Optical Characterisation of Bone Tissue for Diffusion Optical Tomography Applied to Skeletal Implants

Little is known about the information that can be gained optically about clinically relevant properties of osseous tissue. However, optical methods have the potential to recover rich information about bone condition around skeletal implants in-vivo. In this paper this potential was investigated by relating time-resolved optical measurements on 15 excised samples of trabecular bone to corresponding microCT-derived parameters. A statistically significant correlation (R² =0.39, p=0.05) has been found between the reduced optical scattering and absorption coefficients at 710 nm and the apparent mineral density. Adding the degree of mineralization of the calcified matrix to the predictive variables significantly improves the regression (R² =0.75, p=0.001), implying that multi-wavelength measurements could separately resolve bone volume fraction and mineralization degree. These results are a step forward towards implant-integrated Diffuse Optical Tomography systems able to monitor the supporting bone bed. They can also enable new applications such as the optical diagnosis of osteoporosis and other bone diseases.