Assessment of the biomechanical properties of newly formed bone tissue using micro-Brillouin scattering

The assessment of implant stability in bone tissue remains difficult because remodelling phenomena in the vicinity of the implant are still poorly understood. The present multimodality study investigates the potentiality of micro Brillouin scattering technique to differentiate mature and newly formed bone microscopic elastic properties following an approach coupled with histological analysis. Coin-shaped Ti-6Al-4V implants were placed in vivo in rabbit tibia. After seven weeks of implantation, bone samples were removed, embedded in methyl methacrylate and sliced into 190 μm thick sections. A micro-Brillouin scattering technique was used to measure ultrasonic velocities in 10 μm diameter regions located in mature and newly formed bone. The same section was then stained for histological analysis of the mineral content of the bone sample. The mean values of the ultrasonic velocities were equal to 4.98 10^-3 m/s in newly formed bone tissue and 5.20 10^-3 m/s in mature bone. ANOVA (p=0.029) tests revealed significant differences between the two groups of measurements. Histological observations showed a lower degree of mineralization in newly formed bone than in mature cortical bone. The higher ultrasonic velocity measured in newly formed bone tissue compared to mature bone might be explained by the higher mineral content in mature bone, which was confirmed by histology. The results demonstrate the feasibility of micro-Brillouin scattering measurements to investigate the elastic properties of newly formed bone tissue.