The Relationship Between the Optical Properties of Articular Cartilage and the Biomechanical Parameters of the Tissue

This study investigates the relationship between the optical properties of articular cartilage with its biomechanical parameters. The absorption and reduced scattering coefficients of articular cartilage, and average maximum penetration depth, average maximum lateral spread, and average path length of photons were estimated by optical measurements and Monte Carlo simulation. The equilibrium and instantaneous moduli, and initial fibrillar network, strain-dependent fibrillar network, and nonfibrillar network moduli, and initial and deformation-dependent permeability of the tissue were estimated by multistep stress-relaxation measurement and fibril-reinforced poroelastic modeling. The relationship between the optical properties and biomechanical parameters was assessed using predictive regression modeling. A strong relationship was found between reduced scattering coefficients, averaged maximum penetration depth, averaged maximum lateral spread, and average path length of photons with equilibrium, instantaneous, and initial fibrillar network moduli. We attribute this relationship to the collagen fibers as the main contributor to the scattering and biomechanical properties of the tissue.