Impact of freezing on bone graft incorporation biomechanical evaluations in rats

BackgroundWith an increasing clinical application of grafting for bone reconstruction, it is important to understand the physiological and biological events of graft incorporation. In this study, we have investigated the impact of deep freezing on the biopotency for incorporation of bone grafts.MethodsFresh and deep-frozen autogenous bone grafts were implanted in an 8-mm segmental defect in the tibia. The construct was stabilized with intramedullary nailing. Incorporation of the graft was assessed with use of conventional radiography, biomechanical testing and measurements of bone mineral content and density after 2 and 4 months, respectively.FindingsFrozen grafts were significantly less integrated after 2 months as compared to fresh grafts. After 4 months, however, the frozen grafts showed an overall reconstruction that was not significantly different from the fresh grafts. Both frozen and fresh grafted segments had only reached 70% strength of intact bone at 4 months.InterpretationThis study indicates that in the long run there are no significant consequences, radiologically or biomechanically, of deep freezing as compared to fresh bone grafts.