Articles
Healing power of skin
Skin grafts and flaps are ideal for surgeons to reliable repair a variety of wounds and to reconstruct complex loss of tissue. Dr Kippen explains the pros and cons of both.
Once a skin lesion or spot is excised (cut out) it may not be possible to simply stitch the wound closed. This may be due to the size of the wound (too big), the position (close to the nose, ears or eyes) or the shape. It is then necessary to use either a skin graft or skin flap to obtain closure of the wound.
A skin graft involves taking skin from one part of the body and moving it to another. There are two main types. A split thickness graft takes only some of the skin thickness, leaving enough depth of skin for the donor area (where the skin was taken from) to heal by itself. This is similar to the healing of a graze. The donor site is carefully dressed until healing is complete.
A full thickness graft takes the full thickness of the skin so the donor site is usually stitched closed and heals as a normal surgical incision. The skin is taken from a site where there is enough skin to allow this closure.
Blood supply
The skin graft is lifted and separated from its original site so a new blood supply must grow in to allow the graft to ‘take’ in its new position. It is not possible to reject a skin graft because it is your own skin. The skin graft may not ‘take’ but this is more commonly due to infection, bleeding or movement.
Keeping the graft still and in perfect apposition with the new site is important to allow the new blood vessels to grow in.
Skin flaps
A skin flap is an element of tissue or skin that is moved to close or reconstruct a surgical defect. It is different from a skin graft because it maintains its blood supply. The flap is therefore more reliable and robust.
Because the skin flap is usually moved to an adjacent area, the characteristics of the skin are more closely matched. Flaps are designed using geometric patterns and ratios of width and lengths.
Large or specialized areas can be reconstructed using flaps containing more than just skin. Muscles, bone, nerves and cartilage may be moved and then function in the new position. At times more complex flaps are used and it may be necessary to re-establish the blood supply using microsurgery to join the arteries and veins.
Burn wounds
The advantages of skin grafts are that very large areas can be closed or covered. With large burn wounds, a split thickness graft is used so that when the donor site has healed it can be used again. The grafts can be stored sterile in the fridge and used up to two weeks later. It is also possible to cut a series of slits in the skin to allow it to open as a lattice pattern which covers a larger area, saving the amount of skin that is needed.
The disadvantage of skin grafts is that the skin is often of different colour, texture, contour and thickness. Some grafts may become darker or pigment over time. Skin grafts require more dressing dressing until they have finally healed. Composite grafts may contain skin with cartilage or hair.
Using skin grafts and flaps enables surgeons to reliably repair a wide variety of wounds and to reconstruct complex loss of tissue.