A biphasic multiscale study of the mechanical microenvironment of chondrocytes within articular cartilage under unconfined compression

Abstract

Computational analyses have been used to study the biomechanical microenvironment of the chondrocyte that cannot be assessed by in vitro experimental studies; yet all computational studies thus far have focused on the effect of zonal location (superficial, middle, and deep) on the mechanical microenvironment of chondrocytes. The aim of this paper was to study the effect of both zonal and radial locations on the biomechanical microenvironment of chondrocytes in inhomogeneous cartilage under unconfined stress relaxation. A biphasic multiscale approach was employed and nine chondrocytes in different locations were studied. Hyperelastic biphasic theory and depth-dependent aggregate modulus and permeability of articular cartilage were included in the models. It was found that both zonal and radial locations affected the biomechanical stresses and strains of the chondrocytes. Chondrocytes in the mid-radial location had increased volume during the early stage of the loading process. Maximum principal shear stress at the interface between the chondrocyte and the extracellular matrix (ECM) increased with depth, yet that at the ECM-pericellular matrix (PCM) interface had an inverse trend. Fluid pressure decreased with depth, while the fluid pressure difference between the top and bottom boundaries of the microscale model increased with depth. Regardless of location, fluid was exchanged between the chondrocyte, PCM, and ECM. These findings suggested that even under simple compressive loading conditions, the biomechanical microenvironment of the chondrocytes, PCM and ECM were spatially dependent. The current study provides new insight on chondrocyte biomechanics.

A multi-scale finite element model for investigation of chondrocyte mechanics in normal and medial meniscectomy human knee joint during walking

“…Since there was free fluid flow through all the interfaces (ECM-PCM, PCM-cell), similarly as has been done in several earlier studies (Guilak and Mow, 2000;Guo et al, 2014;Han et al, 2011Han et al, , 2007Julkunen et al, 2009;Korhonen et al, 2011;Sibole et al, 2013;Tanska et al, 2013), fluid pressure was homogenously distributed in the cell, PCM and ECM. However, in the cell model incorporating the impermeable membrane, fluid pressure in the cell was slightly smaller than that in the PCM and ECM.…”

“…Even though these models were able to evaluate the effects of the depth-dependent cartilage structure and mechanical properties on knee joint mechanics during walking (Halonen et al, 2014(Halonen et al, , 2013Mononen et al, 2015Mononen et al, , 2013Mononen et al, , 2012Räsänen et al, 2013), they did not incorporate cells. Cell level responses have been studied by applying multi-scale approaches (Guo et al, 2014;Halloran et al, 2012;Han et al, 2011; Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jbiomech www. JBiomech.com et al, 2009;Korhonen et al, 2011;Moo et al, 2012;Sibole and Erdemir, 2012;Sibole et al, 2013;Tanska et al, 2013;Varadarajan et al, 2008).…”

A statistically-augmented computational platform for evaluating meniscal function

“…However, before investigating certain clinical conditions, such as meniscectomy or ligament deficiencies, it may be necessary to also include force-driven models that would capture the influence on kinematics and knee stability. In the FEM, articular cartilage was modeled as a homogeneous linear elastic material, thus ignoring its inhomogeneous, anisotropic, and biphasic features (Guo et al, 2014; Mow et al, 2005). Since we are studying gait at a loading rate of 0.5 Hz, the elastic material model is a reasonable starting point for modeling the force distribution across the tibial plateau (Ateshian et al, 2007).…”

A biphasic finite element study on the role of the articular cartilage superficial zone in confined compression

“…Removing the SZ will expose the middle and deep zones to higher magnitudes of stress and strain. Biphasic multiscale finite element studies (Guo et al, 2014a) are necessary in the further to investigate how the changes at tissue level affect the microenvironment of a cell within the articular cartilage. While only static creep loading was investigated in the current study, it would be of interest in future studies to investigate the effect of the SZ on the dynamic mechanical behavior of the articular cartilage, as similar findings have been previously reported for cyclic creep loading (Torzilli, 1984).…”