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.
source-image
Oct 01, 2004

A mesh graft is a full- or partial-thickness sheet of skin that has been fenestrated to allow drainage and expansion.1-8 Full-thickness grafts consist of the epidermis and the entire dermis, while split-thickness grafts include the epidermis but only a portion of the dermis. Once fully vascularized and mature, full-thickness grafts may resemble normal skin in color, texture, and hair growth and are resistant to trauma.1

Mesh grafts are useful in many locations on the body because they conform to uneven surfaces. They can be placed in locations that have excessive motion because they can be sutured to the underlying wound bed. Additionally, their fenestrations provide outlets for fluid that may accumulate beneath the graft, which helps reduce tension and the risk of infection and improve vascularization of the graft.2,3 As granulation tissue grows up into the mesh openings, it further stabilizes the graft, and blood vessels can grow laterally from the plugs of granulation tissue into the dermis to enhance graft revascularization.6 Mesh grafting is especially useful in the distal limb where a minimal amount of tissue is available for local closure and in patients such as burn victims that have large defects and limited amounts of donor skin.1,3

How the graft takes hold

The survival of a mesh graft depends on early vascularization from the underlying tissue. Therefore, many veterinarians will wait seven to 10 days until a wound has a recipient bed of healthy granulation tissue before placing a graft. However, mesh grafts can be placed over any soft tissue that is vascular enough to produce granulation tissue. Nourishment of the graft initially depends on plasmatic imbibition—the uptake of serumlike fluid and cells into the dilated blood vessels of the graft by capillary action.6 Because hemoglobin products are absorbed at this time, the graft may appear cyanotic. Additionally, leakage of the absorbed fluid into the interstitial spaces results in edema. Circulation is reestablished about 48 to 72 hours after graft placement, but edema may persist or even increase until venous and lymphatic drainage are adequate.6 Anastomosis of graft and recipient vessels, known as inosculation, usually occurs 48 to 72 hours after graft placement. Only a few anastomosed vessels survive, but some of the graft vessels may proliferate and connect with the vascular bed. Eventually, vessels from the wound bed grow into the graft, growing at a rate of about 0.5 mm/day.6 Normal blood flow velocity is usually present by the fifth or sixth day after grafting, and lymphatic drainage is present by the fourth or fifth day.6