L'étude a comparé les propriétés mécaniques de l'os trabéculaire humain cryoconservé avec une nouvelle allogreffe issue de tissu humain traitée par Osteopure™. Nous avons utilisé une procédure de test par compression, non destructive, sur trois faces orthogonales (70 échantillons 10x10x10 mm provenant de têtes fémorales humaines). Les tests mécaniques ont été appliqués sur les échantillons frais et après la procédure de nettoyage Osteopure™ et de stérilisation. Des tests destructifs ont finalement été appliqués suivant la direction axiale et les résultats comparés à ceux d'un groupe contrôle (31 échantillons). Les courbes contrainte-déformation obtenues pour les échantillons traités ne diffèraient pas significativement de celles observées pour des échantillons cryoconservés humains. Les modules de Young obtenus, aussi bien pour les procédures non-destructives (os frais, dégraissé et après stérilisation) que destructives (os frais et après stérilisation) n'ont pas été significativement différents (respectivement 183 ± 71, 192 ± 96, 202 ± 92 et 325 ± 200, 311 ± 92 MPa).

La force maximale de rupture était de 6,62 ± 3,58 MPa pour les os traités par Osteopure™ et de 9,94 ± 2,74 MPa pour les os cryoconservés.

Les propriétés mécaniques de l'os cryoconservé ne sont pas significativement modifiées par le traitement Osteopure™ en particulier en ce qui concerne le module de Young, autorisant un bon comportement mécanique et fonctionnel du greffon.

Bone grafts and bone substitutes must be biocompatible osteoconductors with satisfactory mechanical properties similar to native bone. When the bone treatment is conducted under specific conditions, the elasticity module under infra-maximal loading can be optimized to achieve reproducible values. The purpose of this work was to determine the effect of the cleaning and sterilization process using Osteopure™ on the biomechanical properties of trabecular bone harvested from human femoral heads.

Seventy trabecular bone samples were tested: group 1F (fresh samples); group 1N (after application of Osteopure™ cleaning); group 1S (after Osteopure™ cleaning and sterilization). Non-destructive and destructive tests (group 1D) were performed. Two fresh femoral heads were used as controls for the destructive test (group 2). The first non-destructive test was applied directly after section (group 1F). Other samples were then purified with Osteopure™ treatment and a second non-destructive test was conducted (group 1N). A third non-destructive test was conducted after sterlization with 25kgray radiation (group 1S).

Treatments 1 and 2 were performed by OST Developpement SA (Clermont-Ferrand). Finally a destruction test was applied along the directional axis (group 1D). For the 31 samples in group 2 (control) the destructive test was applied along the directional axis immediately after section. Compression tests were performed at a deformation speed of 3 mm/min for 0.3% deformation.

The Young module did not exhibit any significant difference between the three steps of the testing in the three orthogonal directions. The Young module was not significantly different between group 1F and group 2 (controls). Maximal force of compression was significantly different (P≪0.01). There was a linear relationship between maximal force at rupture and the Young module obtained during destructive tests, for groups 1D and 2 respectively. The compression curves obtained from sterilized samples (group 1D) were not significantly different from those observed for fresh trabecular bone in group 2 (controls).

The Young module values measured from 70 - 673 MPa. For non-destructive tests, the module values were to the order of 64% of those obtained for destructive tests. Decreased maximal force of rupture observed for treated samples in comparison with fresh samples can be explained by the extraction of most of the lipids.

The Osteopure™ method does not alter stiffness of bone allografts. The elasticity module observed in treated bones is close to that observed in fresh bones. Mechanical resistance to compression is however only half the force of compression observed in the hip joint for daily activities. The linear relationship between the elasticity mode and loading required for rupture is not affected by treatment with Osteopure™. The advantages related to elimination of prions or viral contamination appear by far to be more important than the minor changes observed in the mechanical characteristis of allografts.