Rheology of synovial fluid¹

Article type: Research Article

Authors: Schurz, J. | Ribitsch, V.

Affiliations: Institut für Physikalische Chemie, Karl-Franzens-Universität, Graz, Austria

Note: [1] Dedicated to Prof. Dr. h.c. multo Otto Kratky on the occasion of his 85th birthday.

Note: [] Accepted by: Editor D. Liepsch

Abstract: After a discussion of the role of synovial fluid as a joint lubricant, rheological measurements are described with both normal (healthy) synovial fluids and pathological ones. Shear stress and first normal stress difference are measured as a function of shear gradient to calculate the apparent shear viscosity η′ and the apparent normal viscosity ψ1 as well as an apparent Shear modulus G′. It is found, that in case of diseased synoviae all rheological parameters deteriorate. Most significant changes are observed with the zero shear viscosity η0 , the shear modulus G′, and a characteristic time θ which is the reciprocal of the critical shear rate Dc which determines the onset of shear thinning. The rheological deterioration of synovial fluids is explained in terms of solute structure. whereby a molecular rmass of the backbone hyaluronic acid of at least 107 g.mol−1 is required for satisfactory function. A theory of the rheological performance of normal synovial fluid as well as its pathological deterioration is proposed.

Keywords: synovial fluid, rheumatic joint diseases, viscosity curves, viscoelasticity, shear modulus, hyaluronic acid

DOI: 10.3233/BIR-1987-24404

Journal: Biorheology, vol. 24, no. 4, pp. 385-399, 1987