An estimation of mechanical propertes of articular cartilage for biphasic finite element analyses

The purpose of this study is to estimate material properties of articular cartilage by curve fitting method using finite element (FE) analysis. While various material tests have been conducted to predict the behavior of articular cartilage, one of the recent interests was the accurate estimation of material properties under physiological and dynamic condition. In this study, cylindrical indentation was experimentally conducted in high compressive amount and high compression rate in considering the physiological condition. Each single specimen was sequentially exposed to compressive tests at definite deflection with different compressive amount and different compression rates and compressive creep test. The time-dependent compressive force given by a precise compression tester was utilized for estimation of material properties by curve fitting method with FE analysis. Five typical material properties, which represented total apparent Young's modulus, strain dependent permeability and fibril reinforcement by collagen network, were selected for the estimation process with depth-dependency of Young's modulus. In the curve fitting processes by FE analysis, each material property had specific roles on reproducing experimental time-dependent reactional force. A single material property set estimated in this study successfully reproduced the four different experimental time-dependent behaviors.