RECONSTRUCTIVE SURGERY
Comparison of Synthetic and Biologic Mesh in Ventral Hernia Repair Using Components Separation Technique Brinkley K. Sandvall, MD,* Daniel W. Suver, MD,* Hakim K. Said, MD,* David W. Mathes, MD,* Peter C. Neligan, MD,* E. Patchen Dellinger, MD,Þ and Otway Louie, MD* Abstract: Ventral hernia repair (VHR) for large abdominal wall defects is challenging. Prior research established that the use of mesh is superior to suture closure alone and that component separation is an effective technique to combat loss of abdominal domain. Studies comparing component separation technique (CST) outcomes utilizing synthetic versus biologic mesh are limited. A retrospective review was conducted of 72 consecutive patients who underwent VHR with CST between 2006 and 2010 at our institution. Surgeon preference and the presence of contamination guided whether synthetic mesh (27 patients) or biologic mesh (45 patients) was used. Mean follow-up interval for all comers was 13.9 months and similar in both groups (P 9 0.05). Degree of contamination and severity of premorbid medical conditions were significantly higher in the biologic mesh group, as ref lected in the higher Ventral Hernia Working Group (VHWG) score (2.04 versus 2.86). Clinical outcomes, as measured by both minor and major complication rates and recurrence rates, were not significantly different. Minor complication rates were 26% in the synthetic group and 37% in the biologic group and major complication rates 15% in the synthetic group and 22% in the biologic group. There was 1 recurrence (4%) in the synthetic mesh group versus 5 (11%) in the biologic mesh group. Multivariable analysis for major complications revealed no significant difference for either synthetic or biologic mesh while controlling for other variables. Subset analysis of uncontaminated cases revealed recurrence rates of 4% in the synthetic mesh group and 6% in the biologic mesh group. VHR using CST and either synthetic mesh or biologic mesh resulted in low recurrence rates with similar overall complication profiles, despite the higher average VHWG grading score in the biologic mesh group. Our results support the VHWG recommendation for biologic mesh utilization in higher VHWG grade patients. In VHWG grade 2 patients, our clinical outcomes were similar, supporting the use of either type of mesh. Key Words: ventral hernia, components separation, mesh, hernia repair, abdominal wall reconstruction, recurrent hernia (Ann Plast Surg 2016;76: 674Y679)
I
ncisional ventral hernias are common problems for many patients with a surgical history of abdominal procedures, particularly midline laparotomy. Although the aesthetics of protruding bowel is of concern to patients, bowel incarceration and ultimately strangulation are medical emergencies that can occur as intestinal loops pass through the fascial wall defect. Repair is necessary to reduce occurrence of these
Received September 28, 2013, and accepted for publication, after revision, April 3, 2014. From the *Division of Plastic Surgery, †Department of General Surgery, University of Washington, Seattle, WA. Conflicts of interest and sources of funding: Dr. Said has acted as a consultant for a pharmaceutical company. Dr. Dellinger has acted and still acts as a consultant and speaker for various pharmaceutical companies; however, no direct funding was received for this work. Reprints: Otway Louie, MD, Division of Plastic Surgery, University of Washington, Seattle, WA, 1959 NE Pacific St., Box 356410, Seattle, WA 98195. E-mail: [email protected]. Copyright * 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0148-7043/16/7606-0674 DOI: 10.1097/SAP.0000000000000253
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complications, but it is extremely difficult in the setting of giant or recurrent ventral hernias with loss of abdominal domain. The component separation technique (CST) is an ideal method to deal with such defects. First described in 1990 by Ramirez et al and popularized by subsequent authors, CST involves bilateral release of the external oblique from the musculature of the abdominal sidewall.1 This results in a greater distance traversed medially by the rectus abdominis, internal oblique, or transversalis myofascial subunit and restoration of the linea alba under minimal tension.1Y5 Mesh is ideally employed after midline approximation to reinforce the closure and promote long-term stability. Prospective evidence detailing the superiority of synthetic mesh reinforcement compared with suture closure alone supports this practice in the setting of small midline hernias.6,7 However, synthetic mesh is only ideal for use in clean cases.8Y11 Although some patients undergoing CST have clean wounds, many patients have either ostomies, fistulae, dense adhesions that increase the risk of incidental enterotomies, and/or conditions that require concomitant bowel surgery. In the context of existing or potential contamination, the likelihood of bacterial colonization of synthetic mesh is high, and unacceptably high levels of inflammation, postoperative infection, enterocutaneous fistulae, bowel erosions, and ultimately repair failure may result.6,11Y13 Surgeons, still seeking reinforcement in this setting, have thus turned to biologic mesh. Biologic and synthetic meshes have been used with variable success; however, research comparing their outcomes in ventral hernia repair (VHR) with CST is lacking and limited by the fact that there are no definitive indications or guidelines for when each mesh should be employed.14Y16 In 2010, the Ventral Hernia Working Group (VHWG) published a literature review assessing patient and wound characteristics in those undergoing VHR.17 They proposed an evidence-based, 4-tiered grading system to offer guidance in material choice and repair technique.17 In patients without comorbidities or wound infection who are undergoing open repair of defects greater than 2 centimeters (cm), they recommended the choice of material be guided by surgeon preference and patient factors.17 In patients with comorbidities that increase the risk of surgical site infection [ie, smoker, obese, diabetic, immunocompromised, and chronic obstructive pulmonary disease (COPD)] but without contamination, they suggested that biologic mesh is potentially advantageous compared with synthetic mesh.17 They proposed that patients with potentially contaminated surgical fields (ie, stoma, gastrointestinal tract violation, and prior wound infection) are best served with biologic mesh, and they recommended against using synthetic mesh in obviously contaminated fields (ie, infected mesh and septic dehiscence).17 Although these guidelines marked an essential step toward coordinating clinical practice, more outcomes data for synthetic and biologic mesh utilization are needed to define the risk factors for hernia recurrence and repair complications.17 In this study, we aimed to assess complication profiles between 2 groups of patients who underwent VHR with CST and either synthetic or biologic mesh.
METHODS A retrospective chart review was conducted on all CST procedures performed at the University of Washington Medical Center Annals of Plastic Surgery
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TABLE 1. Group Characteristics Characteristic No. of patients Male Female Age at surgery, y Mean Range
Synthetic
Biologic
27 9 18
45 17 28
54.3 34Y75
54.1 30Y81
from November 2006 to November 2010. Patients who had abdominal wall reconstructions with either synthetic or biologic mesh were included. Our Institutional Review Board approved this study. Data gathered from medical records included age, sex, hernia size, operative time, operation date, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), American Society of Anesthesiologists physical status score, preoperative comorbidities known to affect the stability of hernia repair (ie, smoking, diabetes, COPD, immunosuppression, prostatism, and history of abdominal aortic aneurysm), albumin level, history of irradiation, number of prior hernia and abdominal surgeries, placement position of mesh, type of mesh, presence and type of concurrent abdominal procedures, length of hospital stay, minor complications (ie, cellulitis, wound breakdown, and seroma or hematoma requiring aspiration), major complications (ie, infection requiring irrigation and debridement, reoperation for any complication, myocardial infarction, pulmonary embolism, and death), presence of recurrence, and followup time. Follow-up time was calculated based on the last attending abdominal exam or computed tomography scan. Most individuals included in the study had preoperative computed tomography scans to assess hernia size and abdominal wall architecture. Coronal and sagittal views were used to define boundaries of the hernia sac; all measurements were performed using axial cuts. VHWG grades were calculated based on preoperative status and intraoperative findings. Patients with no comorbidities, no history of wound infection, and no evidence of wound contamination were categorized as grade 1. Those with comorbidities (ie, smoker, obese, diabetic, immunosuppressed, or pulmonary complications) but no history of or evidence of infection were grade 2. Those with a prior wound infection, stoma present, or violation of the bowel lumen during herniorrhaphy were grade 3. Grade 4 patients had obvious intraabdominal infection (ie, infected mesh or septic dehiscence). General surgeons and plastic surgeons performed all procedures together using an open approach. The general surgery team performed all but 1 of the hernia repairs with synthetic mesh, whereas plastic surgeons did all but 3 of the repairs reinforced with biologic mesh. The types of synthetic mesh were polypropylene (C.R. Bard-Davol Inc, Providence, RI), polypropylene retrorectus with vicryl mesh reapproximating the posterior sheath, polyester (Mersilene; Ethicon Inc, Somerville, NJ), and polyester with a single-sided coat of resorbable collagen (Parietex; Covidien, Mansfield, MA). Biologic meshes were either human-derived (AlloDerm; LifeCell Co, Branchburg, NJ or FlexHD; Ethicon Inc, Somerville, NJ) or porcine-based (Strattice; LifeCell Co, Branchburg, NJ or Permacol; Covidien, Mansfield, MA). All CST procedures were performed by plastic surgeons with bilateral external oblique release without additional releases or fascial turnover. Mesh was positioned either retrorectus or intraperitoneal. Permanent synthetic mesh was placed retrorectus, and either vicryl mesh (absorbable synthetic mesh) or AlloDerm was used as a bridge if the posterior rectus sheath/peritoneum could not be closed primarily, thus shielding bowel from direct contact with the permanent synthetic material. Biologic mesh was placed as an intraperitoneal underlay. * 2014 Wolters Kluwer Health, Inc. All rights reserved.
Ventral Hernia Repair: Synthetic and Biologic Mesh
Descriptive statistics were calculated, and the groups compared using the 2-tailed t test for continuous variables and Fisher exact test for categorical variables. Nominal logistic regression was use to perform the multivariable analysis using JMP Pro 11 statistical software package (SAS Institute, Cary, North Carolina). P e 0.05 were considered statistically significant.
RESULTS Seventy-two consecutive patients were included, 27 patients in the synthetic mesh group and 45 in the biologic mesh group. Mean age at surgery in all comers was 54.2 years and similar in both groups (Table 1) (P = 0.9). Mean follow-up interval in all comers was 13.9 months and similar in both groups (P = 0.5). Mean follow-up interval was 15.6 months (range, 1Y63 months) in the synthetic mesh group and 12.9 months (range, 1Y67 months) in the biologic group. Table 2 summarizes baseline patient characteristics. Groups were statistically similar with respect to all preoperative measures except hernia height, operative time, BMI, immunosuppression, and VHWG grade. Patients in the biologic mesh group averaged significantly larger hernia heights, longer operating times, more immunosuppression, and higher VHWG grades compared with the synthetic mesh group. Mean hernia defect area in the synthetic mesh cohort was 179.8 versus 238.8 cm2 in the biologic mesh cohort (P = 0.06). Degree of contamination and severity of premorbid medical conditions were significantly higher in the biologic mesh group, as ref lected in the higher VHWG grade (2.04 versus 2.86). Patients in the synthetic mesh group averaged significantly larger BMIs than the biologic mesh cohort (38.0 versus 32.4) (P G 0.01). Average BMI for all comers was 34.5 kg/m2. All other preoperative measures were not significantly different. Mean number of previous abdominal surgeries TABLE 2. Summary of Results Variable No. of cases in which hernia size was measured Mean hernia height, cm Mean hernia width, cm Mean hernia area, cm2 Mean operative time, h:min Mean ASA score Mean albumin level Mean no. of prior abdominal surgeries Mean no. of prior hernia repairs Mean body mass index, kg/m2 Smoking, n (%) Diabetes mellitus, n (%) Chronic obstructive pulmonary disease, n (%) Steroids/immunosuppression, n (%) Mean Ventral Hernia Working Group grade Grade 1 (low risk), n (%) Grade 2 (comorbid), n (%) Grade 3 (potentially contaminated), n (%) Grade 4 (infected), n (%)
Synthetic (n = 27)
Biologic (n = 45)
26
41
14.4 12.2 179.8 5:16 2.8 3.3 4.5
17.7 12.7 238.8 7:19 2.8 3.2 4.1
1.3 38.0 7 (26) 10 (37) 5 (19)
1.1 32.4 8 (18) 15 (33) 4 (9)
0 (0)
8 (18)
0.02*
2.03
2.86
G0.01*
2 (8) 22 (81) 3 (11)
4 (9) 13 (29) 13 (29)
0 (0)
15 (33)
P
0.03*
G0.01*
G0.01*
*Statistically significant, P e 0.05. ASA, American Society of Anesthesiologists.
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TABLE 3. Simultaneous Procedures Procedure Performed Simultaneous bowel procedure, n (%) Bowel resection, n (%) Ostomy takedown, n (%) Fistula takedown, n (%) Removal of infected mesh, n (%)
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TABLE 5. Outcomes
Synthetic (n = 27)
Biologic (n = 45)
1 (3.7) 1 (3.7) 0 0 0
29 (64.4) 16 (35.6) 6 (13.3) 8 (17.8) 10 (22.2)
Complication P G 0.01*
Synthetic (n = 27)
Biologic (n = 45)
7 (26) 4 (15) 1 (4)
17 (38) 10 (22) 5 (11)
Minor, n (%) Major, n (%) Recurrence, n (%)
Minor indicates cellulitis, wound breakdown, and seroma or hematoma requiring aspiration; Major indicates infection requiring irrigation and debridement, reoperation for any reason, myocardial infarction, pulmonary embolism, and death.
*Statistically significant, P e 0.05.
was similar in both groups (4), as was mean number of previous hernia repairs (1). This was the primary VHR in 9 (33.3%) of the synthetic mesh patients and in 16 (35.6%) of the biologic mesh patients. It was the second repair in 12 (40%) of the synthetic mesh patients and in 9 (40%) of the biologic mesh patients. Of the 5 main comorbidities identified by the VHWG to increase the risk of surgical site infection (ie, smoker, obese, diabetic, immunocompromised, and COPD), the mean number of comorbidities in the synthetic mesh group was 1.6 versus 1.4 in the biologic mesh group. Significantly, more patients in the biologic mesh group underwent simultaneous bowel procedures (3.7% of patients in the synthetic mesh group versus 64.4% of patients in the biologic mesh group) (P G 0.01) (Table 3). Overall, 1 simultaneous bowel procedure was performed in the synthetic mesh group versus 40 simultaneous bowel procedures in 29 patients in the biologic mesh group. These procedures included bowel resection, ostomy takedown, fistula takedown, and removal of infected mesh. In the synthetic mesh group, there was 1 (3.7%) bowel resection performed secondary to inadvertent enterotomy and bowel injury during adhesiolysis. At the time of surgery, there were 0 enterocutaneous fistulae present in the synthetic group versus 9 (20%) in the biologic group. Only 1 patient (3.7%) in the synthetic mesh group had an ostomy present versus 12 patients (26.7%) in the biologic group. In the synthetic mesh group, all patients (100%) had their anterior rectus reapproximated in the midline, and 19 of these (70%) had their posterior rectus sheath bridged. In the biologic mesh group, 9 patients (20%) had their defects bridged with intraperitoneal biologic mesh. Table 4 shows the types and distribution of mesh used. Outcomes are shown in Table 5. Though minor complication rates, major complication rates, and recurrence rates were each slightly higher in the biologic mesh group, none reached statistical significance. A power calculation was performed and did not reach the level of 0.80. Thus, our study was underpowered to definitely state that there was no difference between the 2 groups using descriptive statistics. However, TABLE 4. Types of Mesh Synthetic (n = 27)
Mesh Polypropylene alone, n (%) Polypropylene with vicryl, n (%) Polypropylene with AlloDerm, n (%) Parietex, n (%) Parietex with vicryl, n (%) Mersilene, n (%) AlloDerm, n (%) Strattice, n (%) FlexHD, n (%) Permacol, n (%)
676
Biologic (n = 45)
1 (3.7) 5 (18.5) 2 (7.4) 6 (22.2) 12 (44.4) 1 (3.7) 13 (28.9) 15 (33.3) 16 (35.6) 1 (2.2)
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in a univariable analysis, significant factors leading to major complications were simultaneous bowel procedures, a VHWG grade of 4, and a longer duration of the procedure (Table 6). Increasing area of the defect was trending toward significance. The use of biologic mesh was not a significant factor leading to major complications (Table 6). In a multivariable analysis, only a VHWG grade of 4 was significant in leading to major complications (Table 6). When adjusting for VHWG grade, the use of biologic mesh was still not a significant factor leading to major complications. Time to recurrence was 4 months in the 1 synthetic mesh patient and averaged 11.6 months (range, 2Y23 months) in the biologic mesh group. Mean hospital stay was 5.7 days in the synthetic group and 10.1 in the biologic group. Subset analysis of uncontaminated cases (grades 1 and 2) in both groups was performed to control for the fact that biologic mesh was used in more contaminated cases (Table 7). When contaminated cases (grades 3 and 4) were excluded, hernia recurrence rates did not increase; rather, they stayed the same at 4% in the synthetic mesh group and decreased from 11% to 6% in the biologic mesh group. There were no statistically significant differences in minor or major complication rates, regardless of contamination. Again, our study was underpowered to definitely state that there was no significant difference using descriptive statistics; however, multivariable analysis on the subset of uncontaminated cases revealed no significant difference for the synthetic and biologic mesh groups (odds ratio 1.7, CI 0.3 to 10, P = 0.9) in total complications, either before or after adjusting for area of defect, operative time, BMI, simultaneous bowel procedure, or immunosuppressive therapy. To avoid overfitting the model, only 2 controlling variables were placed in the algorithm at 1 time for the analysis.
DISCUSSION Our objective was to determine if any clinically relevant differences in outcomes exist for VHR using CST and either synthetic mesh or biologic mesh. This review of 72 consecutive cases suggests that the 2 groups have similar acceptable rates of minor and major complications and hernia recurrence. The lone recurrence in our synthetic mesh group was a 61year-old nonsmoking man with a BMI of 39 and a very large hernia that required a 3-stage repair. In the first stage, he was taken to the operating room (OR) for enterolysis. His defect was estimated to be too large to close at that time, even with CST; thus, silastic mesh was sutured to the hernia borders and tightened as much as possible. He remained intubated and returned to the OR within days for another round of tightening. He again remained intubated, and only on the third trip to the OR was it thought possible to close his midline. CST was performed and hernia repair carried out with a polypropylene retrorectus underlay. Vicryl mesh was used to bridge the posterior rectus sheath, and the rectus muscles were brought into apposition. This gentleman was fully anticoagulated for medical comorbidities, and 10 weeks after herniorrhaphy, he returned with a rectus sheath hematoma. He subsequently underwent embolization of the inferior epigastric artery and within 4 months was found to have hernia recurrence. * 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Ventral Hernia Repair: Synthetic and Biologic Mesh
TABLE 6. Univariable and Multivariable Analysis for Major Complications Univariable Variable Biologic mesh Mean body mass index Steroids/immunosuppression Mean hernia height Simultaneous bowel procedure Ventral Hernia Working Group grade 4 Mean operative time
Multivariable
OR (LCIYUCI)
P
1.6 (0.5Y6.6) 1 (0.92Y1.1) 1.4 (0.2Y7.2) 1.01 (1Y1.02) 4.1 (1.2Y16.4) 8.3 (2.1Y38.8) 1.008 (1.001Y1.01)
0.4 1 0.7 0.09 0.02* 0.01* 0.05*
OR (LCIYUCI)
P
6.3 (1.7Y23.5)
G0.01*
*Statistically significant, P e 0.05. OR indicates odds ratio; LCI, lower confidence interval; UCI, upper confidence interval.
In our biologic mesh group, all 5 patients with recurrence underwent second simultaneous intra-abdominal procedures at the time of VHR. Three had been repaired with AlloDerm and 2 with Strattice. Only 1 of the 5 had a bridged repair. Three developed recurrence in areas of poor wound healing characterized by abscess or seroma. The fifth recurrence was in an active, nonsmoker who felt the repair fail while working out in a gym 8 months after surgery. Three of the recurrences were in immunosuppressed patients. Mean hospital length of stay was longer in the biologic mesh group because of the increased proportion of simultaneous bowel procedures performed in this group. Studies comparing different biologic meshes are few and have yet to identify an ideal biologic mesh. One study intentionally contaminated 4 types of biologic mesh used in VHR in a rat model and found that the degree of contamination affected the rate of bacterial clearance, wound-healing ability, and repair strength.18 All biologic meshes performed poorly in grossly contaminated settings, and no ideal graft material was identified.18 Additionally, in a small TABLE 7. Patients Without Contamination Variable Sex Male Female Age Mean Range Standard deviation No. of cases in which hernia size was measured Mean hernia height, cm Mean hernia width, cm Mean hernia area, cm2 Mean body mass index, kg/m2 Smoking, n (%) Diabetes mellitus, n (%) Chronic obstructive pulmonary disease, n (%) Steroids/Immunosuppression, n (%) Minor complication, n (%) Major complication, n (%) Recurrence, n (%)
Synthetic (n = 24) 8 16
Biologic (n = 17)
P
5 12
54.7 34Y75 9.2 23
50.8 30Y71 14.6 17
14.3 12.1 172.7 37.7 6 (25) 9 (38) 5 (21)
16.5 11.8 194.4 30.3 4 (24) 3 (18) 0 (0)
0 (0) 6 (25) 3 (13) 1 (4)
2 (12) 7 (41) 1 (6) 1 (6)
*Statistically significant, P e 0.05.
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G0.01*
retrospective study evaluating clinical outcomes (ie, recurrence, mesh explantation, and mesh infection) of patients who underwent complex VHR (some bridging and some CST) with different types of biologic mesh, there was no clear ideal biologic mesh.19 In our study, 4 different biologic meshes were used, and none particularly outperformed another. In the early years of our study, it was our tendency to use FlexHD. However, as different materials became available to our hospital, we began using AlloDerm and more recently have transitioned to almost purely Strattice. The biologic mesh in our study seems to have provided additional protection, decreasing hernia recurrence to less than previously reported rates without mesh.3,20 Our results support the durability of biologic mesh repairs at 14-month follow-up. The VHWG recommended mesh to reinforce all VHRs, whether the midline fascia is reapproximated or not.6,7,17 However, there remains some concern that when AlloDerm is used as a bridge (without primary fascial reapproximation) rather than as reinforcement (after primary fascial reapproximation), that it may be prone to increased hernia recurrence and laxity, often requiring intervention.21,22 When the fascial defect cannot be closed primarily, one may choose to bridge the defect with mesh, recognizing that abdominal laxity may eventually ensue and warrant rerepair, or to stage the repair with serial tightening to eventually gain primary reapproximation.23 At our institution, we have tried both approaches. We have concern about placing synthetic mesh in direct continuity with the bowel, and thus, our tendency is to place it retrorectus. The retrorectus plane positions well-vascularized tissue on both sides of the mesh and may slightly increase mobility of the tissue f laps as a result of releasing the posterior rectus sheath when gaining access to the retrorectus plane. In our study, 2 of the 6 recurrences (1 in the synthetic group and 1 in the biologic group) were in bridged repairs. Some studies with intraperitoneal synthetic mesh have shown low incidences of bowel obstruction, adhesions, infection, and development of enterocutaneous fistulas; however, as it is a real possibility with significant consequences, we avoid it.15,20,24,25 The retrorectus dissection may be difficult if the patient has a history of an ostomy or if the mesh was previously placed there. Unfortunately, there is no high-level data to support an ideal mesh position. In contrast to our findings, Ko et al demonstrated a significantly higher rate of hernia recurrence with biologic mesh (human cadaveric dermis) as opposed to synthetic mesh (soft polypropylene) at an average of 10-month follow-up (0% versus 33.3%).20 They compared no mesh, synthetic mesh, and biologic mesh VHR with CST in 200 consecutive patients; endpoints were similar to those in our studyVminor and major complication rates and recurrence rates (20). Minor and major complications rates in their synthetic and biologic mesh groups were not significantly different (soft propylene 16.7% and 16.7% versus human cadaveric dermis 16.7% and 22.2%, respectively).20 A second, smaller study by the same group reviewed www.annalsplasticsurgery.com
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54 patients after VHR with CST and synthetic (soft polypropylene) or biologic mesh (human cadaveric dermis) reinforcement at an average of 16-month follow-up; again, endpoints were minor and major complication rates and recurrence rates.15 Their biologic mesh group, which was significantly more contaminated, had a higher recurrence rate than their synthetic group (46% versus 11%, respectively), and this increased even more when contaminated cases were excluded (61% versus 12%, respectively).15 The groups had similar minor and major complication rates that did not significantly change when contaminated cases were excluded.15 Their results support synthetic mesh (soft polypropylene) over biologic mesh (human cadaveric dermis) and call into question the long-term reinforcement provided by cadaveric dermis.15 The biologic mesh recurrence rates reported by Ko et al are relatively high compared with other published studies with at least 1-year follow-up.15,20,21,26,27 Perhaps, some of the variation can be attributed to differences in the various types of biologic mesh utilized. In contrast to Ko et al, our biologic mesh recurrence rate was quite a bit lower and did not increase, but rather decreased, when contaminated cases were excluded.15,20 This seems logical when one considers that contamination is associated with increased recurrence.6,12 Though there were more recurrences in our biologic group, we did not find a statistically significant difference in the recurrence rates. Our results support the use of either synthetic or biologic mesh in grade 2 patientsVnot one over the other. A recent retrospective review by Krpata et al examined 88 patients with VHR and supported synthetic mesh in the retrorectus space for VHWG grade 2 patients.28 They reported 0 recurrences and 16% surgical site occurrence (defined by the VHWG as an infection, clinically relevant seroma requiring intervention, dehiscence, and formation of an enterocutaneous fistula) at an average of 18-month follow-up.28 Though multiple comorbidities increased the risk of surgical site occurrence, no single variable was found to contribute more than others.28 Our findings also support the potential use of synthetic mesh use in grade 2 patients. Another recent manuscript by Souza et al retrospectively reviewed 87 patients with VHR with synthetic mesh and suggested that synthetic mesh is safe in VHWG grades 1 through 3, challenging the notion that biologic mesh should be favored in higher VHWG grade patients.29 They demonstrated low rates of complications (10.1% minor and 1.2% major) and recurrence (5.6%) with polypropylene intraperitoneal mesh underlay at an average of 23-month follow-up.29 Compared with our study, their synthetic mesh was placed in a different location (intraperitoneal rather than retrorectus), and we had a smaller cohort of patients with shorter follow-up. Only 3 patients (11%) in our synthetic mesh group were VHWG grade 3 (most were grade 2). Similar to Souza et al, our results also support the use of synthetic mesh in a group with multiple comorbidities.29 Single-stage complex VHR with biologic mesh and enterocutaneous fistula takedown is challenging and has been reported with mixed results, some reporting high rates of complications and recurrence.30,31 Krpata et al recently reported a 32% recurrence at an average of 20-month follow-up.31 In our study, though all 5 of the recurrences in the biologic group underwent simultaneous intraabdominal procedures, only 1 had an enterocutaneous fistula takedown. Of the 8 enterocutaneous fistula takedowns, 1 patient (12.5%) developed recurrence. As contamination increases the risk of hernia recurrence, the importance of source control and intraoperative drain placement must be emphasized. In our practice, when biologic mesh is used, 4 drains are placedV1 retrorectus and superficial to the mesh, 1 subcutaneous and in the midline, and 1 along each of the component release sites. In contrast, when we use synthetic mesh, only 2 drains are placedV1 at each of the component release sites. Standard principles for infection reduction should be followed, including debridement of nonviable tissue, excision of scar tissue, excision of hernia sac remnants, and copious irrigation. 678
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Our study has some limitations. It is retrospective, single institution, and has unequal sample sizes. Additionally, multiple surgeons performed the operations, and 2 different operative techniques were used: synthetic mesh was placed retrorectus to reduce the likelihood of developing bowel adhesions and erosions secondary to contact with bowel, whereas biologic mesh, which is potentially less inf lammatory, was placed intraperitoneal. Though we did not find a statistically significant difference in hernia recurrence rates, there were a greater number of recurrences in the biologic group. With longer follow-up and larger cohorts, additional complications may become evident and longevity of the repair more fully known; thus, our current complication rates and recurrence rates may underreport the true values. However, this is 1 of the largest series comparing outcomes in VHR using CST and either synthetic or biologic mesh. To address these limitations, a prospective study of both synthetic and biologic meshes with larger sample sizes, standard operative technique, and longer follow-up is necessary.
CONCLUSIONS In conclusion, VHR using CST and either synthetic mesh or biologic mesh resulted in low recurrence rates with similar overall complication profiles, despite the presence of contamination and other complicating circumstances among patients receiving biologic mesh. Our results support the VHWG recommendation for biologic mesh utilization in higher VHWG grade patients; however, they do not support the use of biologic mesh instead of synthetic mesh in grade 2 patients. Rather, in grade 2 patients, our clinical outcomes were similar, thereby supporting the use of either type of mesh, not one over the other. Detecting preoperative risk for infection and adjusting operative plans accordingly are important for successful hernia repair. ACKNOWLEDGMENTS The authors thank James D. Perkins, MD, for his statistical consultation.
REFERENCES 1. Ramirez OM, Ruas E, Dellon AL. ‘‘Components separation’’ method for closure of abdominal-wall defects: an anatomic and clinical study. Plast Reconstr Surg. 1990;86:519Y526. 2. Shestak KC, Edington HJ, Johnson RR. The separation of anatomic components technique for the reconstruction of massive midline abdominal wall defects: anatomy, surgical technique, applications, and limitations revisited. Plast Reconstr Surg. 2000;105:731Y738. 3. de Vries Reilingh TS, van Goor H, Rosman C, et al. ‘‘Components separation technique’’ for the repair of large abdominal wall hernias. J Am Coll Surg. 2003;196:32Y37. 4. Vargo D. Component separation in the management of the difficult abdominal wall. Am J Surg. 2004;188:633Y637. 5. Halvorson EG. On the origins of components separation. Plast Reconstr Surg. 2009;124:1545Y1549. 6. Luijendijk RW, Hop WC, van den Tol MP, et al. A comparison of suture repair with mesh repair for incisional hernia. N Engl J Med. 2000;343:392Y398. 7. Burger JWA, Luijendijk RW, Hop WCJ, et al. Long-term follow-up of a randomized controlled trial of suture versus mesh repair of incisional hernia. Ann Surg. 2004;240:578Y583. 8. Dayton MT, Buchele BA, Shirazi SS, et al. Use of an absorbable mesh to repair contaminated abdominal-wall defects. Arch Surg. 1986;121:954Y960. 9. Jones JW, Jurkovich GJ. Polypropylene mesh closure of infected abdominal wounds. Am J Surg. 1989;55:73Y76. 10. Leber GE, Garb JL, Alexander AI, et al. Long-term complications associated with prosthetic repair of incisional hernias. Arch Surg. 1998;133:378Y382. 11. Shankaran V, Weber DJ, Reed RL, et al. A review of available prosthetics for ventral hernia repair. Ann Surg. 2011;253:16Y26.
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12. Iqbal CW, Pham TH, Joseph A, et al. Long-term outcome of 254 complex incisional hernia repairs using the modified Rives-Stoppa technique. World J Surg. 2007;31:2398Y2404. 13. 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;194:219Y223. 14. Kolker AR, Brown DJ, Redstone JS, et al. Multilayer reconstruction of abdominal wall defects with acellular dermal allograft (alloderm) and component separation. Ann Plast Surg. 2005;55:36Y42. 15. Ko JH, Salvay DM, Paul BC, et al. Soft polypropylene mesh, but not cadaveric dermis, significantly improves outcomes in midline hernia repairs using the components separation technique. Plast Reconstr Surg. 2009;124:836Y847. 16. Harth KC, Krpata DM, Chawla A, et al. Biologic mesh use practice patterns in abdominal wall reconstruction: a lack of consensus among surgeons. Hernia. 2013;17:13Y20. 17. Breuing K, Butler CE, Ferzoco S, et al. Incisional ventral hernias: review of the literature and recommendations regarding the grading and technique of repair. Surgery. 2010;148:544Y558. 18. Harth KC, Blatnik JA, Anderson JM, et al. Effect of surgical wound classification on biologic graft performance in complex hernia repair: an experimental study. Surgery. 2013;153:481Y492. 19. Shah BC, Tiwari MM, Goede MR, et al. Not all biologics are equal! Hernia. 2011;15:165Y171. 20. Ko JH, Wang EC, Salvay DM, et al. Abdominal wall reconstruction: lessons learned from 200 ‘‘components separation’’ procedures. Arch Surg. 2009;144: 1047Y1055. 21. Jin J, Rosen MJ, Blatnik J, et al. Use of acellular dermal matrix for complicated ventral hernia repair: does technique affect outcomes? J Am Coll Surg. 2007; 205:654Y660.
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Ventral Hernia Repair: Synthetic and Biologic Mesh
22. Bluebond-Langner R, Keifa ES, et al. Recurrent abdominal laxity following interpositional human acellular dermal matrix. Ann Plast Surg. 2008;60: 76Y80. 23. Lipman J, Medalie D, Rosen MJ. Staged repair of massive incisional hernias with loss of abdominal domain: a novel approach. Am J Surg. 2008;195: 84Y88. 24. Vrijland WW, Jeekel J, Steyerberg EW, et al. Intraperitoneal polypropylene mesh repair of incisional hernia is not associated with enterocutaneous fistula. Br J Surg. 2000;87:348Y352. 25. Alkhoury F, Helton S, Ippolito RJ. Cost and clinical outcomes of laparoscopic ventral hernia repair using intraperitoneal nonheavyweight polypropylene mesh. Surg Laparosc Endosc Percutan Tech. 2011;21:82Y85. 26. Kolker AR, Brown DJ, Redstone JS, et al. Multilayer reconstruction of abdominal wall defects with acellular dermal allograft (alloderm) and component separation. Ann Plast Surg. 2005;55:36Y42. 27. Guy JS, Miller R, Morris JA, et al. Early one-stage closure in patients with abdominal compartment syndrome: fascial replacement with human acellular dermis and bipedicle flaps. Am J Surg. 2003;69:1025Y1028. 28. Krpata DM, Blatnik JA, Novitsky YW, et al. Evaluation of high-risk, comorbid patients undergoing open ventral hernia repair with synthetic mesh. Surgery. 2013;153:120Y125. 29. Souza JM, Dumanian GA. Routine use of bioprosthetic mesh is not necessary: a retrospective review of 100 consecutive cases of intra-abdominal midweight polypropylene mesh for ventral hernia repair. Surgery. 2013;153:393Y399. 30. Connolly PT, Teubner A, Lees NP, et al. Outcome of reconstructive surgery for intestinal fistula in the open abdomen. Ann Surg. 2008;247:440Y444. 31. Krpata DM, Stein SL, Eston M, et al. Outcomes of simultaneous large complex abdominal wall reconstruction and enterocutaneous fistula takedown. Am J Surg. 2013;205:354Y358.
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Comparison of Synthetic and Biologic Mesh in Ventral Hernia Repair Using Components Separation Technique Brinkley K. Sandvall, MD,* Daniel W. Suver, MD,* Hakim K. Said, MD,* David W. Mathes, MD,* Peter C. Neligan, MD,* E. Patchen Dellinger, MD,Þ and Otway Louie, MD* Abstract: Ventral hernia repair (VHR) for large abdominal wall defects is challenging. Prior research established that the use of mesh is superior to suture closure alone and that component separation is an effective technique to combat loss of abdominal domain. Studies comparing component separation technique (CST) outcomes utilizing synthetic versus biologic mesh are limited. A retrospective review was conducted of 72 consecutive patients who underwent VHR with CST between 2006 and 2010 at our institution. Surgeon preference and the presence of contamination guided whether synthetic mesh (27 patients) or biologic mesh (45 patients) was used. Mean follow-up interval for all comers was 13.9 months and similar in both groups (P 9 0.05). Degree of contamination and severity of premorbid medical conditions were significantly higher in the biologic mesh group, as ref lected in the higher Ventral Hernia Working Group (VHWG) score (2.04 versus 2.86). Clinical outcomes, as measured by both minor and major complication rates and recurrence rates, were not significantly different. Minor complication rates were 26% in the synthetic group and 37% in the biologic group and major complication rates 15% in the synthetic group and 22% in the biologic group. There was 1 recurrence (4%) in the synthetic mesh group versus 5 (11%) in the biologic mesh group. Multivariable analysis for major complications revealed no significant difference for either synthetic or biologic mesh while controlling for other variables. Subset analysis of uncontaminated cases revealed recurrence rates of 4% in the synthetic mesh group and 6% in the biologic mesh group. VHR using CST and either synthetic mesh or biologic mesh resulted in low recurrence rates with similar overall complication profiles, despite the higher average VHWG grading score in the biologic mesh group. Our results support the VHWG recommendation for biologic mesh utilization in higher VHWG grade patients. In VHWG grade 2 patients, our clinical outcomes were similar, supporting the use of either type of mesh. Key Words: ventral hernia, components separation, mesh, hernia repair, abdominal wall reconstruction, recurrent hernia (Ann Plast Surg 2016;76: 674Y679)
I
ncisional ventral hernias are common problems for many patients with a surgical history of abdominal procedures, particularly midline laparotomy. Although the aesthetics of protruding bowel is of concern to patients, bowel incarceration and ultimately strangulation are medical emergencies that can occur as intestinal loops pass through the fascial wall defect. Repair is necessary to reduce occurrence of these
Received September 28, 2013, and accepted for publication, after revision, April 3, 2014. From the *Division of Plastic Surgery, †Department of General Surgery, University of Washington, Seattle, WA. Conflicts of interest and sources of funding: Dr. Said has acted as a consultant for a pharmaceutical company. Dr. Dellinger has acted and still acts as a consultant and speaker for various pharmaceutical companies; however, no direct funding was received for this work. Reprints: Otway Louie, MD, Division of Plastic Surgery, University of Washington, Seattle, WA, 1959 NE Pacific St., Box 356410, Seattle, WA 98195. E-mail: [email protected]. Copyright * 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0148-7043/16/7606-0674 DOI: 10.1097/SAP.0000000000000253
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complications, but it is extremely difficult in the setting of giant or recurrent ventral hernias with loss of abdominal domain. The component separation technique (CST) is an ideal method to deal with such defects. First described in 1990 by Ramirez et al and popularized by subsequent authors, CST involves bilateral release of the external oblique from the musculature of the abdominal sidewall.1 This results in a greater distance traversed medially by the rectus abdominis, internal oblique, or transversalis myofascial subunit and restoration of the linea alba under minimal tension.1Y5 Mesh is ideally employed after midline approximation to reinforce the closure and promote long-term stability. Prospective evidence detailing the superiority of synthetic mesh reinforcement compared with suture closure alone supports this practice in the setting of small midline hernias.6,7 However, synthetic mesh is only ideal for use in clean cases.8Y11 Although some patients undergoing CST have clean wounds, many patients have either ostomies, fistulae, dense adhesions that increase the risk of incidental enterotomies, and/or conditions that require concomitant bowel surgery. In the context of existing or potential contamination, the likelihood of bacterial colonization of synthetic mesh is high, and unacceptably high levels of inflammation, postoperative infection, enterocutaneous fistulae, bowel erosions, and ultimately repair failure may result.6,11Y13 Surgeons, still seeking reinforcement in this setting, have thus turned to biologic mesh. Biologic and synthetic meshes have been used with variable success; however, research comparing their outcomes in ventral hernia repair (VHR) with CST is lacking and limited by the fact that there are no definitive indications or guidelines for when each mesh should be employed.14Y16 In 2010, the Ventral Hernia Working Group (VHWG) published a literature review assessing patient and wound characteristics in those undergoing VHR.17 They proposed an evidence-based, 4-tiered grading system to offer guidance in material choice and repair technique.17 In patients without comorbidities or wound infection who are undergoing open repair of defects greater than 2 centimeters (cm), they recommended the choice of material be guided by surgeon preference and patient factors.17 In patients with comorbidities that increase the risk of surgical site infection [ie, smoker, obese, diabetic, immunocompromised, and chronic obstructive pulmonary disease (COPD)] but without contamination, they suggested that biologic mesh is potentially advantageous compared with synthetic mesh.17 They proposed that patients with potentially contaminated surgical fields (ie, stoma, gastrointestinal tract violation, and prior wound infection) are best served with biologic mesh, and they recommended against using synthetic mesh in obviously contaminated fields (ie, infected mesh and septic dehiscence).17 Although these guidelines marked an essential step toward coordinating clinical practice, more outcomes data for synthetic and biologic mesh utilization are needed to define the risk factors for hernia recurrence and repair complications.17 In this study, we aimed to assess complication profiles between 2 groups of patients who underwent VHR with CST and either synthetic or biologic mesh.
METHODS A retrospective chart review was conducted on all CST procedures performed at the University of Washington Medical Center Annals of Plastic Surgery
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TABLE 1. Group Characteristics Characteristic No. of patients Male Female Age at surgery, y Mean Range
Synthetic
Biologic
27 9 18
45 17 28
54.3 34Y75
54.1 30Y81
from November 2006 to November 2010. Patients who had abdominal wall reconstructions with either synthetic or biologic mesh were included. Our Institutional Review Board approved this study. Data gathered from medical records included age, sex, hernia size, operative time, operation date, body mass index (BMI; calculated as weight in kilograms divided by height in meters squared), American Society of Anesthesiologists physical status score, preoperative comorbidities known to affect the stability of hernia repair (ie, smoking, diabetes, COPD, immunosuppression, prostatism, and history of abdominal aortic aneurysm), albumin level, history of irradiation, number of prior hernia and abdominal surgeries, placement position of mesh, type of mesh, presence and type of concurrent abdominal procedures, length of hospital stay, minor complications (ie, cellulitis, wound breakdown, and seroma or hematoma requiring aspiration), major complications (ie, infection requiring irrigation and debridement, reoperation for any complication, myocardial infarction, pulmonary embolism, and death), presence of recurrence, and followup time. Follow-up time was calculated based on the last attending abdominal exam or computed tomography scan. Most individuals included in the study had preoperative computed tomography scans to assess hernia size and abdominal wall architecture. Coronal and sagittal views were used to define boundaries of the hernia sac; all measurements were performed using axial cuts. VHWG grades were calculated based on preoperative status and intraoperative findings. Patients with no comorbidities, no history of wound infection, and no evidence of wound contamination were categorized as grade 1. Those with comorbidities (ie, smoker, obese, diabetic, immunosuppressed, or pulmonary complications) but no history of or evidence of infection were grade 2. Those with a prior wound infection, stoma present, or violation of the bowel lumen during herniorrhaphy were grade 3. Grade 4 patients had obvious intraabdominal infection (ie, infected mesh or septic dehiscence). General surgeons and plastic surgeons performed all procedures together using an open approach. The general surgery team performed all but 1 of the hernia repairs with synthetic mesh, whereas plastic surgeons did all but 3 of the repairs reinforced with biologic mesh. The types of synthetic mesh were polypropylene (C.R. Bard-Davol Inc, Providence, RI), polypropylene retrorectus with vicryl mesh reapproximating the posterior sheath, polyester (Mersilene; Ethicon Inc, Somerville, NJ), and polyester with a single-sided coat of resorbable collagen (Parietex; Covidien, Mansfield, MA). Biologic meshes were either human-derived (AlloDerm; LifeCell Co, Branchburg, NJ or FlexHD; Ethicon Inc, Somerville, NJ) or porcine-based (Strattice; LifeCell Co, Branchburg, NJ or Permacol; Covidien, Mansfield, MA). All CST procedures were performed by plastic surgeons with bilateral external oblique release without additional releases or fascial turnover. Mesh was positioned either retrorectus or intraperitoneal. Permanent synthetic mesh was placed retrorectus, and either vicryl mesh (absorbable synthetic mesh) or AlloDerm was used as a bridge if the posterior rectus sheath/peritoneum could not be closed primarily, thus shielding bowel from direct contact with the permanent synthetic material. Biologic mesh was placed as an intraperitoneal underlay. * 2014 Wolters Kluwer Health, Inc. All rights reserved.
Ventral Hernia Repair: Synthetic and Biologic Mesh
Descriptive statistics were calculated, and the groups compared using the 2-tailed t test for continuous variables and Fisher exact test for categorical variables. Nominal logistic regression was use to perform the multivariable analysis using JMP Pro 11 statistical software package (SAS Institute, Cary, North Carolina). P e 0.05 were considered statistically significant.
RESULTS Seventy-two consecutive patients were included, 27 patients in the synthetic mesh group and 45 in the biologic mesh group. Mean age at surgery in all comers was 54.2 years and similar in both groups (Table 1) (P = 0.9). Mean follow-up interval in all comers was 13.9 months and similar in both groups (P = 0.5). Mean follow-up interval was 15.6 months (range, 1Y63 months) in the synthetic mesh group and 12.9 months (range, 1Y67 months) in the biologic group. Table 2 summarizes baseline patient characteristics. Groups were statistically similar with respect to all preoperative measures except hernia height, operative time, BMI, immunosuppression, and VHWG grade. Patients in the biologic mesh group averaged significantly larger hernia heights, longer operating times, more immunosuppression, and higher VHWG grades compared with the synthetic mesh group. Mean hernia defect area in the synthetic mesh cohort was 179.8 versus 238.8 cm2 in the biologic mesh cohort (P = 0.06). Degree of contamination and severity of premorbid medical conditions were significantly higher in the biologic mesh group, as ref lected in the higher VHWG grade (2.04 versus 2.86). Patients in the synthetic mesh group averaged significantly larger BMIs than the biologic mesh cohort (38.0 versus 32.4) (P G 0.01). Average BMI for all comers was 34.5 kg/m2. All other preoperative measures were not significantly different. Mean number of previous abdominal surgeries TABLE 2. Summary of Results Variable No. of cases in which hernia size was measured Mean hernia height, cm Mean hernia width, cm Mean hernia area, cm2 Mean operative time, h:min Mean ASA score Mean albumin level Mean no. of prior abdominal surgeries Mean no. of prior hernia repairs Mean body mass index, kg/m2 Smoking, n (%) Diabetes mellitus, n (%) Chronic obstructive pulmonary disease, n (%) Steroids/immunosuppression, n (%) Mean Ventral Hernia Working Group grade Grade 1 (low risk), n (%) Grade 2 (comorbid), n (%) Grade 3 (potentially contaminated), n (%) Grade 4 (infected), n (%)
Synthetic (n = 27)
Biologic (n = 45)
26
41
14.4 12.2 179.8 5:16 2.8 3.3 4.5
17.7 12.7 238.8 7:19 2.8 3.2 4.1
1.3 38.0 7 (26) 10 (37) 5 (19)
1.1 32.4 8 (18) 15 (33) 4 (9)
0 (0)
8 (18)
0.02*
2.03
2.86
G0.01*
2 (8) 22 (81) 3 (11)
4 (9) 13 (29) 13 (29)
0 (0)
15 (33)
P
0.03*
G0.01*
G0.01*
*Statistically significant, P e 0.05. ASA, American Society of Anesthesiologists.
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TABLE 3. Simultaneous Procedures Procedure Performed Simultaneous bowel procedure, n (%) Bowel resection, n (%) Ostomy takedown, n (%) Fistula takedown, n (%) Removal of infected mesh, n (%)
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TABLE 5. Outcomes
Synthetic (n = 27)
Biologic (n = 45)
1 (3.7) 1 (3.7) 0 0 0
29 (64.4) 16 (35.6) 6 (13.3) 8 (17.8) 10 (22.2)
Complication P G 0.01*
Synthetic (n = 27)
Biologic (n = 45)
7 (26) 4 (15) 1 (4)
17 (38) 10 (22) 5 (11)
Minor, n (%) Major, n (%) Recurrence, n (%)
Minor indicates cellulitis, wound breakdown, and seroma or hematoma requiring aspiration; Major indicates infection requiring irrigation and debridement, reoperation for any reason, myocardial infarction, pulmonary embolism, and death.
*Statistically significant, P e 0.05.
was similar in both groups (4), as was mean number of previous hernia repairs (1). This was the primary VHR in 9 (33.3%) of the synthetic mesh patients and in 16 (35.6%) of the biologic mesh patients. It was the second repair in 12 (40%) of the synthetic mesh patients and in 9 (40%) of the biologic mesh patients. Of the 5 main comorbidities identified by the VHWG to increase the risk of surgical site infection (ie, smoker, obese, diabetic, immunocompromised, and COPD), the mean number of comorbidities in the synthetic mesh group was 1.6 versus 1.4 in the biologic mesh group. Significantly, more patients in the biologic mesh group underwent simultaneous bowel procedures (3.7% of patients in the synthetic mesh group versus 64.4% of patients in the biologic mesh group) (P G 0.01) (Table 3). Overall, 1 simultaneous bowel procedure was performed in the synthetic mesh group versus 40 simultaneous bowel procedures in 29 patients in the biologic mesh group. These procedures included bowel resection, ostomy takedown, fistula takedown, and removal of infected mesh. In the synthetic mesh group, there was 1 (3.7%) bowel resection performed secondary to inadvertent enterotomy and bowel injury during adhesiolysis. At the time of surgery, there were 0 enterocutaneous fistulae present in the synthetic group versus 9 (20%) in the biologic group. Only 1 patient (3.7%) in the synthetic mesh group had an ostomy present versus 12 patients (26.7%) in the biologic group. In the synthetic mesh group, all patients (100%) had their anterior rectus reapproximated in the midline, and 19 of these (70%) had their posterior rectus sheath bridged. In the biologic mesh group, 9 patients (20%) had their defects bridged with intraperitoneal biologic mesh. Table 4 shows the types and distribution of mesh used. Outcomes are shown in Table 5. Though minor complication rates, major complication rates, and recurrence rates were each slightly higher in the biologic mesh group, none reached statistical significance. A power calculation was performed and did not reach the level of 0.80. Thus, our study was underpowered to definitely state that there was no difference between the 2 groups using descriptive statistics. However, TABLE 4. Types of Mesh Synthetic (n = 27)
Mesh Polypropylene alone, n (%) Polypropylene with vicryl, n (%) Polypropylene with AlloDerm, n (%) Parietex, n (%) Parietex with vicryl, n (%) Mersilene, n (%) AlloDerm, n (%) Strattice, n (%) FlexHD, n (%) Permacol, n (%)
676
Biologic (n = 45)
1 (3.7) 5 (18.5) 2 (7.4) 6 (22.2) 12 (44.4) 1 (3.7) 13 (28.9) 15 (33.3) 16 (35.6) 1 (2.2)
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in a univariable analysis, significant factors leading to major complications were simultaneous bowel procedures, a VHWG grade of 4, and a longer duration of the procedure (Table 6). Increasing area of the defect was trending toward significance. The use of biologic mesh was not a significant factor leading to major complications (Table 6). In a multivariable analysis, only a VHWG grade of 4 was significant in leading to major complications (Table 6). When adjusting for VHWG grade, the use of biologic mesh was still not a significant factor leading to major complications. Time to recurrence was 4 months in the 1 synthetic mesh patient and averaged 11.6 months (range, 2Y23 months) in the biologic mesh group. Mean hospital stay was 5.7 days in the synthetic group and 10.1 in the biologic group. Subset analysis of uncontaminated cases (grades 1 and 2) in both groups was performed to control for the fact that biologic mesh was used in more contaminated cases (Table 7). When contaminated cases (grades 3 and 4) were excluded, hernia recurrence rates did not increase; rather, they stayed the same at 4% in the synthetic mesh group and decreased from 11% to 6% in the biologic mesh group. There were no statistically significant differences in minor or major complication rates, regardless of contamination. Again, our study was underpowered to definitely state that there was no significant difference using descriptive statistics; however, multivariable analysis on the subset of uncontaminated cases revealed no significant difference for the synthetic and biologic mesh groups (odds ratio 1.7, CI 0.3 to 10, P = 0.9) in total complications, either before or after adjusting for area of defect, operative time, BMI, simultaneous bowel procedure, or immunosuppressive therapy. To avoid overfitting the model, only 2 controlling variables were placed in the algorithm at 1 time for the analysis.
DISCUSSION Our objective was to determine if any clinically relevant differences in outcomes exist for VHR using CST and either synthetic mesh or biologic mesh. This review of 72 consecutive cases suggests that the 2 groups have similar acceptable rates of minor and major complications and hernia recurrence. The lone recurrence in our synthetic mesh group was a 61year-old nonsmoking man with a BMI of 39 and a very large hernia that required a 3-stage repair. In the first stage, he was taken to the operating room (OR) for enterolysis. His defect was estimated to be too large to close at that time, even with CST; thus, silastic mesh was sutured to the hernia borders and tightened as much as possible. He remained intubated and returned to the OR within days for another round of tightening. He again remained intubated, and only on the third trip to the OR was it thought possible to close his midline. CST was performed and hernia repair carried out with a polypropylene retrorectus underlay. Vicryl mesh was used to bridge the posterior rectus sheath, and the rectus muscles were brought into apposition. This gentleman was fully anticoagulated for medical comorbidities, and 10 weeks after herniorrhaphy, he returned with a rectus sheath hematoma. He subsequently underwent embolization of the inferior epigastric artery and within 4 months was found to have hernia recurrence. * 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Ventral Hernia Repair: Synthetic and Biologic Mesh
TABLE 6. Univariable and Multivariable Analysis for Major Complications Univariable Variable Biologic mesh Mean body mass index Steroids/immunosuppression Mean hernia height Simultaneous bowel procedure Ventral Hernia Working Group grade 4 Mean operative time
Multivariable
OR (LCIYUCI)
P
1.6 (0.5Y6.6) 1 (0.92Y1.1) 1.4 (0.2Y7.2) 1.01 (1Y1.02) 4.1 (1.2Y16.4) 8.3 (2.1Y38.8) 1.008 (1.001Y1.01)
0.4 1 0.7 0.09 0.02* 0.01* 0.05*
OR (LCIYUCI)
P
6.3 (1.7Y23.5)
G0.01*
*Statistically significant, P e 0.05. OR indicates odds ratio; LCI, lower confidence interval; UCI, upper confidence interval.
In our biologic mesh group, all 5 patients with recurrence underwent second simultaneous intra-abdominal procedures at the time of VHR. Three had been repaired with AlloDerm and 2 with Strattice. Only 1 of the 5 had a bridged repair. Three developed recurrence in areas of poor wound healing characterized by abscess or seroma. The fifth recurrence was in an active, nonsmoker who felt the repair fail while working out in a gym 8 months after surgery. Three of the recurrences were in immunosuppressed patients. Mean hospital length of stay was longer in the biologic mesh group because of the increased proportion of simultaneous bowel procedures performed in this group. Studies comparing different biologic meshes are few and have yet to identify an ideal biologic mesh. One study intentionally contaminated 4 types of biologic mesh used in VHR in a rat model and found that the degree of contamination affected the rate of bacterial clearance, wound-healing ability, and repair strength.18 All biologic meshes performed poorly in grossly contaminated settings, and no ideal graft material was identified.18 Additionally, in a small TABLE 7. Patients Without Contamination Variable Sex Male Female Age Mean Range Standard deviation No. of cases in which hernia size was measured Mean hernia height, cm Mean hernia width, cm Mean hernia area, cm2 Mean body mass index, kg/m2 Smoking, n (%) Diabetes mellitus, n (%) Chronic obstructive pulmonary disease, n (%) Steroids/Immunosuppression, n (%) Minor complication, n (%) Major complication, n (%) Recurrence, n (%)
Synthetic (n = 24) 8 16
Biologic (n = 17)
P
5 12
54.7 34Y75 9.2 23
50.8 30Y71 14.6 17
14.3 12.1 172.7 37.7 6 (25) 9 (38) 5 (21)
16.5 11.8 194.4 30.3 4 (24) 3 (18) 0 (0)
0 (0) 6 (25) 3 (13) 1 (4)
2 (12) 7 (41) 1 (6) 1 (6)
*Statistically significant, P e 0.05.
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G0.01*
retrospective study evaluating clinical outcomes (ie, recurrence, mesh explantation, and mesh infection) of patients who underwent complex VHR (some bridging and some CST) with different types of biologic mesh, there was no clear ideal biologic mesh.19 In our study, 4 different biologic meshes were used, and none particularly outperformed another. In the early years of our study, it was our tendency to use FlexHD. However, as different materials became available to our hospital, we began using AlloDerm and more recently have transitioned to almost purely Strattice. The biologic mesh in our study seems to have provided additional protection, decreasing hernia recurrence to less than previously reported rates without mesh.3,20 Our results support the durability of biologic mesh repairs at 14-month follow-up. The VHWG recommended mesh to reinforce all VHRs, whether the midline fascia is reapproximated or not.6,7,17 However, there remains some concern that when AlloDerm is used as a bridge (without primary fascial reapproximation) rather than as reinforcement (after primary fascial reapproximation), that it may be prone to increased hernia recurrence and laxity, often requiring intervention.21,22 When the fascial defect cannot be closed primarily, one may choose to bridge the defect with mesh, recognizing that abdominal laxity may eventually ensue and warrant rerepair, or to stage the repair with serial tightening to eventually gain primary reapproximation.23 At our institution, we have tried both approaches. We have concern about placing synthetic mesh in direct continuity with the bowel, and thus, our tendency is to place it retrorectus. The retrorectus plane positions well-vascularized tissue on both sides of the mesh and may slightly increase mobility of the tissue f laps as a result of releasing the posterior rectus sheath when gaining access to the retrorectus plane. In our study, 2 of the 6 recurrences (1 in the synthetic group and 1 in the biologic group) were in bridged repairs. Some studies with intraperitoneal synthetic mesh have shown low incidences of bowel obstruction, adhesions, infection, and development of enterocutaneous fistulas; however, as it is a real possibility with significant consequences, we avoid it.15,20,24,25 The retrorectus dissection may be difficult if the patient has a history of an ostomy or if the mesh was previously placed there. Unfortunately, there is no high-level data to support an ideal mesh position. In contrast to our findings, Ko et al demonstrated a significantly higher rate of hernia recurrence with biologic mesh (human cadaveric dermis) as opposed to synthetic mesh (soft polypropylene) at an average of 10-month follow-up (0% versus 33.3%).20 They compared no mesh, synthetic mesh, and biologic mesh VHR with CST in 200 consecutive patients; endpoints were similar to those in our studyVminor and major complication rates and recurrence rates (20). Minor and major complications rates in their synthetic and biologic mesh groups were not significantly different (soft propylene 16.7% and 16.7% versus human cadaveric dermis 16.7% and 22.2%, respectively).20 A second, smaller study by the same group reviewed www.annalsplasticsurgery.com
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Annals of Plastic Surgery
Sandvall et al
54 patients after VHR with CST and synthetic (soft polypropylene) or biologic mesh (human cadaveric dermis) reinforcement at an average of 16-month follow-up; again, endpoints were minor and major complication rates and recurrence rates.15 Their biologic mesh group, which was significantly more contaminated, had a higher recurrence rate than their synthetic group (46% versus 11%, respectively), and this increased even more when contaminated cases were excluded (61% versus 12%, respectively).15 The groups had similar minor and major complication rates that did not significantly change when contaminated cases were excluded.15 Their results support synthetic mesh (soft polypropylene) over biologic mesh (human cadaveric dermis) and call into question the long-term reinforcement provided by cadaveric dermis.15 The biologic mesh recurrence rates reported by Ko et al are relatively high compared with other published studies with at least 1-year follow-up.15,20,21,26,27 Perhaps, some of the variation can be attributed to differences in the various types of biologic mesh utilized. In contrast to Ko et al, our biologic mesh recurrence rate was quite a bit lower and did not increase, but rather decreased, when contaminated cases were excluded.15,20 This seems logical when one considers that contamination is associated with increased recurrence.6,12 Though there were more recurrences in our biologic group, we did not find a statistically significant difference in the recurrence rates. Our results support the use of either synthetic or biologic mesh in grade 2 patientsVnot one over the other. A recent retrospective review by Krpata et al examined 88 patients with VHR and supported synthetic mesh in the retrorectus space for VHWG grade 2 patients.28 They reported 0 recurrences and 16% surgical site occurrence (defined by the VHWG as an infection, clinically relevant seroma requiring intervention, dehiscence, and formation of an enterocutaneous fistula) at an average of 18-month follow-up.28 Though multiple comorbidities increased the risk of surgical site occurrence, no single variable was found to contribute more than others.28 Our findings also support the potential use of synthetic mesh use in grade 2 patients. Another recent manuscript by Souza et al retrospectively reviewed 87 patients with VHR with synthetic mesh and suggested that synthetic mesh is safe in VHWG grades 1 through 3, challenging the notion that biologic mesh should be favored in higher VHWG grade patients.29 They demonstrated low rates of complications (10.1% minor and 1.2% major) and recurrence (5.6%) with polypropylene intraperitoneal mesh underlay at an average of 23-month follow-up.29 Compared with our study, their synthetic mesh was placed in a different location (intraperitoneal rather than retrorectus), and we had a smaller cohort of patients with shorter follow-up. Only 3 patients (11%) in our synthetic mesh group were VHWG grade 3 (most were grade 2). Similar to Souza et al, our results also support the use of synthetic mesh in a group with multiple comorbidities.29 Single-stage complex VHR with biologic mesh and enterocutaneous fistula takedown is challenging and has been reported with mixed results, some reporting high rates of complications and recurrence.30,31 Krpata et al recently reported a 32% recurrence at an average of 20-month follow-up.31 In our study, though all 5 of the recurrences in the biologic group underwent simultaneous intraabdominal procedures, only 1 had an enterocutaneous fistula takedown. Of the 8 enterocutaneous fistula takedowns, 1 patient (12.5%) developed recurrence. As contamination increases the risk of hernia recurrence, the importance of source control and intraoperative drain placement must be emphasized. In our practice, when biologic mesh is used, 4 drains are placedV1 retrorectus and superficial to the mesh, 1 subcutaneous and in the midline, and 1 along each of the component release sites. In contrast, when we use synthetic mesh, only 2 drains are placedV1 at each of the component release sites. Standard principles for infection reduction should be followed, including debridement of nonviable tissue, excision of scar tissue, excision of hernia sac remnants, and copious irrigation. 678
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Our study has some limitations. It is retrospective, single institution, and has unequal sample sizes. Additionally, multiple surgeons performed the operations, and 2 different operative techniques were used: synthetic mesh was placed retrorectus to reduce the likelihood of developing bowel adhesions and erosions secondary to contact with bowel, whereas biologic mesh, which is potentially less inf lammatory, was placed intraperitoneal. Though we did not find a statistically significant difference in hernia recurrence rates, there were a greater number of recurrences in the biologic group. With longer follow-up and larger cohorts, additional complications may become evident and longevity of the repair more fully known; thus, our current complication rates and recurrence rates may underreport the true values. However, this is 1 of the largest series comparing outcomes in VHR using CST and either synthetic or biologic mesh. To address these limitations, a prospective study of both synthetic and biologic meshes with larger sample sizes, standard operative technique, and longer follow-up is necessary.
CONCLUSIONS In conclusion, VHR using CST and either synthetic mesh or biologic mesh resulted in low recurrence rates with similar overall complication profiles, despite the presence of contamination and other complicating circumstances among patients receiving biologic mesh. Our results support the VHWG recommendation for biologic mesh utilization in higher VHWG grade patients; however, they do not support the use of biologic mesh instead of synthetic mesh in grade 2 patients. Rather, in grade 2 patients, our clinical outcomes were similar, thereby supporting the use of either type of mesh, not one over the other. Detecting preoperative risk for infection and adjusting operative plans accordingly are important for successful hernia repair. ACKNOWLEDGMENTS The authors thank James D. Perkins, MD, for his statistical consultation.
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Annals of Plastic Surgery
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Ventral Hernia Repair: Synthetic and Biologic Mesh
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