The effects of sterilization methods on lyophilized cartilage grafts in an experimental model

Background: Cartilage graft is an effective method for reconstructing the bony framework of the face and covering the bony defect site. As a process method of cartilages, lyophilization has the advantages of long-term storage and easy handling. We hypothesized that the type of procedure used to sterilize lyophilized cartilage may affect outcomes after implantation into the body. We compared the effects of ethylene oxide (EO) gas, γ-irradiation, and autoclaving methods on cartilage grafts. Methods: After sterilization, lyophilized human rib cartilage was inserted into subperiosteal pockets created in New Zealand white rabbit skulls. We assessed the weights and ratios of the remaining cartilage and examined histologic changes throughout the implantation period. Results: Over a 5-week period, the γ-irradiated grafts remained more than the other grafts, but after more than 5 weeks, there were no significant differences between γ-irradiated and EO gas-sterilized cartilages. Autoclave-sterilized cartilages were totally resorbed at 10 weeks. Conclusions: Over 10 weeks of follow-up, based on persistence measurements and histologic appearance, there was little difference between γ-irradiated and EO gas-sterilized lyophilized cartilage used in experimental bone grafts.