Residual Stress Levels on the Cortical Section of Vertebral Bone Tissue

Abstract

Objective: Residual stress can cause deformation and cracks in the bone tissue. The aim of our study is to measure the residual stress level and distribution in the cortical bone of the extremities of vertebrates.Methods: Residual stress levels in the bone tissue of 12 sheeps aged 2 years were measured by observing the cortical parts of 6 different (C1, C3, Th1, Th 13, L1, and L6) vertebral bones by means of the X-ray diffraction method. This method is recognized as the one that can measure residual stress in the bone tissue most accurately. By means of special methods, the cortical part of vertebral bone was separated from its trabecular part. The bone tissue was left to stand for a long time to dry completely. Measurements were performed on completely dried tissues using an X-ray diffraction apparatus. The residual stress values obtained from all the subject groups were compared statistically. Results: It was found that the residual stress level was the highest in C3 and that it showed a statistically significant change as compared to the levels in C7, Th1, and Th13. Although the level in C3 was high as compared to the levels in L1 and L6, it was not statistically significant.Conclusion: The residual stress level in the C3 vertebral cortical section was significantly higher than other parts and was interpret-ed as such by us, i.e., anatomically, it is one of the vertebrae that keep the head upright and is the vertebra carrying the maximum load in all natural processes.