ARTICLE | PHOTOTHERAPY | molecules and charged ions, and converts this
mechanical energy into heat causing above-normal temperatures in the dermis and hypodermis, without affecting the epidermis (non-ablative). The dermis contains elements specific to the skin and
is composed of a mixture of cells, whereas fibroblasts are the main cells of the dermis and the extracellular matrix (ECM). The fibroblasts secrete ECM components that comprise collagen-sensitive reticular fibres, elastin and other proteins. The collagen fibres (type I) are delicate, unbranched fibres that form the structure of the dermis and give strength and firmness to the skin. The collagen enzyme specific to that matrix (collagenase MMP-1) is capable of initiating the degradation of collagen type I. The main applications known are for soft facelifts or skin tightening, the treatment of cellulite, and now stretch mark treatment under certain conditions42–47
.
Radiofrequency and stretch marks The endothermic reaction causes a number of phenomena, approved by the Food and Drug Administration (FDA) in March 1999, which led us to imagine the interest that we could hope to draw in the treatment of stretch marks. Studies have shown that heating human skin with RF causes an immediate contraction of collagen48–51
. Collagen
fibres become shorter and thicker, causing an overall contraction of the tissue. The mechanical effect of warming the collagen can be reversible (i.e. partial denaturation) or irreversible (complete denaturation). Moderate warming results in a local deployment in the collagen, leading to shrinkage; it seems that the collagen regains its original structure once the temperature is returned to normal levels. The deployment of the collagen fibres is a result of the rupture of a small number of consecutive hydrogen bonds52, 53
. The other immediate effect of applying mild heat to
the bipolar RF is causing the migration and proliferation of the fibroblasts47
(it is important not to exceed 40 at the
surface of the skin, causing denaturation of the new collagen fibres through excessive heat). The skin is quickly tightened, firmer and smoother. Visible effects occur from the third or fourth session of treatment on stretch marks: the red colour of recent stretch marks disappears, swelling on the outer edges of stretch marks is reduced, and the stretch marks are filled and smoothed. RF can be used on any skin type, at any time of year.
Specific publications on stretch marks As previously mentioned, one of the first studies41
was
conducted at the hospital of La Piti• Salp‘t ri’ re, Paris, by a private company. Dr Manuskiatti, Professor of Dermatology and Head of Siriraj Skin Laser Center, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, commented: ÔS tretch marks are a skin disease that has traditionally been very difficult to treat. The study confirms that collagen remodelling induced by radiofrequency is an effective mechanism to improve the appearance of [the] stretch marksÕ surface. The technology produces measurable results that have been
48 ❚ March 2012 |
prime-journal.com Studies
have shown that heating human skin with RF causes an immediate contraction of collagen.
.
Collagen fibres become shorter and thicker, causing an overall contraction of the tissue.
Figure 4 Patient four (A) before and (B) after treatment
maintained during the period of follow-up and without painÕ 54
.
Study results Three criteria were chosen to estimate the degree of satisfaction to the patient: ■ Visual appearance in the improvement of stretch marks (width, length)
■ Changes in the skinÕs surface over the treated areas (smoother, tighter skin)
■ Disappearance of the ÔfracturesÕ when the skin is pinched or folded at the area of stretch marks
■ Disappearance or decrease in the number of stretch marks.
At the end of treatment, the doctor responsible for
treatment carried out an objective assessment of the visual results with the patient, by comparing them with pictures that were taken before the initiation of treatment. After merging the three criteria of evaluation and
taking as a base of calculation 100% representing 103 subjects who participated in this study, the percentages of improvement were: ■ Non-responding patients 5% ■ Treatment protocol not completed 4% ■ Interruption of the treatment by the patient 8%. The causes of interruption before the end of treatment
included non-responders, pregnancy, treatment considered too hard by the patient, moving, and occupation inconsistent with the strict protocol followed to stay within the framework of this evaluation.
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