Mechanisms of idiopathic osteonecrosis.

Bone death is always due to a disparity between the oxygen need of the bone cell and the ability of the local circulation to supply that need. As with infarction anywhere else, this can be brought about either by interruption of the arterial supply or by occlusion of the venous drainage, resulting in stasis and gradual oxygen starvation. In this article, these mechanisms and the events surrounding them are discussed, and the pathogenetic pathways linking the various clinical disorders with osteonecrosis are explored.