Skin grafting serves as a primary method for treating deep burn wounds. Different techniques are selected based on wound conditions following debridement and the source of the donor skin. Skin grafting can be categorized into autologous, allogeneic, and xenogeneic types based on the source of the graft. Most deep burn wounds require autologous skin grafts for repair, as allogeneic and xenogeneic grafts, due to their strong antigenicity, are usually limited to being biological dressings. These grafts cover the wound area, providing an improved microenvironment for wound healing or wound bed preparation. Based on the shape and size of the skin grafts, the techniques include full-thickness grafts, postage stamp grafts, mesh grafts, MEEK micrografts, and microskin grafts. Smaller individual grafts allow for coverage and repair of larger burn areas using the same amount of skin. Based on the thickness of the grafts, the techniques are classified as split-thickness, medium-thickness, and full-thickness skin grafts. Split-thickness grafts primarily close wounds, while medium-thickness and full-thickness grafts emphasize functional and cosmetic restoration. Based on the vascular connection between the graft and the body during the procedure, grafting can be divided into free skin grafting and skin flap grafting. Skin flap procedures are mainly used for the repair of deep burns involving tendon, bone, large blood vessels, and nerve exposure. Depending on whether the vasculature is anastomosed, skin flaps are further classified into pedicled flaps and free flaps.
Skin Harvesting
Free skin grafts of varying thicknesses and sizes can be harvested using electrical or pneumatic dermatomes, roller knives, drum-type skin grafters, or surgical scalpels, depending on the purpose and requirements. These grafts can be processed into large sheets, smaller pieces, mesh grafts, MEEK micrografts, or microskin. Donor sites should meet criteria of concealment and minimal damage. The scalp is commonly used as a donor site for split-thickness grafts due to its thickness, abundance of stem cells, rapid repair capacity, and ability to be harvested repeatedly at intervals of approximately 7 days. Repeated harvesting from the scalp typically does not affect hair growth or leave scars.
Large-Sheet Medium/Full-Thickness Autologous Grafting
This method is often used for the repair of deep burn wounds on the hands, face, joints, and other functional areas. Medium-thickness grafts are harvested using drum-type or electrical/pneumatic dermatomes and transplanted onto fully debrided wounds. The grafts are kept under mild tension and pressed firmly onto the wound bed. The edges are secured with sutures or skin staples, followed by compression dressing. Dressing changes are generally performed after 5–7 days. This technique yields reduced scarring, good elasticity, and satisfactory functional and cosmetic outcomes.
Mesh Grafting
Large sheets of split-thickness or medium-thickness autologous skin are perforated with a mesh dermatome or fine-bladed knife to create dense, uniformly spaced holes. The skin is stretched to form a mesh-like structure, typically expanding its surface area by 1.5 to 3 times, before it is transplanted onto the wound. Advantages of this technique include:
- Efficient use of limited donor skin to repair larger wound areas.
- Improved drainage, promoting graft survival.
- Maintenance of some tissue continuity, allowing the mesh to partition scar tissue and reduce contracture.
- Reduced surgical time and high efficiency.
Small-Piece or Postage Stamp Grafting
Split-thickness grafts are cut into square pieces measuring 0.5–1.5 cm using scissors or a skin compressor. These postage stamp-like grafts are transplanted onto the wound with spacing of 0.5–1.0 cm between grafts, depending on donor skin availability and wound conditions. This technique often results in significant scarring and is unsuitable for use on the face, functional areas, or joints.
Microskin Grafting
Autologous split-thickness grafts are fragmented into micro-particles with diameters below 0.6 mm using scissors or a skin fragmentation device. The micrografts are uniformly applied to the dermal surface of an allogeneic (or xenogeneic) skin, which is then transplanted onto the excised wound. The allogeneic (or xenogeneic) skin optimizes the microenvironment for the survival, growth, and expansion of the autologous micrografts underneath, facilitating repair of extensive burn wounds. This method allows for a high donor-to-recipient ratio, ranging from 1:6 to 1:10 or higher, offering an effective solution to donor skin shortages.
MEEK Micrografting
Split-thickness donor skin is placed dermis-side down on a 4.2 cm2 cork carrier and processed using a MEEK micrografting device to divide the skin into 196 equal micrografts. A specialized adhesive spray is applied to the epidermal side, facilitating the transfer of grafts from the cork carrier to a polyamide fabric with the dermis-side facing outward. The fabric is uniformly stretched to evenly distribute the micrografts across its surface. The graft-bearing fabric is then applied to the wound bed and secured with dressing. This technique provides a semimechanized, efficient, and simple option for repairing extensive deep burn wounds in cases of limited donor skin. The expansion ratio can reach 1:4, 1:6, or 1:9 with high graft survival rates.
Large Allogeneic (or Xenogeneic) Sheets Combined with Autologous Grafting
This method is suitable for treating extensive deep burn wounds following excision or debridement. Large sheets of allogeneic (or xenogeneic) skin are perforated uniformly with 0.5 cm holes and transplanted onto the wound bed. Sutures or staples secure the grafts in place, which are then dressed. Autologous skin grafts are applied to the perforations after 2–3 days or immediately upon transplantation in some cases. The allogeneic (or xenogeneic) grafts dissolve and peel away over time, while the autologous skin expands and merges beneath to repair the wound. This approach can increase the coverage area of autologous skin by 8–10 times.
Epidermal Cell/Epidermal Stem Cell Grafting
Small split-thickness skin samples are obtained from the patient, and epidermal cells or epidermal stem cells are isolated through enzymatic digestion. These cells are either directly applied to the wound or cultured in vitro to form epidermal cell sheets, which are subsequently transplanted onto excised burn wounds.