Assessing the Practical Application of Rheological Properties of Hyaluronic Acid Fillers: A 1-Year Follow-Up Photographic Analysis.

BackgroundA hyaluronic acid filler is a viscoelastic substance that can be evaluated by rheology. Rheological properties are important for the longevity of the filler, which can be deformed due to the various forces that exist on the face. This study aimed to evaluate the maintenance of the lifting capacity of hyaluronic acid filler injection.MethodsRheological evaluation of five different products was performed on nine patients who had undergone hyaluronic acid filler injection from Jan 18, 2021 to Jan 27, 2022. Photographs from different time points up to 1 year after filler injection were used to determine the maintenance of the lifting effect of the filler injection.ResultsAfter 1 year of follow-up, the filler on the forehead, temple area, nose, chin, nasojugal fold, and mid-cheek groove areas showed good maintenance, while the nasolabial fold slightly improved.ConclusionsAppropriate rheological parameters of hyaluronic acid fillers should be considered before injection into different facial areas. A good choice of filler can result in a good aesthetic effect 1 year after injection.Level of Evidence VThis journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.