The effect of supercritical carbon dioxide sterilization on the anisotropy of bovine cortical bone
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Bone allografts are used to replace bone that has been removed or to augment bone tissue in a number of clinical scenarios. In order to minimize the risk of infection and immune response, the bone is delipidated and terminally sterilized prior to implantation. The optimal method for bone graft sterilization has been the topic of considerable research and debate. Recently, supercritical carbon dioxide (SCCO2) treatments have been shown to terminally sterilize bone against a range of bacteria and viruses. This study aimed to evaluate the effect of these SCCO2 treatments on the anisotropic mechanical properties of cortical bone. Adult bovine cortical cubes were prepared and treated using SCCO2 and a range of common processing additives (ethanol, peracetic acid and hydrogen peroxide). The bone was mechanically tested in uniaxial compression in the axial, radial and tangential orientations. Ultimate stress, strain, elastic modulus, energy and stiffness were evaluated. This study found that SCCO2 treatment without additive did not alter the ultimate stress, stiffness or energy to failure depreciably in any orientation. The addition of sterilants peracetic acid and hydrogen peroxide also preserved mechanical function, with no deleterious effect on stress or stiffness. This study highlights the expediency of SCCO2 treatment for bone allograft processing as terminal sterilization can be achieved while maintaining the intrinsic mechanical properties of the graft.
KeywordsSterilization Allograft Bone Mechanical Anisotropy Supercritical fluid
The authors would like to acknowledge funding support for this research was provided by a grant from the Australian Orthopaedic Association.
Conflict of interest
The authors declare there are no conflicts of interest in the preparation of this manuscript.
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