Distraction osteogenesis following low-dose hyperfractionated irradiation in the rat mandible.

ABSTRACT

PURPOSE: The investigators hypothesized that low-dose hyperfractionated radiation would impair mandibular distraction osteogenesis (DO) in a murine mandibular model. MATERIALS AND METHODS: Male Sprague-Dawley rats underwent fractionated radiation (30 Gy) of the left mandible. After a 2-week recovery period, an external frame distractor was applied and gradual distraction of the mandible was performed. Tissue was harvested after a 28-day consolidation period. Gross, radiologic, and histologic evaluations were undertaken. Control animals underwent surgery for an identical time frame without preoperative radiation. RESULTS: Animals subjected to preoperative radiation (n = 10) showed suboptimal bone formation, including bone atrophy, incomplete bridging of the distraction gap, and gross bony defects or nonunion, compared with controls (n = 10). Although physical lengthening was achieved, irradiation consistently led to a detrimental effect on the normal process of DO. CONCLUSION: This set of experiments establishes a valuable rodent model to evaluate the effects of radiation on DO and may help to formulate strategies to optimize DO before it is widely applied in oncologic reconstruction.