Effects of gamma irradiation on mechanical properties of defatted trabecular bone allografts assessed by speed-of-sound
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Effects of gamma irradiation on mechanical properties of defatted trabecular bone allografts assessed by speed-of-sound measurement L. Vastel Æ C. Masse Æ E. Crozier Æ F. Padilla Æ P. Laugier Æ D. Mitton Æ R. Bardonnet Æ J.-P. Courpied
Received: 31 March 2006 / Accepted: 19 October 2006 / Published online: 5 January 2007 Springer Science+Business Media B.V. 2006
Abstract New sterilization methods for human bone allografts may lead to alterations in bone mechanical properties, which strongly influence short- and medium-term outcomes. In many sterilization procedures, bone allografts are subjected to gamma irradiation, usually with 25 KGy, after treatment and packaging. We used speed-ofsound (SOS) measurements to evaluate the effects of gamma irradiation on bone. All bone specimens were subjected to the same microbial inactivation procedure. They were then separated into three groups, of which one was treated and not irradiated and two were exposed to 10 and 25 KGy of gamma radiation, respectively. SOS was measured using high- and low-frequency L. Vastel (&) J.-P. Courpied AP-HP, Orthopedic Surgery Department A, Bone Bank, Cochin Teaching Hospital, 27 rue du Faubourg St Jacques, 75014 Paris, France e-mail: [email protected] C. Masse E. Crozier D. Mitton Laboratoire de Biome´canique (UMR CNRS 8005), ENSAM, 151 Bd de l’hoˆpital, 75013 Paris, France F. Padilla P. Laugier Laboratoire d’Imagerie Parame´trique, (UMR CNRS 7623), Universite´ Paris 6, 15 Rue de l’Ecole de Me´decine, 75006 Paris, France R. Bardonnet Bone Bank, Biobank, La Presle en Brie, Briez, France
ultrasound beams in each orthogonal direction. SOS and Young modulus were altered significantly in the three groups, compared to native untreated bone. Exposure to 10 or 25 KGy had no noticeable effect on the study variables. The impact of irradiation was small compared to the effects of physical or chemical defatting. Reducing the radiation dose used in everyday practice failed to improve graft mechanical properties in this study. Keywords Defatted Bone Mechanical properties Gamma irradiation Ultrasound wave propagation
Introduction The recent emergence of new communicable diseases, most notably HIV infection (Smith et al. 2001) and variant Creutzfeldt–Jakob disease, has focused attention on the procedures used to sterilize tissue allografts. Conventional techniques include irradiation, heating, and freeze-drying (Anderson et al. 1992; Cornu et al. 2000; Grieb et al. 2005; Loty et al. 1990). Sophisticated methods for sterilizing bone allografts have been developed over the last few years (Chappard et al. 1993; Kalus et al. 2005; Mitton et al. 2005; Mroz 2006; Poumarat and Squire 1993). They seek to achieve a high level of
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safety by using several methods in sequence. The first step consists in defatting and dehydration, which virtually eliminates the bone marrow. Then, procedures for inactivating bacteria and viruses are applied. Protein denaturation may be used to inactivate prions. Finally, the graft is packaged and steri
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