THE NICOLAS-ANDRY-AWARD - 1995 - FRACTURE-HEALING - RADIATION-INDUCEDALTERATIONS

This study investigated the effects of radiation on fractures in a rat femur model. Two different radiation dosage fractionation schemes (11 00 rads given in one dose and 2500 rads given in 10 divided doses over 12 days) and three different times of initiation of radiation (1 day before fracture, 3 or 10 days after fracture) were studied. Fractures exposed to these levels of radiation all appeared to heal during the c ourse of this experiment, although with varying degrees of delay, with the exception of those exposed to a single dose of 1100 rads 3 days a fter fracture. These animals remained at a more immature level of repa ir histologically compared with the control group, throughout the enti re time evaluated. The strength of the final repair remained less than the control for all the groups receiving treatment. These results may offer some explanation for the clinical observations of an increased incidence of delayed union and nonunion of fractures, an increased inc idence of fracture and refracture in irradiated bone, and an increased incidence of fracture and nonunion in constructs using radiation in c onjunction with allogeneic bone. Furthermore, the observed effects wer e generally no different in the animals treated with the two clinicall y relevant dose fractionation schemes chosen for this study.