Acellular Dermal Allograft for Ventral Hernia Repair in the Compromised Surgical Field

Transcription

1 Acellular Dermal Allograft for Ventral Hernia Repair in the Compromised Surgical Field JOSE J. DIAZ, JR., M.D., JEFREY GUY, M.D., MARSHALL B. BERKES, B.S., OSCAR GUILLAMONDEGUI, M.D., RICHARD S. MILLER, M.D. From the Division of Trauma and Surgical Critical Care, Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee A ventral hernia and acontaminated surgical field are a difficult surgical combination. We hypothesize that acellular human dermis (AHD) can be a suitable biological tissue alternative in the repair of a ventral hernia. The study involved a retrospective review of the use of AHD in the repair of ventral hernia from Inclusion criteria included a ventral hernia repair in a clean-contaminated (CC) or contaminated-dirty (CD) surgical field. The primary outcome of the study was wound infection and mesh removal. Patients were stratified into CC and CD, and management of a wound infection [medically managed (MM) or surgically managed (SM)]. Seventy-five patients met the study criteria. The most common comorbidity was hypertension (45.3%). There was one death in the study (from multiple organ dysfunction syndrome). The overall wound infection rate was 33.3 per cent: 11 MM (14.7%) and 14 SM (18.7%). The average length of stay was 16.7 days (±20.8) with a mean follow-up of 275 (±209) days. Subgroup analysis: CC (n = 64) had 9 wound infections that were MM (14.1%) and 12 wound infections that were SM (18.8%); CD (n = 11) had 2 wound infections that were MM (18.2%) and 2 wound infections that were SM (18.2%). Five of 14 SM (35.7%) wound infections required removal of the mesh. Wound infection in the contaminated surgical field occurred 33.3 per cent of the time. Some (18.7%) of the cases required SM management, and 35.7 per cent of these reqired removal of the AHD. V ENTRAL HERNIA REPAIR in the setting of a contaminated surgical field presents a difficult surgical dilemma. Prosthetic mesh is widely used in the elective repair of a ventral hernia, but its use is contraindicated in clean-contaminated (CC) and contaminated-dirty (CD) surgical fields because of high complication rates. 1-4 The alternative closure of a ventral hernia with an absorbable mesh presents its own set of problems. It only serves to keep the patient from evisceration and is a temporizing procedure for a planned ventral hernia repair, and continues to be associated with a high rate of wound infection unaffected by the use of an absorbable mesh. 5-7 The development of human acellular dermis (AHD) as a fascial graph replacement presents a potential alternative to hernia closure in a compromised surgical field. AHD is derived from human donors (LifeCell Corp., Branchburg, NJ). The donated human skin is Presented at the Annual Scientific Meeting and Postgraduate Course Program, Southeastern Surgical Congress, Lake Buena Vista, FL, February 18-21, Address all correspondence and reprint requests to Jose J. Diaz, JR., M.D., CNS, F.A.C.S., Division of Trauma and Surgical Critical Care, Department of Surgery, Vanderbilt University Medical Center, 2100 Pierce Avenue, 243 MCS, Nashville, TN supplied by the American Association of Tissue Banks and is FDA approved as banked, human tissue. Using a preparatory process, AHD is cleansed of any immune reactive cells or cellular components. AHD is being used to reduce complications seen with prosthetic mesh, such as infection, adhesions, fistula formation, seromas, bleeding, and skin erosion. 8, 9 We hypothesize that AHD allograft would be a suitable biological tissue alternative in the repair of a ventral hernia in the presence of a contaminated surgical field by better tolerating wound infection, thereby reducing the incidence of prosthesis removal. Patients and Methods We performed a retrospective study of a single institution experience with AHD. Patients were admitted from January 21, 2001 to December 31, 2004 to Vanderbilt University Medical Center and included surgical cases from the trauma, general surgery, and emergency general surgery services. Before starting the study, approval was granted by the Vanderbilt University Institutional Review Board. Study Population Patients were included if they were greater than 15 years of age and underwent repair of a ventral hernia or traumatic anterior wall fascial defect with AHD in 1181

2 1182 THE AMERICAN SURGEON December 2006 Vol. 72 All Study Patients N = 75 Clean-contaminated N = 64 Contaminated or Dirty N = 11 SSI SSI Yes N = 21 No N = 43 Yes N = 4 No N = 7 Medically Managed N = 9 Surgically Managed N = 12 Medically Managed N = 2 Surgically Managed N = 2 Mesh Removed = 4 Mesh Removed = 1 *SSI = Surgical Site Infection FIG. 1. Study Design a compromised surgical field. The surgical involvement of the following organ systems was required for inclusion: stomach, small bowel, colon, appendix, hepatobiliary system, urinary bladder, spleen, and ostomy formation. This also included removal of infected mesh or repair of enterocutaneous fistula. The medical center electronic data repository (Star Panel ) and hospital administrative database were used to accurately collect patient data. Demographic data collected included age, gender, sex, race, hospital length of stay, and comorbidities, including diabetes mellitus, hypertension, renal insufficiency (serum creatine <30 mg/h), chronic obstructive pulmonary disease, heart disease, and hepatic disease (cirrhosis). The wound classification was recorded for each patient. The Centers for Disease Control and Prevention (CDC) wound classification system was used to define surgical wounds (Table 1). 10 The operative technique for each hernia repair was also recorded (Table 2). The type of suture used for each AHD repair (absorbable vs permanent) was also recorded in the database. The study population was divided into two groups: CC and CD.

3 No. 12 AHD ALLOGRAFT IN THE COMPROMISED SURGICAL FIELD Diaz et al TABLE 1. Wound Classification Wound Classification Clean Clean-contaminated Contaminated Dirty Wound Criteria Elective, nonemergent, nontraumatic, primarily closed; no acute inflammation; no break in technique; respiratory, gastrointestinal, biliary, and genitourinary tracts not entered Urgent or emergent case that is otherwise clean; elective opening of respiratory, gastrointestinal, biliary, or genitourinary tract with minimal spillage (e.g., appendectomy) not encouraging infected urine or bile; minor technique break Nonpurulent inflammation; gross spillage from gastrointestinal tract; entry into biliary or genitourinary tract in the presence of infected bile or urine; major break in technique; penetrating trauma <4 h old; chronic open wounds to be grafted or covered Purulent inflammation (e.g., abscess); preoperative perforation of respiratory, gastrointestinal, biliary, or genitourinary tract; penetrating trauma >4 h old TABLE 2. Operative Repair Type Repair Type Inlay Onlay Component separation Interposition Outcomes Repair Description Reinforcing sheet of acellular human dermas is positioned deep to the anterior abdominal wall defect Reinforcing sheet of acellular human dermas is positioned superficial to the defect Releasing incisions are made in the external oblique muscle with rectus reinforcement with acellular human dermas The edges of the acellular human dermas graft are sutured directly to the edges of the fascial defect The primary outcome measured in this study was incidence of surgical site infection (SSI) as per the CDC Definitions for Nosocomial Infections (Table 3). The management of the wound infection was divided into medical management (IV antibiotic only) or surgical management (operative incision and drainage plus IV antibiotics). Also recorded was whether the AHD was removed. Secondary variables included early hernia recurrence (HR; <1 year) and septic complications, including VAP, UTI, and BSI. Statistics Statistical analysis was performed using chi-squared tests to evaluate for statistical significances between patient subgroups. Results A total of 75 patients underwent ventral hernia repair and met the study criteria (Table 4). Thirty-six (48%) patients were men; thirty-nine (52%) patients were women. The average patient age was 51.5 years (range, 17-87). The most prevalent comorbidity was hypertension (45.3%). The average length of stay was 16.7 days and the average length of follow-up was 275 days. There was one death in the study from uncontrolled sepsis, and three patients were lost to followup. With respect to the entire patient population (CC and CD), 25 of 75 (33,3%) patients developed a surgical site infection, and 12 (16%) patients had HR. Subgroup Analysis The patient population was divided into two subgroups based on wound type: CC and CD. Sixty-four patients had CC wounds and 11 patients had contaminated or dirty wounds (Table 5). Within the CC group, there were 21 SSI: 9 of 64 (14.1%) patients were medically managed (MM) and 12 (18.8%) of 64 pa- TABLE 3. CDC Infection Definitions SSI superficial SSI deep Infection Ventilator-associated pneumonia (VAP) Urinary tract infection (UTI) Blood stream infection (BSI) Criteria All positive cultures/signs and symptoms unrelated to infection at separate site. Occurs within 30 days postoperatively Involves only skin and subcutaneous tissue of the incision At least one of the following: purulent drainage, isolated organisms, local signs and symptoms of infection, and/or diagnosis of SSI by physician Same as above, except involves deep muscle and/or fascia Nosocomial pneumonia in a patient on ventilator support at least 48 h before infection onset Appropriate signs and symptoms combined with positive culture Recognized pathogen in positive blood culture Or fever, chills, or hypotension plus at least one of the following: Common skin contaminant in two or more cultures Common skin contaminant cultured at least once from an intravascular line and antimicrobial therapy is instituted Positive antigen test on blood

4 1184 THE AMERICAN SURGEON December 2006 Vol. 72 TABLE 4. Study Demographics 75 n Value %/SD Age Gender Male Female Race (%) White Black Other Comorbidity (%) Cardiac Hypertension Diabetes mellitus Renal Chronic obstructive pulmonary disease Hepatic Chronic steroids Hospital Length of stay Charges $158,183 $206,896 Disposition (%) Died* Home Transfer/rehab * Sepsis. tients were surgically managed (SM). Of the 12 SM wound infections, four necessitated removal of the AHD (33.3%). The AHD was removed because of enterocutaneous fistula formation (n = 4) or AHD infection (n = 1; Table 6). Within the follow-up period (average, 269 days), a total of 12 (16%) patients in the CC group experienced HR. The CD patient subgroup included 11 patients, and 4 (36.4%) of these patients developed a SSI. Two (18.2%) wound infections were MM and the other two (18.2%) required surgical intervention, one of which involved AHD removal because of an intra-abdominal abscess. One SSI occurring after discharge required readmission for treatment. VAP and UTI occurred in one patient (9.1%) each, and six (54.5%) patients developed a BSI during their hospital stay. Two (18.2%) patients experienced HR within the CD patient subgroup with a follow-up period of 306 days. The differences between the CC and CD subgroups with respect to SSI, nosocomial infection, and HR were not statistically significant. Surgical Technique and Suture Analysis Outcomes were also evaluated with respect to the type of hernia repair implemented (Table 7). The ventral hernia repair type with the lowest occurrence of wound infection was the onlay technique (n = 15), with 6.7 per cent of patients developing a SSI. This was followed by inlay (n = 27, 33.3%), interposition (n = 23, 43.5%), and component separation (n = 10, 50%). The repair method most successful at preventing HR was the inlay method, as only 7.4 per cent of patients developed a secondary hernia. This was followed by component separation (10%), onlay (13.3%), and interposition (30.4%). Although general trends in differences in wound infection and HR rates are evident, none of these differences are statistically significant. Patients were also stratified by the type of suture used for the procedure, and outcomes were determined. Thirty-one percent (31.3%) of the patients who were repaired with absorbable sutures (n = 32) developed a postoperative SSI and 25 per cent experienced HR. Patients repaired with permanent sutures (n = 38) had a slightly higher SSI rate at 34.2 per cent, but a lower rate of HR, at 10.5 per cent. Again, the differences between infection and recurrence rates were not statistically significant. It should be noted that the type of suture used in five patients was unknown, and two developed a surgical wound infection. Bacteriologic wound cultures were available for 16 of 25 SSI. The most common species identified was Staphylococcus aureus (40%) with three cases of methicillin-resistant S. aureus (Table 9). Discussion Because of the high rates of infection, HR, and the occasional need for mesh removal with synthetic hernia repair in contaminated surgical field, surgeons continue to search for other methods and materials to manage this difficult dilemma. 11, 12 One such material that has garnered attention is AHD. Studies have demonstrated that acellular grafts like AHD have shown reduced postsurgical inflammation, rapid cellular infiltration, and neovascularization. This is attrib- 13, 14 utable to the macro-architecture of the acellular graft, which is native human dermis. The acellular matrix is a three-dimensional implant of tissue with intact base- TABLE 5. CC and CD Subgroup Analysis Wound Closure during Follow-Up Groups n HR (%) Length of Stay (SD) Initial Procedure Days (SD) Clean contaminated Contaminated/dirty Total

5 No. 12 AHD ALLOGRAFT IN THE COMPROMISED SURGICAL FIELD Diaz et al TABLE 6. Inpatient Infection Rate Inpatient n (%) Total (%) MM (%) SM (%) CC* CD Totals * Five patients mesh removal ment membrane, collagen fibers, elastin filaments, hyaluronan, and proteoglycans, as well as patent capillary network channels. 15 The very nature of its structure allows AHD to remain innocuous once implanted into the anterior abdominal wall. Animal models have also shown that AHD offers the same tensile strength as synthetic materials, while achieving superior revascularization. 16 The results of this study substantiate the increasing amount of evidence demonstrating the utility of AHD in ventral hernia repairs, especially in a compromised surgical field. It is generally accepted that synthetic prostheses are contraindicated in a compromised surgical field because of unacceptably high rates of infection and HR. However, there are no prospective trials that evaluate outcomes between AHD and synthetic mesh repairs. Our results and those of others suggest that ventral hernias repaired with AHD have an acceptably low rate of infection and HR rate compared with those repaired with a nonbiological prosthesis. Voyles et al. 17 reported nine (31%) polypropylene mesh removals of 29 surgically contaminated ventral hernia repairs because of infection or fistula formation. Animal models have also reported high rates of polypropylene and polytetrafluoroethylene mesh removal from infection. 18, 19 Geisler et al. 20 reported HR at 43 per cent with synthetic mesh in compromised surgical fields. The overall rates of wound infection (33.3%) and HR (16%) in this study are consistent with studies reporting complication rates for synthetic prosthesis in compromised surgical fields. Several preexisting studies have also evaluated outcomes in hernia repair using AHD and have demonstrated lower complication rates as well. Buinewicz and Rosen 8 conducted a retrospective review of 44 patients who underwent incisional hernia repair or TRAM flap surgery using AHD and they reported a 7 per cent postoperative wound infection rate and a 5 per cent HR in clean surgical fields. No patients required reoperation or removal of the AHD graft. 8 Kolker et al. 21 reported no HRs and only two seromas from a pool of 16 ventral hernia patients in clean surgical settings. Butler et al. 22 evaluated the effectiveness of AHD in 13 suboptimal surgical patients where polypropylene mesh was contraindicated (perioperative radiation, placement of mesh directly over bowel, and bacterial contamination). Only two (15%) seromas, one (8%) hematoma, one (8%) occurrence of partial flap necrosis, one (8%) case of enterocutaneous fistula formation, and one (8%) case of wound dehiscence were noted. This study demonstrates the usefulness of AHD in compromised surgical fields. Scott et al. 23 also explored the application of AHD for open abdominal wound closure. AHD was used to definitively close 37 open abdomens that would not have otherwise closed primarily. The results were favorable; two (5.4%) SSIs, one (2.7%) intraabdominal abscess, and no HRs. A prosthetic mesh infection is a complex surgical problem. In most cases, it progresses to a chronic septic state that usually mandates removal of the mesh. Under these circumstances, immediate repair requires autologous tissue material or a staged surgical repair. Yet, these cases have a universally high wound infection rate. In our study, we had a 33 per cent wound infection rate, but only five cases require removal of the AHD during the early experience. The revascularization of the AHD coupled with early SM of complex surgical wound infections allowed us to salvage the repair. It became clear that a surgical wound infection did not always equal a mesh infection. TABLE 7. Surgical Repair Technique and Outcomes Repair Type n Wound Infection (%) MM (%) SM (%) HR (%) Inlay Onlay Interpositional Component separation TABLE 8. Suture Type and Outcomes Suture Type n WI (%) MM (%) SM (%) HR (%) Absorbable (PDS) Permanent (Prolene) * Five cases with unknown suture type.

6 1186 THE AMERICAN SURGEON December 2006 Vol. 72 TABLE 9. Wound Infection and Bacteriology Graph n MM SM Removal (+) Cultures Escherichia coli Enterococcus faecium 1 1 Enterobacter cloacae 1 1 Staphylococcus aureus 1 1 Methycillin-resistant S. aureus Pseudomonas anginosa Mix growth No cultures Totals Along with AHD, surgisis also represents a biological prosthesis alternative to synthetic mesh. This material is constructed from a bioabsorbable tissue scaffold of porcine submucosal small intestine extracellular matrix. Studies have shown that surgisis promotes revascularization to help prevent infection in 24, 25 much the same manner as AHD. The literature relating the usefulness of surgisis in contaminated surgical fields is mixed. Franklin et al. 26 reported minimal infection rates (1 of 58 cases) and no HRs. On the other hand, Ueno et al. 27 reported surgical wound infections in 8 (44.4%) of 18 ventral hernia patients and an overall recurrence rate of 30 per cent. Clearly, this product needs to be further studied, but the results of our patient population using AHD seem to be competitive, if not preferable. The impact of hernia repair type on patient outcomes demonstrates general agreement with existing literature. Several studies have shown that the interposition technique yields the highest frequency of complications, whereas the inlay approach involves complications least frequently. 28, 29 Although no particular method was statistically superior in our small patient population, the numbers strongly discourage the use of interpositional hernia repair. The existing literature also favors inlay repair, but in our study, the onlay technique proved to be less prone to infection and just as resistant to HR as the inlay technique. Component separation repairs also had a low rate of recurrence (10%), but a much higher rate of wound infection (50%). Again, the size of our patient population did not allow for statistical significance, but the results favour inlay or onlay AHD placement. Repair of these complex ventral defects with onlay, inlay, or component separation surgical techniques commonly requires the development of large adjacent skin flaps. This allows for mobilization of the skin and primary closure of the surgical wound. This technique results in large subcutaneous spaces that are commonly managed with drains to allow egress of collected fluid and collapse of the space. In our study, drains were universally used for this purpose. White et al. 24 found in their study that abnormal fluid collections are the most frequent problem in these types of hernia repairs. However, the use of drains does not reduce the incidence of complications such as wound infection or seroma formation. Strenghts and Limitations This is the largest study to date using AHD in a compromised surgical field, and it was conducted at a large academic referral center. This is a retrospective review with all the limitations and problems associated with such a study. We did not have a control arm, and the follow-up period was extremely limited. This was a heterogenous population with trauma, general surgery, and emergency general surgery cases. As such, no long-term analysis or conclusion can be gathered from the data. Future studies are required to directly compare the use of AHD vs prosthetic mesh in the long-term success of ventral repair in a prospective fashion. Conclusion Our analysis demonstrates the value of AHD in the repair of a ventral hernia in a compromised surgical field. The relatively low rate of surgical wound infection and HR coupled with the infrequent necessity for AHD removal favors its use over synthetic mesh for contaminated ventral hernia closure. 30 REFERENCES 1. Trupka AW, Schweiberer L, Hallfeldt K, Waldner H. Management of large abdominal wall hernias with foreign implant materials (Gore-tex patch). Zentralbl Chir 1997;122: Bleichrodt RP, Simmermacher RKJ, Van der Lei B, Schakenraad JM. Expanded polytetrafluoroethylene patch versus polypropylene mesh for the repair of contaminated defects of the abdominal wall. Surg Gyn Obst 1993;176: Voyles CR, Richardson JD, Bland KI, et al. Emergency abdominal wall reconstruction with polypropylene mesh. Short-term benefits versus long term complications. Ann Surg 1981; 194: Temudom T, Siadati M, Sarr MG. Repair of complex giant or recurrent ventral hernias by using tension-free intraparietal prosthetic mesh (Stoppa technique): lessons learned from our initial experience (50 patients). Surgery 1996;120: Finan KR, Vick CC, Kiefe CI, et al. Predictors of wound infection in ventral hernia repair. Am J Surg 2005;190: Scott BG, Feanny MA, Hirschberg A. Early definitive closure of the open abdomen: a quiet revolution. Scand J Surg 2005; 94: Mayberry JC, Burgess EA, Goldman RK, Pearson TE, Brand D, Mullins RJ. Enterocutaneous fistula and ventral hernia after absorbable mesh prosthesis closure for trauma: the plain truth. J Trauma 2004;57: Buinewicz B, Rosen B. Acellular cadaveric dermis (acellular human dermas): a new alternative for abdominal hernia repair. Ann Plast Surg 2004;52: Bauer JJ, Harris MT, Kreel I, et al. Twelve-year experience

7 No. 12 AHD ALLOGRAFT IN THE COMPROMISED SURGICAL FIELD Diaz et al with expanded polytetrafluoroethylene in the repair of abdominal wall defects. Mt Sinai J Med 1999;66: The Hospital Infection Control Practices Advisory Committee. Guidelines for prevention of surgical site infection. Am J Infect Control 1999;27: Diaz JJ Jr, Gray BW, Dobson JM, et al. Repair of giant abdominal hernias: does the type of prosthesis matter? Am Surg 2004;70: Leber GE, Garb JL, Alexander AI, Reed WP. Long-term complications associated with prosthetic repair of incisional hernias. Arch Surg 1998;133: Livesey SA, Herndon DN, Hollyoak MA, et al. Transplanted acellular allograft dermal matrix. Potential as a template for the reconstruction of viable dermis. Transplantation 1995;60: Eppley BL. Experimental assessment of the revascularization of acellular human dermis for soft-tissue augmentation. Plast Reconstr Surg 2000;107: Available at accessed Nov. 6, Silverman RP, Singh NK, Li EN, et al. Restoring abdominal wall integrity in contaminated tissue-deficient wounds using autologous fascia grafts. Plast Reconstr Surg 2004;113: Voyles CR, Richardson JD, Bland KI, et al. Emergency abdominal wall reconstruction with polypropylene mesh: shortterm benefits versus long-term complications. Ann Surg 1981;194: Bleichrodt RP, Simmermacher RKJ, van der Lei B, et al. Expanded polytetra-fluoroethylene patch versus polypropylene mesh for the repair for contaminated defects of the abdominal wall. Surg Gynecol Obstet 1993;176: Brown GL, Richardson JD, Malangoni MA, et al. Comparison of prosthetic materials for abdominal wall reconstruction in the presence of contamination and infection. Ann Surg 1985;201: Geisler DJ, Reilly JC, Vaughan SG, et al. Safety and outcome of use of nonabsorbable mesh for repair of fascial defect in the presence of open bowel. Dis Colon Rectum 2003;46: Kolker AR, Brown DJ, Redstone JS, et al. Multilayer reconstruction of abdominal wall defects with acellular dermal allograft (acellular human dermas) and component separation. Ann Plast Surg 2005;55: Butler CE, Langstein HN, Kronowitz SJ. Pelvic, abdominal and chest wall reconstruction with acellular human dermas in patients at increased risk for mesh-related complications. Plast Reconstr Surg 2005;116: Scott BG. Early aggressive closure of the open abdomen: a new approach. Presented at the American Association for the Surgery of Trauma, September 22, White TJ, Santos MC, Thompson JS. Factors affecting wound complications in repair of ventral hernias. Am Surg 1998; 64: Badylak SF, Coffey AC, Lantz GC, et al. Comparison of the resistance to infection of intestinal submucosa arterial autografts versus polytetrafluoroethylene arterial prostheses in a dog model. J Vasc Surg 1994;19: Clarke KM, Lantz GC, Salisbury SK, et al. Intestine submucosa and polypropylene mesh for abdominal wall repair in dogs. J Surg Res 1996;60: Franklin ME Jr, Gonzalez JJ Jr, Glass JL. Use of porcine small intestinal submucosa as a prosthetic device for laparoscopic repair of hernias in contaminated fields: 2-year follow-up. Hernia 2004;8: Ueno T, Pickett LC, de la Fuente SG, et al. Clinical application of porcine small intestinal submucosa in the management of infected or potentially contaminated abdominal defects. J Gastrointest Surg 2004;8: de Vries Reilingh TS, van Geldere D, Langenhorst B, et al. Repair of large midline incisional hernias with polypropylene mesh: comparison of three operative techniques. Hernia 2004;8: Langer C, Liersch T, Kley C, et al. Twenty-five years of experience in incisional hernia surgery. A comparative retrospective study of 432 incisional hernia repairs. Chirurg 2003;74: DISCUSSION GREGORY J. MANCINI, M.D. (Columbia, MO): Dr. Diaz presents a study entitled, Acellular Dermal Allograft for Ventral Hernia Repair in the Compromised Surgical Field. This paper is a retrospective study of 75 patients who have a clean-contaminated or frankly-contaminated abdominal case an abdominal wall defect. This defect was repaired by implanting human acellular dermis known as Alloderm. Various implantation techniques were used including inlay, interposition, and onlay with or without component of separation. Also, varied in the technique was the suture used, including PDS and Prolene. Primary outcomes were the incidence of wound infection and surgical management. Secondary outcomes include hernia recurrence after less than 1 year and overall complication rates. The overall surgical site infection rate was 33 per cent with 12 of those 75 patients requiring a secondary surgery for treatment, which included Alloderm removal in five patients. The hernia recurrence rate at 1 year was 16 per cent. The material used in this abdominal wall defect repair in this series was human acellular dermis. The concept of Alloderm in hernia repair is that the innate tensile strength in the material would provide adequate early strength until the body s own healing process revascularizes the material, creating new fascia. This concept of biologic materials as mesh in abdominal hernia repair is a hot topic clinically and commercially. According to the 2005 Annual Report from LifeCell, the manufacturer of Alloderm, over 10,000 abdominal hernia cases used Alloderm as their reconstructive material. To date, no scientific data exists on how or if Alloderm, or any other biologic material, works in the setting of ventral hernia. Questions are raised about the tensile strength and the quality of cellular and collagen ingrowth when a biologic mesh is used for hernia repair. This study is one of the first to look at this complex set of issues. However, there are several design study weaknesses that limit the conclusions that we can draw from this study.

8 1188 THE AMERICAN SURGEON December 2006 Vol. 72 First, this is a retrospective cohort study with a highly homogenous patient population. The authors used a wide variation in technique. Additionally, there is no report about the hernia defect size or the amount of Alloderm used to close the defect. I have a few questions for the authors. First, in regard to the overall infection rate, did you observe a correlation in the surgical site infection and the development of early hernia recurrence? Second, do you have any data about the size of the abdominal wall defect or the amount of Alloderm used in your series? Third, there are at least three separate groups, including Ramshaw, Franklin, and Helton, that have reported some success using biologic mesh in the rectorectus position or intra-abdominally. In both examples, the biologic mesh lies behind the closed anterior rectus sheath. What techniques do you now use based on your study results? Finally, in five patients the postoperative surgical site infections required Alloderm to be removed. How do you manage the remaining wounds in these patients? In conclusion, this is a very interesting paper. It seeks to find a better solution to manage the complex abdominal wound closure in the face of a contaminated surgical field. The authors do show that human acellular dermis may be implanted, in such cases, with an acceptable comparable postoperative surgical site infection. Prospective studies with long-term follow-ups are needed to assess the success of human acellular dermis or other biologic options as hernia repair material. These studies should focus on the cost and long-term hernia recurrence, particularly in those prone to hernia formation that remodeled this biologic mesh with defective collagen or elastin. YURI W. NOVITSKY, M.D. (Charlotte, NC): When larger pieces of Alloderm are used, we often notice a lax in the abdominal wall rather than a true hernia. Did you have patients develop the laxity that would not truly qualify as a recurrence but sometimes be pretty bothersome to those patients? ROBERT R. ADERHOLD, M.D. (Chattanooga, TN): I was wondering if you took into account which of your patients were smokers and how that affected their outcomes. STEPHEN W. BEHRMAN, M.D. (Memphis, TN): We presented a very similar series about 5 or 6 years ago at this meeting using polypropylene in inguinal and ventral hernia repairs in clean-contaminated and contaminated wounds. We had a similar incidence of infection rate, however, none of our mesh had to be removed. Given about a 10 per cent Alloderm removal rate and given the high cost of this material, what is your opinion about whether this should continue to be used in this scenario? Furthermore, can you talk about how you manage these patients, particularly the ones in which the mesh was removed and the ones that had a hernia recurrence? Were these hernias redone with Alloderm? What was the overall cost of this? JOSE J. DIAZ, JR., M.D. (Nashville, TN; Closing Discussion): As far as hernia recurrence in the presence of a surgical site infection, there is a clear correlation, at least in my mind; however, we do not have the data to support that conclusion. There is a well-known, significant correlation with surgical site infection and hernia recurrence, especially with the use of absorbable sutures. As far as the size, most of these were not quantified. They were all on the Large or Giant category, usually a large open abdominal wound. None of them were traumatic hernias they were all midline ventral hernias. Regarding the use of the posterior technique, i.e., Stoppatype repair, we have gone to a similar technique in similar clinical scenarios where we are actually removing infected mesh. That allows us to not place any drains, which obviously has a direct correlation to the incidence of wound infection. It also supports the repair in a more physiologic fashion, attempting to reestablish the dynamic abdominal wall. As far as abdominal wound after the removal of the Alloderm, how did we manage that? It depends. If we did not have a fistula, sometimes we would let it granulate in, skin graft, and then come back to fight again another day as opposed to trying to expend another several thousand dollars of Alloderm. Under the circumstance where we did have a fistula, then that obviously complicated the wound management and sometimes required attempting to skin graft over exposed bowel, thus leaving us with an atmospheric fistula, which is a completely separate topic. Regarding the question asked earlier about the development of laxity and the size of these defects, I think it is one of the problems we are finding out as we develop new operations, new processes, and new techniques. Patients often appear fine for 6 months or 1 year. After a period of time, laxity develops. Whether this is from the fact that we have not reestablished a dynamic abdominal wall with a dynamic reconstruction versus whether or not the patient has significant increase or decreased in weight or increase in activity level resulting in a stretching out of the implant is difficult to determine. We did not specifically look at tobacco use. Although I would imagine in a larger series this would give us some insight as to what the healing rate and the wound infection would be, especially in those patients that had large skin flaps. As far as the polypropylene mesh and its use in compromised surgical fields, before the present experience, all that we had was polypropylene. I have had to put polypropylene into a compromised field under the circumstance of the elective ostomy takedown or the elective inadvertent enterotomy and gotten away with it. I am now in the business of taking out everyone else s polypropylene, so I have subsequently developed a bias against it to some extent. Although we should not practice medicine using anecdotal experience, it obviously has tempered my decision as far as when to use polypropylene and when not to.