The Static Stiffness Index: an important parameter to characterise compression therapy in vivo.

The compression pressure, which corresponds to the dosage of compression therapy, has been widely neglected up to now, not only concerning scientific literature, but also in clinical practice. It is evident that compression pressures in the upright position and during walking are clinically more relevant than just the resting pressure. The Static Stiffness Index (SSI), which is the difference between standing and resting pressure, is a valuable parameter characterising the efficacy of a specific compression product to narrow/occlude the venous lumen. This is a prerequisite for reducing venous reflux and exerting a massaging effect necessary to improve the venous pumping function during movement. This article provides an overview of the recent literature on the SSI, which supports the recommendations of the International Compression Club. In addition, it aims to provide an insight on the importance of the SSI in daily practice, as an educational tool as well as in defining the properties of applied compression therapy in clinical research.