Caracterização das propriedades mecânicas de osso irradiado, utilizando ensaios destrutivos e não destrutivos

Abstract

Radiotherapy causes metabolic changes in bone compromising its biomechanical properties. This study evaluated the mechanical properties of irradiated bone subjected to four different tests . Sixteen rats were divided into two groups according to period of sacrifice: 30D, sacrifice after 30 days of radiotherapy; 60D, sacrifice after 60 days of radiotherapy. The left femoral received 30 Gy radiations in a single dose using linear accelerator of electrons. The right femur was not irradiated and served as control. The femurs were subjected to tensile test associated with srain gauge test for obtaining Poisson s ratio (u) and three-point bending for obtaining the flexural modulus (FM), flexural strength (FS).And nanoindentantion test was used to obtain the modulus of elasticity (E) and Vickers hardness (VHN) . Data were statistically analyzed by factorial analysis of variance (2x2) followed by Tukey test (P<0.05). There was a significant reduction in CP, MF, E and VHN of femurs tested in periods of 30 and 60 days compared to their respective controls. However there was no difference in FS between non- irradiated and irradiated bone , regardless of the evaluation period . The radiation greatly reduces the values of Poisson ratio, elastic modulus and Vickers hardness of bone tissue. The combination of methodologies, especially strain gauge test and nanoindentation enables more accurate mapping of the biomechanical changes in bone subjected to radiotherapy.