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Promoting healing of scar tissue

Anna Coulborn
Clinical Lead
Tissue Viabilty Nurse
The Wound Healing Centres UK Ltd

Scar tissue is a normal response to wounding. However, in some cases, it can become abnormal and unsightly. A variety of methods for reducing potential for abnormal scar tissue can be recommended by the primary care nurse

Scar tissue formation is the normal response to a wound that has healed, and usually consists of a pale, thin line that fades further with time. The wound can be caused by surgery, trauma or a burn on any part of the body, but it has been found that in foetuses during the first two trimesters scarring does not occur.1 When a wound produces a scar, the tissue will be devoid of hair follicles, sweat and sebaceous glands.
As wounds heal, inflammation subsides, granulation tissue abates, the numbers of fibroblasts and endothelial cells decrease, and newly laid down collagen becomes cross linked into thicker bundles - this is the formation of a scar (see Figure 1 overleaf).1

[[Fig 1. Scars]]

Abnormal scars can be classified as 'hypertrophic' or 'keloid'. Both of these types of scars are caused by the overproduction of collagen, and can be unsightly and cause dysfunction with mobility due to contractures at joints. Hypertrophic scarring occurs within the original boundaries of the wound, while keloid scars extend beyond the boundaries of the original wound and invade the surrounding normal skin.2

The exact mechanism by which fibroblasts are stimulated to produce excessive amounts of collagen in abnormal scars has yet to be established and appears to be complex. There may be a different pathogenesis in keloid scarring than in hypertrophic scarring, and more than one mechanism might stimulate the same abnormal scarring.2 Keloid scarring occurs mainly in people of Afro-Caribbean and Asian origin. In the USA about 15% of the population are prone to keloid scarring.1 While hypertrophic scars flatten and soften with time, keloids do not. Keloids usually form over body sites with high skin tension, such as the sternum and deltoid regions (see Figure 2 overleaf). The exception to this is the earlobe, which may also develop pendulous keloid scars.3 
 
Assessment
The impact hypertrophic and keloid scarring can have on individuals cannot be underestimated. Recently there has been a move towards the use of more patient-friendly scar assessment tools. A variety of subjective scar assessment tools have been developed to give an overall impression of the quality of the scar - the most common of which is the Vancouver scar scale. The scale scores pigmentation, vascularity, pliability and scar height, with the sum of scores resulting in a number bigger for hypertrophic scars.4
The Patient and Observer Scar Assessment scale is the only tool to include a component for patients to fill in. The few
studies that have investigated the effectiveness of this scale
have found that it is a reliable, valid and feasible tool that is well suited to everyday practice.5

The Phases Shift Rapid in vivo Measurement of Skin
(PRIMOS) system can be used to evaluate scar surface. It produces a computerised image of the scar, with a high definition and reducibility. PRIMOS is an optical system that produces three-dimensional measurements of the skin surface. A sensitive, high-speed camera records the image using an optical sensor. The PRIMOS system can measure differences in the levels of the skin surface up to 10 mm with a resolution over 0.004 mm.6
 
Treatment options
When selecting treatment options, healthcare practitioners must consider the scar and the implications for the patient, such as the overall outcome expected by the patient, physical and psychological restraints and visual appearance.7  

Topical applications
Topical silicone gel sheeting has been used for more than 30 years to help reduce the size of hypertrophic scars and keloids. It appears to soften, flatten and blanch the scar, making it conformable and improving its appearance, and its clinical efficacy and safety are well established.7,8

In Turkey, a study was undertaken to evaluate the therapeutic activity of topical onion extract in gel form on hypertrophic and keloid scars, focusing on problems such as elevation, hardness, itching and pain.

The researchers concluded that onion extract improved hypertrophic and keloid scars via multiple mechanisms. However, it was statistically ineffective in improving scar height and itching. For this reason, it was suggested that onion extract therapy should be used in combination therapy with an occlusive silicone dressing to achieve a satisfactory decrease in scar height.9

Compression garments
Made-to-measure compression garments are invaluable as a treatment for extensive scarring caused by burn injuries. The garment ensures that pressure is applied uniformly over the body to fit over the scarred areas.3

A combination of therapies can be used successfully; for example, silicone gel sheeting with compression garments.

Steroids
Intralesional corticosteroids have been used since the 1960s to reduce abnormal scars and are now one of the main treatments for keloid scars.3 Treatment with corticosteroids aims to increase the lysis (cell breakdown) of collagen, which helps to flatten and soften the appearance of the scar.
Cryotherapy is an option for the treatment of keloid scarring and can be used in conjunction with steroid injections. Cryotherapy is less invasive - liquid nitrogen is applied to freeze the scar, in a similar fashion to removing warts from the skin.1 

Surgery
Laser surgery is often tried by those patients who are anxious to remove a scar, in particular keloids. It may reduce redness and flatten raised scars, and is suggested for treating severe acne.1

Excision of the scar alone may result in recurrence of the abnormal scar and is, therefore, rarely used as the sole therapy.3 

Radiation
Little research is available on radiation therapy. Despite its cost-effectiveness, the major caution and side-effect is the potential for carcinogenic activity.7

Conclusion
Treatment options are many and varied, but more research into the prevention of hypertrophic and keloid scars could be the way forward. It is expected that there will be more research into cases of foetal wounds that heal without scars forming which may help expand our knowledge about scars and future treatments.

References
1.     O'Kane S. Wound remodelling and scarring. J Wound Care 2002;11(8):296-9.
2.     Pellard S. Epidemiology, aetiology and management of abnormal scarring: a review of the literature. J Wound Care 2006;15(1):44-8.
3.     Beldon P. Management of abnormal scar tissue. J Wound Care 1999;8(10):509-12. 
4.     Nguyen DQA, Potokar T, Price P. A review of current objective and subjective scar assessment tools. J Wound Care 2008;17(3);101-6. 
5.     Stavrou D, Haik J, Weissman O, Goldan O, Tessone A, Winkler E. Patient and observer scar assessment scale: how good is it? J Wound Care 2009;18:171-6.
6.     Roques C, Teot L, Frasson N, Meaume S. PRIMOS: an optical system that produces three-dimensional measurements of skin surfaces. J Wound Care 12(9):362-4.
7.     Smith FR. Causes of and treatment options for abnormal scar tissue. J Wound Care 2005;14(2):49-52.
8     Gold MH, Foster TD, Adair MA, Burlison K, Lewis T. Prevention of hypertrophic scars and keloids by the prophylactic use of topical silicone gel sheets following a surgical procedure in an office setting. Dermatol Surg 2001;27(7):641-4.
9.     Hosnuter M, Payasli C, Isikdemir A, Tekerekoglu B. The effect of onion extract on hypertrophic and keloid scars. J Wound Care 2007;16(6):
25-4.