James N. Long, Jorge de la Torre, and Luis O. Vasconez
DEFINITION
Upper extremity wounds that are candidates for skin grafting very closely parallel wounds suitable for skin grafting in other areas of the body. Certain wound conditions must be adhered to, and the principles of grafting remain constant, no matter the location of a wound.
Terminology
Autograft refers to skin that is harvested from the same individual to whom it will be applied at a different location.
Isograft refers to skin harvested from an identical twin of the recipient individual. Isograft behaves like autograft.
Allograft refers to skin harvested from an individual of the same species as the recipient individual. Due to histocompatibility mismatch, these grafts eventually separate from the wound, except in immunosuppressed patients, and so provide only temporary coverage.
Xenograft refers to the use of skin grafts from a species different from the recipient individual. Due to histocompatibility mismatch, these eventually separate from the wound, except in the immunosuppressed patient, and so provide only temporary coverage. Xenograft use is associated with an elevated rate of wound bed infection.
Split-thickness skin grafts contain epidermis, along with a varying thickness of dermis that represents less than the full thickness of the dermis.
Full-thickness skin grafts incorporate the full thickness of dermis and epidermis.
Donor site refers to an area from which either a splitor full-thickness skin graft is harvested. Depending on the thickness of the graft, donor site treatment varies, from topical dressings, which typically are used for split-thickness skin graft donor sites, to direct closure, which is the usual method for addressing full-thickness skin donor defects.
Skin substitutes are semisynthetic or purely synthetic constructs designed to act as replacements for lost skin structures. Ideally, they will be incorporated into the host to act as durable long-term replacements for lost tissue. In 1984, Pruitt and Levine11 described the characteristics of ideal biologic dressings and skin substitutes. Their list of qualities considered to be ideal for skin substitutes still holds true more than 20 years later:
Little or no antigenicity
Tissue compatibility
Lack of toxicity
Permeability to water vapor, as would be seen in normal skin
Impenetrability to microorganisms
Rapid and long-term adherence to the wound bed
Capacity for ingrowth of fibrovascular tissue from the wound bed
Malleability, which would allow the construct to conform to the wound bed
Inherent elasticity that would not impede motion
Structural stability against linear and shear forces
Smooth surface to hinder bacterial proliferation
Good to tensile strength that would allow it resist fragmentation
Biodegradability
Low cost
Ease of storage
An indefinite shelf life
Wound Bed
Before making a decision about using skin grafts or a substitute, it is important to be familiar with the characteristics of a wound bed that make it suitable for grafting.
Graft beds should be properly débrided so that they are free of dead tissue and made as clean as possible to help minimize the risk of graft loss from infection.
Beds that are being considered for grafting must have an appropriate substrate from which the graft can derive its blood supply. In the context of upper extremity wounds, the bed specifically should contain no areas of denuded tendon or bone, as these denuded areas will not support inosculation (ie, neovascularization of the graft).
A further requirement, once débridement is complete, is the reduction of bacteria in the wound, which usually is effected through the use of a pulse lavage system. Enhanced skin graft survival by means of reducing bacterial counts is supported by studies published by Perry10 in 1989.
A useful tool in maturing a wound bed for grafting is the vacuum-assisted closure device (VAC). This device provides microdébridement of the wound bed and can help to promote the development of healthy granulation tissue, an ideal substrate for the support of skin graft adherence. Moreover, the vacuum-assisted closure device can be used over the top of a skin graft applied to a wound and, through its negative pressure effect, limit fluid collection beneath the graft, also helping to ensure contact between graft and bed through an even distribution of pressure across the interface.
Elements key to the development of an adequate graft bed are:
Débridement of all nonviable tissue
Minimization of bacterial colonization within the wound bed
Ensuring that there exists an appropriate substrate for adherence of graft
Microdébridement and maturation of the graft bed using appropriate dressings, which may include myriad measures ranging from the use of wet-to-moist saline gauze dressings to use of the VAC device.
ANATOMY
The decision-making process in choosing splitversus fullthickness graft in the distal upper extremity involves both gross and microanatomic considerations.
The lack of secondary contraction seen in full-thickness skin grafts supports their use on surfaces that overlie or are juxtaposed to joints. This lack of secondary contraction helps minimize the risk of unwanted joint contracture as the grafts mature.
Over broad flat surfaces, such as the dorsal or volar aspect of the forearm, split-thickness skin grafts perform well.
Wounds that involve the glabrous surface of the hand ideally are replaced with skin that possesses the same characteristics as the adjacent skin.
Harvest of glabrous skin from the sole of the foot or from the contralateral uninjured hand should be considered for such use.
In some cases, the wound may be so large that it is not possible to harvest sufficient donor skin while still permitting primary closure of the donor site. When this is the case, the arch within the sole of the foot may yield a full-thickness glabrous skin graft sufficient to cover the area of the original wound; however, the donor site then may require a skin graft itself. The donor site from the arch of the foot can be grafted with nonglabrous, meshed split-thickness graft with minimal morbidity due to its minimal weight-bearing requirement.
Microanatomy
As suggested earlier, the surgeon must be concerned with the microanatomic conditions of the wound bed.
An appropriately vascular substrate is required to ensure proper graft take. Healthy fat, muscle, paratenon, or periosteum must be present within the base of the wound to ensure success.
Additional considerations include proper débridement of nonviable tissues from the wound bed as well as the minimization of bacterial contamination.
Donor Sites
Glabrous skin
The sole of foot within the arch, beginning at the junction of glabrous and nonglabrous skin along the medial aspect of the arch
The ulnar aspect of the hand, beginning at the junction of the glabrous and the nonglabrous skin along the ulnar aspect of the palm
Full-thickness skin
Redundant areas of full-thickness skin available for harvest that maintain ease of primary closure of the donor defect include the lower abdomen, running from the anterior superior iliac spine in a gentle arc around the lower portion of the abdomen to the contralateral anterior superior iliac spine.
Skin harvested from this area may be hair-bearing. Depending on requirements of the recipient site, selection of full-thickness skin graft can range from the relatively hairless portions found laterally to the hirsute areas found centrally.
Smaller areas of satisfactory full-thickness skin can be harvested from the upper inner arm. This skin, located at the junction of the medial biceps and triceps muscle groups, is thin and usually hairless.
Split-thickness skin graft
Traditionally preferred sites have included the anterior thighs due to the ease of harvest and postoperative care of these areas.
Another site that has favorable characteristics in terms of quality of graft donor, as well as healing of donor site, includes the scalp.
Harvest of split-thickness skin graft from the scalp requires shaving of the head and the injection of epinephrinecontaining wetting solution, eg, Pitkin’s solution or Klein’s solution, which is directed via puncture into a subgaleal plane to help minimize blood loss from the harvest.
The very rich vascular supply to the scalp makes splitthickness skin grafts from this site quite robust.
If the harvest is kept within the hair-bearing portions of the scalp, little to no donor defect can be detected once hair has grown back. Moreover, because of the high density of epidermal appendages in the scalp, re-epithelialization of this area is more rapid than at other sites on the body. This rapid re-epithelialization helps to minimize the potential for donor deformity (ie, scarring and dyspigmentation).
Harvest
Skin harvest is greatly facilitated by proper preparation of the chosen site.
First, a template of the bed to be grafted should be transferred to the donor site to ensure an adequate harvest. This is easily done with gentian violet and a sterile glove wrapper.
Limiting blood loss from the harvest site is desirable and is easily achieved by pre-injecting the hypodermis of the planned harvest area with an epinephrine-containing local anesthetic.
If a long-acting local anesthetic such as Marcaine with epinephrine is used, the patient will have the additional benefit of prolonged donor site anesthesia postoperatively.
As split-thickness donor sites are typically quite painful, this is a real benefit and is appreciated by the patient.
When a large area is planned for harvest, attention must be paid to the appropriate maximum dosage for the local anesthetic selected. Dilute solutions in these cases can provide the benefits sought for these larger surface areas while still respecting the maximum allowed dosages.
PATHOGENESIS
Wounds in the distal upper extremity requiring coverage arise from a host of different mechanisms. Among the most common are traumatic injuries, which commonly result in avulsive loss of skin. Other causes include burn injury to the upper extremity, as well as defects created by tumor removal.
Any one of these mechanisms may result in a wide range of injuries, from simple skin loss to injuries of deeper structures, including loss of paratenon or periosteum.
NATURAL HISTORY
Skin graft healing varies from site to site on the body, and each location will vary from person to person.
Skin in young adults is thick and healthy; however, in about the fourth decade the skin begins to thin.
Despite differences in skin thickness at differing anatomic locations, the overall dermal-to-epidermal ratio remains relatively constant: about 95% dermis to 5% epidermis.
Blood vessels form arborizations into the dermis of the skin through access portals in the dermal papillae.
How Do Grafts Work?
After application to an appropriately prepared wound bed, both splitand full-thickness grafts undergo a process that has been commonly termed “take.”
The process involved in adherence of skin graft to wound bed is complex and involves an initial hypermetabolic condition within the graft, supported by plasmatic imbibition. Plasmatic imbibition is the process whereby nutrients and oxygen are drawn into the graft by absorption and capillary action. During this time, the graft remains adherent by a thin and friable film of fibrin between wound bed and graft.
This early phase of graft support is followed by inosculation and capillary ingrowth. Before inosculation, there is a period during which ischemia and, therefore, hypoxia within the graft, with attendant histologic findings, are present.
Once capillary ingrowth occurs and makes contact with the vascular network inherently present within the graft, blood flow is re-established, and the skin graft takes on a pinkish hue. This process likely involves both the use of the inherent network of vessels within the graft and new vascular proliferation.
Secondary adherence is mediated through fibrovascular ingrowth. The new vascular connections between graft and bed, as well as the new fibrous connections, solidify graft adherence.
Properties of Skin Grafts
Skin grafts have been used to provide both temporary and permanent coverage, offering the inherent benefit of protection of the host bed from additional trauma while also providing an important barrier to infection.
Split-thickness grafts tend to adhere to wound beds more easily and under adverse conditions that would not typically support full-thickness graft viability. This characteristic of split-thickness skin grafts provides a considerable advantage in managing difficult wounds; however, certain disadvantages can arise from their use. Once healed, split-thickness skin grafts undergo secondary contraction which, under uncontrolled conditions, can lead to pathologic contracture.
Contracture refers to a disability in function that arises from secondary contraction.
Additional disadvantages arising from the use of splitthickness skin grafts include dyschromia, poor elasticity, and reduced durability when referenced against their fullthickness counterparts.
Full-thickness skin grafts include the full thickness of the dermis, along with the epidermis. In the initial phases, fullthickness skin grafts tend not to show the hardy “take” often seen with split-thickness skin grafts. To ensure full-thickness graft success, their use should be limited to well-vascularized recipient beds only.
Once established, full-thickness grafts offer distinct advantages; specifically, secondary contraction is far less problematic. Their thickness offers more resistance to external trauma and tends to be less likely to experience the dyspigmentation often associated with split-thickness grafts. They have much better inherent elasticity than split-thickness grafts, and for this reason they are the graft of choice for use over and around joints.
Contraction
As mentioned earlier, split-thickness skin can undergo a process of secondary contraction that ultimately may lead to skin grafts behave differently.
The phenomenon of primary contraction refers to the tendency of a graft to shrink on elevation from the donor site. Substantial primary contraction is more often associated with full-thickness skin grafts than with split-thickness skin grafts.
It is clinically important to remember that the immediate and long-term elasticity of full-thickness skin grafts is much greater that in split grafts. It is this elastic property that makes full-thickness skin grafts an ideal choice for use around joints.
Once skin grafts have healed in place, the secondary process of contraction occurs more than in split-thickness grafts.
Full-thickness grafts tend to remain about the same size and, for practical purposes, show little to no secondary contraction. Full-thickness skin grafts have the capacity to increase their surface area with limb growth over time, whereas split-thickness grafts tend to decrease in size by a process of contraction, or, alternatively, their size remains static.
Reinnervation
The restoration of sensation in skin grafts is mediated through both peripheral ingrowth and direct growth into the graft from the bed.
Factors affecting reinnervation of skin grafts include the location and quality of the recipient bed, as well as the choice of fullversus split-thickness skin graft.
Timing of recovery is variable, with some sensory recovery at between 4 and 6 weeks post grafting. The return of normal sensation occurs between 12 and 24 months.
The speed with which sensory recovery is realized depends on the accessibility of graft neural sheaths to wound bed nerve fibers. Accessibility of neural sheaths is improved in fullthickness grafts over their split-thickness counterparts, and, therefore, sensory recovery in full-thickness grafts is both more rapid and more complete.
Dyspigmentation
The harvest of a graft disrupts its normal circulation, causing a loss of melanoblast content. This reduction results in a significant decrease in the number of pigment-producing cells within the graft.
After graft revascularization, the initial hypoxia is corrected, and the melanocyte population recovers to a normal level.
Skin Substitutes
The use of skin substitutes for wound coverage in the distal upper extremity typically is considered when the surface area involved is greater than that which could be reasonably covered with a full-thickness skin graft, but for which a splitthickness skin graft is suboptimal, for cosmetic or functional reasons.
Of the several skin substitutes on the market, the most clinically relevant are AlloDerm (LifeCell Corporation, Branchburg, NJ) and Integra Dermal Regeneration Template (Integra LifeSciences Corporation, Plainsboro, NJ). AlloDerm is a deantigenized human cadaveric acellular dermal construct. Integra consists of a bovine collagen dermal matrix sheathed with a silicone top membrane creating a bilaminar structure.
Prognosis
For beds that have been prepared using proper technique with an appropriate choice of graft type, a high degree of successful take with excellent functional results can be obtained.
It is important to bear in mind the process whereby the graft becomes mated with the bed to achieve good end results. Improperly prepared beds will not provide the vascularity required to ensure graft take.
Excessive bacterial colonization of the wound also can lead to graft loss.
Graft immobilization on the wound bed after placement is key to successful adherence.
Additional agents that act to prevent successful adherence include the accumulation of subgraft hematoma or seroma as well as shearing forces acting across the graft–wound interface.
Immobilization strategies must be directed toward the prevention of unwanted shear while providing pressure adequate to minimize the accumulation of fluid between graft and bed.
All efforts should be made to minimize the risk of infection before graft application by means of débridement, lavage, and the use of both topical and systemic antibiotics, as directed by culture results.
The rigid application of these principles produces high success rates.
PATIENT HISTORY AND PHYSICAL FINDINGS
When considering a patient for skin grafting, along with the normal complete history and physical examination, special attention should be given to inspection of the wound bed.
The surgeon should ascertain that all tissues within the prospective graft bed are viable and that bacterial growth within the wound is addressed through both wound débridement and treatment with appropriate antimicrobials. Areas of denuded tendon or bone are not acceptable for graft adherence.
Other factors that negatively impact graft take are factors known to be responsible for impaired wound healing. The most common of these are cigarette smoking, diabetes mellitus, and malnourished states. It is important to elicit this information before proceeding with the operative plan.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Wounds with a bacterial content greater than 105 colonyforming units (CFUs) have significantly reduced successful graft take. A quantitative culture can be performed to assess this variable before skin grafting.
A punch biopsy is used to obtain a portion of vascularized wound bed, and this tissue sample is sent to the laboratory, where it is homogenized and then plated. CFUs on the culture plate are counted and then referenced against the initial sample weight. A concentration of more than 105 CFUs per gram of sample tissue is a negative predictor of successful graft adherence.
The area of tissue biopsied must be delivered from the viable portions of the tissue bed and not from devitalized tissues, which will show very high colony counts and are not representative of the graftable bed.
DIFFERENTIAL DIAGNOSIS
Superficial or partial thickness skin loss
Full-thickness skin loss
Full-thickness skin loss concomitant with deep tissue injury
Loss of paratenon or periosteum
Wound over or adjacent to joints
Wound over broad, flat surface that does not overlie a joint
NONOPERATIVE MANAGEMENT
Superficial abrasions or burns over broad surfaces with maintained viability of the dermal and hypodermal structures can be treated by local wound care without the use of grafting. Areas of skin with abundant epidermal appendages (sebaceous glands, sweat glands, and hair follicles) have inherent source tissue for re-epithelialization of these superficial wounds.
Conservative management ideally includes a moist wound-healing environment that limits bacterial growth and does not inhibit the process of neoepithelialization, such as the petrolatum-based antimicrobial ointments (eg, Neosporin [Johnson & Johnson, New Brunswick, NJ] and Xeroform gauze [Covidien, Mansfield, MA).
When conservative wound management is being employed, serial observation is advised to ensure that the process of neoepithelialization is underway and is not hindered by the development of local infection or other unforeseen factors.
If the process of re-epithelialization is complete by the end of 2 weeks after the event of the initial injury, scarring at the site of injury will be minimized.
Smaller wounds that are deeper and penetrate through dermis into the hypodermis may be treated conservatively as well.
Local wound care, with serial wet-to-moist changes or by use of the Vacuum-Assisted Closure (VAC) Device (KCI, Inc., San Antonio, TX) can help facilitate healing by secondary intention.
Larger areas of skin loss allowed to heal by secondary intention can result in a substantial delay in wound healing. In addition, functionally limiting contractures can develop as a byproduct of secondary intention healing.
Larger, superficial dermal wounds such as second-degree burns can be managed nonoperatively by use of synthetic membrane dressings such as Biobrane (Smith & Nephew, Hull, UK, FIG 1) or TransCyte (Smith & Nephew). These dressings are applied immediately after débridement of nonviable skin.
This class of dressing is effective for superficial wounds that penetrate only to middermal levels. They depend on retained epidermal appendages (ie, hair follicles, sebaceous and sweat glands) to accomplish the task of re-epithelialization.
Deeper, full-dermal thickness areas of wounding require deeper débridements that typically are followed by skin grafting or skin graft substitutes.
SURGICAL MANAGEMENT
Preoperative Planning
Once appropriate débridement has been performed, and the wound is deemed clean and the wound bed is appropriately vascularized, the surgeon can proceed with skin grafting.
Before beginning in the operating room, the surgeon should have discussed the proposed donor site with the patient and also should have decided whether a fullor split-thickness graft is most appropriate.
FIG 1 • A. Superficial second-degree burn to the dorsal hand. B. Biobrane glove designed for superficial second-degree hand burns. C. Biobrane glove applied.
Positioning
The volar and dorsal aspects of the distal upper extremity can be accessed easily with the patient in a supine position with the arm placed on an arm table.
Occasionally, patients who have limited range of motion in their joints at the shoulder or elbow must be placed prone to facilitate access to certain areas.
Decisions about positioning should be made well in advance of initiation of the procedure.
Approach
Wounds that are being considered for placement of skin graft or skin graft substitutes are, by definition, vascularized wound beds with direct superficial access.
Logical preoperative planning determines the approach.
TECHNIQUES
SPLIT-THICKNESS SKIN GRAFT
Determining Wound Size and Making a Template
To begin the procedure, a sterile ruler is used to measure the size of the wound to be addressed with skin grafting.
A simple and effective way to determine the shape of a wound bed is to place a sheet of sterile glove paper within the wound. The mark left on the paper by the wound is a close match of the wound bed. (This technique is not as accurate for wounds with markedly irregular contours.)
Once the wound has transferred moisture onto the glove paper, the paper can be trimmed with scissors to provide a template of the wound bed. This template then can be transferred to the area of planned skin harvest.
The shape of the template is marked with a dashed line, using a gentian violet marker, on the skin that is to be harvested.
Harvesting the Graft
Most modern dermatomes are designed to harvest skin in a quadrangular pattern.
To ensure that the harvested graft is capable of proper wound coverage, it should be larger than the gentian violet marks on all sides, both to offset shrinkage from primary graft contraction and to compensate for the difficulties in harvesting amorphous shapes with an instrument designed to cut quadrangular patterns.
The degree of primary contraction is a function of the depth of dermis harvested. For very thin split-thickness grafts, primary contraction is virtually absent.
Grafts usually are harvested with either nitrogenor electric-powered dermatomes (TECH FIG 1), which can be adjusted for depth of harvest as well as the desired harvest width.
TECH FIG 1 • Technique of split-thickness skin graft harvest.
The usual appropriate depth for harvesting skin to be applied to a wound bed in the distal upper extremity is between 0.012 and 0.014 inch.
Unmeshed versus Meshed Grafts
Once a graft of appropriate size has been harvested, it must be decided whether to use the graft as a sheet graft (unmeshed) versus an expanded graft (meshed) (TECH FIG 2).
Sheet grafts, because of their contiguous nature, have a greater tendency to develop subgraft seromas and hematomas.
This complication can lead to graft loss; for this reason, it is worth considering the use of meshed grafts.
Under ideal circumstances, a meshed graft can be used in its nonexpanded state.
To do this, simply mesh the graft using the appropriate device, and after placing it in the wound bed, close the small fenestrations made by meshing.
This closure will give a final healed appearance very close to that of a sheet graft but without the complication of accumulated fluid beneath the graft, which can lead to graft loss.
Placing the Graft
Once the graft has been placed in the wound with the dermis side down, the graft can be secured in place using either staples or sutures around the periphery.
As this is done, excess peripheral graft may develop. This is the byproduct of the quadrangular shape of the harvest versus the amorphous shape of the typical wound.
Excesses are easily trimmed by holding the graft in place and using thin, sharp scissors to skirt just outside the periphery of the wound.
Once excess has been removed and the entire peripheral edge of the skin graft has been secured, any surface irregularity leading to noncontact with the undersurface of the graft can be addressed by placement of quilting sutures.
These sutures are placed through the surface of the graft into the depth of the contour irregularity and then back out of the graft.
When tied, the sutures draw the deep surface of the graft into contact with the wound bed.
A suitable suture for this purpose is 4-0 chromic.
A nonadherent interface (eg, Xeroform [Kendall, Mansfield, MA] or Aquaphor [Beiersdorf AG, Hamburg, Germany] gauze) should be placed over the graft to prevent the graft from adhering to the bolster that will further secure the graft in position.
If Aquaphor gauze is used and the patient is not allergic to bacitracin ointment, a triple antibiotic ointment doping of the Aquaphor further inures the graft from injury when the overlying bolster is removed.
TECH FIG 2 • Meshed graft. Appearance of meshed splitthickness graft, dermis side up.
In the upper extremity, lightly applied circumferential dressings work well as bolsters.
Tie-over bolsters typically are not required, but they can be used if preferred. Reston foam (3M, St. Paul, MN) or salineand mineral oil–doped cotton batting secured in place with light gauze and an elastic overwrap from the tips of the fingers to a point several centimeters beyond the most proximal aspect of the grafted site is sufficient.
A sugar-tong splint should then be applied to help prevent the shear stress created between the wound bed and the undersurface of the graft, which occurs as a byproduct of pronation and supination, as well as wrist and finger flexion and extension.
The patient’s arm should be elevated to help minimize accumulation of edema at the graft site.
Postoperative Care
On postoperative day 5, dressings should be removed and the graft examined. Typically, at this time, the graft will have acquired a pink coloration, and although most of the fenestrated areas may not have fully epithelialized, it should be clear that graft take is underway. If this is not the case, the wound should be inspected to determine why the graft is not taking.
For fenestrated grafts, it is unusual for either hematoma or seroma to be a cause of graft failure. The more common cause for graft failure with fenestrated split-thickness grafts is wound infection.
Quantitative cultures obtained preoperatively will help guide the surgeon in appropriate antibiotic treatment for these patients pre-, intra-, and postoperatively.
Once early graft healing has occurred, wound infection is unlikely, and the application of a hypoallergenic emollient cream helps keep the graft supple and moisturized while at the same time promoting slough of scaling stratum corneum and eschar.
FULL-THICKNESS SKIN GRAFT
Donor Site
If the area of the wound is over or in proximity to a joint, it may be decided to use a full-thickness graft. Again, a template can be made using sterile glove paper, with this glove-paper template then transferred to the area desired for harvest of the full-thickness graft.
There are limitations on the surface area that can be obtained from full-thickness skin graft donor sites, and, therefore, consideration should be given to the recipient bed surface area when deciding on the type of graft.
Typical donor sites include the lower abdomen and the inner aspect of the upper arm.
Graft Harvest
Once the template has been transferred to the skin, harvest can be facilitated by injection of 1% lidocaine with epinephrine into the subcutaneous fat directly beneath the area planned for harvest.
Allow approximately 7 minutes for the epinephrine to take effect and help minimize bleeding during harvest.
A no.15 scalpel blade can be used to accurately incise the periphery of the planned graft harvest, followed by elevation of the full-thickness graft in the plane directly beneath the undersurface of the full thickness of dermis, directly above the subdermal fat and below dermal papillae.
In most cases, some fat is adherent to the underlying dermis after elevation.
The full-thickness skin graft can be stretched over the finger and curved scissors used to directly excise fat from the undersurface of the full-thickness graft.
The removal of unwanted fat maximizes the surface area of deep dermis in direct contact with the wound bed, which helps to facilitate the inosculation and revascularization process.
Full-thickness grafts have a greater degree of primary contraction than do split-thickness grafts; therefore, upon immediate harvest the graft will appear much smaller than it did when in situ. Once sewn in place around the periphery, however, the graft will return to the actual size of the template with little effort.
This ability to return to the template size, and even extend beyond it, means that when harvesting fullthickness graft, the harvest should not be extended much beyond the periphery of the template, as is done with split-thickness grafts.
Graft Placement
To improve the precision of dermal edge contact of the graft in the wound, suture fixation is preferred over staple fixation. Again, an ideal suture for this purpose is 4-0 chromic.
The process for dressing this graft is the same as that for a split-thickness graft: the use of either Aquaphor or Xeroform gauze dressings with an overlying bolster of Reston foam or cotton batting secured with gauze and an elastic wrap, followed by appropriate immobilization of the area.
The VAC is not recommended for unmeshed grafts and so should not be used for full-thickness skin grafts even if pie-crusted (TECH FIG 3).
TECH FIG 3 • Full-thickness graft to dorsal hand. Appearance of mature full-thickness skin graft applied over joint.
Graft Preparation
To minimize the accumulation of hematoma or seroma beneath the graft, a well-prepared bed is required.
One measure to help prevent subgraft fluid accumulation is “pie-crusting,” a technique in which the surgeon simply makes random perforations through the full thickness of the graft using a no.11 scalpel blade.
These perforations provide avenues of egress for accumulated subgraft fluid in much the same way that meshing does for split-thickness grafts.
SKIN SUBSTITUTES
The goal with skin substitutes is to place within the wound bed a biosynthetic dermal construct that will offer the advantages of a full-thickness skin graft, but without the physical cost of obtaining such a large fullthickness skin graft harvest from the patient.
The dermal constructs are placed within the wound in much the same manner as a full-thickness graft. They become fibrovascularly integrated into the wound bed as a synthetic neodermis. After maturity, application of a thin split-thickness skin graft (0.008 to 0.010 inch) converts these nonepithelialized constructs to closed wounds.
The technical application of AlloDerm and Integra is the same as placement of a full-thickness skin graft.
AlloDerm and Integra usually are secured in place around the periphery with either 4-0 chromic or staples (TECH FIG 4A).
Once a split-thickness skin graft is applied to a site treated with either AlloDerm or Integra, these splitthickness grafts should be treated in just the same manner as split-thickness skin grafts on any wound bed, observing the postoperative technical requirements of such grafts (TECH FIG 4B).
TECH FIG 4 • A. Appearance of mature Integra applied over open forearm wound. B. Very thin split-thickness graft applied and now adherent to mature Integra bed.
AlloDerm
When using AlloDerm, bolstering dressings are applied over a petrolatum-doped nonadherent gauze interface, and the dermal construct is observed periodically at twice-weekly intervals.
AlloDerm will demonstrate granulation tissue issuing through the pores of the dermal construct, typically at about 2 to 3 weeks after graft placement.
Once this has occurred, the AlloDerm is ready for splitthickness skin grafting.
Integra
On initial placement, Integra appears white, with a transition over the succeeding 2 to 3 weeks to a rosy color, the byproduct of neovascularization. At this point the Silastic layer of the Integra can be separated and the vascularized dermal construct grafted with a thin splitthickness skin graft.
If desired, Integra can be meshed 1:1 with a specialized mesher designed not to crush the construct (eg, Brennen Medical Skin Graft Mesher, Brennen Medical, LLC, St. Paul, MN).
Meshing may help the construct conform to the wound bed and also help limit subgraft fluid accumulations.
The meshed construct should not be expanded on the wound bed, since its purpose is to replace absent dermis. Its expansion thins the Integra construct and diminishes its benefits.
Fenestrations in Integra are made only for the purpose of creating an avenue for fluid escape. Integra has a Silastic membrane that acts as an external barrier.
Integra’s Silastic membrane obviates the need for petrolatum-doped dressing and is transparent, which allows direct observation of the process of maturation of the dermal construct beneath.
Biobrane
Biobrane is appropriate for use only in wounds that have some retained dermis and, because of this distinction, acts as an advanced wound dressing rather than a skin substitute. For wounds with full-thickness loss of skin, Biobrane is not an appropriate choice, because epidermal appendages, which are required to act as the source of cells needed for re-epithelialization, must be present.
Biobrane acts as a protective barrier and a scaffold for the healing process. It notably decreases pain; allows for the retention of moisture within the wound, improving the healing environment; acts as a barrier to infection; and promotes more rapid healing.
Its clinical use is most evident in treatment of burn injuries, but it also may be used to treat split-thickness skin graft donor sites to minimize morbidity in these areas.
The application of Biobrane includes tangential excision of nonviable tissues or rough débridement with an antibiotic solution–doped lap sponge, followed by drying and then application of the Biobrane to the wound surface.
It is secured in place around the periphery using staples.
This is followed by application of a nonadherent gauze dressing with placement of an absorbent dressing, such as a sterile absorbent gauze pad held in place with gauze and an elastic wrap.
The site is immobilized for 24 hours, after which all dressings are removed, leaving Biobrane in place.
At this stage, the Biobrane should be adherent to the wound bed.
Biobrane is observed over time and allowed to separate from the wound without disturbance.
Small abscesses below the Silastic layer, if they develop, can be treated by simple incision and drainage. As edges release they are trimmed.
POSTOPERATIVE CARE
On admission to the postanesthesia care unit, the patient’s operated extremity should be placed in elevation and kept relatively immobile until time to take down dressings and evaluate the graft.
Examination of the graft can be done as early as 3 days postoperatively; however, the graft at this point is very sensitive to manipulation.
If takedown of the dressings is done on postoperative day 5 or 6, allowing time for additional graft maturation, the risk of disturbing the graft is reduced.
Once maturation of the graft has been noted to be underway, application of a nonadherent dressing such as Xeroform or Aquaphor gauze should be continued, with light overpressure provided by an absorbable gauze dressing held in place by gauze and a light elastic wrap and splinting.
After the graft has more fully matured, with all interstices fully epithelialized, at between 2 and 3 weeks postoperatively, the graft will require no further application of nonadherent dressings. Instead, light application of a hypoallergenic emollient cream such as Eucerin (Beiersdorf North America Inc., Wilton, CT) is preferred. This helps to keep the graft hydrated while maturation continues without the restrictions of constant compression and splinting.
An occupational therapist should be consulted to help develop a program of appropriate splinting in tandem with an exercise regimen that will provide the foundation for maximizing the patient’s final functional range of motion.
OUTCOMES
Because of the disparate nature of wounds and the significant variation that exists in patient physiology, it is impossible to provide standardized outcome measures for skin grafting.
The goal of the general principles defined in this chapter is to assist the surgeon in optimizing outcomes for all cases. Collectively, they will work to help limit complications while maximizing functional outcomes.
COMPLICATIONS
Wound or graft infection with loss
Subgraft seroma or hematoma
Hypertrophic or keloid scarring
Contractures
Loss of functional range of motion
Tendon adherence to graft
Poor durability
Hyperpigmentation
REFERENCES
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