Fig 1.
Rheology of clinical HA formulations.
(A) Flow sweep experiments revealed shear thinning behavior of all HA formulations, but orders of magnitude variations in dynamic viscosity were evident. (B,C) Storage and loss moduli of the same HA formulations as a function of angular frequency.
Table 1.
Carreau-Yasuda model parameters for 6 clinically approved HA viscosupplements.
Interestingly, the zero shear viscosities (i.e., η0) of these formulations spanned more than two orders of magnitude.
Table 2.
Viscoelastic properties of the HA formulations for three different angular frequencies, ω.
Fig 2.
(A) All HA formulations exhibited decreased friction as a function of increased sliding speed. (B) However, presenting friction as a function of the Sommerfeld number (S, Eq 2) did not collapse all of the data onto a master friction curve when S was calculated based on η0 values obtained in Table 1 (n = 4 samples per group).
Fig 3.
Calculation of an effective lubricating viscosity (ηeff) collapsed all of the data onto a master friction curve with friction coefficient as a function of the Sommerfeld number (Eq 3).
Fig 4.
R2 values for pair-wise comparisons of rheological properties, friction properties, and changes in WOMAC from baseline.
Red indicates poor correlations and blue indicates strong correlations. Bolded values indicate significant correlations with p < 0.05. Of note is the correlation between frictional properties and change in WOMAC.
Fig 5.
(A,B) Collection of data from all products studied indicated that rheological properties (i.e., η0 and G’) were not predictive of mean change in WOMAC score from baseline. (C,D) However, the effective lubricating viscosity (lubricating viscosity (ηeff) and friction coefficient (μ) provided strong correlations with the clinical data.