Skin reconstruction techniques: Full-thickness mesh grafts - Veterinary Medicine
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Skin reconstruction techniques: Full-thickness mesh grafts
Areas that are particularly difficult to close, such as uneven surfaces and locations with lots of movement, benefit from mesh grafts that include the entire epidermis and dermis.


VETERINARY MEDICINE


For revascularization to occur, the graft must adhere to the wound bed.6 Within the first 24 hours after surgery, a weak fibrin seal forms to give the graft some adherence to the wound.3,6 Over time, fibroblasts produce collagen to give the graft a firm attachment to the wound. The graft may contract initially; however, it usually returns to its original size between 10 and 21 days after placement.4 In the early stages of healing, granulation tissue grows and expands through the slits of the grafts.2 In some patients, the skin of maximally expanded grafts may remain pink after the wound heals, and hair growth may be sparse; however, expanded grafts are often indistinguishable from surrounding tissue because they contract and are covered by adjacent hair.6 Occasionally, the new hair growth on the graft will be a different color: In dogs, the new hair may be white, while in cats the hair may regrow several shades darker than at the donor site.3

Performing the graft


Figure 1. Granulation tissue with a new epithelial margin (black arrow) over the antebrachium ready for grafting. The arrow drawn on the skin with a sterile purple marker indicates the direction of hair growth.
When choosing a donor site, consider the hair color, texture, and length and the skin thickness relative to the recipient site.3 Areas of loose skin, such as the lateral thoracic and abdominal walls make the best donor sites, because primary closure can be used, even if large grafts are harvested.1 Skin in these areas is relatively thin, which favors early revascularization. The neck is also a good donor site because of excess skin in the region.3 Skin from this area is relatively thick, however, especially on the dorsum of the neck, which could slow revascularization of the graft.6 Prepare the graft donor site by clipping and surgically scrubbing the area. Make sure to clip widely so that closure is not hindered by the surrounding hair.


Figure 2. The donor site on the ventrolateral thorax. The arrow denotes the direction of hair growth.
If the graft bed is granulation tissue, remove the epithelium at the wound edge before making a pattern for the graft, because the wound often becomes larger after this procedure (Figure 1). 1 A punch biopsy of the graft bed can be submitted for culture; this will provide more accurate assessment of bacterial invasion than a simple swab. Cultures may be unnecessary if epithelium is advancing along the wound edge, since a granulation tissue bed that is healthy enough to support epithelium at its edge should be healthy enough to support a graft.6 Next, cover the prepared graft bed with moistened gauze to prevent the tissues from drying.3 If chronic granulation tissue is present, excise it and delay grafting for four or five days until a healthy granulation bed forms.6

The size of the graft depends on the amount of expansion desired. For unexpanded grafts, use an exact pattern of the wound to determine the size of the donor site. Because of the loss of length with an increase in width, cut an expanded graft about one-third longer than and half the width of the defect.3


Figure 3. Removing the subcutaneous tissue. The graft is secured to sterile corrugated cardboard with hypodermic needles and stay sutures.
To make a pattern of the wound, place a piece of sterile cloth or paper over the granulation tissue to obtain a blood imprint of the wound. Cut the pattern to the shape of the wound. Make sure to mark which side of the pattern faces away from the wound to avoid cutting a useless mirror image of the recipient site. When tracing the pattern on the donor site, ensure that it is oriented so that the hair growth of the grafted skin will be the same as that of the recipient site (Figure 2). 1,3


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Source: VETERINARY MEDICINE,
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