy. Predominant radiologic feature of these disorders is widening of medullary cavity without increase of external diameter of bone. Although, the exact mechanism of loss of bone mass in these disorders is not clearly demonstrated, it is suggested that sympathetic nerve, hormonal imbalance, arterial blood supply, and venous congestion play important roles in the pathogenesis of these disorders. It may be necessary to demonstrate these local causes of transient osteoporosis in order to show the exact mechanism of systemic osteoporosis.