@Article{mcb.2010.007.045,
AUTHOR = {Q Wang, YP Zheng, HJ Niu},
TITLE = {Changes in Triphasic Mechanical Properties of Proteoglycan-Depleted Articular Cartilage Extracted from Osmotic Swelling Behavior Monitored Using High-Frequency Ultrasound},
JOURNAL = {Molecular \& Cellular Biomechanics},
VOLUME = {7},
YEAR = {2010},
NUMBER = {1},
PAGES = {45--58},
URL = {http://www.techscience.com/mcb/v7n1/28496},
ISSN = {1556-5300},
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 (<i>Ha<sub>1</sub></i>= 20.6±18.2 MPa) in comparison with the middle zone and the surface layer (<i>Ha<sub>2</sub></i>= 7.8±14.5 MPa and <i>Ha<sub>3</sub></i>= 3.6±3.2 MPa, respectively) (p < 0.001). The normalized thickness of the deep layer <i>h<sub>1</sub></i> was 0.68±0.20. After the trypsin digestion, the parametric values decreased to <i>Ha<sub>1</sub></i> = 13.6±9.6 MPa, <i>Ha<sub>2</sub></i> = 6.7±11.5 MPa, <i>Ha<sub>3</sub></i> = 2.7±3.2 MPa, and <i>h<sub>1</sub></i> = 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.},
DOI = {10.3970/mcb.2010.007.045}
}