Skin transplantation is the complete surgical removal or detachment of healthy skin areas from any part of the body (usually the inner side of the thigh/upper arm, buttocks, back) with subsequent reinsertion of this removed skin at another location. It is now one of the most frequently used basic techniques in the field of plastic surgery. The aim of skin transplantation is to cover larger, defective areas of skin that can no longer be closed by conservative therapy or a simple surgical suture.
Skin transplantation is also used to treat wounds whose natural healing process would be very lengthy and risky. This can be the case, for example, after burns, burn accidents and chronic, therapy-resistant wounds. Important prerequisites for the success of the transplantation are an infection-free, well-perfused recipient wound and completely healthy donor tissue. According to observations, the closer the donor site is to the wound to be covered, the better the aesthetic results.
Reasons for skin transplantation
Among the most common reasons leading to open wounds that cannot be healed or closed by conservative or standard surgical therapy are major injuries after accidents and arterial or venous vascular diseases (open skin defects often on the legs, e.g. leg ulcers, “open legs”). Larger areas of burns or burns and large skin defects caused by ulcers (e.g. decubitus = “ulcer caused by lying down”, diabetic ulcers, etc.) can also necessitate a skin transplant.
It is therefore desirable to cover such wounds as quickly as possible, since large, open wound surfaces form entry ports for bacteria and thus have a slight tendency to infection. In addition, the body continuously secretes protein-rich fluid into/over the non-healing wounds, which, depending on the size of the defect, can lead to increased or even life-threatening fluid loss. Likewise, the natural function of the skin as a protective barrier is lost in these areas, so that the tissue immediately below is at risk and can be damaged more easily.
There are two different types of common transplantation that are frequently used in plastic surgery: full skin transplantation and split skin transplantation. For both procedures either so-called “autologous grafts” (autologous grafts/skin areas: the donor and the recipient are the same person) or “foreign skin grafts” (allogenic grafts: the donor and the recipient are not the same person) can be used. The latter method must always be used if more than 70% of the affected person’s skin is damaged and the patient’s own skin is not sufficient to cover this large wound area.
In full skin transplantation, skin areas are removed that consist of the two uppermost skin layers (epidermis/epidermis and the entire dermis/dermis) and the skin appendages (hair follicles, sweat glands, etc.). These grafts are very thick (0.8-1.1 mm) compared to split skin grafts. The wound resulting from the removal must be closed by a primary wound suture, which is why only smaller grafts can be removed.
In the course of the procedure, scarring will form in the removal area, which means that it cannot be used for further removal. Despite slower growth, the cosmetic and functional result is significantly better than that of split skin grafts. This type of graft is preferred for deeper, smaller, non-infectious wounds.
In the context of full-thickness skin transplantation, the technique of producing a shifting or swiveling skin flap is also possible, provided that intact, healthy skin is available in the immediate vicinity of the wound to be treated. In this technique, a skin flap is cut out on three sides and swivelled over the wound area and later fixed in place. The advantage here is that the swiveling graft maintains contact with the original skin area at one point, thus facilitating blood circulation and growth.
Split skin grafts usually only preserve the epidermis and parts of the dermis and are thinner (0.25-0.75 mm) than full-thickness skin grafts.The advantage that results from this is that the wound areas created by the removal usually heal spontaneously within 2-3 weeks and the donor area can even be used several times (in contrast to full skin removal, there is no scarring). For the removal of split skin, special knives (dermatome, Humby knife) are required, but so-called “mesh grafts” can also be produced using another special device by making mesh-like incisions in the removed skin. These grafts are 1.5-8 times the surface area of the originally removed skin area, thus enabling the coverage of particularly large wound areas. Further advantages of split skin grafts are that wounds with poor blood supply and not infection-free can be covered. A further method of obtaining skin grafts is the cultivation of autologous skin starting from individual, removed skin cells, which grow on artificial nutrient media in the laboratory within 2-3 weeks to become transplantable preparations.
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