3. Skin grafting
1. A ‘Skin grafting’ is performed when skin is lost and the resultant defect cannot be closed primarily or will not heal satisfactorily, that is it will heal by deposition of fibrous tissue with thin layers of epithelium on the surface. This type of healing can lead to contracture, instability and frequent and troublesome ulceration. When such areas are large for e.g. in burn wounds they invariably lead to altered homeostasis in the individual.
2. Skin grafting can only be done on vascular beds or beds which are capable of and ultimately produce healthy granulation tissue. Skin grafting therefore cannot be done on bare bone or tendons. However, periosteum and paratenon will accept skin grafts because they are vascular structures and are the extrinsic supply of bone and tendons.
3. In large fresh wounds or wounds of large dimensions which are covered by healthy granulation tissue thin split skin grafts are preferred because their ‘take’ is easier and the surgeon’s aim is to close the wound as quickly as possible.
Full Thickness Graft
4. As opposed to the above, small defects in areas that are critical either from the point of view of appearance or function are covered by full thickness skin grafts. This applies particularly to the face. But even here when wounds are granulating split skin grafts may be preferred for rapid closure as in burn wounds of the eyelids so that an ectropion is prevented.
5. In a vast majority of cases, full thickness skin grafting is performed in surgically created defects which are small and are in critical areas, for example in eyelids or elsewhere on the face or on the volar surface of the palm and fingers after release of contractures.
6. Because of their small dimensions a defect left behind by cutting a full thickness graft can be closed by suturing. A full thickness graft can be harvested from the post-auricular area, from the supraclavicular area or the transverse creases of the elbow, wrist or groin (from a non hair bearing area). A hair bearing full thickness graft from the scalp may be used in the area of the moustache or for eyebrows but the results are not very satisfactory. A hair follicular graft for baldness is also a full thickness graft.
7. A full thickness graft for a defect on an eyelid can be taken from the contra-lateral upper eyelid up to one-third of the breadth of the donor eyelid.
8. Generally speaking under Indian conditions grafts taken from areas exposed to sunlight will have a better match in colour when transferred to an area normally exposed to sun light. This refers particularly to the face. When large areas on the face need to be covered in order to avoid excess pigmentation a thick split skin graft from the medial side of the arm is a good but not ideal option. A fair amount of skin is available from behind the ear and when both postauricular areas are used, the quantity of skin is doubled. These postauricular wounds can be closed primarily but if almost all the skin is harvested from the area a split skin graft can be applied to the wound.
9. All the donor areas for full thickness grafts indicated above have thin skin. While harvesting full thickness grafts the cutting needs to be meticulous. Even after the graft is cut, it requires to be cleared on its raw surface of any areolar tissue. Some thinning of the dermis is invariably done by a blunt tipped scissors to improve the chances of a ‘take’. A majority of the donor areas are located in transverse creases or along the direction of the elastic tissue (Langer’s Lines) and can be closed and are expected to give imperceptible scars. The wrist crease is by far the best in this regard.
10. A full thickness graft can also be harvested from the inner layer of the prepuce and is now used to cover the raw area left behind by release of chordee in a two stage repair of hypospadias. Similarly a full thickness graft from the labia minora is useful for vulval reconstruction. In post mastectomy reconstruction, full thickness grafts of part of the nipple-areola complex from the contralateral breast are routinely used on the newly created breast mound. Skin can also be used from amputated digits to cover fresh clean wounds on the other surviving digits. But the grafts require careful and adequate thinning.
11. The demands of a full thickness graft for a ‘take’ are high and by a rider so must be the surgical skill employed at the time of the procedure. The size of the defect and the dimension of the graft must be identical and this can be done by cutting a paper pattern that fits the defect, which then is placed on the donor area and marked out prior to infiltration by a vasoconstrictor solution. It must be noted that a defect has a different size as compared to the original lesion which is excised. Infiltration for vasoconstriction, expands skin and distorts dimensions.
12. In view of its thickness there have been some reports that revascularization of a full thickness graft can occur through its edges from the periphery in addition to the normal revascularization from the bed.
13. In view of this, once haemostasis has been secured in the bed of the defect and the graft has been cut and trimmed, it should be carefully sutured to the edges of the defect. One end of the sutures can be left long and tied over a bulky soft padded dressing.
14. Such a dressing can be left alone for several days, even for a couple of weeks if there are no complaints of local discomfort. This waiting allows the area to be fully rested and is the most important factor for the graft’s revascularization. When the dressing is removed and the graft is stable, some moisturising substance may be applied regularly to the graft as it is incapable of providing it on its own immediately.
John Reisburg Wolfe is usually given the credit for describing the technique of using a full thickness graft in the treatment of ectropion though Lawson, a contemporary surgeon had used such a graft for an ectropion but had not given details of the technique of exact measurement by a pattern and the method of application. Wolfe was born in Poland (Breslow, 1823) and because of fear of religious persecution arrived in Scotland in 1845 (Glasgow). He was enrolled as a medical student but also taught Hebrew. His training in Ophthalmology took place in Paris, France and while in Paris he published a paper on Iridectomy for glaucoma and served as the Paris correspondent of Lancet. After returning to Scotland he established the Glasgow Institute of Ophthalmology and became a fellow of the Royal College of Surgeons of Edinburgh. His paper on the treatment of ectropion by a full thickness graft appeared in the British Medical Journal in 1875. He died in Glasgow in 1904. (Phil Sykes, Archivist)
15. Splintage or pressure are normally not possible or required on the face when the graft survives and takes well. In areas such as the hand, which moves constantly the graft might need some protective dressing or a temporary protective splint.