Bone Abstracts

Biomechanical strength testing of bones, considered a key component in bone quality assessment, is a critical end-point in the evaluation of safety and efficacy of test compounds in preclinical studies. Bones are usually preserved frozen and tested within a few months following harvesting. They can also be stored for longer periods and only tested when additional information is required. The objective of this study was to evaluate if differences in biomechanics data between different specimens are maintained by long term storage using vertebrae stored at −20  °C from cynomolgus monkeys (cynos) 5 months after harvesting (L3 and L4) relative to 7.5 years after harvesting (T12). Effect of long term storage on absolute strength parameters was not evaluated as destructive tests were performed. L3, L4 and T12 vertebral specimens were prepared from cynos which underwent either sham or ovariectomy (OVX) surgery 17 months earlier: Sham (n=17) and OVX (n=20). Specimens were tested in compression to failure and peak load, yield load, stiffness and AUC reported. Correlation analysis of each parameter was performed between L3 and T12 tested more than 7 years apart. Correlation analyses between L3 and L4 both tested 5 months following collection were performed to evaluate the correlations between two different vertebrae stored for the same duration.

For L3, L4 and T12, group means and S.D. were comparable in sham and OVX groups, respectively, Table 1. Correlation analysis showed significant positive linear relationships between peak load, yield load or AUC between L3 and T12, Table 1 (r=0.69 to 0.89). Correlation between L3 and L4 tested after the same storage duration were comparable.

Although the absolute preservation of bone strength with long term storage cannot be confirmed with destructive tests, the strong correlation of biomechanical properties of different specimens before and after storage, support the validity of long-term preservation of specimens for future biomechanical testing.