T H E SKIN-DERMIS G R A F T AS AN ALTERNATIVE TO

T H E DIRECT OR T U B E D FLAP

By WILFRED HYNES, F.R.C.S.

Plastic and Jaw Department, the United SheffieM Hospitals

FLAPS (local, direct, or tubed) are used to provide cover for defects for which skin grafts are unsuitable for one reason or another. Thus skin cover by means of a flap is recommended if the base of a defect consists of tissue with a scanty blood supply, i f the repaired area will be required to bear pressure, or i f the defect is :in the neighbourhood of a joint or other mobile structure where contractures are apt to occur.

Local flaps have much to recommend them but the more ambitious flaps have :many disadvantages. The direct flap and the tubed flap require multiple operations over a long period ; they may involve the patient in uncomfortable "ac roba t i c" positions ; they are subject to necrosis by reason of hmmatoma or by a deficiency in their blood supply ; and they are particularly hazardous in fat or elderly patients.

The full-thickness Wolfe graft " takes " with difficulty on defects whose vascularity is deficient. When it does " take " on a suitable defect, however, it possesses some of the advantages of a flap in that it does not contract and can sustain pressure and withstand considerable wear and tear, qualities which are due to the thickness of its dermal layer. The dermis is, in fact, the most important constituent of any skin graft-- the thicker the dermal layer, the greater is the stability of the graft and the less is its tendency to contract.

I t follows that i f a skin graft with a very substantial layer of dermis could be persuaded to " t a k e " on a defect in an ischmmic area, on a pressure-bearing area, or in the neighbourhood of a joint or other mobile structure, it would provide a hardy, durable skin cover which would subsequently undergo little or no :shrinkage. I t would therefore obviate the use of direct flaps or tubed pedicles in a proportion of the cases for which these are now normally required.

The method described below provides, by means of a free graft, a skin cover containing a layer of dermis as thick as, or thicker than, that in an ordinary full- thickness Wolfe graft, and it has been used instead of a cross-leg flap or abdominal tubed pedicle to replace extensive, unstable scars on the lower limb adherent to underlying sclerosed bone. The writer has called this type of skin graft a dermis- :skin graft as it consists of two main layers--a thick split-skin graft and an equally thick layer of dermis--with a small quantity of fat between them.

The survival of such a dermis-skin graft depends on the fact that dermis, without its epithelial cover, " takes " as a free graft much more readily than does an ordinary split-skin graft of equal thickness ; the reason for this is discussed later. Such a thick dermis graft not only "take3 " on freshly prepared defects involving healthy tissue but it also " takes " readily on defects covered by healthy granulation tissue. In this way a dermis graft can be used to cover ischmmic ,defects which have been allowed to granulate to increase their surface blood supply.

The structure of the deep surface of the dermis is of considerable importance. 2 A 97

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When the subcutaneous fat is dissected from the overlying skin the deep surface of the dermis thus exposed is seen to be dead-white in colour and to present a large number of small greyish " pits " (Fig. I). This appearance is very familiar to the surgeon who unwittingly dissects too close to the skin while raising a flap of skin and fat. The number of these dermal " p i t s " varies with the thickness of the skin, being very numerous in thick skin (e.g., of the back, thigh, and extensor and outer aspects of the arm and forearm) and less numerous where the skin is thin (e.g., the anterior abdominal wall, the inner aspects of the arm and forearm, the neck, the post-auricular regions, and over the clavicles).

FIG. I

T h e deep surface of the dermis showing numerous " pits." × 6.

Each " p i t " contains either the follicle of a hair or the proximal end of a sweat gland, surrounded by a plug of fat which can be seen on microscopic examination (Fig. 2, B), even though, on naked-eye inspection, the dermis appears to have been completely stripped of fat. When a Wolfe graft is cut from a donor area where the skin is thick, about 4 ° per cent. of its deep surface is occupied by these " p k s " with their contained islands of fat (Fig. 2, h). When such a Wolfe graft is used to cover a defect, only about 6o per cent. of its deep surface is therefore available to receive tissue fluid and, later, blood from the surface of the defect, the remaining 4o per cent. being useless for this purpose owing to the presence of these small islands of fat. A Wolfe graft, cut from a donor area where the skin is thin, has fewer " p i t s " on its deep surface, about 8o to 9o per cent. of which is therefore available to receive nourishment from a defect on which it it placed. This explains why Wolfe grafts, especially thick ones, " take" satisfactorily only on highly vascular defects (e.g., on the face and hand) and why they so often fail

THE S K I N - D E R M I S GRAFT 99

A

B

FIG. 2

Horizontal sccdon through the deepest layer of the dermis.

A, Showing the " pits ." x 6.

B, Showing a single " pit " which contains both a hair follicle and a sweat gland surrounded by a plug of fat. x 60.

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in less vascular areas. By contrast, an ordinary split-skin graft " takes " on most defects as the whole of its fat-free dermal surface is available for the reception of tissue fluid and blood from the host. The deep surface of clavicular skin appears to possess fewer " p i t s " than does skin from any other area, and skin from this site should therefore provide the best material for a Wolfe graft.

I f the surface epithelium of a thick Wolfe graft is removed and the thick layer of dermis (i.e., the dermis graft) so formed is then placed on a leg or other defect in a reversed position (i.e., with its superficial surface lying on the defect and its " pi t ted" deep surface lying superficially), it will " t a k e " very readily as, like an ordinary split-skin graft, it now presents the whole of its fat-free dermal surface to the vascularising influence of the host. When such a reversed, thick dermis graft " t a k e s , " the small islands of fat which lie in the " p i t s " of what is now its superficial surface also survive, as they receive tissue fluid and blood from the living dermis on which they lie through their common blood supply.

This manoeuvre of using a thick dermis graft in a reversed position therefore provides a defect with a cover consisting of almost the whole thickness of a thick layer of skin, together with a small amount of living fat on its surface ; and this dermis-fat layer is so vascular when it has " taken" that it will then, in turn, support an ordinary thick split-skin graft placed on its surface in the usual manner. In this way the original defect is finally covered by a dermis-skin graft which consists of two substantial layers--a thick dermis graft with a thick split-skin graft on its surface--with a small amount of fat in between.

TECHNIQUE FOR APPLYING A DERMIS-SKIN GRAFT

The method will be described as applied to an extensive, unstable scar involving the front of the leg and closely adherent to the underlying sclerosed tibia (see Case I below).

Operation x: Preparation of the Defec t . - -The scar (Fig. 3, A) is excised in its whole extent exposing a mass of sclerosed bone. The surface of the thickened tibia is chipped away with a hammer and chisel until bleeding bone is encountered ; this occurs when the deeper layers of the cortex are reached and there is no fear of weakening the tibia which is usually massively enlarged. A simple dressing is applied and is left untouched for a week. After this the wound is treated by daily saline dressings for a further ten to fourteen days, by which time it is usually completely covered by flat, bright red healthy granulation tissue (Fig. 3, B) ; the defect is then ready for the next stage.

Operat ion 2 : Appl i ca t ion o f a T h i c k D e r m i s Graft . - -A thick dermis graft of appropriate size is prepared from the skin of the thigh in the following way. Using saline and not petroleum jelly as a lubricant, a thin split-skin graft is first cut from the donor thigh and this skin graft is put on one side for later use. The dermis thus exposed, together with a thin layer of subjacent fat, is then removed from the thigh by knife dissection. After the resulting thigh defect has been covered with a skin graft taken from the opposite thigh, the fat is lightly pared from the deep aspect of the dermis graft by means of curved scissors, until the dead-white surface of the dermis, showing greyish " pits," is encountered (Fig. I). This fat dissection is not carried out too closely, so that tiny scattered clumps of

THE SKIN-DERMIS GRAFT I O I

fat remain adherent to the deep surface of the dermis and, of course, also occupy the " pits " present on this aspect of the dermis.

The thick dermis graft so prepared is applied to the granulating defect in a reversed position, i.e., with its superficial surface on the granulating wound and its deep, " pitted " surface, with its tiny clumps of adherent fat, superficially. Great care must be taken to prevent the dermis graft from tenting over irregularities on the surface of the defect as a thick graft of this nature must lie in close contact with its vascular bed if it is to " take." Tenting of the graft is avoided by stitching it loosely to the edges of the defect without making any effort to keep the graft at normal skin tension ; and, in the case of a defect with a very irregular surface, the dermis graft is applied as a number of separate strips with their edges in contact, and not as a continuous sheet.

The reversed dermis graft is then covered with the thin split-skin graft which was cut from the thigh as the first step in this operation--this skin graft is used as a physiological dressing and is not expected t o " take" (though, as will be mentioned later, it occasionally does). A pressure dressing is applied.

The first dressing is carried out on the seventh day. It will then be found that, as a rule, the thin covering skin graft is not adherent--it is picked off by means of dissecting forceps to expose the thick dermis graft which has " taken " and forms a firmly adherent cover for the original leg defect. Close inspection of the surface of the dermis graft shows that a point of granulation tissue is starting to appear at each of the numerous " pits " and that the small scattered clumps of Fat are alive.

At this stage, therefore, the original defect is covered by a thick layer of dermis on the surface of which is a small amount of living fat. This area is now dressed daily with saline dressings for three to four days, by which time the white surface of the dermis graft will be seen to be moist, due to tissue fluid exudate, and to present at each " pit " a bright red dot of granulation tissue of pin-head size (Fig. 4, c) ; it is now ready for the next stage.

In some patients in whom the granulating leg defect is highly vascular the thin skin graft, which was used as a physiological dressing in Operation 2, will be found to be alive and firmly adherent to the underlying dermis graft at the first dressing. In this event the original defect is covered by what is, in effect, a Wolfe graft, and no further operations are necessary (see Case 3).

Operation 3 : The application of a Thick Split-skin Graf t . - -A th ick split- skin graft is placed on the surface of the " taken " dermis graft and a pressure dressing is applied.

At the first dressing, seven days later, it will be found that this covering skin graft has " taken." The original defect is now, therefore, covered by two main layers--a deep thick layer of dermis and a more superficial thick split-skin graft, with a scanty but useful layer of fat between them.

CHARACTERISTICS OF DERMIS-SKIN GRAFTS

On occasion the final covering thick-skin graft applied at Operation 3 will not " t a k e " in its entirety on the underlying dermis graft, but this need cause no anxiety. Any portion of the dermis graft left uncovered by epithelium in this way will rapidly and completely epithelialise its own surface by the proliferation of the

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epithelial cells of the hair follicle or sweat gland which is present in each exposed " p i t . " Four or five weeks after the application of the dermis graft in Operation 2, naked-eye examination can easily detect the spread o f an epithelial layer around the mouth o f each " p i t " ; this epithelium extends very rapidly over the surrounding exposed dermis until it coalesces with the epithelium growing from adjacent " p i t s . "

The part of the exposed dermis graft, which heals by spreading epithelialisation in this way, remains stable when the patient gets up because it has a firm backing o f dermis. This is in direct contrast to the thin, uns tab le healing which occurs when the residual granulating area, which remains when an ordinary skin graft fails to " t a k e " completely on a defect, is allowed to heal naturally by epithelialisation from the edges.

I t might be thought that a dermis-skin graft, though providing a satisfactory skin cover, could give trouble due to the development of epithelial cysts in its deeper dermal layer. The writer has used dermis-skin grafts in twenty-one cases over a period of two years and has not yet met with this complication. I f such a cyst (or cysts) were to develop in the deep layer of a dermis-skin graft, however, the treatment would be simple in comparison with the difficulties which can be encountered when tubed pedicles and direct flaps are used.

The dermis-skin graft provides a skin cover which does not become adherent to underlying structures. Even when such a graft is placed directly on granulating bone (Cases I, 2, and 3 below) it forms a thick covering layer which can be moved over the bone by the examining finger (Fig. 3, D)--in contrast to the fixation of the skin cover provided by an ordinary split-skin graft when used ,in similar circumstances.

Dermis-skin grafts do not contract and they are therefore especially useful for the repair of defects in the neighbourhood of joints.

CASE REPORTS

Case I . - -L . S., aged 42 years. In this case a dermis-skin graft has l:een used to replace an unstable leg scar for which a cross-leg flap was originally contemplated.

History.--Electric burn ten years previously, resulting in a scar on the lower third of the right leg ; the scar was adherent to the underlying bone and broke down repeatedly (Fig. 3, A),

Operation I (26th June I95I) . --The scar was excised~ resulting in a defect 7"5 by 7"5 cm. ; in the centre of this defect sclerosed bone was exposed over an area of 4 by 2" 5 cm. The sclerosed cortex was removed with a chisel until bleeding bone was encountered and a dry dressing was applied.

Operation 2 (I2th July I95i ) .RThe defect was now covered with bright red healthy granulation tissue (Fig. 3, B). A thick reversed dermis graft was applied and this was in turn covered with a thin skin graft as a physiological dressing.

The wound was dressed one week later when it was found that the covering skin graft had not " taken " ; it was removed with forceps to expose the dermis graft which had " taken " completely.

The patient developed a pulmonary embolism two weeks after this operation and the next stage of his treatment had therefore to be postponed until he had recovered.

Operation 3 (I7th August I95I).--A thick split-skin graft was placed on the surface of the dermis graft applied at the previous operation. This skin graf t" took " completely and the original defect was therefore covered by a skin-dermis graft which was about half as thick again as a Wolfe graft. The patient was allowed to get up ten days later.

THE SKIN-DERMIS GRAFT IO 3

FIG. 3

Case I. An adherent ulcerated leg scar treated by a dermis-skin graft.

A, Before treatment. B, Excised defect covered with healthy granulations. C, The result two years after treatment. D, The result showing the mobility of the skin-dermis graft.

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The result in this case has been most gratifying (Fig. 3, c). Though the patient is doing heavy work and is on his feet all day the graft has never given the slightest trouble during the two years since his discharge from hospital. The graft has the appearance of a thinned cross-leg flap and not only moves over the underlying bone but can be lifted off it by the fingers (Fig. 3, D).

Case 2 . - -K. P., aged 36 years. In this case a dermis-skin graft has been used to replace an unstable adherent scar of the leg for which a cross-leg flap was originally contemplated.

History.--Compound fracture of the middle third of the left leg six years previously, resulting in an unstable papery scar, firmly adherent to the upper half of the tibia (Fig. 4, A).

Operation I . - - T h e scar was excised, creating a defect 15 by 7"5 cm., the inner half of which was occupied by bare sclerosed tibia and the outer half by fibrosed anterior tibial muscles. The surface of the exposed tibia was removed until bleeding bone was encountered in the deeper cortical layers and a dressing was applied.

Two weeks later the defect was covered with bright red healthy granulation tissue (Fig. 4, B) and was then treated by local streptomycin applications for three days.

Operation 2 (seventeen days after Operation I ) . - -A reversed thick dermis graft with some small scattered clumps of fat on its surface x~as placed on the granulating defect and was, in turn, covered by a thin split-skin graft as a physiological dressing.

The wound was dressed one week later when it was found that the covering thin split-skin graft was not adherent ; it was picked off with forceps to expose the reversed dermis graft which had " taken " completely.

Operation 3 (eleven days after Operation 2 ) . I T h e surface of the reversed dermis graft, which now showed a multitude of tiny buttons of granulation tissue lying on a white background (Fig. 4, c), was covered with a thick split-skin graft.

The wound was dressed one week later when it was found that 80 per cent. of the covering sprit-skin graft had " taken." With daily saline dressings epithelialisation was complete two weeks later. The patient was then allowed to get up and Fig. 4, 9 shows the appearance of the graft six months after his discharge from hospital. The skin cover is equivalent to one and a half thicknesses of normal skin and it can be moved easily over the underlying bone. This patient has now been ambulant for over six months and is back at work. The grafted area is intact and shows no sign of breakdown.

Case 3.--A. E. P., aged 36 years. In this case a dermis-skin graft has been used to replace an extensive, unstable, adherent scar of the leg for which an abdominal tubed pedicle would normally have been necessary.

History.--Osteomyelitis in childhcod resulting in an unstable adherent scar which involved the leg over almost the whole length of the tibia (Fig. 5, A).

Operation I . - - T h e scar was excised exlcosing bare sclerosed bone in almost the whole extent of the wound (Fig. 5, B). The surface of the tibia was removed until bleeding bone was encountered in the deep cortical layer. A dressing was applied.

Three weeks later the whole of the defect was covered with bright red flat granulation tissue (Fig. 5, c) which was then treated by local applications ef streptomycin for three days.

Operation 2 (twenty-four days after Operation I ) . - -A reversed thick dermis graft was placed on the granulating defect and was, in turn, covered with a thin split-skin graft.

The wound was dressed one week later when it was found that both the dermis and split-skin grafts had " taken " completely so that the original scar ~as now replaced by what was, in effect, a Wolfe graft. Although the grafts had been placed directly on granulating tibia, the resulting skin cover could be moved over the bcne t y the examining

THE SKIN-DERMIS GRAFT IO~

FIG. 4 Case 2. An adherent leg scar treated by a dermis-skin graft.

A, Before treatment. B, Excised defect covered with healthy granulations. C, The reversed dermis graft eleven days after it had been applied

showing the buttons of granulation tissue lying on a white back- ground.

D, The result six months after discharge from hospital.

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finger. T h e pat ient was al lowed to get up four weeks after the second operat ion, and Fig. 5, n shows the appearance o f the graft six months after the c o m m e n c e m e n t o f

C

FIG. 5

An unstable adherent scar of the leg following chronic osteomyelifis of the tibia treated by a dermis-skin graft.

A, Before treatment. B, Photograph during the operation--the scar has been excised and

sclerosed bone exposed. C, Excised defect covered with healthy granulation tissue. D, The result six months after the commencement of treatment.

treatment. He has now been ambulant for five months and is walking three to four miles a day without trouble and without the slightest sign of instability in the grafted area.

T H E S K I N - D E R M I S G R A F T 10 7

C O N C L U S I O N

The dermis-skin graft provides a stable, non-adherent skin cover which does not contract. I t can be used directly on freshly made defects with a good blood supply, and it can also be persuaded to " t a k e " on defects in ischmmic areas which have been allowed to granulate to increase their surface vascularity. I t provides a skin cover which contains a layer of dermis as thick as, or thicker than, that of a Wolfe graft, and in addition it contains a small amount of fat. I t " t akes " much more readily than a Wolfe graft and can therefore be used to cover many defects for which direct or tubed flaps are usually considered necessary.

The use of a dermis-skin graft is, however, contraindicated in those patients in whom the defect to be covered extends so deeply that it is impossible to expose reasonably healthy tissue without seriously weakening the limb ; in such cases a direct or tubed flap is indicated.