A study of irradiated bone: I. histopathologic and physiologic changes.

Histologic and tracer techniques were used to investigate and document alterations in bone pathophysiology subsequent to irradiation of the left hind limb of rabbits. Numerous time-dependent changes were observed. Among these were an inflammatory response shortly after irradiation, and an increase in the remodeling of cortical bone, which peaked between 3 and 6 mo after irradiation. The changes in bone remodeling correlated with changes in vascular patency in a manner consistent with the hypothesis that radiation damage in mature bone is mediated primarily through alterations in the fine vasculature. The findings of this study provide important information on the time course of changes in bone pathophysiology following regional irradiation. They are used in the second of this series of papers to help establish which mechanisms are responsible for postirradiation alterations in the localization of Tc-99m pyrophosphate in these rabbits.