[Tensile mechanical characteristics of decalcified cortical bone matrix]

To evaluate the tensile mechanical characteristics of decalcified cortical bone matrix with different thicknesses so as to provide an experimental basis for the scaffold of tissue engineering.

Decalcified cortical bone matrix was prepared from fresh bovine tibia with rapid decalcification techniques. Its physical characteristics including colour, texture, and so on, were observed. Then the decalcified rate was calculated. Decalcified cortical bone matrices were radially cut into slices with different thicknesses along longitudinal axis and divided into 4 groups: group A (100-300 microm), group B (300-500 microm), group C (500-700 microm), and group D (700-1000 microm). Then the slice specimens of each group were characterized with tensile test and histological examination.

General observation showed that decalcified cortical bone matrix with hydrogen peroxide treatment was ivory white with good elasticity and flexibility. The decalcified rate was 97.6%. The tensile strength and elastic modulus of groups B, C, and D were significantly higher than those of group A (P < 0.05); there was no significant difference among groups B, C, and D (P > 0.05). The stiffness in 4 groups increased gradually with the increasing thickness, it was significantly lower in group A than those in groups B, C, and D (P < 0.05), and in groups B and C than that in group D (P < 0.05). While there was no significant difference in ultimate strain within 4 groups (P > 0.05). Histologically, intact osteon was observed in every group, with an average maximum diameter of 182 microm (range, 102-325 microm).

The mechanical properties of decalcified cortical bone matrix might depend on the integrity of the osteons. Slices with thickness of 300 microm or more could maintain similar mechanical properties when decalcified cortical bone matrix is used as a scaffold for tissue engineering.