The biomechanical properties of cartilage are governed by the dominant polymeric components of the cartilage matrix: proteoglycans (mainly aggrecan-hyaluronic acid complexes) and collagen (mainly type II). The anionic proteoglycan assemblies entrapped in the collagen network exhibit high osmotic swelling pressure and define the compressive resistance to external load. The collagen network counterbalances the swelling pressure and provides resistance to tension. The load bearing capacity of cartilage varies with depth from the articular surface. The depth-dependence of physical properties reflects changes in the composition (e.g., water content, proteoglycan content) and changes in the orientation of the collagen fibers that varies from the surface to the bone. With aging the compressive modulus and proteoglycan concentration decreases, while the collagen content only weakly varies. The load bearing ability of cartilage is also strongly altered with diseases (e.g., osteoarthritis). Our objective is to determine the dependence of the osmotic swelling pressure on the composition of cartilage using a home built tissue micro-osmometer. In addition we make scattering measurements (small-angle neutron scattering, static and dynamic light scattering) and AFM nanoindentation measurements on well-controlled biomimetic model systems to gain insights into the organization of tissue components and to map the local mechanical and osmotic properties of cartilage.

Effect of osmotic stress on the structure and biomechanical properties of cartilage

248th National Meeting (2014)

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