Bone regeneration after fast electron irradiation

Unilateral irradiation of standardized defects with fast electrons results had the expected effect on bone regeneration. Irradiation does not prevent regeneration (in fact, all defects are covered with bone after 26 weeks); rather, there is a dose-dependent retardation of the maximum regenerative activity. However, this retardation is little pronounced; at the end of the experimental period, the maximum difference in opposition is less than 100 μm. This difference between irradiated animals and control animals is not significant. After a certain period of latency, the growth data of the experimental animals are the same as those of the control animals, in spite of irradiation. In all groups, opposition is lower in the periosteal and endosteal region than in the defect region. In the periosteum, radiation effects are proved to take place, espcecially in 4000 rad animals, by the lack of opposition. In the endosteum, the difference between experimental and control animals is significant. At the same time there is a marked latency period of 10 weeks (2000 rad), or rather 14 weeks (4000 rad), in the maximum regenerative activity. (orig./AJ)