Different storage times and their effect on the bending load to failure testing of murine bone tissue.

Cryopreservation is a well-established method for bone storage. However, the ideal timing of mechanical testing after sacrificing the experimental animals is still under discussion and of significant importance to the presentation of accurate results. Therefore, the aim of this study was to investigate and compare different cryopreservation durations to native murine bone and whether there was an influence on mechanical bone testing. For this study the tibias of 57 female C57BL/6 mice-18-weeks of age-were harvested and randomly allocated to one of four groups with varying storage times: (1) frozen at -80 °C for 3 months, (2) frozen at -80 °C for 6 months, (3) frozen at -80 °C for 12 months and (4) native group. The native group was immediately tested after harvesting. The comparison of the mean strength and load to failure rates demonstrated a significant difference between the storage groups compared to the native control (p = 0.007). However, there was no difference in the strength and the load to failure values of bones of all storage groups when compared against each other. Once cryopreservation at -80 °C is performed, no differences of mechanical bone properties are seen up to 12 months of storage. When actual in vivo data is of close interest, immediate testing should be considered and is preferred. If comparison of groups is required and long-time storage is necessary, cryopreservation seems to be an accurate method at present.

Author Correction: Effect of two (short-term) storage methods on load to failure testing of murine bone tissue.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effect of two (short-term) storage methods on load to failure testing of murine bone tissue.

Since mechanical testing of bone quality is often delayed following euthanasia, the method of bone storage is of high importance in animal studies. Different storage methods may cause a change in the properties of bone tissue during mechanical testing. Therefore, the aim of this study was to investigate the biomechanical effects of two different fixation methods for bone tissue. We hypothesized that there is a difference between the load to failure values between the two groups. The tibias of fifteen 18-week-old female C57BL/6 mice were harvested and randomly allocated to three different groups with varying storage methods: (1) frozen at -80 °C, (2) paraformaldehyde working solution, and (3) native group. A storage time of two weeks prior to testing was chosen for groups 1 and 2. In group 3, referred to as the "native group", bones were immediately tested after the harvesting procedure. The comparison of the mean load to failure of all 3 groups (group 1: 28.7 N ± 6.1 N, group 2: 23.8 N ± 3.8 N and group 3: 23.7 N ± 5.7 N) did not reveal a significant difference. There was also no difference in strength or stiffness. The findings of the present study demonstrate that the two most common storage methods, do not have an influence on the biomechanical properties of murine bone over a two week period.