title: Mechanical strength of cortical allografts with gamma radiation versus ethylene oxide sterilization.
abstract: We investigated the effects of gamma irradiation versus ethylene oxide (ETO) sterilization on the mechanical strength of cortical bone grafts. Tibias were collected from cadavers of mature goats. Sixty test specimens were randomized into four groups: fresh (no processing), frozen (freezing at -70 degrees C), gamma-irradiated, and ETO-sterilized specimens. Torsion, three-point bending, and compression testing were separately performed with a material testing machine. Parameters studied included maximum stress, strain, deflection, extension, load, shear modulus, and E-modulus. Compared with findings for the fresh specimens, findings were as follows for gamma-irradiated specimens: maximal shear modulus, reduced by 48%; shear stress, by 55%; deflection, by 71%; bending stress, by 51%; bending strain, by 74%; extension, by 60%; and compression strain, by 50%. However, there were no reductions in those parameters for the frozen specimens or the ETO-sterilized specimens. These findings confirm that shear, bending, and compression strength of cortical allografts are weakened by gamma irradiation at room temperature. To maintain optimum mechanical properties, ETO sterilization of allografts is better than gamma sterilization, especially for cortical bone, because it is usually used in load-bearing settings.
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital of Sichuan University, Chengdu, China. zhouzongke@scu.edu.cn
authors.forename: Zongke
authors.initials: Z
authors.lastname: Zhou
authors.forename: Tingwu
authors.initials: T
authors.lastname: Qin
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Bin
authors.initials: B
authors.lastname: Shen
authors.forename: Pengde
authors.initials: P
authors.lastname: Kang
authors.forename: Fuxing
authors.initials: F
authors.lastname: Peil
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D016025:Bone Transplantation; D001842:Bone and Bones / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D015925:Cryopreservation; D005027:Ethylene Oxide / Q000494:pharmacology*; D005720:Gamma Rays; D006041:Goats; D066298:In Vitro Techniques; D013242:Sterilization; D013977:Tibia
chemical_list: D005027:Ethylene Oxide