title: Osteoarthritic synovial fluid rheology and correlations with protein concentration.
abstract: BACKGROUND
  Osteoarthritis is a common, localized joint disease that causes pain, stiffness and reduced mobility. Osteoarthritis is particularly common in the knees. The effects of osteoarthritis on the rheology of synovial fluid in the knees are not fully understood and consequently require further study.
  
  
  OBJECTIVE
  The purpose of this study is to investigate the effects of protein content on synovial fluid shear rheology. A secondary study outcome will include study of the temperature dependence of synovial fluid behaviour.
  
  
  METHODS
  38 osteoarthritic synovial fluid samples were studied under shear flow. Shear properties were correlated with protein concentration. Viscosupplement was used as a comparison and to verify measurement reliability. The effects of temperature were investigated at 20, 29 and 37°C.
  
  
  RESULTS
  Shear rheological properties were found to vary widely between samples, however all samples demonstrated clear non-Newtonian shear thinning behaviour. In general viscoelastic properties were lower in osteoarthritic samples than previously studied healthy synovial fluid. A moderate correlation was observed between synovial fluid dynamic moduli at a frequency of 2.5 Hz and protein concentration. Temperature was found to affect the rheology of osteoarthritic synovial fluid and was fitted with the Arrhenius model.
  
  
  CONCLUSIONS
  Increased protein concentration has been correlated with decreased shear rheological parameters. Temperature dependence of synovial fluid was also demonstrated and modelled for use in Part 2 of this article.
authors: Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada.|Biomedical Engineering Program, University of British Columbia, Vancouver, BC, Canada.
authors: Anwar
authors: A
authors: Madkhali
authors: Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada.|Biomedical Engineering Program, University of British Columbia, Vancouver, BC, Canada.
authors: Michael
authors: M
authors: Chernos
authors: Department of Mechanical Engineering, University of British Columbia, Vancouver, BC, Canada.|Biomedical Engineering Program, University of British Columbia, Vancouver, BC, Canada.
authors: Dana
authors: D
authors: Grecov
authors: Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC, Canada.|Biomedical Engineering Program, University of British Columbia, Vancouver, BC, Canada.
authors: Ezra
authors: E
authors: Kwok
mesh_terms: D004548:Elasticity; D006801:Humans; D010003:Osteoarthritis / Q000503:physiopathology*; D011506:Proteins / Q000378:metabolism*; D012212:Rheology; D013582:Synovial Fluid / Q000502:physiology*; D014783:Viscosity
chemical_list: D011506:Proteins
keywords: Rheopexy; centrifugation; dynamic moduli; temperature