Water loss and defects dependent strength and ductility of articular cartilage

Abstract

Water loss and surface defects of articular cartilage extremely aggravate the risk of osteoarticular diseases. The effects of water content and surface defects on the mechanical properties of cartilage need to be taken into further account. By using a self-developed in-situ tensile tester, the tensile stress-strain relationship and real-time morphological changes under conditions of different water contents are obtained with and without a micro void. It is confirmed that tissue structure and permeability are the main factors affecting the strength and ductility of cartilage. The less water content contributes to the lower permeability, inducing higher strength but poorer plasticity. Raman spectroscopy analysis results directly reveal the transition from the bonding water with stronger hydrogen bonds to the free water with weaker hydrogen bonds in cartilage layer caused by both drying treatment and tensile deformation, which results in decreased permeability and enhanced resistance to deformation. Raman-based organic matrix content is negatively correlated with permeability but positively correlated with the strength of cartilage. The obtained experimental data may facilitate to predict cartilage damage and develop artificial cartilage materials.