Investigation of the mechanical behavior of kangaroo humeral head cartilage tissue by a porohyperelastic model based on the strain-rate-dependent permeability

Investigation of the mechanical behavior of kangaroo humeral head cartilage tissue by a porohyperelastic model based on the strain-rate-dependent permeability

Solid–interstitial fluid permeability,is significant to the strain-rate-dependent mechanical behavior of humeralhead(shoulder)cartilage.Due to anatomical and biomechanical similarities to that of thehumanshoulder,kangaroos present a suitable animal model. Therefore,indentation experiments were conducted on kangaroo shoulder cartilage issues from low(10-4/s) tomoderatelyhigh(10-2/s)strain-rates. A porohyperelastic model was developed based on the experimental characterization; and a permeability function that takes into account the effect of strain-rate on permeability (strain-rate-dependent permeability)was introduced into the model to investigate the effect of rate-dependent fluid flow ontissueresponse.The prediction of the model with the strain-rate- dependent permeability was compared with those of the models using constant permeability and strain-dependent permeability. Compared to the model with constant permeability,the models with strain-dependent and strain-rate- dependent permeability were able to better capture the experimental variation at all strain-rates (po0.05).Significant differences were not identified betweenmodels with strain-dependent and strain-rate-dependent permeability at strain-rateof5-10-3/s (p=0.179). However,at strain-rate of 10-2/s, the model with strain-rate-dependentpermeability was significantly better at capturing the experimental results(p<0.005). The findings thus revealed the significance of rate-dependent fluid flow on tissue behavior at large strain-rates,which provides insights into the mechanical deformation mechanisms of cartilage tissues.

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