Rheologic properties of soft tissue fillers and implications for clinical use.

[BACKGROUND] The use of injectable soft-tissue fillers has become an essential tool in esthetic rejuvenation. Rheology, the study of flow of matter, helps to understand the function of these products.

[AIMS] The purpose of this article is to review the rheologic properties of soft-tissue fillers currently available in the United States and to evaluate how these properties relate to clinical performance.

[METHODS] This article explains basic rheologic terms and describes how rheologic properties of specific soft-tissue fillers affect filler performance.

[RESULTS] The currently available soft-tissue fillers have unique rheologic and physicochemical properties that influence performance and cosmetic outcome. These properties determine that filler product is most appropriate based on degree of soft-tissue defect and anatomic location.

[CONCLUSION] It is imperative for physicians to have an in-depth understanding of the rheologic properties of soft-tissue fillers in order to appropriately select and utilize these products for the desired cosmetic outcome.