Characterization of the visco-elastic properties of hyaluronic acid.

BACKGROUND: Hyaluronic acid (HA) is a polysaccharide present in almost all animal tissues, in which it carries out important biological functions, among them, the protection of the joints by lubricating them and dampening the tension in them.

OBJECTIVE: This study compares the viscoelastic properties of several commercial preparations of HA, to determine their suitability for use as viscosupplementation therapy in joint pathology (osteoarthritis).

METHODS: 4 HA hydrogels: Durolane®, Synocrom_Forte_One®, Synvisc_One® and Viscoplus_Matrix® and 4 HA solutions: Ostenil®, Ostenil_Plus®, Viscoplus_Gel® and Orthovisc® were analyzed to compare their viscoelatsic rheological parameters using an oscillatory-rotational rheometer.

RESULTS: With respect to the 4 HA hydrogels, comparison of crossover frequencies allowed division into two main groups: Synvisc_One® and Viscoplus_Matrix®, with crossover frequencies in the order of magnitude of 10-2 Hz, while Synocrom_Forte_One® and Durolane® showed crossover frequencies on the order of 10-1 Hz. Only one of the 4 HA solutions, Viscoplus_Gel®, showed a crossover frequency on the order of 10-2, whereas Ostenil_Plus® and Orthovisc® showed crossover frequencies on the order of 10-1, and Ostenil® remained as a predominantly viscous fluid for frequencies as high as 4.8 Hz.

CONCLUSIONS: The viscoelastic properties of the HA preparations can be ordered according to the values of G∗ (the rigidity, or vector sum of the elastic modulus G' and the viscous modulus G'') at both transition points (0.5 and 2.5 Hz) as follows: Viscoplus_Matrix®  > Viscoplus_Gel®  > Durolane®  > Synocrom_Forte_One®  > Ostenil_Plus®  > Synvisc_One®  > Orthovisc®  > Ostenil®.