**2. Thermal collagen contraction basics**

Soft tissue contouring depends upon deflation and contraction. As we age, collagen stretches, fragments and attenuates whether in the dermis, fibrous septae, connective tissue around fat lobules, retaining ligaments, SMAS or other fascia. Soft tissue laxity is a result of decreasing underlying support from atrophy of the dermis, fibrocollagenous and vascular matrices, adipose layers, muscle and bony mass. In particular, skin laxity is evidenced by decreased type 1 collagen formation, increased degradation of the extracellular matrix and overall loss of dermal elastic recoil. Attempts at modifying the deep dermal tissue level with superficial liposuction have been met with mixed results of skin shrinkage, and not uncommonly are associated with adverse events such as pigmentation changes, chronic induration, seroma, surface irregularities, and full thickness skin necrosis. Consequently, attempts to restore collagen fibers safely and predictably has become the focus of

*Contractile Effects of Radiofrequency Energized Helium Plasma on the Fibrous Septal Network DOI: http://dx.doi.org/10.5772/intechopen.97849*

liposuction research. Collagen fibers rapidly contract approximately one third the resting length, in response to heat to an extent that is dependent upon the temperature and duration of the temperature [2]. The temperature at which collagen denaturation occurs is 66.8° C, depending upon the tissue type [3, 4]. Thermally induced soft tissue contraction that follows is a product of the wound healing response that includes neo-collagenesis, restructuring of collagen fibers and tissue remodeling. These same changes reinforce the use of tumescent solution during liposuction to reduce the energy conductance of tissue, to reduce tissue impedance and distribute delivered heat. It has been observed that the behavior of collagen fibers changes with the aging process, making heat assisted lipo-contouring more challenging in older patients. It is believed that in older skin, collagen is less responsive to thermal energy because irreducible multivalent cross links replace the heat labile collagen intramolecular bonds found in younger skin [5]. Effectively altering the thermomechanical behavior of tissue constituents embedded in a plexus of collagen and elastin is then the primary mechanism of energy assisted lipo-contouring in patients of all ages.
