Characterization and comparison of shear and extensional flow of sodium hyaluronate and human synovial fluid.

The focus of this work is on a comparative rheological characterization of sodium hyaluronate (NaHA) samples from fermentative production (NaHA-1, Mw = 1.7 × 106 g/mol) and from rooster comb (NaHA-2, Mw = 4.6 × 106 g/mol) with synovial fluid (SF) taken post mortem from different patients above 60 years. Steady state shear flow and uniaxial extension experiments were carried out for different concentrations of NaHA in 0.01 M phosphate-buffered saline (PBS) and on several SF samples.The synovial fluid of older patients was found to have a viscoelasticity comparable to that of younger patients investigated in earlier studies. Comparison of steady state shear experiments revealed a comparable progression for the viscosity curves of NaHA-2 and SF. This behavior was also observed in extensional flow, where comparable results for NaHA-2 and different SF samples were obtained.