Effect of ethylene oxide sterilization and storage conditions on canine cortical bone harvested for banking

Two hundred seventeen cortical bones were harvested cleanly and prepared for banking for 2 months by using one of three types of packing materials, two ethylene oxide (EO) concentrations and procedures, and two storage temperatures. Bone subjected to the various treatments was compared to freshly harvested cortical bone and bone tested immediately after sterilization. Parameters evaluated were handling characteristics during preparation for and placement of a 3.5 mm cortex screw, and the percentage of weight lost as water when the bones were dried in an oven at 100 degrees C for 72 hours. Methods of sterilization, packaging material, and temperature of storage affected the handling characteristics and dehydration of the bone specimens. Twelve per cent EO at an elevated temperature and pressure, paper packaging, and room temperature storage appeared to cause the most significant changes. The use of 84% EO at room temperature and pressure, polyethylene wrapping material, and storage at -20 degrees C appeared to protect bone from dehydration. There was an increase in cracking and splitting of the bones as the percent of water loss decreased (indicating dehydration at the time of testing). Dehydration due to sterilization and storage processes may lead to difficulty in preparing bone for insertion of a bone screw and subsequently jeopardizing the stability of a repair in which such alloimplants are used.