Split-thickness skin grafting
Split-thickness skin grafting
Split-thickness skin grafting (STSG) is the gold standard of treatment for major loss of skin.57 STSG is comprised of the epidermis and part of the dermis.56,58 STSG can be divided into three categories based on thickness of the graft—thin (0.005–0.012 in), intermediate (0.012–0.018 in), and thick (0.018–0.030 in).58 In a prospective, casecontrolled study of STSG compared to conservative wound dressing in DFUs, mean healing time was significantly less in the STSG group compared to the control group.59 Dermal thickness included in STSG is inversely related to scarring and wound contracture of the graft site.60 One study evaluated the effectiveness of excision with STSG on healing in 357 patients with chronic legs ulcers of various etiologies. At 1 year, 64% of the patients had maintained wound healing. Healing rates at 1 year for each etiology were as follows: venous—64%, venous/ischemic—60%, arterial—20%, traumatic—86%, vasculitis—43%, and miscellaneous—75%.61
Indications STSGs are indicated when there is a defect in the skin or soft tissues where healing by secondary intention is expected to be too slow because of the refractory nature of the wound or the size of the wound.60,62 STSGs are more likely to take than FTSGs, though they typically produce a less favorable cosmetic result.55 While radiated skin previously had graft failure rates ranging from 30% to 100%, improvements in surgical and wound healing techniques have produced more favorable outcomes.63–66 For example, in patients who had received radiation therapy preoperatively, STSGs in conjunction with vacuum-assisted closure (VAC) therapy resulted in 71% graft take.63
Contraindications Contraindications are the presence of poor blood supply to the wound bed, infection, and exposure of bone, tendon, vessels, nerves, or implants without soft-tissue coverage.55,67
Procedural Technique Several considerations should be taken into account when choosing a donor site for STSG, including the size of the defect to be covered, ease of wound care to the donor site, visibility of scar, and the similarity to graft site in color, texture, and presence/absence of hair.58,68,69 While STSGs can be taken from anywhere on the body, some locations are preferred.62 The proximal anterior and lateral thigh as well as the proximal inner arm are commonly chosen donor sites, as the locations are easy to cover with clothing and cause minimal discomfort during reepithelialization.58 The ipsilateral buttocks is another commonly used donor site, though there may be more pain associated with healing than occurs on other locations.
In order to maximize graft success, the recipient site should have a healthy,
granulating wound bed and a low bacterial load, ideally less than 10.70 The wound bed should be prepared appropriately, including removal of necrotic tissue, prior to skin grafting. Underlying medical comorbidities such as diabetes mellitus and hypertension should be optimized prior to the procedure.
Once the appropriate form of anesthesia is induced and a sterile field has been prepared, the skin graft can be harvested from the donor site.61 A dermatome is one of the most commonly used methods as it has an oscillating blade that consistently harvests tissue with uniform thickness.61,71 The thickness, width, and length can each be adjusted based on recipient site need. A carrier, meshing device, or scalpel can be used to mesh the skin obtained with the dermatome in order to cover more surface area.61 Meshing allows for up to nine times more surface area coverage as well as drainage of fluids. Fluid buildup under sheet grafts may lead to graft failure. For areas such as the face, neck, hands, and joints, sheet grafts are preferred over meshed grafts as they demonstrate less contraction and better cosmetic outcomes.72
The graft is placed dermis-side down over the prepared wound bed and is secured in place, usually using sutures. Bolster dressings are helpful in preventing hematoma formation.55 The original dressing should be left in place for the first 3 to 7 days unless there are signs of complications or infection such as excessive pain, odor, or exudate.58
For the donor site, a semi-occlusive dressing that promotes a moist wound environment has been shown to significantly decrease pain and time to wound healing.58,73 Typically, the donor site heals in several weeks through reepithelialization. During this period, daily wound care and dressing changes are important to minimize the risk of infection and maximize healing. The donor site often leaves a permanent scar and discoloration.62
Complications and limitations Complications include loss of the graft, bleeding, infection, poor wound healing, and pain. Loss of graft can be due to a variety of factors including friction, pressure, insufficient blood supply, hematoma, seroma, and infection.1,56 Sheet grafts are more susceptible than meshed grafts to hematoma formation since they do not have fenestrations to allow for drainage of fluid.72 Pain associated with healing of the donor site can be significant, as nociceptive pain fibers are activated in proportion to the size of the wound created. Furthermore, the inflammatory response that occurs during wound healing augments pain.74
Limitations of STSG include donor-skin availability, high rate of graft failure, and its operator dependence.1,57,58 Use of STSGs results in the creation of a second wound, the donor site, thereby incurring the risks associated with a new wound (bleeding, pain, delayed wound healing, infection, etc.). When STSGs are used in the closure of full-
thickness skin defects, scarring and wound contracture can occur.75 Additionally, they may be hypo- or hyperpigmented in relation to surrounding skin and lack hair.58
Follow-up care Instruct the patient to keep the dressing dry and leave it in place for 1 week. During this time, minimizing shearing forces and strenuous activity is important to reduce bleeding and trauma at the graft site. On postoperative day 7, the patient will return to the clinic or hospital for the first follow-up visit. A healthy graft will look pink to violaceous. It can be gently cleansed with sterile saline before applying petrolatum to the wound and covering it with gauze secured by tape. This should be kept dry and in place for 2 to 3 days, at which point the patient may begin personal wound care. The patient should be instructed to clean the wound gently twice daily, before covering it with petrolatum and a bandage. At 3 weeks after the procedure, the patient is not required to cover the site. At 1 month after the procedure, the patient may treat the skin normally.76