Time-dependent change of load sharing between two non-linear visco-elastic materials: Experiment and model

Cartilage and meniscus display a non-linear visco-elasticity and the relationship between stress and strain follows a power function, as determined in this study. Furthermore, during application of a constant load to the knee, the stress in the menisci, measured with intrameniscal conductive pressure sensors, increased with time. This phenomenon was confirmed in a non-linear visco-elastic power model with 2 different materials. The material parameters for the power function were taken from the stress relaxation results of joint cartilage and meniscus. Both the experiments and the model show that load is transferred from cartilage to meniscus over time. This avoids damage to the cartilage when standing for prolonged periods.