Hand Surgery
1st Edition

65
Skin Grafts and Tissue Expanders
Guenter Germann
Sigrid A. Blome-Eberwein
Skin grafting has been the most commonly used technique for reconstruction of cutaneous defects over the last decades. Numerous variations, such as mesh graft, cultured epithelial autografts, and combined alloautograft techniques (sandwich technique), have significantly enhanced the therapeutic spectrum of the traditional skin graft technique, especially in the treatment of severely burned upper extremities. The introduction of tissue expansion has added a new dimension for secondary scar corrections or the treatment of neoplastic skin lesions that are not suitable for excision and primary closure. As in all surgical procedures, correct indications, a well-designed treatment plan, good selection of the proper technique, and excellent technical execution are the keys to success in reconstruction of major and minor defects of the skin of the arm and hand.
SURGICAL ANATOMY
Skin of the Hand
Distinct qualities of the dorsal and palmar hand skin make them especially suited for their different tasks. Although both have in common an irregular border between the basal layer of the epidermis and the dermis, the epidermis (keratin layer) in the palmar skin with its thick stratum corneum is approximately three times as thick as it is in dorsal skin. This structure is responsible for the enormous capacity of spontaneous healing in abrasion injuries, burns, or contusion injuries. There are no hair follicles or sebaceous glands on the palmar side of the hand. Instead, specialized encapsulated nerve endings are found. Meissner’s corpuscles are present in dermal papillae, and Vater-Pacini corpuscles are present in the deep dermis. The submacroscopic structure resembles the honeycomb architecture of the plantar skin. The aponeurotic system with its structural arrangement of fibrous and elastic fibers provides stability and resistance to shear forces.
All other features, such as epidermal rete ridges, intraepidermal nerve endings that terminate in Merkel cell neurite complexes, a dense network of blood vessels, sensory and autonomic nerve fibers, and sweat glands, which are located in the base of the dermis, as well as subcutaneous fat, are found in dorsal and palmar skin (Figs. 1 and 2) (1,2,3,4 and 5).
Skin of the Arm
The skin of the arm resembles the skin in any other part of the body. In general, the inner-flexor side skin contains fewer hair follicles, and the dermis is thinner than the outer-extensor side skin.
Superficial Nerves
Seven nerves provide sensibility for the skin of the arm and hand. In the shoulder region that overlies the deltoid muscle, the axillary nerve is supplying the skin. The upper arm is supplied by the medial cutaneous brachii nerve (upper inner arm and axilla) and the medial cutaneous antebrachii nerve (upper and lower inner arm). The radial nerve and its branches (cutaneous brachii posterior nerve, cutaneous antebrachii posterior nerve, ramus superficialis, digitales dorsales nerves) supply the upper and lower lateral aspect of the arm, as well as the dorsum of the hand up to the meta-carpophalangeal joints of the index, middle, and ring fingers and the dorsum of the thumb.
The musculocutaneous nerve and its branch (cutaneous antebrachii lateralis nerve) reach the radial flexor side of the lower arm, including the thumb, and up to the proximal interphalangeal joints of the index and middle fingers. The cutaneous branches of the median and ulnar nerves provide sensibility and tactile gnosis for both aspects of the digits (3,4 and 5).
PATHOPHYSIOLOGY
Skin Defects of the Fingers, Hand, Wrist, and Arm
Cutaneous defects of the hand and wrist most commonly result from trauma (including burns) or its sequelae. Tumor
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resection or the sequelae of extravasation of intravenous drug applications are less frequent causes for skin defects. Secondary skin losses can result from operative procedures in traumatized hands, Dupuytren’s contracture release, or the treatment of congenital deformities (e.g., syndactyly, club hand). Skin grafts are the easiest method of coverage for skin defects. The type of skin graft that is used depends on the type of defect, the characteristics of the wound, the personal profile of the patient, and the aesthetic requirements of the individual patient (see Skin Grafts). In the case of exposed or destroyed important functional structures, such as tendons, bones, or joints, different reconstructive techniques have to be considered (see Fig. 9) (6).
FIGURE 1. Light microscopic histologic section of palmar skin. Note the thickness of the keratin layer and the transiting sweat pore.
Scars
The process of scar formation is complicated and is not yet completely understood. Wound healing proceeds in three stages, beginning with the inflammatory phase, followed by the proliferative phase, and then followed by contraction and maturation with rearrangement of the collagen fibrils in a more organized way. In hypertrophic scarring, the appropriate end point for continuous collagen production is neglected by the tissues, and the orientation of fibrils is unorganized (7). Hypertrophic scars are common over joints, in burns, and in scars that are perpendicular to the resting skin tension lines (Fig. 3).
FIGURE 2. Light microscopic histologic section of dorsal skin. Note the thinness of the keratin layer compared to the palmar skin in Figure 1 but the otherwise similar histologic organization.
FIGURE 3. Typical hypertrophic scars resulting from burns. Not only do the scars cross the joint lines, but also the reduced compliance of scar tissue limits motion by reducing excursion of the skin.
Keloids display different properties. They grow beyond the limits of the scar into healthy tissue and exhibit tumorlike growth properties. They have a higher incidence in very fair and dark skin.
The disruption of the ideal wound healing process is caused by multiple factors, such as ischemia (8), hypovolemia (9), infection, and mechanical forces. Some nutritional deficiencies, such as deficits in protein, vitamins C and E, zinc, and copper, can also cause disturbances in the wound healing process. There are a few hereditary diseases (e.g., factor XIII deficiency, protein C and A deficiencies) that interfere with wound healing, and drug-related disturbances of the normal healing process may occur (e.g., glucocorticoid therapy) (10).
CLINICAL SIGNIFICANCE (INCIDENCE)
Skin defects of the tips of fingers are common owing to the exposed location. In most cases, superficial, as well as deeper, lesions without exposure of bone or tendons heal spontaneously under moist or occlusive dressings. Complex defects can usually be reconstructed with some type of local or regional flap (11).
In the authors’ patient population, the authors treat approximately 300 burn patients per year, of which 80% demonstrate involvement of the hand. Approximately 50% of these patients require some form of skin grafting to the hand. In Dupuytren’s contracture release, only 0.5% of all procedures leave a skin defect that requires
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skin grafting. Approximately 50 cases per year are treated with skin grafting for skin defects that are caused by infection or some other complication from trauma or with surgical intervention. In syndactyly release, skin grafting is indicated in 80% of the cases. Compound defects are usually treated by pedicled or microvascular flap transfer (approximately 250 cases per year).
NATURAL HISTORY
Only superficial skin defects, such as in first-degree burns (also known as superficial partial-thickness burns), heal spontaneously without scar formation. However, changes in skin pigmentation may occur, especially in very fair- or dark-skinned patients. Usually, reepithelialized areas remain reddish or pink in color for several months, until the underlying hyperemia resolves, and the skin color returns to the preinjury tan. Deeper (partial-thickness burns) skin defects of the upper extremity, if left untreated, heal by secondary intention through the formation of granulation tissue and consecutive wound edge contracture. Deeper defects of the fingertips are the exception. They usually heal under occlusion dressings without scarring, and even the fingerprint may be regenerated. Because normal function of the joints largely depends on a supple soft tissue envelope, secondary healing leads to the development of severe contractures that result in marked functional losses. The same holds true for hypertrophic scars and keloids. Keloids in general tend to become worse over time and with the number of attempts of keloid excision, if no further adjunctive treatment is applied [i.e., radiation, corticoid injection, pressure garment application, percutaneous silicone sheet application(12,13)]. Unstable scars are another sequel of spontaneously healing larger defects. Recurrent ulceration, diminished resistance for shear forces, and impaired healing of ulcerated areas are typical characteristics. Ultimately, Marjolin’s ulcer may evolve (14).
EVALUATION
Physical Examination
The physical examination of skin defects in the upper extremity includes the determination of the exact location and size of the defect, the assessment of viability of underlying and surrounding tissues, the presence of chronically unstable areas, the extent of functional limitation, the skin quality in the vicinity of the defect, the overall appearance of the patient, and the patient’s personal profile.
Scars are described by size and as being pale, hyperemic or blue, hyper- or hypopigmented, soft and pliable or hard and rigid, and at or above the level of the surrounding tissue and by whether they constitute a limitation to movement. The skin quality of the individual needs to be taken into consideration (e.g., age, gender, and drug therapy, such as corticoids or blood thinners) (Fig. 4).
FIGURE 4. Flowchart of patient factors that must be considered when contemplating treatment options for scar tissue. STSG, split-thickness skin graft.
Imaging Studies
In case of scar contractures, especially after major burns or in polytrauma patients, conventional x-ray studies should be taken to exclude heterotopic ossification or secondary bony deformities. Computed tomography scan or magnetic resonance imaging is usually indicated only in cases of malignant soft tissue tumors; angiography or magnetic resonance angiography is required only in vascular malformations or after severe trauma.
NONOPERATIVE TREATMENT
There is no nonoperative treatment option for deeper skin defects in the upper extremity, except in defects of the fingertips. Fingertip defects epithelialize over a period of time under moist or occlusive dressings and yield better sensitivity and appearance than grafted fingertips (15).
Hypertrophic scars respond well to nonoperative measurements, which represent the foundation of scar treatment. The stepwise concept includes a primary application of pressure garments or bandages. This can be combined with a cutaneous application of silicone gel sheets, silicone cream,
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or adhesive silicone foils. It is important to monitor the perfect fit, and the patient has to wear his or her pressure garment 23 hours per day for at least 6 months after trauma. This treatment has to be initiated early after complete epithelialization, because matured hypertrophic scars usually do not respond to this treatment. The effects of pressure or percutaneous silicone application have not yet been completely understood. When the relative hypoperfusion under pressure garments is made responsible for the prevention of hypertrophic scarring, no comprehensive explanation has been found for the efficacy of silicone application.
TABLE 1. CONSERVATIVE (NONOPERATIVE) TREATMENT OPTIONS FOR SCAR AND DYSPIGMENTED TISSUE
Hypertrophic scar Scar contracture Surface and pigmentation irregularities
Pressure garments Physical therapy: Peelings
Silicone gel sheets    Stretching Coblation
Face mask    Massage Dermabrasion
Intralesional injection of cortisone Pressure garments Permanent makeup (tattoo)
Anticytokine injection Silicone gel sheets Camouflage makeup
Massage
Intralesional injection of cortisone is another conservative measure that can be combined with pressure therapy. Injections with anticytokines are still under clinical investigation and, their efficacy has not yet been proven.
Physical therapy, including scar massage and electrostimulation, can resolve or prevent joint contractures in many cases by softening the areas that are involved. Scar massage always has to be directed perpendicular to the course of the scar to prevent or break the collagen fibril organization. This is of special importance in deeper burns, in which the deeper subcutaneous layers may also be contracted. The therapist has to be familiar with the special needs of a patient whose limitation results from skin and subdermal contractures rather than from isolated joint stiffness.
Laser treatment, peelings, coblation, and dermabrasion are other adjunctive procedures that may resolve dyspigmentation or smooth rippled skin surfaces, and some patients can be helped with permanent makeup (tattooing) to ameliorate the effects of dyspigmentation (Table 1).
SURGICAL MANAGEMENT
Tissue Expansion
History
The first expandable air-filled tissue expander was reported in 1957 by Neumann (16). Radovan reported about the use of an expansion device to stretch the periauricular skin for the purpose of ear reconstruction (17). Despite all technical improvements, increasing knowledge about the tissue reactions, and the geometric responses to expanders of different shape, the principles of skin stretching have remained the same. With improved technology, the principle gained a widespread popularity for scar correction or defect closure after skin tumor resection in the 1980s. The initial enthusiasm surrounding their use in reconstructive surgery was soon dampened by a considerable complication rate, including infection, extrusion of the expander, or skin breakdown (18,19,20,21,22,23 and 24). The analysis of these inherent complications led to a better definition of the indications. The main applications today include correction of alopecia, head and neck reconstruction, scar correction in the trunk after burns or trauma, or breast reconstruction combined with alloplastic implants. Provided suitable indications, tissue expansion may be a reasonable alternative to serial excision, local flaps, or regional pedicled flaps, and it avoids an additional donor site. The newly gained tissue matches the color and texture of the surrounding tissue and remains sensate. The use of tissue expansion in the upper extremity has only been occasionally reported (18,25,26,27 and 28). The method has been proposed in this location for scar corrections, contracture release, coverage of tumor resection defects, and congenital anomaly corrections (i.e., syndactyly), but actual numbers in the literature are small (29,30 and 31). An interesting method of tissue expansion for the treatment of syndactyly has been proposed by Ogawa et al. (32). They applied outside pressure to the to-be-created interdigital space with a pincer device and created enough laxity of the skin to perform the syndactyly operation with local flaps only. This way they spared the patient a second operation and skin graft coverage.
Principle
Tissue expansion uses the ability of the skin that is adjacent to a scar or a future defect (for instance, in tumor resection) to stretch to mechanical forces. The effect is achieved by placing a silicone-shelled balloon into a subcutaneous pocket that is adjacent to the area to be reconstructed. The incision for this pocket should be perpendicular from the edge of the soft tissue–deficient area to minimize the risk of extrusion. Endoscopically assisted expander placement can eliminate this problem (33). The balloon is sequentially filled with saline through an integrated portal system, or a remote port is used that is placed into another pocket at some distance from the expander. The remote port is the safer solution, because the risk of incidental injection into the expander with subsequent deflation is considerably higher in integrated ports (34). Expansion is delayed in this concept for 2 to 3 weeks to allow proper soft tissue healing and to prevent skin breakdown or extrusion of the balloon. The expansion is then progressively continued, usually over a period of 6 to 12 weeks, always according to the individual patient’s tolerance.
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The expanded skin is thinned; despite an epidermal hypertrophy, the vascularity of the expanded tissue is also enhanced owing to a delaylike phenomenon. A membrane with pseudoendothelium is formed around the silicone balloon. This membrane is well vascularized and may serve as a gliding surface in upper extremity reconstructions that use preexpanded free flaps. After removal of the expander, shrinkage of 25% of the expanded surface has to be expected due to the elastic properties of the expanded skin. Therefore, many surgeons tend to leave the maximally inflated expanders in place for another 4 weeks to reduce this phenomenon, whenever the patients tolerate this.
There are many different shapes and sizes of expanders with various geometric responses of the expanded tissue. The bottom plate determines the size in two planes; the actual tissue gain is created by the projected height of the expander, which has to be considered during the planning. Ideally, the bottom plate is placed on a hard resistant surface, such as the skull, in which the expansion is only directed toward the skin. In concave areas or in areas with a soft bed, the expansion may also be directed into the underlying tissues and does not sufficiently stretch the skin. In children, it has to be considered that bony impressions, for instance, in the ribs or the skull, are possible (35).
The advantages of tissue expansion include the close match in tissue texture and color and the fact that sensible innervation is maintained. The disadvantages of tissue expansion include the risk of extrusion, infection, and skin breakdown, as well as the fact that it always includes a minimum of two operative procedures with insertion of the expander, and subsequent expander removal and scar correction. In selected cases, in which the primary tissue gain is not sufficient, the expander can be reinserted, and repeated expansion can be initiated. Multiple clinic visits for wound control and expander filling are time and cost consuming for the patient and physician.
Operative Technique
Careful planning of the procedure is the most important key to success. The scar has to be measured in all dimensions, and a corresponding expander has to be chosen. The incision for placement of the expander should be made perpendicular to the long edge of the scar. It has to be included into the actual scar excision and the spreading of the expanded skin. This requires some experience with tissue handling and knowledge of the skin resting-tension lines. In the upper extremity, it also must be considered not to create straight lines across joints and to design the expanded skin flaps in a way to conceal the resulting scar on the medial side of the arm. Contrary to the most common recommendation, the authors prefer placement of the expander in the arm epifascially, more precisely in the fascial cleft (36). The pocket is usually created by sharp and blunt dissection with an instrument like the Korn tongs. The pocket has to be large enough to fit the expander without wrinkles at the bottom plate. A separate pocket is created for the port, well away from the expander, to avoid accidental puncture of the expander or even coverage of the port by the inflated device. After meticulous hemostasis, the cavity is rinsed with diluted iodine solution, and the device is tested for leakage by inflating it with air and holding it under diluted iodine solution (1:10). After this test, all air is aspirated, and the expander is inserted after glove change. Folds and wrinkles in the pouch have to be removed before wound closure. The device is slightly filled to smooth any residual wrinkles, to avoid dead spaces, and to provide additional hemostasis. Wrinkles promote uneven distribution of pressure during the expansion process, which predisposes for skin irritation with subsequent infection or perforation. The skin is closed in two layers.
Inflation may be started after wound healing (from 8 to 10 days to 2 to 3 weeks after insertion). Once or twice weekly, the port is punctured under sterile conditions with a 22-gauge needle, and sterile saline or Ringer’s lactate solution is injected until the patient feels pain or until the skin above the expander blanches. At this point, 2 mL are removed, and the needle is withdrawn. Intraluminal pressures can exceed capillary closing pressures without affecting skin capillary refill (28).
Endoscopically assisted expander placement has significantly improved the tissue expansion procedure. After a small incision that is remote from the projected expander pocket, the fascial cleft is identified and a “spacemaker” balloon is inserted through a small canal of approximately 3 to 5 cm in length. This is an inflatable device that is inserted with a guiding rod. The balloon is then filled with air and creates its own optical cavity to incorporate the expander. The cavity can then be endoscopically inspected for bleeders, and hemostasis can also be achieved with endoscopic instruments. The combination of a small incision and an insertion canal creates a “bottleneck effect.” This prevents extrusion of the expander through the incision line and allows for a significantly greater initial filling volume than with the conventional technique. Often, as much as 30% of the nominal expander volume can be filled during expander placement without waiting for wound healing. This is a major advantage, especially in children, because it causes less pain, requires fewer filling sessions, and abbreviates the total reconstruction period.
The initial patient consultation deserves special attention. The necessity for weekly fillings, the temporary deformity caused by the expansion, the duration of the process, the necessity for two surgical procedures, as well as possible complications have to be discussed in detail with the patient to obtain the necessary compliance for the process (Fig. 5).
Skin Grafts
History
The concept of autologous skin grafting was not reported until 1838 (37) and 1845 (38). Reverdin (39) and Thiersch
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reported successful transplantation of split-thickness skin in 1869 and 1874 (40). In 1875, Krause (41) and Wolfe (42) established full-thickness grafts. Since then, these techniques have become the backbone of reconstructive procedures. However, there are indications in medical history that skin grafting was used by Hindu surgeons as well as Greek surgeons long before a medical literature existed.
FIGURE 5. Lateral view of a hand with hypertrophic scar before surgical intervention.
Type of Graft
The best choice for a skin graft depends on the location of the defect or scar, the properties that are expected of the grafted skin, the expected aesthetic appearance, the size of the defect or scar, the donor availability, and the donor site morbidity. In general, two histologic types of skin grafts can be distinguished, split-thickness and full-thickness grafts. Split-thickness grafts include dermal components, depending on the thickness of the harvested graft, but they do not include the full dermal layer. Full-thickness skin grafts include all layers of the skin, so that the donor site has to be primarily closed or, in rare cases, grafted with a thinner graft itself. This distinction is, although principally correct, nevertheless insufficient. First, the donor site for the graft determines how many skin appendages are included into the graft. This means that various skin grafts can be differently composed, although they have been harvested with the same dermatome adjustments. Second, there is not much scientific evidence that a groin full-thickness graft has better properties, with respect to contraction, pliability, and aesthetic appearance, than a thick split-thickness graft from the back. It can certainly be said that a standard 0.001- to 0.002-in. setting on the dermatome, which is recommended in most of the literature, does not guarantee a histologically standardized graft. Inter- and intraindividual variations in skin thickness, which is dependent on age, gender, and constitution, as well as possibly medication (e.g., glucocorticoids), require some routine in skin grafting to choose the ideal graft for a defect or scar correction. In most of the literature, full-thickness grafts are preferred for palmar hand defects, and split-thickness grafts are preferred for defects on the arm and the dorsum of the hand. It can be generally stated that the thinner the graft, the better the take of the graft, but the higher the incidence of resulting graft contracture.
Graft healing proceeds through a series of stages that are unique to skin grafting. The first 24 hours are called plasmatic imbibition (43). During these hours, the graft is attached by fibrin to the wound bed and takes up wound exudate, gaining up to 40% of its weight. This prevents drying out and keeps the vessels inside the graft open. Eventually, the fibrin is replaced by granulation tissue, and revascularization proceeds. The first “neovessels” are formed within 72 hours [inosculation (44)]. Subsequently, vascular proliferation occurs in the graft and its bed. Full circulation is restored to the graft within 4 to 7 days (45). Restoration of lymphatic vessels parallels restoration of the vascular supply during the first week; reinnervation may start as early as 2 to 4 weeks after grafting, although full sensation is usually not achieved. Epidermal proliferation and hyperplasia are seen on and after the fourth postoperative day and persist for weeks (45).
Even after the blood supply has been reestablished, many factors can still interfere with graft take. The graft is vulnerable to infection, shear forces, and ischemic periods (e.g., through cigarette smoking), so that meticulous care and control are needed, and the graft has to be protected from mechanical forces for another 1 to 3 weeks, until secure graft take and healing are secured. Especially in full-thickness grafts in the hand, shear forces may disrupt the vulnerable neovascularization, may lead to hematoma, and may cause secondary graft loss. A careful balance has to be maintained between graft protection and urgently indicated physical therapy during this time, and only experienced physical therapists should be trusted with this task.
Operative Technique
Preparation of the Wound Bed
To guarantee secure graft take, the wound bed has to be clean, free of residual necroses, and well vascularized. This applies for burn wounds, as well as for traumatic defects. In burn wounds, skin defects predominantly result from tangential or epifascial burn eschar excision. If the excision is performed down to layers of healthy, well-perfused tissues, skin grafting can be performed immediately after meticulous hemostasis.
In trauma defects, wound conditioning is sometimes required when tissue of questionable viability remains in the wound or when perfusion disturbances occur after severe contusion or avulsion injuries or in débrided, infected areas. Contamination should be avoided, and, in case of infection, the wound has to be topically treated before grafting is considered. It has been shown that bacterial counts of more than 106 per gram of wet weight lead
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almost inevitably to graft loss. Topical treatment may consist in soaking the wound with antiseptic solutions, topical antibacterial creams, or repeated surgical débridement.
Conditioning the wound to promote growth of granulation tissue can be achieved with moist dressings, frequent rinsing, mechanical débridement of the wound, temporary wound closure with xenograft or allograft, and the application of intermittent or constant vacuum over polyurethane foam dressing in a hermetically sealed wound. It has been shown that application of vacuum-assisted closure generates granulation tissue, reduces bacterial contamination, and enhances the vascularity of the wound bed. However, this technique should be used solely for wound preparation over a short period of time, before definitive closure is achieved. Prolonged application over tendons, joints, or bony surfaces leads to significant stiffness of the joints and severely limited tendon excursion.
Donor Site Choice
The selection of the donor site is essential to achieve the best possible results. The closer the donor site is to the defect, the better the color and texture match. However, there are only limited sites for full-thickness grafts in the upper extremity. The upper inner arm usually has excess skin that can be used for full-thickness grafts; the elbow crease is another possible site, but it has the potential risk of scar contracture. The area between rascetta and restricta at the wrist can be used as a donor site for finger defects. However, incisions at the volar aspect of the wrist should only be considered in rare cases, because patients have reported that they have been suspected of attempted suicide when their environment registered the scars. The ulnar side of the hypothenar has recently been described as a donor site for palmar defects of the hand (46). Patients in general prefer donor sites at which scars can be hidden, such as under a watchband or a T-shirt. This needs to be discussed before surgery.
For split-thickness grafts, in general, convex areas of the body are easier to harvest than concave areas. Depending on the size of the defect, the thighs or upper arms may be used (Fig. 6). Bony prominences have to be avoided, as do areas that overlie bone or tendon (e.g., anterior tibial crest, Achilles tendon, radial head). The lower arms and legs should be avoided as donor sites because of unsightly pigment disturbances and delayed healing. The back and the scalp are excellent donor sites for split-thickness grafts. The back skin is thick, and the donor site can usually be concealed with clothing. The scalp is a perfect donor site, because there remains no visible scar, the hair growth is usually not affected, and the dermis contains a large number of hair follicles, so that healing is accelerated. Disadvantages are the limited accessibility when the patient is in the supine position (back skin) and the necessity for general anesthesia. When performing a reconstructive procedure on one hand, it may be much more practical to use the same arm as a donor site for skin grafts, regardless of possible advantages of other areas. However, cosmetic appearance is of increasing importance, so that, especially in young women or children, the donor sites should be as inconspicuous as possible.
FIGURE 6. Harvesting a split-thickness skin graft from the anterolateral thigh with a dermatome.
Difficult donor sites can be prepared by injection of large volumes of sterile saline solution. Blood loss can be limited by injecting epinephrine in saline 1:106, and the authors have had excellent experience with adding a long-lasting local anesthetic for postoperative pain control.
After the donor site has been chosen and prepped, the skin is lubricated (with mineral oil, Vaseline, or saline), and the graft of the desired thickness is harvested. For small grafts, a Weck knife can be used; larger grafts are more evenly cut with a dermatome. When using a dermatome, it is important to pay special attention, before every use, to the adjusted thickness, the fixation of the blade, and the correct width of the graft, so that the graft does not inadvertently turn into a full-thickness graft or a narrow or disrupted graft. Particularly in children and people with atrophic skin, this is of utmost importance. The thickness of the graft can also be altered by the pressure that is applied to the instrument while cutting.
Once the graft has been taken, local epinephrine is applied for hemostasis, and a dressing is chosen. Because there are hundreds of dressings available for fresh donor sites, and every user swears by his or her preferred dressing, the authors only mention the basic principles of dressing use here. There are nonadhesive dressings, which are based on Vaseline gauze and silicone films; tanning and air drying have been used, as well as hydrogels. In general, it is essential for rapid healing to maintain a moist and clean environment. Healing does not occur if the wound becomes infected or if the newly epithelialized surface is disrupted by a dressing change every other day. According to these principles, the authors use a Vaseline gauze that is soaked with scarlet red, which has bactericidal properties. The dressing is left in place until it can be peeled off easily after
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healing has occurred (10 to 14 days). The gauze allows secretions from the wound to drain into the overlying dressing material. Our experience with silicone film has not been as satisfactory, because fluid collects frequently underneath the film, which may prompt superinfection.
When preparing the graft for transplantation, it is important to keep it moist, but soaking in saline should be avoided. The saline may be absorbed, and the keratinocytes swell and burst. Split-thickness grafts can be prepared as sheet grafts, for example, in digital defects, or as mesh grafts, when larger surface areas have to be covered. It is recommended to punch little draining holes into a sheet graft by using a no. 11 blade to facilitate drainage of wound fluid. The graft can be secured with sutures or staples. A tie-over bolster dressing is applied over multilayered gauze to generate a moist environment with some pressure. Control for graft take is usually performed on the fifth day posttransplantation. In case of suspected infection or hematoma, a dressing change has to be scheduled earlier.
Full-thickness graft donor sites are usually closed primarily. Secondary split-thickness transplantation for donor site coverage should be avoided whenever possible. The graft is then defatted until the dermis with the skin appendices is clearly visible (Fig. 7). This can be done by extending the graft over one finger of the surgeon to create a convex surface or wrapping it around one of the cylindrical containers for needles on the operating room table. The graft is harvested a little smaller than the defect. This allows suturing of the graft under slight tension, so that it nicely adheres to the underlying wound bed. This creates slight pressure for better hemostasis and better contact with the wound bed. Full-thickness grafts have higher metabolic demands than split-thickness grafts. Therefore, meticulous hemostasis is mandatory in full-thickness grafts. Accumulation of fluid prevents adhesion of the graft and leads to impaired neovascularization and subsequent graft loss.
The graft should also be perforated with a no. 11 blade for fluid drainage. Fixation is usually performed with sutures to guarantee a perfect fit. Skin staples, fibrin glue, and OpSite spray (Smith & Nephew, London) have been suggested as alternatives or adjunctives to suture. A tie-over bolster dressing over multiple gauze layers is then applied (Fig. 8). Immobilization is indicated to secure graft take for 5 days until the first dressing change. Depending on the clinical appearance, immobilization may be prolonged if a secure graft take has not yet occurred.
FIGURE 7. An elliptical full-thickness skin graft is defatted with scissors before placement on the recipient site.
FIGURE 8. Full-thickness skin grafts are secured with peripheral sutures to the recipient site. Compression is achieved with the application of cotton bolsters.
Postoperative Care
Although early mobilization is the key principle in most reconstructive procedures in the upper extremity, skin grafts require immobilization of the involved segments until the graft has securely healed. To minimize additional functional loss, the best possible positions have to be selected. For the hand, this means the so-called intrinsic plus position, that is, the wrist extended to 30 degrees, metacarpophalangeal joints flexed to 90 degrees, and the proximal interphalangeal and distal interphalangeal joints fully extended. This position leads to minimal ligamentous shrinking and joint stiffness. However, to gain maximum skin length after grafting, a fist position has been recommended for 7 to 9 days (47).
The wrist is best immobilized in 30 degrees of extension; the elbow is best immobilized in 70 degrees of extension. Rarely, adjacent joints have to be immobilized, so that physical therapy is immediately initiated in all joints that do not require immobilization. Physical therapy of the grafted areas is usually started after 5 days, when the take of the graft is secure. This applies for traumatic defects, as well as for burn defects. Applications of stress and shear forces have to be avoided during this period until 2 to 3 weeks posttransplantation, when they cannot lead to graft disruption. After complete graft healing, it is recommended to keep the grafted area supple by application of moisturizing creams. Pressure garments are frequently indicated to prevent scar hypertrophy. Alternatives and adjunctive methods are external application of silicone films, silicone cream, or silicone gel sheets (13).
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Complications
Complications of Skin Expansion
In discussing a certain operative plan with the authors’ patients, the authors have to be aware and to talk about the most common complications in detail. The complication rate with tissue expansion is reported in the literature to be between 10% and 50%, depending on the location and indication (18,22,24,48,49 and 50). All studies report a steep learning curve, with the complication rate significantly dropping with the experience of the surgeon. Strict antisepsis and minimal handling of the devices, as well as the tissues, seem to be important factors in the prevention of infection. There are certain conditions and age groups in which tissue expansion appears to be especially difficult. For the correction of burn sequelae, a higher than usual complication rate has been reported; likewise, a higher complication rate has been reported for preschool- to adolescent-age children.
Hematoma is reported to be an infrequent event with expander placement. It can be prevented by placing it in the interfascial plane, with meticulous hemostasis and placement of drains for 1 to 3 days. Further complications include infection, extrusion, damage to the expander, insufficient skin gain, and aesthetically disadvantageous scar placement (with the scar producing another functional deficit).
Complications of Skin Grafting
Complications include complications of the graft and of the donor sites. Loss, or partial loss, of the graft can be caused by infection, mechanical shear forces, or collection of fluids (51,52). There are no studies in the literature that describe the incidence of graft loss. If the wound bed is prepared according to the criteria mentioned previously, the graft is protected from shear forces, the incidence of massive infections is low, the patient doesn—t smoke, and no other factors that could interfere with normal wound healing are present, graft take may be expected to reach 100%. Because of the multiple factors that influence the healing of skin grafts, it is difficult to assess a definitive complication rate.
Donor site problems are usually caused by superinfection or by excessively deep graft harvesting due to too much pressure or wrong settings on the dermatome. Pain can become a problem if grafts have been harvested from areas such as the back or buttocks.
Late complications of skin grafting include graft contractures, keloid formation, hypertrophic scarring, and unstable scars with the potential for the development of Marjolin’s ulcer.
Treatment of Complications
Control of the complications is an essential part of successful surgery. Many complications, such as inflammatory reactions in tissue expansion or beginning graft infections, can be controlled by proper conservative management. Immobilization of the affected area for a few days, oral antibiotics, and antiinflammatory drugs may be indicated. If complications in graft take are suspected, early dressing change is recommended. Thereafter, fluid accumulation can be evacuated, superinfection can be treated topically with a diluted iodine preparation, mafenide acetate, or silver nitrate, and nonadhering parts can be excised. These measures can salvage many grafts from complete loss. Donor site complications are also treated by local wound care, and, in the case of nonhealing donor sites, they may have to be overgrafted with thin partial-thickness skin grafts themselves.
Severe complications, such as expander extrusion or complete graft loss, need retreat strategies. In the case of extrusion of the expander, removal of the expander and usage of the already-gained expanded skin for limited correction is appropriate. The expander pocket can be left in place, including its capsule. After an interval of 3 to 6 months, a new expander can be reinserted, and expansion is started over again.
A defect expander is removed, the pocket is rinsed with saline and antiseptic solutions, and a new expander is inserted. In some instances, a leakage has occurred at the connection between the port and the tubing to the expander. The authors routinely place a suture around the connecting part for extra safety. Leakage has also been reported from the port itself. Repeated puncture with large bore needles may cause a permanent opening in the puncture membrane. This can be avoided only by using sharp small bore needles (22 gauge) (28). In the case of pocket infection, removal of the expander and rinsing of the pocket often suffice to primarily solve the problem. After an interval of 3 to 6 months, the insertion of another expander can be attempted with acceptable risk. Careful and compassionate guiding of the patient during this period is of utmost importance to maintain the patient’s compliance.
In the case of graft loss, the treatment options are usually straightforward. Conservative or surgical débridement of the wound bed, cleansing and reduction of bacterial contamination, generation of a well-vascularized wound bed, prevention of hypergranulation, and regrafting are the essential steps. In rare cases, alternative treatment options like Integra artificial skin (Integra LifeSciences, Plainsboro, NJ) or foam suction dressing may be used to treat complications of skin grafting and tissue expansion. They can be used to help create a granulating wound bed or to cover untransplantable tissues, such as tendons and bone, in case there are no alternatives (e.g., in burn patients, cases of necrotizing fasciitis, or severe peripheral vascular disease, which precludes free flap coverage) (Fig. 9). As already mentioned previously, patient guidance is important in these situations.
Hypertrophic scar management can become a challenge during follow-up of patients who received skin grafts, as
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well as scar contracture, which may require secondary reconstruction. The whole repertoire of plastic and reconstructive procedure options may be required, from Z-plasty and glucocorticoid injections, to local and distant flap coverage, to free tissue transfer.
FIGURE 9. Algorithm for the treatment of scar tissue.
Prevention of Complications
Most of the complications of skin grafting can be avoided by proper selection of the donor site, such as the back as opposed to the lower leg in elderly patients and the scalp as opposed to the extremities in children to avoid hypertrophy of the donor site; selection of the right thickness of graft; and proper preparation of the wound bed. A bacterial count of 105 or greater always causes major graft infection and has to be reduced before grafting (51). Obviously, sterile technique is of utmost importance, and the graft should be touched as little as possible (41).
After grafting, the area has to be immobilized for at least 5 to 7 days, depending on the age of the patient and the area grafted (47). Joints and pressure points need longer protection from shear forces. In children, it has proven advantageous to immobilize the whole extremity rather than just one joint or to use tie-over dressings. In elderly
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patients, it may speed healing time to apply continuous suction dressing over the graft for 5 to 10 days. If there is any suspicion of contamination of the grafted area, early dressing change and wet soaks with antiseptic solution (e.g., Lavasept, mafenide acetate) may prevent graft loss. Unstable scarring may be prevented by using a slightly thicker graft, provided that there is sufficient donor site.
To prevent complications of tissue expansion in the upper extremity, the aseptic technique should be used when placing the expander and when filling it. Care should be taken not to overexpand the balloon. This is recognized by prolonged blanching of the skin that overlies the expander, and it may cause necrosis and subsequent extrusion of the device. If at all possible, a healthy area of skin should be selected for expansion. For successful tissue expansion, proper and careful planning of incisions and expected tissue gain is essential. Even if premature removal becomes necessary, a good final result can still be achieved in 90% of cases via a repeated expansion. In general, complication rates are higher in burn patients and children of certain ages (48). Careful monitoring and extensive preoperative counseling of patients and their parents are paramount for success.
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