Transplantation techniques

Significant skin defects or granulating wound surfaces can be covered using skin transplantation techniques. For this, autografts are generally used. Homotransplants or allografts (coming from another individual from the same species) do not attach. They can be used as a temporary biological bandage in processed form. Autotransplantation of the skin can be accomplished through 2 methods:

1. the pedicle flap, where a flap is partially prepared free and is sutured onto the defect at another location on the body. This method is only applied in human and companion animal medicine. The pedicle skin flap keeps its original blood supply via the pedicle.

2. the free skin graft, where a patch of skin is completely removed from the original location and is transferred to another area. Because there is no longer a connection between the transplant and the field of origin, the transplant must receive its nutrition by diffusion for the first few days (by plasmatic imbibition). The thinner the transplant, the better the diffusion occurs. Ingrowth of capillaries out of the wounded supply the transplant with blood and nutrients after a few days. For the connection of a free transplant, the wound area must be free of infection, and there should be no movement between the wound bed and transplant. The movement will delay or hinder capillary reattachment.

Free skin grafts can be performed in various manners:

1. whole patches of the skin using the Wolfe-Krause technique (full-thickness skin graft). This method has as an advantage an excellent cosmetic effect, but the chance of attachment is minimal because the diffusion and vessel ingrowth from the wound bed is usually not sufficient;

2. Thiersch’s graft: epidermal patches of approximately 0.5 mm thick (split-thickness skin graft) are harvested using a dermatome from abdomen or thigh and transferred to the transplant location. Although suturing can damage the flaps and the chance of bleeding is increased, it is still a necessity. Otherwise, the transplant can move. A proper bandage will promote healing in the affected area. If significant defects must be bridged, than a mesh graft can be considered. The advantage of this is that with almost no donor-skin, a large surface area can be covered. The open structure of the mesh allows proper drainage of secretions. In human medicine, this type of transplant is often used in burn wounds, sometimes preceded by a temporary cover of a prepared heterotransplantation (tissue from another species, or xenograft), or artificial skin. A variation of the mesh graft is the Meek transplant;

3. small grafts, using the Reverdin method (stamp-size grafts), which are, in general, not sutured. The likelihood of connection is more significant than in the Wolfe-Krause method, but the cosmetic effect is less desirous;

4. Braun method of transplantation: implantation of small patches of skin (approximately 2 x 2 mm, pinch grafts) in the granulation tissue. This type of graft can be done on moveable parts. A disadvantage of this method is that after healing, hair growth is not all in the same direction and can appear rumpled.

Skin transplantations should be covered with non-sticky absorbent gauze (such as Cuticerin® or Melonin®) before applying the rest of the bandage to prevent sticking of the wound.

Sometimes adequate rest of the wound area is not easily achieved, and the stability of the transplant poses a problem. This should not be a deterrent to performing the transplant. There remains a stimulating effect in the wound area, which will encourage epithelialization — the re-epithelialization of the donor area after skin grafting using dermatome proceeds without a problem in general.

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