Experience with Bilaminate Bioartificial Skin Substitute and Ultrathin Skin Grafting in Non-Burn Soft-Tissue Wound Defects

Presented at the International Society for Burn Injuries (ISBI) 11th Congress, Seattle, Washington, August, 2002. Introduction Surgical closure of large soft-tissue wounds presents a surgical problem in the care of patients who develop these defects. These defects predispose the patients to the development of infection and sepsis with subsequent high morbidity and mortality rates. Early excision and grafting have shortened hospital stay and decreased infectious complications in burn patients.[1] As with burns, autografting is necessary for definitive wound closure in patients with large non-burn soft-tissue defects. If an autograft is to be durable and provide the recipient with a functional skin cover, it should contain a significant amount of dermis.[2] Extremely thin autograft placed on an excised or granulating wound does not provide satisfactory long-term healing. For large surface area injuries, the provision of a conventional autograft may be challenging due to limited donor site availability.[3] New biosynthetic materials for dermal repair have been developed with the intention of providing an unlimited availability and advanced permanent closure of soft-tissue defects.[4] Bilaminate bioartificial skin substitute (BBSS, Integra® Dermal Regeneration Template, Integra LifeSciences Corp., Plainsboro, New Jersey) consists of an inner biodegradable collagen/glycosaminoglycan matrix and an outer silicone layer. The inner dermal matrix provides a three-dimensional template, which supports cellular in-growth, collagen synthesis, and vascularization for subsequent autograft support. The outer silicone layer functions as a temporary epidermal substitute to control fluid loss and provides mechanical protection and strength to the underlying matrix. The silicone component is removed after two to three weeks at which time an autograft is applied to the engrafted dermal matrix.[5] First used by Burke and Yannas in 1981,[6] BBSS has since been used with varying degrees of success in full-thickness burns.[7,8] Large burn wound excision followed by early surgical wound closure can be achieved utilizing this skin substitute. Because a much thinner autograft is required for coverage upon removal of the silicone lamina, donor sites may be harvested more frequently, thus optimizing limited autologous donor resources. By providing a dermal component, BBSS has the advantage of lessening future scarring and wound contraction by preventing mechanical instability at the graft site.[2] Clinical outcome appears to be superior in terms of final function and cosmesis.[9–11] Since open soft-tissue wounds following debridement and control of infection are not dissimilar from excised burn wounds, the hypothesis would be that grafting results should be the same with the use of this material. Prior to this report, only limited case studies have reported the use of BBSS for coverage of wounds other than burns.[12–14] Purpose The purpose of this study was to evaluate the benefit of BBSS and ultrathin skin grafting for the closure of large soft-tissue wounds. Methods The University of New Mexico Health Sciences Center is a designated Level I Trauma Center serving New Mexico and the regional southwest. From March, 2001, through December, 2001, 2004 patients were admitted to the Trauma Center, of which 15 patients with large non-burn soft-tissue wound defects were treated with BBSS. Etiology of wound occurrence included both traumatic and infectious processes. All patients were admitted to the Trauma Service and underwent routine resuscitation and care. All subjects in the study gave informed consent for use of BBSS. This study conformed to institutional guidelines and those of the American Physiology Society. Wounds were evaluated and managed in a similar fashion including excision, surgical debridement, and topical antimicrobials. Five-percent sulfamylon solution was applied to the wounds and open soft-tissue areas on burn flat dressings, which were held in place with sterile, rolled, fluffed, cotton wraps. Wounds were dressed and inspected daily by both the nursing and physician staff. All obviously necrotic tissue was surgically removed. All wounds were judged ready to engraft by BBSS by the development of a clean, healthy, granulating wound base. This was confirmed by the wound’s ability to vascularly accept cadaveric homograft as a temporary biologic cover for a period of three days. At this point, the homograft was removed and BBSS was applied as previously described5 and allowed to engraft over a period of 17 to 28 days. Wound closure was accomplished by ultrathin skin grafting. Ultrathin graft thickness ranged between 0.06 and 0.08 of an inch in thickness and was harvested in a routine fashion with a dermatome (Zimmer™, Zimmer Mid-Atlantic, Midlothian, Virginia). Epidermal grafts were meshed at a ratio of 2 to 1 or left as sheet grafts either based on cosmetic result or anatomic location. Grafts were secured with staples or a bonding agent (Dermabond®, Ethicon Inc., New Brunswick, New Jersey). Sheet grafts or grafts anchored with the bonding agent were visualized at 24 hours following placement to ensure graft integrity. Meshed grafts were visualized at 72 hours and redressed with antibiotic-impregnated fine mesh gauze and wrapped in sterile burn flats. Post-operative graft management included daily dressing changes following graft visualization. Graft staples were removed at one week following the grafting procedure. Donor sites were dressed with a silver-coated antimicrobial dressing (Acticoat®, Smith & Nephew Wound Management, Hull, United Kingdom), dampened with sterile water twice daily for five days, then left to separate naturally, and trimmed as reepithilization occurred. Results The results of the investigation are tabulated in Table 1. During the period of investigation, 15 patients were admitted with non-burn soft-tissue defects and treated with BBSS. All patients survived. Eight patients were male and seven were female. The mean age of the group was 33 years (range 3 to 66 years). Seven patients had traumatic soft-tissue injuries, and eight patients had soft-tissue defects as a consequence of necrotizing fasciitis. An average of 2.3 operative procedures was required to obtain a clean wound bed. Wound defects ranged from 85 to 3000cm2, mean 727 ± 220cm2. BBSS wound coverage ranged from 46 to 2790cm2, mean 574 ± 202cm2. Because of an insufficient bolstering of her wound dressing, Patient 1 lost the entirety of her BBSS in the first 24 hours following placement and had her wound closed by standard split-thickness skin grafting technique. Overall engraftment of BBSS averaged 88 percent. Ultrathin skin grafts ranged from 40cm2 to 2790cm2, mean 570 ± 213cm2. Ultrathin skin graft take averaged 92 percent. Three patients required additional grafting for closure because of graft loss. Case reports. Patient 3. This patient was a 27-year-old, steroid-dependent woman with systemic lupus erythematosis who developed necrotizing fasciitis of the left lower face and neck requiring an extensive debridement for infection control (Figure 1). She underwent delayed primary closure and placement of BBSS on Hospital Day 12 (Figure 2). She was discharged home on Day 5 following BBSS and allowed to engraft at home. She was readmitted and returned to surgery on postoperative Day 18 (Figure 3) and underwent ultrathin sheet graft placement anchored with the bonding agent and staples (Figure 4). Because of tension with lateral neck rotation, a small area at the superior edge of the graft sheared requiring a 15cm2 graft revision 24 hours later. Figure 5 shows the cosmetic result of near 100-percent epidermal take at three weeks post-operatively. The cosmetic result is quite satisfactory with no step-off defect at this early postoperative point. Patient 8. This thirty-six year-old female firefighter sustained a compression injury after being trapped between a fire truck and concrete wall. This patient demonstrates the cosmetic benefit in the use of this product with a difficult wound. This patient’s large posterior back wound, representing a 17-percent total body surface area defect, was difficult to manage because of its size and location (Figure 6). The nature of this wound and the patient’s clinical condition required the management of the patient on her back following the placement of BBSS (Figure 7). Contact pressure and shearing resulted in a 35-percent loss at the mid and upper area of the wound (Figure 8). This continued to be a problem following skin grafting, with a loss of 25 percent of the skin graft. She required two additional skin grafting procedures at the lower part of her wound at three and nine months postinjury for ultimate closure. Figure 9 shows the final result in BBSS placement. The cosmetic result of ultrathin grafting success over engrafted BBSS in the lateral portions of the wound is significantly better than in the areas of BBSS slough medially requiring traditional skin grafting techniques. Discussion The efficacy in the use of BBSS for wound closure in burns has been demonstrated in many studies.[2,7,8,12] Heimbach, et al., in a multicenter study, demonstrated excellent success with BBSS placement and epidermal graft take in burn patients. In this study, there was a demonstrated improved cosmetic result and comparable survival rates when judged against routine burn wound excision and skin grafting techniques.[7] With accumulating clinical experience, the optimal use of BBSS for additional applications is emerging. The use of BBSS for scar revision has been described both in burn and surgical scars.[13,14] Soft-tissue wounds created by trauma or infectious processes represent integumental defects, which require closure. The clean wound with a satisfactory granulating vascular bed is the same for a full-thickness excised burn, a traumatic wound, or an excised necrotizing fasciitis defect. All require coverage to reduce exposure to bacterial invasion and to eturn the host to homeostasis. This study demonstrates that soft-tissue injuries, both infectious and traumatic, may be closed satisfactorily with this product. It has been argued that the use of this product delays ultimate wound closure, as the engraftment period of BBSS takes a period of two to three weeks and extends hospital care. In this study, the advantage of this product was that early coverage with BBSS allowed patients to be transferred from an acute care hospital environment to a step-down unit or ward bed requiring significantly less hospital resource utilization. Over 50 percent of the patients in this study were treated out of the hospital at skilled nursing care facilities or at home as outpatients during their engraftment period, thereby eliminating inpatient hospital expenses. The success in the use of BBSS requires a certain amount of experience. Like any surgical procedure, there is a learning curve during which optimal placement of BBSS and success of ultrathin skin grafting are developed. Patient 1 is an example of the need to secure BBSS with a satisfactory dressing in an anatomically difficult site to prevent shearing of the product. This patient had a large wound defect in the right gluteal area from necrotizing fasciitis and had satisfactory placement of BBSS. She subsequently experienced a total loss of the graft because of myoclonic muscle contractions and an inadequately secured dressing. In comparison to its use in burn care, this study shows that the success of BBSS placement with ultrathin skin is similar in the management of certain soft-tissue defects. In this study, the average engraftment success of BBSS was 88 percent and the average skin graft take was 92 percent, which are similar to standard grafting techniques and the use of BBSS in burn wound management as reported by Heimbach, et al.[7] Conclusions BBSS is a satisfactory alternative to closure of certain large soft-tissue defects from traumatic and infectious causes. Its success of closure is comparable to its use in the closure of full-thickness burn injuries. Its cosmetic results are superior when compared to standard skin grafting for closure of these wounds.