Evaluation of radiation therapy on grafted and non-grafted defects - an experimental rat model

Abstract

Objectives To evaluate the effect of radiation therapy in a single dose (15Gy) on grafted and non-grafted defects regarding the bone microarchitecture and collagen maturity. Materials and Methods Bone defects were surgically created in rat femurs. The right femur defect was filled by blood clot (“Clot”) and the left femur defect- by deproteinized bovine bone mineral graft (“Xenograft”). The animals were aleatory divided into 2 groups: without radiation therapy (nRTX) and with radiation therapy (RXT). Microtomographic (bone volume fraction - BV/TV, trabecular thickness - Tb.Th, trabecular number - Tb.N, trabecular separation - Tb.Sp), histological, and histomorphometric analyses were performed 14 days after the surgery. Two-way ANOVA with Tukey post-hoc test was used to compare the groups (α = 5%). Results Microtomographic analysis revealed that radiotherapy led to smaller BV/TV and Tb.N in both Clot and Xenograft. Regardless of the radiotherapy, defects filled with xenograft showed larger Tb.N. In contrast, Clot groups demonstrated increased values of BV/TV and Tb.Th. Histomorphometric results agreed with those of microtomography. Intermediately and densely packed collagen were predominant among the groups. Histological analysis revealed a disorganized bone formation bridging the cortical borders of the lesion in RTX groups. Primary bone involving the graft particles was commonly observed in all Xenograft groups, and radiotherapy did not affect the percentage of bone-graft contact. Conclusions Radiation therapy in a single dose affected the bone repair with smaller amount of newly formed bone in both grafted and non-grafted defects. Clinical Relevance: The use of bone substitute grafts might be feasible prior to radiotherapy.