SCARRING

WHENEVER A WOUND IS MADE IN THE SKIN, a scar forms. This may happen accidentally, intentionally, or for a surgical operation. It is not possible to make any sort of wound without producing a scar. This is because the tissue which repairs the deeper part of any wound is always much more coarse (and less organised) than normal tissue.

Sometimes a scar is so fine that it is hardly noticeable, whereas other scars may be extremely disfiguring. Scars of the same type may even produce more disfigurement on one area of the body than another. For example, a narrow 2cm long scar on a person's back may be hardly noticeable, but a similar scar on the face of a young person may be disfiguring and obvious.

If the conditions are right for good scar formation, the resulting scar may be visible only as a fine, white line. In less ideal conditions, the scar may be wide and thick, and sometimes may be raised, red, irritating and disfiguring for years. This latter type of healing is known as "hypertrophic scarring". Some of the reasons for differences in scar healing and "resolution" (settling) are now becoming apparent.

Before		After

FACTORS AFFECTING WOUND HEALING

• Age
• Situation of the scar
• Direction of the scar in relation to the grain of the skin
• Type of wound closure
• Race
• Genetic factors
• Tension
• Security of repair

In general, old people and young babies form the least visible scars, whereas wounds in growing children, adolescents and young people with tight skin tend to produce unacceptable, raised, red, permanent scars. Although these differences may be due to changes in the growth potential of tissue at different ages, it now seems more likely that they are due to differences in the physical properties of the skin, particularly its elasticity or tension.

Skin tension

Skin tension is currently thought to be the most important factor. Skin is like two-way stretch material that has more "give" in one direction than the other. In the direction where there is less give, the tissue fibres are constantly tighter and have less stretchability than those at right angles to them. This means incisions or cuts made in the same direction as this tension are subjected to less pull across their width than wounds made across the lines of skin tension.

It also means they are more likely to heal better and with finer scarring than those made across these lines. Therefore, the location of the wound is most important in determining the way the wound heals and the type of scarring that is left.

Surgeons can now use this information to help with wound healing and reduce scarring by placing incisions, for example, the excision of a tumour, along the lines of skin tension whenever possible. Methods have been developed to enable them to predict accurately the direction of the least, or most, skin tension.

If an accidental wound occurs in the right direction of the skin tension it may heal on its own with relatively little scarring. However, if a wound occurs in the other direction it is likely to produce a noticeable permanent scar, even though it may have been carefully sutured and looked after.

Repairing scars

In the past surgeons have tended to avoid operating on hypertrophic scars because surgical intervention often made them worse. Patients were usually advised that nothing could be done to help them until nature had run its course and the scar had started to soften spontaneously. This process often took several years and during this time people who had extensive scarring on their faces, for example, had to endure the severe psychological and emotional trauma that went with it.

A more thorough understanding of skin tension has led surgeons to realise that there is generally no point in trying to improve the quality of scarring by excising the old scar and carefully closing the wound again in the same direction. If the conditions were not ideal for scar formation with the first wound, they are unlikely to be any better a second or third time. In fact, they may be worse because the excision of the scar will produce more tension and make the scarring more noticeable.

THE MULTIPLE W-PLASTY PROCEDURE

Surgeons have now devised techniques of correcting scars by changing the direction of the wound - and the eventual scar - by making a series of small saw-toothed flaps and darts which, when fitted together, produce a zig-zag effect. None of the lines of the zig-zag runs in the same direction as the old scar. (Diagrams 2a, b, c and d). Practical experience with this type of scar excision has shown that if it is done carefully, it will produce a remarkable improvement in the appearance of the scar and make it virtually invisible.

SKIN PIGMENTATION

One common factor which is still not well understood is the fact that wounds in people of certain races produce more persistent and troublesome scarring than in people of other races. This usually occurs in people with darker skin - Chinese, Indian, Maori, black Africans or black Americans and even people of Mediterranean extraction. All these groups are more likely to develop hypertrophic scars than people of Northern European descent. No one knows why this is, but it may be partly attributable to the organisation and tension of pigmented skin. Also, the behaviour of wound healing cells is probably different in people with darker skin.

Until more is known about the causes of these differences in scarring, surgeons have to be cautious in recommending surgery to people with darker skin and must always warn them of the possibility of post-operative scarring. There is also a risk of developing either increased or decreased skin pigmentation around the wound, or in the areas of skin that are injured or grazed, either accidentally or surgically.

KELOIDS

People occasionally produce quite large masses of raised, red scarring called keloids. These may develop from small wounds or even from skin blemishes, such as acne. These scars are different from the raised hypertrophic scars which seem to occur because of the effects of cross-tensional pull on wounds and which, in many cases, tend to improve with time.

Keloids do not resolve spontaneously and seem to behave like slow-growing tumours, gradually encroaching on to the surrounding skin, often with irregular claw-like extensions. They are usually resistant to treatment, particularly surgical intervention. Various surgical treatments have been devised to try to control keloids, but none has been very successful. There seems to be a strong genetic influence in the production of keloid scarring from parents or grandparents who have produced similar scars.

TREATMENT OF SCARRING

Prevention

There are several measures which can be taken to minimise scarring which has resulted from elective surgical wounds:

• Care can be taken to align the wound along the line of maximum skin tension. The wound can be closed by internal suturing to avoid persistent cross-hatch suture marks.
• After the sutures have been removed, the wound and the surrounding skin can be supported by adhesive paper tape. This relieves the wound of excessive stretch across its width while it heals completely. It can take four to six months for a wound to be strong enough to resist the pull of the surrounding skin, so in important areas it is necessary to maintain proper and adequate support of the wound for the longer period of time.

The paper tape can be worn without any inconvenience, especially if the skin is cleaned first with ether or alcohol to help the grip. It will withstand showering, normal exercise and swimming, and can be replaced weekly or when required.

Steroid treatment

The irritation and tenderness from thickened hypertrophic scars can be reduced by injections of a strong steroid such as Triamcinolone or Kenacort-A. Steroids appear to decrease the metabolic activity of the cells, which causes the thickened scar process. By overcoming the increased activity of these cells, the scar will quickly soften and flatten within 10 days and become less irritating.

A second injection can be given after six weeks but the activity of these injections lasts for about three months, so time must be allowed for the injection to work completely before further treatment. It is important that the injections are not given too frequently because they may cause skin thinning, ulceration and the development of new, superficial blood vessels. Steroid injections will not eradicate the scar completely.

Surgical correction

It is best to leave wounds to settle for as long as possible before trying to correct them surgically. The multiple W-plasty procedure is extremely effective for treating some resistant scarring. This can be carried out in hospital on a day-stay basis using local anaesthetic and sedation. Sometimes the operation may take two to three hours to complete successfully. For example, a scar extending from the corner of the mouth to the ear may take three-and-a-half hours to correct. This can be done quite successfully under local anaesthetic.

A scar revision operation must be done meticulously to produce ideal results. For this reason, surgery may be expensive because of the time taken for the operation.

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