Short Notes in Plastic Surgery

September 30, 2011

Skin grafting on granulating wounds

Filed under: Chapter 6 — mthatte @ 4:09 am

1. The take of a graft on granulating wounds is dependent on the health of the capillaries as well as their number. In fact a granulating surface is a bed of capillaries.
2. Traditionally a healthy (ready to receive a graft) granulating wound is described as pink and also the one which bleeds on touch. Of these the latter might not be always true. The word pink is also subjective. On the other hand a wound which discharges very little over a period of several hours as seen from the dressing that covers it, has no overt suppuration, which shows tell tale signs of epithelialisation at its margin and is painless can be called as fit to take grafts.
3. It is to be expected that general debility, hypoproteinaemia, anaemia, or the not so common condition called scurvy in modern times will influence the quality of capillaries as well as the basic protein building blocks which helps in the take and consolidation of grafts.
4. A good granulating wound emerges from a situation where first there is dead tissue which is allowed to separate, or where removal of dead tissue is helped by a chemical agent or where the dead tissue is mechanically excised. The first two take time and granulation tissue comes on naturally. In mechanical excision planes are difficult to find excision is not always complete, expectations are high but more than one excision might be needed. The one exception to this in modern times is tangential excision in burn wounds where the excision is continued in one go over a limited area till the bed bleeds. Large fresh friction wounds, or contused lacerated or avulsed skin following for e.g. traffic accidents belong to the same category as burn wounds.
5. Preparation of a good granulating surface is a matter of both, judgment and craft. In a large majority of cases a suitable antibiotic is already being administered as the wound sheds its slough. As granulation starts forming the liquid used to dress the area should be as far as possible be homeostatic and normal saline therefore is a common and sensible choice. Most other chemical applications are likely to have a corrosive effect on the young capillaries. Application of local antibacterial (or antibiotic) ointments or creams can be best described as empirical or traditional usage and probably serve little purpose. In any event powders are to be avoided, they tend to ‘cake’ and insinuate into crevices within the granulation tissue.
6. For granulating areas which appear indolent pale and are of considerable duration and therefore have a collagenous deposition within them and also some sparse epithelialisation, it is a good idea to scrape and scrub them mechanically or even to take off its superficial layers by tangential excision by a skin grafting knife till they bleed. This bleeding stops with pressure and after the bleeding stops, a wet absorbent pressure dressing over the area will render it very suitable for a subsequent grafting in a couple of days. This is particularly true of extremities.

Indolent pale granulation tissue on the foot and the lower leg, post-traumatic, 3 weeks old, scraped and grafted immediately with a reasonable take of graft. It will be necessary that these grafts are nursed over a period of time so that an almost perfect result will be obtained over the next several weeks (to the right).  Contributed by Bharati Khandekar, Dombivali

Example of a large granulating wound ready for skin grafting with no need for any further preparation. The white areas seen in the pre-operative photos are an artifact because of the flash. Late post-op picture shows how an ordinary split skin graft not only serves the functional purpose but is aesthetically pleasing. Photographs courtesy: Vinita Puri, KEM Hospital, Mumbai

When such areas are on the torso and a circular dressing is impractical care must be taken to stop the bleeding on the table by spending more time. The back of the torso will any case be pressed by the bed when the patient is in supine position, it is the front which needs observation.
7. As a general rule thin split grafts are used for granulating wounds. For a smaller area they are meshed in proportion of 1 to 1 but larger areas where donor areas are limited the grafts can be expanded in a proportion of one to three or four. Any further expansion will lead to fragmentation and will not allow them to be laid down as sheets. A meshed graft has a greater running length because of the holes within the grafts and the circumferential edges of the holes contribute handsomely to epithelialisation. In the closure of large wounds, closure takes precedence over appearance and function and therefore expanded meshed grafts are preferred. The paucity of donor areas has already been mentioned earlier.
8. When grafting needs to be done both on the front as well as back of the trunk, it is preferable that one side is done at a time. When done on the front the grafts can be kept exposed with a thin layer of Vaseline gauze covering them. The grafts are therefore open to inspection and can be attended to if they collect fluid underneath them. These grafts will consolidate in a matter of days when the back can be grafted. To use the exposure method on the back can be difficult. To lie in a prone position for two or three days can be very uncomfortable. Even the lateral position will invariably mean that the patient’s position will have to be changed. This can only be done by lifting the patient clearly of the bed which needs manpower. The closed method of dressing is therefore the only option left. This dressing should be inspected every twenty four hours.
9. With the advent of staples fixing grafts has become very easy and quick. But this comes with a rider. When dressings are removed they might get entangled in the staples and as the staples get lifted the graft can get disturbed and sometimes might get lifted from its bed. Since these dressings are done within a couple of days of the surgery this event is a mini disaster. The surgeon should do these dressings when he has enough time on hand and remove these dressings with utmost care. V. Bhattacharya of Varanasi adds that the contents of this paragraph may be controversial.
10. At the time of the first inspection the take of the graft might not be satisfactory though they are stuck to the bed. This usually means a “dermal take”. An expectant approach needs to be taken in this situation. Loose and floating grafts can be trimmed and any collection of fluid underneath should be squeezed out through the partly closed holes of the mesh or from the side of the graft. Gentle pressure over the whole area will also help.
11. Any graft which looks pale or white is best removed because it can serve as a source for infection.

Dr. Abbas Mistry from Mumbai adds that splintage helps in all kinds of wounds particularly on the extremities and such splintage when used even for wounds which are granulating when they are being prepared for  skin grafting will help prevent contracture.

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