Effects of preservation and sterilization on cortical bone grafts

Abstract
The effects of preservation and sterilization on the structural properties of cortical bone were investigated. Specimens of cortical bone from rat tibiae were frozen (−70°C for 28 days), freeze-dried, irradiated (1, 5, 25 and 50 kGy) or autoclaved (at 134°C for 3 or 5 min), and examined by scanning electron microscopy. Cryopreservation and irradiation had no deleterious effects on the surface structure of the cortical bone. Freeze-drying caused microcracks running parallel to the mineralized fiber bundles. After autoclaving, a time-dependent distension, swelling and amalgamation of the fibrillary matrix was observed. This denaturation of the organic matrix was more pronounced after 5 min than 3 min autoclaving. The alterations of the fibrillary structure described above might be due to a preservation- and sterilization-induced decrease of the biological and biomechanical potential of bone grafts.