%0 Journal Article
%T In Vivo Evaluation of the Skin Tensile Strength by the Suction Method: Pilot Study Coping with Hysteresis and Creep Extension
%A G¨¦rald E. Pi¨¦rard
%A S¨¦bastien Pi¨¦rard
%A Philippe Delvenne
%A Claudine Pi¨¦rard-Franchimont
%J ISRN Dermatology
%D 2013
%R 10.1155/2013/841217
%X From an engineering standpoint, both the skin and subcutaneous tissue act as interconnected load-transmitting structures. They are subject to a variety of intrinsic and environmental influences. Changes in the cutaneous viscoelasticity represent an important aspect in a series of skin conditions. The aim of this work was to explore the methodology of biomechanical measurements in order to better appreciate the evolution and severity of some connective tissue diseases. The Cutometer MPA 580 (C+K electronic) was used in the steep and progressive suction procedures. Adapting measurement modalities was explored in order to mitigate any variability in data collection. The repeat steep suction procedure conveniently reveals the creep phenomenon. By contrast, the progressive suction procedure highlights the hysteresis phenomenon. These viscoelastic characteristics are presently described using the 2 and 4£¿mm probes on normal skin and in scleroderma, acromegaly, corticosteroid-induced dermatoporosis, and Ehlers-Danlos syndrome. The apposition of an additional outer contention on the skin altered differently the manifestations of the creep extension and hysteresis among the tested skin conditions. Any change in the mechanical test procedure affects the data. In clinical and experimental settings, it is mandatory to adhere to a strict and controlled protocol. 1. Introduction Measurements of a number of physical parameters characterizing human skin have been attempted over the recent decades. A diversity of devices assessing skin viscoelasticity were used both in vitro and in vivo [1, 2]. They proved to be useful tools for scientists and medical practitioners [3, 4]. Over a large part of the body, the overall viscoelastic behaviour of the skin primarily depends on the skin connective tissue (SCT) structures present in both the dermis and the subcutis, with minimal contribution from the epidermis [5¨C7]. The suction method is one of the most widely used approach for determining some of the biomechanical characteristics of human skin in health and disease [8¨C17]. The progressive suction mode with a stress-versus-strain graphic recording is a convenient way in this endeavour [9¨C11]. In this procedure, a progressive increase in stress suction for a defined period of time is followed by a symmetrical rate of suction release. During the whole process, skin deformation defined as the strain is recorded. Typically, viscoelastic materials exhibit nonlinear stress-versus-strain properties [1, 2, 9, 17]. The hysteresis loop represents the area delimited by the two curves
%U http://www.hindawi.com/journals/isrn.dermatology/2013/841217/