A CSM Nano-Hardness tester was used to assess the tissue stiffness of the different samples by nano-indentation of the prepared sample surface. We have assessed the stiffness for the three groups and the different time-points. Thus, we got insight in the changes in material during ageing, and caused by the ovariectomy. The Tibolone treated group provided information on how this medicine interacts with ovariectomy and ageing on tissue level. Further, we have distinguished the effects on surface tissue and inner tissue.
At all time points, for the whole material, there is a significant difference between healthy and ovariectomised (p<0.05) and ovariectomised, drug-treated and ovariectomised (p<0.05). It is thought that the rapid stiffening of the edge material from the ovariectomised rats could be due to increased mineralisation of fewer individual trabeculae under unchanging physiological loads. The hormone replacement treatment seems to negate the affects of the ovariectomy and even those of natural ageing.