[Strength of dense, lyophilized and irradiated cortical bone of the human femur].

The ultimate bending strength of compact lyophilized and sterilized by gamma-rays bone samples taken from human middle third femur diaphysis was investigated and compared with the one of fresh bone tissue. The bone samples were taken from 42 individuals aged 32-45 who died suddenly. The measurements were carried out with Contraves balance rheometer at 20 degrees Celsius and under the sample deformation frequency of 12.5 Hz. The samples were divided into 5 groups. In the first one the ultimate bending strength was investigated without loading, in the second one with gentle load and the third one with great load. The fourth and fifth groups consisting of longer lyophilized bone samples, dry and after rehydration respectively were investigated under great load. It was found, that ultimate strength of dry lyophilized and irradiated bone was about 30% lower than of fresh bone, ultimate strength of rehydrated samples was about 18% greater than of dry samples and that the loading and fatigue procedure lowers the ultimate strength of compact bone samples and increases their fragility.