Closure of Abdominal Wall Defects Using Acellular Dermal Matrix Gary An, MD, Robert J. Walter, PhD, and Kimberly Nagy, MD Background: After some abdominal surgical procedures, the abdominal wall defect may be too large for closure by tension-free approximation of the wound margins because of tissue loss or swelling of the abdominal viscera. A variety of ab- sorbable and nonabsorbable prosthetic materials have been used for emergency abdominal wall reconstruction. Of these materials, polytetrafluoroethylene (PTFE) sheets have proved to be the most efficacious. Methods: This study compared the efficacy of allogenic acellular dermal ma- trix (ADM) and PTFE as prosthetic ma- terials for wound closure in rats with sur- gical, full-thickness, 2  3-cm abdominal wounds. Healing was studied among ani- mals with and those without experimen- tally induced peritonitis for 21 days after surgery. Results: Acellular dermal matrix be- came vascularized and incorporated into the wound bed and was partially or fully epithelialized without the need for skin grafting. As a result, little superficial bleeding was seen, and ADM effectively closed the wounds even in the presence of peritonitis. Wounds treated with ADM also showed a significant reduction in wound area (sterile: p < 0.001; contami- nated: p < 0.05). In contrast, PTFE tem- porarily closed the wounds, but was not incorporated into them. It consequently evoked the formation of extensive under- lying granulation tissue that showed sig- nificant superficial bleeding when the PTFE was removed. Very limited wound contraction occurred in PTFE-treated wounds, and some instances of eviscera- tion and fistula formation were observed. Wounds treated with both types of mate- rial showed significant amounts of adhe- sion to visceral organs underlying the wound site. Conclusions: Acellular dermal ma- trix exhibits a number of favorable fea- tures relative to PTFE for closing sterile or contaminated full-thickness abdominal wall defects. Key Words: Abdominal wall, Surgi- cal closure, PTFE, Gore-Tex, Dermal ma- trix, Wound healing. J Trauma. 2004;56:1266 –1275. T he repair of major abdominal wall defects secondary to severe abdominal trauma, wide surgical excision, giant abdominal hernia, or congenital body wall defects presents the surgeon with a challenging problem. Primary closure may be technically impossible because of a large musculofascial defect that prohibits tension-free approximation of the remaining fas- cial tissues. 1 Damage-control laparotomy, severe peritonitis, or hemorrhagic shock followed by aggressive pre- and intraopera- tive resuscitation may result in massive edema of the bowel, compromising the surgeon’s ability to accomplish primary closure of the abdomen. 2,3 Primary closure of the abdominal wall fascia under such circumstances would produce marked increases in intraabdominal pressure, leading to abdominal com- partment syndrome, with organ dysfunction 4 –7 and greatly en- hanced risks of wound infection, fascial necrosis, and subse- quent wound dehiscence. 1,2,5,8 Several techniques for treating such abdominal wall defects have been described including open abdominal packing, 1,2,9 rotation of muscle or fascial flaps, 10 –13 and the use of prosthetic materials to bridge the fascial defect. 1,14 –23 A wide range of prosthetic materials has been tested with experimental animals and patients. 24 Sheets of synthetic nonabsorbable materials (polyester, polypropylene, polytetrafluoroethylene [PTFE, Gore-Tex], silicone, dacron, i.v. bags), 25–30 synthetic resorbable ma- terials (polyglycolic acid), 31,32 and composite materials (urethane/silicone, polypropylene/urethane, PTFE/ polypropylene, silastic) 33–37 have been used. Currently, one of the most widely used synthetic mate- rials for this purpose is expanded PTFE, composed of long chemically inert tetrafluoroethylene (Teflon) polymers de- posited into sheets prepared so that they contain microscopic pores. Sterile PTFE sheets typically are sewn over the ab- dominal defect. The wound then is dressed, and granulation tissue is allowed to form beneath the PTFE. Days or weeks later, the polymer sheet is removed from the wound, and a split-thickness skin autograft (STSG) is implanted on the granulation tissue wound bed. However, several difficulties are associated with this material including poor fluid perme- ability of PTFE, variability in the formation of the granula- tion tissue bed, development of dense visceral adhesions and enteric fistulas under the PTFE or associated with the skin graft, and the temporary nature of the repair, which necessi- tates reoperation. To overcome some of these problems, alternative methods for closing abdominal defects using biomaterials Submitted for publication November 26, 2002. Accepted for publication February 28, 2003. Copyright © 2004 by Lippincott Williams & Wilkins, Inc. From the Department of Trauma, Stroger Cook County Hospital, Chi- cago, Illinois; and the Department of General Surgery Rush University Medical Center, Chicago, Illinois (R.J.W., K.N.). Address for reprints: Robert Walter, PhD, Department of Trauma, Stroger Cook County Hospital, 1900 West Polk Street, Room 1300, Chicago, IL 60612; email: rwalter@rush.edu. DOI: 10.1097/01.TA.0000068241.66186.00 The Journal of TRAUMA  Injury, Infection, and Critical Care 1266 June 2004