title: Osteoarthritic synovial fluid and correlations with protein concentration.
abstract: BACKGROUND
  Osteoarthritis is a common, localized joint disease that causes pain, stiffness and reduced mobility. The effects of osteoarthritis on the extensional rheology of synovial fluid in the knees are not fully understood and consequently require further study.
  
  
  OBJECTIVE
  The purpose of this work is to study the extensional rheology of osteoarthritic synovial fluid and to investigate a possible correlation between synovial fluid protein concentration and extensional rheology. The study will also investigate possible correlations with the shear rheology.
  
  
  METHODS
  21 osteoarthritic synovial fluid samples were studied under extensional flow with a capillary breakup extensional rheometer. Extensional rheological properties were correlated with protein concentration and with shear rheological properties measured in a prior study. Viscosupplement was also studied under extensional flow for comparison.
  
  
  RESULTS
  Extensional rheological properties were found to vary widely between samples, but in general were found to agree with previous studies. No statistically significant correlation was identified between extensional rheological properties and protein concentration. Positive correlations were identified between zero shear viscosity and terminal extensional viscosity (R-squared = 0.73), zero shear viscosity and extensional relaxation time (R-squared = 0.84), and shear relaxation time and extensional relaxation time (R-squared = 0.75).
  
  
  CONCLUSIONS
  Appropriate CaBER operating parameters for study of osteoarthritic synovial fluid were identified. No statistically significant correlation was found to exist between protein concentration and extensional rheological parameters. Positive correlations were identified between several shear and extensional rheological parameters. The reported values for extensional viscosity and relaxation times for synovial fluid were found to be within one order of magnitude with a recent study of post mortem synovial fluid.
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.
authors: Samin
authors: S
authors: Fakhraei
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: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D010003:Osteoarthritis / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D011506:Proteins / Q000378:metabolism*; D012212:Rheology; D013582:Synovial Fluid / Q000378:metabolism*; D014783:Viscosity
chemical_list: D011506:Proteins
keywords: CaBER; osteoarthritis; relaxation time; shear rheology; surface tension