Comparative Rheological Characterization of Hyaluronic Acid Viscosupplements for Synovial Fluid Restoration in Osteoarthritis and Knee Biomechanics

Synovial fluid (SF) rheological properties deteriorate progressively in knee osteoarthritis (OA) due to a reduction in hyaluronic acid (HA) concentration and molecular weight, compromising joint lubrication and load distribution. Restoring these properties through intra-articular viscosupplementation with HA is a widely used therapeutic strategy. However, commercially available linear HA formulations differ substantially in their mechanical behavior, and single-parameter assessments are insufficient for capturing their functional differences. In this study, eight commercially available intra-articular linear HA hydrogels—TrHLINE 1%®, TrHLINE 2%®, Hyalubrix®, Hyalgan Bio®, Pronolis® HD 2.5%, Biolevox™ HA ONE 2.5%, Suplasyn®, and Arthrum H 2%®—were evaluated under standardized conditions using steady-state viscosity, mechanical stress response, first normal stress difference (N1), storage and loss moduli (G′, G″), loss factor (tan δ), and elasticity percentage. Results revealed three distinct functional profiles: lubricant-oriented with low to moderate structural organization (Hyalgan Bio®, Suplasyn®, TrHLINE 1%®); balanced viscoelastic with sustained structural persistence (TrHLINE 2%®, Hyalubrix®, Arthrum H 2%®); and high initial rigidity with reduced dynamic persistence (Biolevox™ HA ONE 2.5%, Pronolis® HD 2.5%). These findings demonstrate that multi-parametric rheological benchmarking effectively discriminates functional differences among HA viscosupplements and supports indication-oriented product selection based on OA severity and patient mechanical demand.