The effect of sterilization on the mechanical properties of intact rabbit humeri in three-point bending, four-point bending and torsion
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Load bearing bone allografts are used to replace the mechanical function of bone that has been removed or to augment bone that has been damaged in trauma. 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. 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 SCCO2 treatment compared with two doses of gamma irradiation, on the mechanical properties of whole bone. Paired rabbit humeri were dissected and randomly assigned into either SCCO2 control, SCCO2 additive or gamma irradiation at 10 or 25 kGy treatment groups. The bones were mechanically tested in three-point and four-point bending and torsion, with the lefts acting as controls for the treated rights. Maximum load, energy to failure and stiffness were evaluated. This study found that SCCO2 treatment with or without additive did not alter maximum load, energy to failure or stiffness significantly under any loading modality. Gamma irradiation had a deleterious dose dependant effect, with statistically significant decreases in all mechanical tests at 25 kGy; while at 10 kGy there were reductions in all loading profiles, though only reaching statistical significance in torsion. 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.
KeywordsAllograft Sterilization Supercritical fluid Gamma irradiation Mechanical
Conflict of interest
The authors declare that there is no conflict of interest in the preparation of this manuscript.
- Hamer AJ, Strachan JR, Black MM, Ibbotson CJ, Stockley I, Elson RA (1996) Biochemical properties of cortical allograft bone using a new method of bone strength measurement. A comparison of fresh, fresh-frozen and irradiated bone. J Bone Joint Surg Am 78(3):363–368Google Scholar
- Lewandrowski KU, Gresser JD, Bondre S, Silva AE, Wise DL, Trantolo DJ (2000) Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: a preliminary histology study in rats. J Biomater Sci Polym Ed 11(8):879–889PubMedCrossRefGoogle Scholar
- Nichols A, Burns D, Christopher R (2009) The sterilization of human bone and tendon musculoskeletal allograft tissue using supercritical carbon dioxide. J Orthopaed 6(2):9–17Google Scholar
- Salehpour A, Butler DL, Proch FS, Schwartz HE, Feder SM, Doxey CM, Ratcliffe A (1995) Dose-dependent response of gamma irradiation on mechanical properties and related biochemical composition of goat bone-patellar tendon-bone allografts. J Orthop Res 13(6):898–906. doi: 10.1002/jor.1100130614 PubMedCrossRefGoogle Scholar
- Zioupos P, Currey JD, Hamer AJ (1999) The role of collagen in the declining mechanical properties of aging human cortical bone. J Biomed Mater Res 45(2):108–116. doi: 10.1002/(SICI)1097-4636(199905)45:2<108:AID-JBM5>3.0.CO;2-A PubMedCrossRefGoogle Scholar