Integrated mechanical and structural characterisation of 24 commercial hyaluronic acid fillers: A multi-parametric framework for comparative analysis

The clinical performance of hyaluronic acid (HA) dermal fillers depends on their mechanical and structural characteristics, as well as their susceptibility to enzyme degradation (hyaluronidase), yet current evaluations often rely on single-point measures. This study examined twenty-four commercial HA fillers under injection-relevant conditions, combining oscillatory shear rheology, enzymatic degradation assays, and uniaxial tensile testing to develop an integrated assessment framework. Their structure at the nanoscale was also examined with small-angle X-ray scattering. The findings indicate that nonlinear rheological metrics, combined with tensile and enzymatic degradation profiles, provide a more comprehensive understanding of filler behaviour than conventional oscillatory shear moduli alone. This multi-parametric approach may support evidence-based product selection, enabling better matching of filler properties to anatomical site requirements, mobility demands, reabsorbability and biodegradability needs in clinical practice.