[Study on the effect of artificial cartilage with different elastic modulus on the mechanical environment of the chondrocyte in defect cartilage repaired area].

A solid-liquid two-phase finite element model of articular cartilage and a microscopic finite element model of chondrocytes were established using the finite element software COMSOL in this study. The purpose of the study is to investigate the mechanics environment and the liquid flow field of the host cartilage chondrocytes in each layer by multi-scale method, under physiological load, with the different elastic modulus of artificial cartilage to repair cartilage defect. The simulation results showed that the uniform elastic modulus of artificial cartilage had different influences on the microenvironment of different layer chondrocytes. With the increase of the elastic modulus of artificial cartilage, the stress of the shallow surface layer and the intermediate layer chondrocytes increased and the stress of deep layer chondrocytes decreased. The flow field direction of the middle layer and the bottom layer of cartilage can also be changed by artificial cartilage implantation, as well as the ways of nourishment supply of the middle layer and underlying chondrocytes change.A barrier to underlying chondrocytes nutrition supply may be caused by this, thus resulting in the uncertainty of the repair results. With cross-scale finite element model simulation analysis of chondrocytes, we can quantitatively evaluate the mechanical environment of chondrocytes in each layer of the host cartilage. It is helpful to assess the clinical effect of cartilage defect reparation more accurately.

Study of the Mechanical Environment of Chondrocytes in Articular Cartilage Defects Repaired Area under Cyclic Compressive Loading

COMSOL finite element software was used to establish a solid-liquid coupling biphasic model of articular cartilage and a microscopic model of chondrocytes, using modeling to take into account the shape and number of chondrocytes in cartilage lacuna in each layer. The effects of cyclic loading at different frequencies on the micromechanical environment of chondrocytes in different regions of the cartilage were studied. The results showed that low frequency loading can cause stress concentration of superficial chondrocytes. Moreover, along with increased frequency, the maximum value of stress response curve of chondrocytes decreased, while the minimum value increased. When the frequency was greater than 0.2 Hz, the extreme value stress of response curve tended to be constant. Cyclic loading had a large influence on the distribution of liquid pressure in chondrocytes in the middle and deep layers. The concentration of fluid pressure changed alternately from intracellular to peripheral in the middle layer. Both the range of liquid pressure in the upper chondrocytes and the maximum value of liquid pressure in the lower chondrocytes in the same lacunae varied greatly in the deep layer. At the same loading frequency, the elastic modulus of artificial cartilage had little effect on the mechanical environment of chondrocytes.

Study of the Mechanical Environment of Chondrocytes in Articular Cartilage Defects Repaired Area under Cyclic Compressive Loading.

COMSOL finite element software was used to establish a solid-liquid coupling biphasic model of articular cartilage and a microscopic model of chondrocytes, using modeling to take into account the shape and number of chondrocytes in cartilage lacuna in each layer. The effects of cyclic loading at different frequencies on the micromechanical environment of chondrocytes in different regions of the cartilage were studied. The results showed that low frequency loading can cause stress concentration of superficial chondrocytes. Moreover, along with increased frequency, the maximum value of stress response curve of chondrocytes decreased, while the minimum value increased. When the frequency was greater than 0.2 Hz, the extreme value stress of response curve tended to be constant. Cyclic loading had a large influence on the distribution of liquid pressure in chondrocytes in the middle and deep layers. The concentration of fluid pressure changed alternately from intracellular to peripheral in the middle layer. Both the range of liquid pressure in the upper chondrocytes and the maximum value of liquid pressure in the lower chondrocytes in the same lacunae varied greatly in the deep layer. At the same loading frequency, the elastic modulus of artificial cartilage had little effect on the mechanical environment of chondrocytes.