BACKGROUND: Long-term outcomes data for hernia recurrence rates after abdominal wall reconstruction. (AWR) with acellular dermal matrix (ADM) are lacking ...
Long-Term Outcomes after Abdominal Wall Reconstruction with Acellular Dermal Matrix Patrick B Garvey, MD, FACS, Salvatore A Giordano, Jun Liu, PhD, Charles E Butler, MD, FACS
MD, PhD,
Donald P Baumann,
MD, FACS,
Long-term outcomes data for hernia recurrence rates after abdominal wall reconstruction (AWR) with acellular dermal matrix (ADM) are lacking. The aim of this study was to assess the long-term durability of AWR using ADM. STUDY DESIGN: We studied patients who underwent AWR with ADM at a single center in 2005 to 2015 with a minimum follow-up of 36 months. Hernia recurrence was the primary end point and surgical site occurrence (SSO) was a secondary end point. The recurrence-free survival curves were estimated by Kaplan-Meier product limit method. Univariate and multivariable Cox proportional hazards regression models and logistic regression models were used to evaluate the associations of risk factors at surgery with subsequent risks for hernia recurrence and SSO, respectively. RESULTS: A total of 512 patients underwent AWR with ADM. After excluding those with follow-up less than 36 months, 191 patients were included, with a median follow-up of 52.9 months (range 36 to 104 months). Twenty-six of 191 patients had a hernia recurrence documented in the study. The cumulative recurrence rates were 11.5% at 3 years and 14.6% by 5 years. Factors significantly predictive of hernia recurrence developing included bridged repair, wound skin dehiscence, use of human cadaveric ADM, and coronary disease; component separation was protective. In a subset analysis excluding bridged repairs and human cadaveric ADM patients, cumulative hernia recurrence rates were 6.4% by 3 years and 8.3% by 5 years. The crude rate of SSO was 25.1% (48 of 191). Factors significantly predictive of the incidence of SSO included at least 1 comorbidity, BMI 30 kg/m2, and defect width >15 cm. CONCLUSIONS: Use of ADM for AWR was associated with 11.5% and 14.6% hernia recurrence rates at 3- and 5-years follow-up, respectively. Avoiding bridged repairs and human cadaveric ADM can improve long-term AWR outcomes using ADM. (J Am Coll Surg 2017;224:341e350. 2016 by the American College of Surgeons. Published by Elsevier Inc. All rights reserved.)
BACKGROUND:
superior outcomes compared with primary direct suture repair without mesh.3-5 When synthetic mesh is used for AWR, studies have shown that the rate of complications, particularly mesh infection and explantation, increases with increasing degrees of wound contamination and patient comorbidities.6-10 To minimize the risk of postoperative complications, surgeons use bioprosthetic devices, such as acellular dermal matrix (ADM), rather than synthetic mesh to reinforce the abdominal wall.11,12 Because of its capacity for revascularization and incorporation with surrounding tissue, ADM has been shown to be associated with lower rates of infection, extrusion, erosion, and adhesion formation compared with synthetic mesh.12-14 Although many surgeons believe that bioprosthetic meshes are appropriate for AWR in the presence of contamination or for patients at high risk of postoperative complications,15,16 some surgeons are reluctant to use ADM
More than 350,000 abdominal wall reconstructions (AWRs) for ventral hernias are performed annually in the US.1-3 Complex AWRs that use mesh result in CME questions for this article available at http://jacscme.facs.org Disclosure Information: Authors have nothing to disclose. Timothy J Eberlein, Editor-in-Chief, has nothing to disclose. Support: This research was supported in part by the NIH through MD Anderson’s Cancer Center Support Grant CA016672. Presented at the European Association of Plastic Surgeons (Euraps) Research Council, Bruxelles, Belgium, May 2016. Received July 15, 2016; Revised November 4, 2016; Accepted November 15, 2016. From the Department of Plastic Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX. Correspondence address: Charles E Butler, MD, FACS, Department of Plastic Surgery, The University of Texas MD Anderson Cancer Center, 1400 Pressler St, Unit 1488, Houston, TX 77030. email: cbutler@ mdanderson.org
ª 2016 by the American College of Surgeons. Published by Elsevier Inc. All rights reserved.
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http://dx.doi.org/10.1016/j.jamcollsurg.2016.11.017 ISSN 1072-7515/16
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Long-Term Outcomes Using Acellular Dermal Matrix
Abbreviations and Acronyms
ADM AWR CS HR OR SSO
¼ ¼ ¼ ¼ ¼ ¼
acellular dermal matrix abdominal wall reconstruction component separation hazard ratio odds ratio surgical site occurrence
because they believe that it results in a less-durable repair compared with synthetic mesh. In addition, given the higher initial cost of ADM compared with synthetic mesh, some surgeons advocate using synthetic mesh even when faced with higher grades of wound contamination.9 However, little is known about the long-term outcomes for AWR with ADM, as most studies evaluating the use of ADM for AWR have insufficient follow-up to adequately assess the rates of hernia recurrence.12,17-19 The aim of this study was to evaluate the long-term outcomes of a large series of patients who underwent AWR with ADM. We hypothesized that AWR with ADM results in durable long-term (>36 months) outcomes with respect to hernia recurrence rates, particularly when surgeons use best practice surgical techniques for complex AWR.
METHODS We retrospectively evaluated all consecutive patients who underwent midline AWR with underlay (retrorectus, preperitoneal, or intraperitoneal) ADM to close a defect caused by ventral hernia repair or oncologic resection at a single center between March 2005 and October 2015. We followed the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines for observational cohort studies,20 the ethical principles of the World Medical Association, Declaration of Helsinki, and laws of the US. This study was approved by The University of Texas MD Anderson Cancer Center’s IRB. Individual informed consent was waived because of the retrospective design of the study and because the source data were de-identified. To determine the long-term durability of AWR with ADM, we analyzed patients who had at least 36 months of postoperative follow-up. To explore the possibility of bias due to this follow-up restriction, we also separately analyzed hernia recurrence rates for the overall patient series (independent of follow-up length). We also excluded patients with defects that did not involve the midline (lateral defects) and patients who had undergone primary closure of their abdominal wall fascia without mesh, onlay mesh reconstruction, or reconstruction with fasciocutaneous flaps or grafts or synthetic or
J Am Coll Surg
resorbable meshes. Patients had been followed up through physical examination and CT imaging. Both clinical and radiologic surveillance had been accomplished according to each patient’s tumor protocol, typically quarterly for the first year and then annually thereafter. Data were obtained both from a prospectively maintained departmental database and from the patients’ electronic medical records. The primary outcomes measure was hernia recurrence. Secondary outcomes measure was surgical site occurrence (SSO), defined as the presence of 1 or more of the following postoperative surgical complications: bulging or laxity of the abdominal wall, wound dehiscence, skin/fat necrosis, cellulitis/abscess, hematoma, and seroma. Hernia recurrence was defined as a contour abnormality associated with a fascial defect, and bulging was a contour abnormality without a fascial defect. Hernia and bulge were considered mutually exclusive conditions and were diagnosed by physical examination and/or CT imaging. Wound dehiscence was defined as a skin breakdown with full-thickness skin separation extending >2 cm with or without infection, and skin necrosis involved clearly demarcated necrotic skin edges at least 1 cm in width. Fat necrosis was a palpable firmness at least 1 cm in diameter that persisted beyond 3 months postoperatively. Infection was an infectious process (cellulitis/ abscess) requiring treatment with IV or oral antibiotics with or without surgery. Hematoma and seroma were subcutaneous collections of blood or serous fluid, respectively, requiring percutaneous or operative drainage. A medical comorbidity was defined as 1 or more of the following: coronary artery disease, diabetes mellitus, hypertension, pulmonary disease, or renal disease. Wounds were considered contaminated if they met the American College of Surgeons NSQIP criteria to be classified as contaminated or infected (class 3 to 4).21 Obesity was defined as a BMI 30 kg/m2.22 Any patient who smoked tobacco within 1 month of surgery was considered an active smoker. Surgical technique The AWRs had been performed using a multidisciplinary approach and a similar general technique for all patients. The extirpative surgical oncologist performed the exploratory laparotomy, adhesiolysis, and tumor resection, where indicated.23 After this, the reconstructive surgeon defined the defect, including excision of the hernia sac and debridement of devitalized tissue and fascia, and decided whether an anterior component separation (CS) was indicated to facilitate the medialization of the rectus abdominis muscles. The indication for CS was an inability to approximate the fascial edges without
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significant tension that might place the repair at risk of failure. Anterior open or minimally invasive CS included release of the external oblique aponeurosis from the pubis to the costal margin to provide lateral release and reduce tension on the midline fascial closure.24,25 For the majority of these reconstructions, our surgeons used an intraperitoneal or preperitoneal underlay ADM bioprosthetic to reinforce the midline fascial repair with 3 to 5 cm of abdominal wall overlap, fixed circumferentially with interrupted #1 polypropylene sutures, followed by midline primary fascial closure over the prosthesis with interrupted #1 polypropylene sutures (reinforced repair).25 Scarred, nonviable, and/or redundant skin was resected, and subcutaneous drains were placed to reduce the risk of seroma formation.24,25 For situations in which the fascial defect could not be closed primarily over the ADM, CS was performed to reduce the size of the bridged portion of the closure. In these few patients, the bioprosthetic was left in place as a bridge to span the residual defect using an underlay technique secured with a dual-circumferential inset technique.24-26 Statistical analysis Descriptive statistics were used to summarize age, BMI, and length of follow-up. Frequencies and percentages were used for categorical variables. Time to hernia recurrence was defined as the time interval from the reconstructive surgery date to the first hernia recurrence date or the last follow-up date if a hernia recurrence had not yet occurred by that date. Recurrence-free survival rates were estimated using Kaplan-Meier curves that accounted for censoring. Patients who did not have a hernia recurrence were censored in the analyses. Logistic regression models were used to estimate associations between reconstruction characteristics and surgical outcomes and SSOs; results are summarized as odds ratios (ORs) and 95% CIs. Cox proportional hazards regression models were used to estimate the hazards ratios (HRs) for risk factors associated with hernia recurrence. The proportional hazard assumption was tested by including a group-time interaction in the model. A backward multivariable model selection method was used to fit a multivariable regression model. Variables with p value not greater than 0.2 in the univariate analysis were the candidates for the model selection prescreening process. The model with the least Akaike information criterion was considered the best-fitting multivariable model. All tests were 2-sided. A p value 50% at more than 5 years follow-up when bioprosthetic rather than synthetic mesh is used.38 We not only found the hernia repairs to be durable when we used bioprosthetic mesh, but our rates also compared favorably with those reported in studies of synthetic mesh. Synthetic meshes are believed to strengthen the hernia repair by eliciting an intense inflammatory response to the foreign body, resulting in a strong scar tissue plate. Champions of synthetic mesh suggest that this encapsulation and scarring contribute to increased abdominal wall stiffness and mesh shrinkage, resulting in a more durable repair than can be achieved with bioprosthetic materials.39 However, we do not believe that our data support this hypothesis. Rather, we believe that bioprosthetic matrices provide not only a reinforcing material, but also a scaffold for cellular and vascular ingrowth, promoting ADM engraftment, tissue regeneration, and eventual integration with surrounding tissue, rather than encapsulation.40 In addition, the engraftment and neovascularization of ADMs appear to result in lower rates of infections, extrusion, erosion, and adhesion formation compared with synthetic meshes.41-43
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Table 5.
Long-Term Outcomes Using Acellular Dermal Matrix
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Univariate and Multivariable Cox Proportional Hazards Regression Models of Hernia Recurrence (n ¼ 191)
Variable
BMI 30 kg/m2 Coronary disease American Society of Anesthesiologists Acellular dermal matrix human Bridged repair Component separation Wound skin dehiscence
Univariate Cox PH regression model of hernia recurrence HR (95% CI) p Value
1.5 3.8 2.6 3.3 10.6 0.5 2.6
(0.8e2.6) (1.5e9.6) (0.7e9.5) (1.4e7.8) (4.7e23.6) (0.2e1.0) (1.1e5.9)
0.19
