Mechanical properties of articular cartilage elucidated by osmotic loading and ultrasound

The time response of surface displacement and acoustic impedance of in situ layers of articular cartilage were measured by using pulse-echo ultrasound. Disturbances were introduced by altering the osmotic pressure. Strongly nonlinear behavior was observed near physiological equilibrium. A model of articular cartilage is proposed which relates our results to cartilage microstructure.