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Changes in Triphasic Mechanical Properties of Proteoglycan-Depleted Articular Cartilage Extracted from Osmotic Swelling Behavior Monitored Using High-Frequency Ultrasound

Q Wang*, YP Zheng∗,†, HJ Niu∗,‡
* Department of Health Technology and Informatics
Corresponding author. Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong. Tel: 852 27667664; Fax: 852 23624365; Email: ypzheng@ieee.org
Department of Biomedical Engineering, The Beihang University, Beijing, China

Molecular & Cellular Biomechanics 2010, 7(1), 45-58. https://doi.org/10.3970/mcb.2010.007.045

Abstract

This study aims to obtain osmosis-induced swelling strains of normal and proteoglycan (PG) depleted articular cartilage using an ultrasound system and to investigate the changes in its mechanical properties due to the PG depletion using a layered triphasic model. The swelling strains of 20 cylindrical cartilage-bone samples collected from different bovine patellae were induced by decreasing the concentration of bath saline and monitored by the ultrasound system. The samples were subsequently digested by a trypsin solution for approximately 20 min to deplete proteoglycans, and the swelling behaviors of the digested samples were measured again. The bi-layered triphasic model proposed in our previous study (Wang et al., J Biomech Eng-Trans ASME 2007; 129: 413-422) was used to predict the layered aggregate modulus Hafrom the data of depth-dependent swelling strain, fixed charge density and water content. It was found that the region near the bone, for the normal specimens, had a significantly higher aggregate modulus (Ha1= 20.6±18.2 MPa) in comparison with the middle zone and the surface layer (Ha2= 7.8±14.5 MPa and Ha3= 3.6±3.2 MPa, respectively) (p < 0.001). The normalized thickness of the deep layer h1 was 0.68±0.20. After the trypsin digestion, the parametric values decreased to Ha1 = 13.6±9.6 MPa, Ha2 = 6.7±11.5 MPa, Ha3 = 2.7±3.2 MPa, and h1 = 0.57±0.28. Other models were also used to analyze data and the results were compared. This study showed that high-frequency ultrasound measurement combined with the triphasic modeling was capable of nondestructively quantifying the alterations in the layered mechanical properties of the proteoglycan-depleted articular cartilage.

Keywords

Articular cartilage, Ultrasound, Osmotic swelling, Biomechanics, Triphasic theory, Proteoglycan-depletion, Trypsin-digestion, Osteoarthritis

Cite This Article

Wang, Q., Zheng, Y., Niu, H. (2010). Changes in Triphasic Mechanical Properties of Proteoglycan-Depleted Articular Cartilage Extracted from Osmotic Swelling Behavior Monitored Using High-Frequency Ultrasound. Molecular & Cellular Biomechanics, 7(1), 45–58.



This work is licensed under a Creative Commons Attribution 4.0 International License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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