Evaluation of porcine dermal collagen (Permacol) used in abdominal wall reconstruction

Innovative approaches to tissue engineering: Utilizing decellularized extracellular matrix hydrogels for mesenchymal stem cell transport

In recent years, the realm of tissue regeneration experienced significant advancements, leading to the development of innovative therapeutic agents. The systemic delivery of mesenchymal stem cells (MSCs) emerged as a promising strategy for promoting tissue regeneration. However, this approach is hindered by hurdles such as poor cell survival, limited cell propagation, and inadequate cell integration. Decellularized extracellular matrix (dECM) hydrogel serves as an innovative carrier that protects MSCs from the detrimental effects of the hostile microenvironment, facilitates their localization and retention at the injection site, and preserves their viability. Regarding its low immunogenicity, low cytotoxicity, high biocompatibility, and its ability to mimic natural extracellular matrix (ECM), this natural hydrogel offers a new avenue for systemic delivery of MSCs. This review digs into the properties of dECM hydrogels (dECMHs), the methods employed for decellularization and the utilization of dECMH as carriers for various types of MSCs for tissue regeneration purposes. This review also sheds light on the benefits of hybrid hydrogels composed of dECMH and other components such as proteins and polysaccharides. By addressing the limitations of conventional hydrogels and enhancing efficacy of cell therapy, dECMH opens new pathways for the future of tissue regeneration.

Nanotechnology approaches in abdominal wall reconstruction: A narrative review about scaffold and meshes

Repairing abdominal wall defects poses challenges for surgeons. Although mesh reinforcement is commonly used for primary repair, nanotechnology has emerged as a promising approach for developing innovative repair techniques. Most research in this area focuses on fabricating scaffolds designed specifically for abdominal wall repair, particularly in cases of hernia. These scaffolds are engineered to replicate the structure and function of the native extracellular matrix. This review aimed to summarize the existing studies on the application of nanotechnology in abdominal wall reconstruction following injury or repair.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

Promising Implants in Rhinoplasty

Many dilemmas in rhinoplasty tempt surgeons to use exogenous materials. We have long looked toward implants to decrease operative time, to achieve a more reliable result, or when there is a paucity of autologous material. More than ever, the innovative and highly lucrative field of nasal implantology is developing technologically advanced products. This article looks at some popular nasal implant choices with a look toward what might be on the horizon.

The Use of Acellular Dermal Matrix (Integra Single Layer) for the Correction of Malformative Chest Wall Deformities: First Case Series Reported

Introduction Autologous tissue transfers have been used in chest wall reconstruction for decades, with high morbidity. Recently, acellular dermal matrices (ADMs) have emerged as an alternative. The aim of this article is to report our initial experience in the reconstruction of malformative chest wall deformities with ADM.

Methods A prospective observational study was performed in patients with malformative chest wall deformities, who were reconstructed with ADM at our institution between 2018 and 2020. We analyzed demographic variables, surgical features, postoperative complications, and cosmetic results at 12 months' follow- up.

Results Four male patients were included (median age: 16 years). Two patients had bilateral costal anomalies, one patient had a unilateral chest deformity, and one patient had Poland syndrome. In all patients, blunt dissection of the subcutaneous cellular tissue overlying the defect was performed through 2.5 to 3 cm skin incisions, creating a pouch. Afterwards, several sheets of Integra Single Layer were placed in the pouch, to replace the volume defect. All patients were discharged same-day. No postoperative infections, hematomas, or seromas were observed. Only one patient presented with a partial surgical wound dehiscence. Revisions were performed at 1, 3, 6, and 12 months. All 4 patients were satisfied with the cosmetic outcome (Nuss Questionnaire: median score: 16 points; Q1–Q3: 22–26).

Conclusion The use of ADM in malformative chest wall deformities reconstruction has not been previously described in children. This study demonstrates that the use of ADM is a safe and reliable technique. However, more studies with long-term follow-up are warranted.

The Role of the Extracellular Matrix (ECM) in Wound Healing: A Review

The extracellular matrix (ECM) is a 3-dimensional structure and an essential component in all human tissues. It is comprised of varying proteins, including collagens, elastin, and smaller quantities of structural proteins. Studies have demonstrated the ECM aids in cellular adherence, tissue anchoring, cellular signaling, and recruitment of cells. During times of integumentary injury or damage, either acute or chronic, the ECM is damaged. Through a series of overlapping events called the wound healing phases—hemostasis, inflammation, proliferation, and remodeling—the ECM is synthesized and ideally returned to its native state. This article synthesizes current and historical literature to demonstrate the involvement of the ECM in the varying phases of the wound healing cascade.

Decellularized Tissues for Wound Healing: Towards Closing the Gap Between Scaffold Design and Effective Extracellular Matrix Remodeling

The absence or damage of a tissue is the main cause of most acute or chronic diseases and are one of the appealing challenges that novel therapeutic alternatives have, in order to recover lost functions through tissue regeneration. Chronic cutaneous lesions are the most frequent cause of wounds, being a massive area of regenerative medicine and tissue engineering to have efforts to develop new bioactive medical products that not only allow an appropriate and rapid healing, but also avoid severe complications such as bacterial infections. In tissue repair and regeneration processes, there are several overlapping stages that involve the synergy of cells, the extracellular matrix (ECM) and biomolecules, which coordinate processes of ECM remodeling as well as cell proliferation and differentiation. Although these three components play a crucial role in the wound healing process, the ECM has the function of acting as a biological platform to permit the correct interaction between them. In particular, ECM is a mixture of crosslinked proteins that contain bioactive domains that cells recognize in order to promote migration, proliferation and differentiation. Currently, tissue engineering has employed several synthetic polymers to design bioactive scaffolds to mimic the native ECM, by combining biopolymers with growth factors including collagen and fibrinogen. Among these, decellularized tissues have been proposed as an alternative for reconstructing cutaneous lesions since they maintain the complex protein conformation, providing the required functional domains for cell differentiation. In this review, we present an in-depth discussion of different natural matrixes recently employed for designing novel therapeutic alternatives for treating cutaneous injuries, and overview some future perspectives in this area.

Prevention of Post-Operative Adhesions: A Comprehensive Review of Present and Emerging Strategies

Post-operative adhesions affect patients undergoing all types of surgeries. They are associated with serious complications, including higher risk of morbidity and mortality. Given increased hospitalization, longer operative times, and longer length of hospital stay, post-surgical adhesions also pose a great financial burden. Although our knowledge of some of the underlying mechanisms driving adhesion formation has significantly improved over the past two decades, literature has yet to fully explain the pathogenesis and etiology of post-surgical adhesions. As a result, finding an ideal preventative strategy and leveraging appropriate tissue engineering strategies has proven to be difficult. Different products have been developed and enjoyed various levels of success along the translational tissue engineering research spectrum, but their clinical translation has been limited. Herein, we comprehensively review the agents and products that have been developed to mitigate post-operative adhesion formation. We also assess emerging strategies that aid in facilitating precision and personalized medicine to improve outcomes for patients and our healthcare system.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Decellularization and In Vivo Recellularization of Abdominal Porcine Fascial Tissue

BACKGROUND

Tissue decellularization has evolved as a promising approach for tissue engineering applications.

METHODS

In this study, we harvested fascial tissue from porcine anterior abdominal wall and the samples were decellularized with a combination of agents such as Triton X-100, trypsin and DNAase. Afterwards, we evaluated cell removal by histological analysis and DNA quantification. Mechanical functionality was evaluated by applying a range of hydrostatic pressures. A sample of decellularized fascia was transplanted into a rabbit and after 15 days a biopsy of this tissue was examined; the animal was observed during 6 months after surgery.

RESULTS

The extracellular matrix was retained with a complete decellularization as evidenced by histologic examination. The DNA content was significantly reduced. The scaffold preserved its tensile mechanical properties. The graft was incorporated into a full thickness defect made in the rabbit abdominal wall. This tissue was infiltrated by granulation and inflammatory cells and the histologic structure was preserved 15 days after surgery. The animal did not develop hernias, infections or other complications, after a 6-months of follow up.

CONCLUSIONS

The protocol of decellularization of fascial tissue employed in this study proved to be efficient. The mechanical test demonstrated that the samples were not damaged and maintained its physical characteristics; clinical evolution of the rabbit, recipient of the decellularized fascia, demonstrated that the graft was effective as a replacement of native tissue.In conclusion, a biological scaffold derived from porcine fascial tissue may be a suitable candidate for tissue engineering applications.

Porcine dermal matrix sandwich graft for lower eyelid reconstruction

Purpose: To report the clinical outcomes of porcine acellular dermal matrix implants sandwiched between skin and conjunctival flaps for lower eyelid reconstruction following Mohs surgery. Methods: A retrospective review was performed on patients with lower eyelid defects following Mohs surgery treated using a porcine acellular dermal matrix sandwich graft from 2013 to 2018. Patient demographics, defect size and characteristics, and collagen matrix implant dimensions were evaluated. Postoperative course and complications were also reviewed. Results: The dermal matrix sandwich graft was performed in 13 cases (12 patients). Average horizontal marginal defect width was 11.7 mm (range: 6-16 mm). Mean width of the implanted dermal matrix was 7.7 mm (range: 5-9 mm). There were no instances of infection or graft failure. The reconstructed lid had an excellent marginal contour in 11 cases (84.6%), while 2 had minimal irregularities. All patients had an excellent thickness of the reconstructed margin. One patient (7.7%) required cauterization of overgrown marginal conjunctiva after surgery. Two patients (15.4%) experienced symptomatic trichiasis, requiring electrolysis (n = 1) and epilation (n = 1). Conclusions: The dermal matrix sandwich graft is an effective method for marginal defect repair when the remaining conjunctiva and skin are sufficient to develop the necessary flaps. While the resolution of edema and erythema may take several months, an excellent final result is achieved in the majority of cases. Complications are mild, relatively uncommon, and similar to those encountered in other reconstructive procedures. This single-stage, tissue-sparing technique preserves the capability of performing future tarsoconjunctival flaps or lateral canthal procedures, should the need arise.

A retrospective, Italian multicenter study of complex abdominal wall defect repair with a Permacol biological mesh

Complex abdominal wall defects (CAWDs) can be difficult to repair and using a conventional synthetic mesh is often unsuitable. A biological mesh might offer a solution for CAWD repair, but the clinical outcomes are unclear. Here, we evaluated the efficacy of a cross-linked, acellular porcine dermal collagen matrix implant (Permacol) for CAWD repair in a cohort of 60 patients. Here, 58.3% patients presented with a grade 3 hernia (according to the Ventral Hernia Working Group grading system) and a contaminated surgical field. Permacol was implanted as a bridge in 46.7%, as an underlay (intraperitoneal position) in 38.3% and as a sublay (retromuscolar position) in 15% of patients. Fascia closure was achieved in 53.3% of patients. The surgical site occurrence rate was 35% and the defect size significantly influenced the probability of post-operative complications. The long-term (2 year) hernia recurrence rate was 36.2%. This study represents the first large multi-centre Italian case series on Permacol implants in patients with a CAWD. Our data suggest that Permacol is a feasible strategy to repair a CAWD, with acceptable early complications and long-term (2 year) recurrence rates.

A novel tool to evaluate bias in literature on use of biologic mesh in abdominal wall hernia repair

PURPOSE

Biologic meshes are being increasingly used for abdominal hernia repair in high-risk patients or patients with a previous history of wound infection, due to their infection-resistant properties. Several studies have been carried out to assess whether biologic mesh is superior to synthetic mesh, as well as to establish guidelines for their use. Unfortunately, most of these studies were not rigorously designed and were vulnerable to different types of bias. The systematic reviews that have been published so far on this topic contain the same biases and limitations of the primary articles that are analyzed. The lack of a literature review on the bias on the use of biological mesh prompted us to conduct the literature search, assessment and plan this article.

METHODS

We performed a literature search in PubMed, Embase and Cochrane databases of systematic reviews on biologic mesh for ventral hernia repair. The literature review was conducted using the Population, Intervention, Comparisons, Outcomes and Design approach. We identified 40 studies that matched the stringent criteria we had set. We then created a 13-point instrument to assess for bias and applied it on the primary studies that we intended to analyze.

RESULTS

Most primary studies are case series or case reports of patients undergoing abdominal hernia repair with biologic mesh, without any comparison group, and the inclusion of cases was only specified to be consecutive in 6 out of 40 cases. In terms of assessing outcomes, in none of the 40 articles were the outcome assessors blinded to the intervention or exposure status of participants.

CONCLUSION

The instrument that we created could allow to assess the risk of bias in different kind of studies. Our assessment of the studies based on the criteria that we had set up in the instrument clearly identified that further research needs to be done due to the lack of unbiased studies regarding the use of biologic meshes for abdominal hernia repair.

Systematic review of the stage of innovation of biological mesh for complex or contaminated abdominal wall closure

Background

Achieving stable closure of complex or contaminated abdominal wall incisions remains challenging. This study aimed to characterize the stage of innovation for biological mesh devices used during complex abdominal wall reconstruction and to evaluate the quality of current evidence.

Methods

A systematic review was performed of published and ongoing studies between January 2000 and September 2017. Eligible studies were those where a biological mesh was used to support fascial closure, either prophylactically after midline laparotomy, or for reinforcement after repair of incisional hernia with midline incision. The primary outcome measure was the IDEAL framework stage of innovation. The key secondary outcome measure was the GRADE criteria for study quality.

Results

Thirty‐five studies including 2681 patients were included. Four studies considered mesh prophylaxis, 23 considered hernia repair, and eight reported on both. There was one published randomized trial (IDEAL stage 3), none of which was of high quality; the others were non‐randomized studies (IDEAL stage 2a). A detailed description of surgical technique was provided in most studies (27 of 35); however, no study reported outcomes according to the European Hernia Society consensus statement and only two described quality control of surgical technique during the study. From 21 ongoing randomized trials and observational studies, 11 considered repair of incisional hernia and 10 considered prophylaxis (seven in elective settings).

Conclusion

The evidence base for biological mesh is limited, and better reporting and quality control of surgical techniques are needed. Although results of ongoing trials over the next decade will improve the evidence base, further study is required in the emergency and contaminated settings.

Evaluating full-thickness skin grafts in intraperitoneal onlay mesh position versus onlay position in mice

BACKGROUND

Importance: Hernia surgery requires reinforcement material with few side effects when used in the intraperitoneal position. Autologous skin grafting may meet this requirement, but animal experiments are obligatory before being applied in humans.

OBJECTIVE

To compare survival and effects of isogeneic full-thickness skin grafts in the intraperitoneal onlay mesh (IPOM) position in mice, with a control group using the onlay position. Primary end point was graft survival and secondary end point adhesion formation and inflammation through NF-κB activity.

METHODS

Design: Intervention study with 8-week follow-up in accordance with ARRIVE criteria, performed between 2015 and 2016.

SETTING

Animal laboratory.

PARTICIPANTS

Transgenic C57BL/6 mice with isogeneic background were used. Recipients were female wild-type phenotype mice >3 mo (n = 24). Donors were male or female mice >7 mo, with phenotype-positive for the luciferase gene (n = 20) or positive for NF-κB-luciferase gene (n = 4).

INTERVENTION

Full-thickness skin was grafted in the IPOM position and compared with grafts in the onlay position as controls. Survival was evaluated by regular longitudinal postoperative luminescence imaging over 8 wk. Adherence formation was evaluated macroscopically after sacrifice. Inflammation of full-thickness skin grafts in IPOM position of NF-κB mice was evaluated in four additional mice. Main outcome and measure: Survival of grafts, evaluated by luminescence.

RESULTS

Ten animals received grafts in the IPOM position, and 10 in the onlay position as controls. Graft survival after 8 wk was 100% (20/20). Average luminescence at the end of the 8-week period was 999,597 flux (min 162,800, max 2,521,530) in the IPOM group (n = 10) and 769,708 flux (min 76,590, max 2,164,080) in the onlay control group (n = 10). No adhesions requiring sharp dissection (Jenkins' scale >2) were seen. Four animals with grafts in the IPOM position showed peak inflammation (NF-κB activity) 5 d after surgery subsiding toward the end of follow-up.

CONCLUSIONS

Full-thickness skin survives as well in the IPOM position as in the onlay control position, and few adherences develop. Further studies are required to fully characterize the tissue remodeling and repair processes associated with IPOM skin grafting. The result is relevant in the search for alternative reinforcement materials to be used in complex hernia surgery in humans.

Reconstruction of the Thoracic Wall With Biologic Mesh After Resection for Chest Wall Tumors: A Presentation of a Case Series and Original Technique

INTRODUCTION

Synthetic materials have traditionally been used for tissue reconstruction in thoracic surgery. New biomaterials have been tested in other areas of surgery with good results. Non-cross-linked swine dermal collagen prosthesis has been used to reconstruct musculofascial defects in the trunk with low infection and herniation rate.

MATERIAL AND METHODS

Retrospectively, we analyze our initial experience of chest wall reconstruction on large defects using a non-cross-linked swine dermal collagen matrix mesh with a thickness of 1.4 mm. A total of 11 consecutive patients were included. Preoperative, intraoperative, and postoperative data were taken into consideration.

RESULTS

Eleven sarcoma patients with a mean age of 58.25 ± 12.9 years underwent chest wall resections. Complete thoracic wall defects ranged from 6 · 9 to 16 · 25 cm in size. In all cases, we used a porcine collagen matrix mesh, and in all patients, it was covered by transposition of myocutaneous flap. The complications occurred in 5 (45%) patients, 1 (9%) pneumonia, 1 atrial fibrillation (9%), and 3 (27%) wound healing difficulty because of hematoma or infection. There was no respiratory impairment, and the pulmonary function (total lung capacity, vital capacity, and forced expiratory volume in 1 second) was not statistically different before and after surgery. The 30-day mortality was 0%, 1-year mortality and 2-year mortality was 27.2%. The collagen material resulted in a durable and good to excellent chest wall stability in clinical follow-ups, and on computer tomography scans spanning over 2 years.

CONCLUSION

Non-cross-linked acellular porcine dermal collagen matrix is a feasible and reliable biological patch material for reconstruction of the thoracic wall. Excellent wound healing, long-term stability, low complication, and good pulmonary function are achieved even in large defects.

Porcine Dermal Collagen Prevents Seroma Formation After Mastectomy and Axillary Dissection in Rats

OBJECTIVE

Seroma occurs as a result of accumulation lymphovascular liquid in the dead space forming after tissue dissection. It is the most common complication after breast surgery. Collagens are the common component of extracellular matrix and have an important role in wound healing. In this study, we aimed to investigate the efficiency of the Porcine Dermal Collagen in preventing Seroma.

MATERIALS AND METHODS

Eighteen young female Wistar rats were used and divided into three groups. Mastectomy and axillary dissection were performed in each group. No other procedures were performed in Group 1 (Control group). Porcine dermal collagen was applied to 50% of the mastectomy field in Group 2 and to 100% of the mastectomy field in Group 3.

RESULTS

Seroma volume was significantly decreased in Group 3 in contrast to Groups 1 and 2 (p<0.001) and in Group 2 in contrast to Group 1 (p<0.001). Vascular proliferation, granulation tissue formation and congestion were significantly increased in Group 3 (p<0.05).

CONCLUSION

We conclude that the use of Porcine Dermal Collagen reduces the formation of seroma in the model of experimental mastectomy and axillary dissection. As the amount of Porcine Dermal Collagen applied increases the formation of seroma reduces.

Single-center ventral hernia repair with porcine dermis collagen implant

INTRODUCTION

This study aims to evaluate the outcomes and utilization of porcine acellular dermal collagen implant (PADCI) during VHR at a large tertiary referral center.

METHODS

Records of 5485 patients who underwent VIHR from June 1995 to August 2014 were retrospectively reviewed to identify patients >18 years of age who had VIHR with PADCI reinforcement. Use of multiple mesh reinforcement products, inguinal hernias, and hiatal hernias were exclusion criteria. The primary outcome was hernia recurrence, and secondary outcomes were early complications and surgical site occurrences (SSOs). Uni- and multivariate analyses assessed risk factors for recurrence after PADCI reinforced VIHR.

RESULTS

There were 361 patients identified (54.5% female, mean age of 56.7 ± 12.5 years, and mean body mass index (BMI) of 33.0 ± 9.9 kg/m²). Hypertension (49.5%), diabetes (24.3%), and coronary artery disease (14.4%) were the most common comorbidities, as was active smoking (20.7%). Most were classified as American Association of Anesthesiologists (ASA) Class 3 (61.7%). Hernias were distributed across all grades of the ventral hernia working group (VHWG) grading system: grade I 93 (25.7%), grade II 51 (14.1%), grade III 113 (31.3%), and grade IV 6 (1.6%). Most VIHR were performed from an open approach (96.1%), and were frequently combined with concomitant surgical procedures (47.9%). Early postoperative complications (first 30 days) were reported in 39.0%, with 71 being SSO. Of the 19.7% of patients with SSO, there were 31 who required procedural intervention. After a mean follow-up of 71.5 ± 20.5 months, hernia recurrence was documented in 34.9% of patients. Age and male gender were predictors of recurrence on multivariate analysis.

CONCLUSION

To the best of our knowledge, this is the largest retrospective single institutional study evaluating PADCI to date. Hernias repaired with PADCI were frequently in patients undergoing concomitant operations. Reinforcement with PADCI may be considered a temporary closure, with a relatively high recurrence rate, especially among patients who are older, male, and undergo multiple explorations in a short perioperative period.

Future Prospects for Scaffolding Methods and Biomaterials in Skin Tissue Engineering: A Review

Over centuries, the field of regenerative skin tissue engineering has had several advancements to facilitate faster wound healing and thereby restoration of skin. Skin tissue regeneration is mainly based on the use of suitable scaffold matrices. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. Appropriate knowledge of the properties, advantages and disadvantages of various biomaterials and scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts.

Outcomes Analysis of Biologic Mesh Use for Abdominal Wall Reconstruction in Clean-Contaminated and Contaminated Ventral Hernia Repair

BACKGROUND

Repair of grade 3 and grade 4 ventral hernias is a distinct challenge, given the potential for infection, and the comorbid nature of the patient population. This study evaluates our institutional outcomes when performing single-stage repair of these hernias, with biologic mesh for abdominal wall reinforcement.

METHODS

A prospectively maintained database was reviewed for all patients undergoing repair of grade 3 (potentially contaminated) or grade 4 (infected) hernias, as classified by the Ventral Hernia Working Group. All those patients undergoing repair with component separation techniques and biologic mesh reinforcement were included. Patient demographics, comorbidities, and postoperative complications were analyzed. Univariate analysis was performed to define factors predictive of hernia recurrence and wound complications.

RESULTS

A total of 41 patients underwent single-stage repair of grade 3 and grade 4 hernias during a 4-year period. The overall postoperative wound infection rate was 15%, and hernia recurrence rate was 12%. Almost all recurrences were seen in grade 4 hernia repairs, and in those patients undergoing bridging repair of the hernia. One patient required removal of the biologic mesh. Those factors predicting hernia recurrence were smoking (P = 0.023), increasing body mass index (P = 0.012), increasing defect size (P = 0.010), and bridging repair (P = 0.042). No mesh was removed due to perioperative infection. Mean follow-up time for this patient population was 25 months.

CONCLUSIONS

Single-stage repair of grade 3 hernias performed with component separation and biologic mesh reinforcement is effective and offers a low recurrence rate. Furthermore, the use of biologic mesh allows for avoidance of mesh explantation in instances of wound breakdown or infection. Bridging repairs are associated with a high recurrence rate, as is single-stage repair of grade 4 hernias.

Outcomes following placement of non-cross-linked porcine-derived acellular dermal matrix in complex ventral hernia repair

Repair of complex ventral hernias frequently results in postoperative complications. This study assessed postoperative outcomes in a consecutive cohort of patients with ventral hernias who underwent herniorrhaphy using components separation techniques and reinforcement with non–cross-linked intact porcine-derived acellular dermal matrix (PADM) performed by a single surgeon between 2008 and 2012. Postoperative outcomes of interest included incidence of seroma, wound infection, deep-vein thrombosis, bleeding, and hernia recurrence determined via clinical examination. Of the 47 patients included in the study, 25% were classified as having Ventral Hernia Working Group grade 1 risk, 62% as grade 2, 2% as grade 3, and 11% as grade 4; 49% had undergone previous ventral hernia repair. During a mean follow-up of 31 months, 3 patients experienced hernia recurrence, and 9 experienced other postoperative complications: 4 (9%) experienced deep-vein thrombosis; 3 (6%), seroma; 2 (4%), wound infection; and 2 (4%), bleeding. The use of PADM reinforcement following components separation resulted in low rates of postoperative complications and hernia recurrence in this cohort of patients undergoing ventral hernia repair.

The use of a biological graft for the closure of large abdominal wall defects following excision of soft tissue tumours

Primary soft tissue tumours arising from the abdominal wall are uncommon and surgical excision of such tumours can result in large abdominal wall defects. There are many techniques available for abdominal wall repair following tumour excision, each having its own advantages and disadvantages. The options range from direct closure to the use of tissue flap reconstructions and/or prosthetic meshes. Currently, synthetic material such as polypropylene mesh is a common choice for closure of abdominal wall defects after tumour excision. Biological meshes are an alternative option for repair, and this report outlines two cases of abdominal wall repair using the porcine intestinal submucosa biological graft following excision of abdominal wall tumours. There was no evidence of infection, recurrence, seroma or hernias at 2-year follow-up. Following excision of soft tissue tumours of the abdominal wall, biological reconstructions can be successfully used to bridge the defect with minimal morbidity.

Use of a porcine dermal collagen implant for contaminated abdominal wall reconstruction in a 105-year-old woman: a case report and review of the literature

INTRODUCTION

Repair of contaminated abdominal wall defect in a geriatric patient is a challenge for the surgeon. We present the case of the oldest patient (105-years old) to successfully undergo a single-stage repair of a contaminated abdominal wall defect with a Permacol™ implant.

CASE PRESENTATION

A 105-year-old Caucasian woman presented to our emergency room with a clinical and radiological diagnosis of small bowel obstruction due to prior operative adhesions. She underwent laparotomy with small bowel resection and primary closure of her abdomen. There was total eventration of her bowel through the suture line 9 days after surgery. She underwent a second laparotomy that revealed no signs of peritonitis or turbid fluid. Her abdomen was closed with a 15 × 10 cm Permacol™ implant sutured sublay with prolene sutures. Her postoperative period was unremarkable. After a follow-up period of 3 years and 2 months, there was no sign of recurrent hernia or wound contamination.

CONCLUSION

We suggest that Permacol™ mesh can be considered an efficient alternative to primary closure or synthetic mesh in geriatric patients with contaminated abdominal wall defects.

Dynamic magnetic resonance imaging evaluation of pelvic reconstruction with porcine dermal collagen mesh following extra-levator abdominoperineal excision for primary rectal cancer

PURPOSE

Extra-levator abdominoperineal excision for rectal cancer includes resection of the levator ani muscle and therefore makes pelvic reconstruction advisable. The aim of our study was to evaluate morphologic and functional long-term results of pelvic floor augmentation with porcine dermal collagen mesh by dynamic magnetic resonance imaging and clinical examination.

METHODS

Twenty consecutive patients underwent perineal reconstruction with porcine dermal collagen mesh following extra-levator abdominoperineal excision for primary rectal adenocarcinoma with curative intent between 2009 and 2012. Patient perioperative and postoperative data were collected prospectively. There were one cancer-related and two noncancer-related deaths in the follow-up period, and another three patients refused the dynamic magnetic resonance imaging.

RESULTS

Fourteen patients were included in the study. The median time period from surgery to dynamic magnetic resonance imaging and clinical examination was 31 months (range 19-56). Wound infections were observed in 43% (6 of 14) of these patients in the postoperative period, but no mesh had to be removed. No focal mesh defect, no damage on the suture line, and no perineal hernia were detected on dynamic magnetic resonance imaging. Clinical examination revealed no pathological findings in any patient.

CONCLUSIONS

The implantation of a porcine dermal collagen mesh is an effective and reliable option for pelvic floor reconstruction after extra-levator abdominoperineal excision. Despite a high incidence of primary wound infections, the healing rate was satisfactory, no mesh had to be removed, and long-term stability could be achieved.

Characterisation and comparison of the host response of 6 tissue-based surgical implants in a subcutaneous in vivo rat model

BACKGROUND

Hernia repair often involves fascial augmentation using biologic prostheses. Small processing changes during preparation modulate host tissue response, which influence material efficacy and longevity. In this pilot study, a rat model was used to determine the specific influence of tissue origin, decellularisation treatment and 1,6-hexamethylene diisocyanate (HMDI) cross-linking.

METHODS

Materials (1 cm2) were implanted subcutaneously into 6-week-old Wistar rats (4 materials per animal, n=6/material per time point) for 2, 5, 7, 14 and 28 days. Histologic processing was carried out after resin infiltration, observing classical histopathology and pathologic indexing. Materials comprised 6 tissue-based grafts covering both experimental and commercial porcine decellularised dermal and small intestinal submucosal materials.

RESULTS

Subcutaneous delivery of biologics demonstrated material-specific inflammatory/host responses. Controlled variations of the PermacolTM manufacturing process showed sodium dodecyl sulfate (SDS) was the most proinflammatory decellularisation reagent, and HMDI cross-linking had no effect on host response. All materials remained recoverable after 28 days, although SurgisisTM had partially resorbed.

CONCLUSION

Differences in host responses exist between biologic implants for hernia repair in this rat model. It is postulated that these modifications are induced during processing and may have an effect on the clinical outcome of hernia repair.

To cross-link or not to cross-link? Cross-linking associated foreign body response of collagen-based devices

Collagen-based devices, in various physical conformations, are extensively used for tissue engineering and regenerative medicine applications. Given that the natural cross-linking pathway of collagen does not occur in vitro, chemical, physical, and biological cross-linking methods have been assessed over the years to control mechanical stability, degradation rate, and immunogenicity of the device upon implantation. Although in vitro data demonstrate that mechanical properties and degradation rate can be accurately controlled as a function of the cross-linking method utilized, preclinical and clinical data indicate that cross-linking methods employed may have adverse effects on host response, especially when potent cross-linking methods are employed. Experimental data suggest that more suitable cross-linking methods should be developed to achieve a balance between stability and functional remodeling.

Dermal matrices and bioengineered skin substitutes: a critical review of current options

Background:

Over recent decades, scientists and surgeons have collaborated to develop various bioengineered and synthetic products as an alternative to skin grafts. Despite the numerous articles and reviews written about dermal skin substitutes, there is no general consensus.

Methods:

This article reviews dermal skin scaffolds used in clinical applications and experimental settings. For scaffold evaluation, we focused on clinical and/or histological results, and conclusions are listed. Explanations for general trends were sought based on existing knowledge about tissue engineering principles and wound healing mechanisms.

Results:

Decellularized dermis seems to remain the best option with no other acellular scaffold being clinically proven to gain better results yet. In general, chemically cross-linked products were seen to be less effective in skin tissue engineering. Biocompatibility could be enhanced by preseeding substitutes with fibroblasts to allow some natural scaffold remodeling before product application.

Conclusions:

Skin substitutes are a useful tool in plastic and reconstructive surgery practices as an alternative to skin grafts. In the choice of substitute, the general plastic surgery principle of replacing like tissue with like tissue seems to be still standing, and products most resembling the natural dermal extracellular matrix should be preferred.

Regional variations in the histology of porcine skin

Porcine skin is commonly used as a model for human skin injury and as a source material for biologic scaffold materials. Although remarkable similarities between porcine and human skin exist, regional anatomic variations present in human skin are also present in porcine skin. The objective of this study was to evaluate the structure of porcine skin from 11 different anatomic regions in the American Yorkshire crossbreed. Both qualitative and quantitative methods were used, with emphasis on epidermal and dermal thickness, hair follicle density, and collagen and elastin composition and distribution. The results showed that significant regional differences in skin histology exist, particularly with regard to the thickness of the dermis and epidermis and the amount of collagen and elastin within each tissue. Differences were also seen in the distribution of type I and type III collagen within the dermis. Therefore, while porcine skin shares many similarities with human skin, distinct regional differences in composition and morphology exist. This study highlights the importance of appreciating these regional differences to avoid misinterpretation of experimental results when using porcine skin as a human analogue.

Effectiveness of porcine dermal collagen in giant hernia closure in patients with deleterious fascia constitution after orthotopic liver transplantation

Incisional hernias (IHs) occur universally after orthotopic liver transplantation (OLT). This study aimed to investigate the effectiveness of porcine dermal collagen (PDC) as a closing aid in giant hernias after OLT in a prospective trial. If direct closure (DC) was not feasible due to the hernia size and abdominal wall constitution, a PDC mesh was implanted. All patients from the PDC and DC groups were followed prospectively for 24 months. IH recurrence rates served as the primary endpoint, and the development of infections and wound healing disorders served as the secondary endpoints. Recurrence rate was 21% (4/19) in DC patients and 12% (2/16) in PDC patients (P = 0.045). Implant site infections occurred in five of PDC and one of DC patients (P < 0.05). All of them were managed with antibiotics; two of the PDC patients required surgical drainage. Histological analysis of PDC mesh biopsies indicated good angiogenesis and integration of the PDC into the abdominal wall. PDC was effective in our study for incisional hernia repair, and our results compared favourably with those of patients in whom direct hernia closure was feasible.

Does mesh location matter in abdominal wall reconstruction? A systematic review of the literature and a summary of recommendations

BACKGROUND

Mesh implantation during abdominal wall reconstruction decreases rates of ventral hernia recurrence and has become the dominant method of repair. The authors provide a comprehensive comparison of surgical outcomes and complications by location of mesh placement following ventral hernia repair with onlay, interposition, retrorectus, or underlay mesh.

METHODS

A systematic search of the English literature published from 1996 to 2012 in the PubMed, MEDLINE, and Cochrane library databases was conducted to identify patients who underwent abdominal wall reconstruction using either prosthetic or biological mesh for ventral hernia repair. Demographic information was obtained from each study.

RESULTS

Sixty-two relevant articles were included with 5824 patients treated with mesh repair of a ventral hernia between 1996 and 2012. Mesh position included onlay (19.6 percent), underlay (60.7 percent), interposition (6.4 percent), and retrorectus (12.4 percent). Prosthetic mesh was used in 80 percent of repairs and biological mesh in 20 percent. The weighted mean incidences of early events were as follows: wound complications, 19 percent; wound infections, 8 percent; seroma or hematoma formation, 11 percent; and reoperation, 10 percent. The weighted mean incidences of late complications included 8 percent for hernia recurrence and 2 percent for mesh explantation. Recurrence rates were highest for onlay (17 percent) or interposition (17 percent) reinforcement. The infection rate was also highest in the interposition cohort (25 percent). Seroma rates were lowest following a retrorectus repair (4 percent).

CONCLUSIONS

Mesh reinforcement of a ventral hernia repair is safe and efficacious, but the location of the reinforcement appears to influence outcomes. Underlay or retrorectus mesh placement is associated with lower recurrence rates.

Bioprosthetic tissue matrices in complex abdominal wall reconstruction

Background:

Complex abdominal defects are difficult problems encountered by surgeons in multiple specialties. Although current evidence supports the primary repair of these defects with mesh reinforcement, it is unclear which mesh is superior for any given clinical scenario. The purpose of this review was to explore the characteristics of and clinical relevance behind bioprosthetic tissue matrices in an effort to better clarify their role in abdominal wall reconstruction.

Methods:

We reviewed the peer-reviewed literature on the use of bioprosthetic mesh in human subjects. Basic science articles and large retrospective and prospective reviews were included in author’s analysis. The clinical performance and characteristics of 13 bioprosthetic tissue matrices were evaluated.

Results:

The majority of the products evaluated perform well in contaminated fields, where the risk of wound-healing difficulties is high. Clinical outcomes, which included infection, reherniation, and bulge formation, were variable, and the majority of the studies had a mean follow-up of less than 24 months.

Conclusions:

Although bioprosthetic matrix has a multitude of indications within the growing field of abdominal wall reconstruction, the functionality, regenerative capacity, and long-term fate of these products have yet to be fully established. Furthermore, the clinical performance, indications, and contraindications for each type of matrix need to be fully evaluated in long-term outcome studies.

Fascia lata allografts as biological mesh in abdominal wall repair: preliminary outcomes from a retrospective case series

BACKGROUND

The use of biological meshes in management of infected abdominal hernias or in abdominal fields at high risk of infection (potentially contaminated or with relevant comorbidities) is well established. Available products include xenogenic patches or decellularized dermal allografts. Despite their biomechanical features, banked fascial allografts have not been investigated yet in this setting. The authors evaluated the safety and effectiveness of banked fascia lata allografts as biological meshes in abdominal wall repair.

METHODS

A consecutive series of patients affected by abdominal wall defects and who were candidates for repair by means of a biological mesh and treated in the authors' institution with banked fascia lata allografts were reviewed retrospectively. Data from clinical and instrumental follow-up evaluations up to 48 months (average, 23 months) were analyzed.

RESULTS

Twenty-one patients (aged 1 to 86 years) with abdominal wall defects resulting from traumatic (n = 1), neoplastic (n = 6), or multiple previous laparotomies (n = 14) were treated from January of 2008 to October of 2012. Operations had no relevant postoperative complications. At clinical/instrumental follow-up examinations, no major signs of recurrence, laxity, infection of grafts, or other related pathologic symptoms were recorded. Three patients suffered from temporary minor complications (e.g., wound seroma, partial cutaneous dehiscence). At instrumental (computed tomographic scan or magnetic resonance imaging) evaluations, the neofascial tissue appeared stable until medium-term follow-up (3 to 6 months), later being gradually degraded and apparently replaced by host tissue.

CONCLUSION

According to limited preliminary outcomes, banked fascia lata allografts seem to provide a biocompatible, safe, and effective alternative to other biological meshes.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Differentiation of human bone marrow mesenchymal stem cells on decellularized extracellular matrix materials

Mesenchymal bone marrow stromal cells may be a source of cells to preseed decellularized biologic mesh materials for improved cellularization and promote a more physiologic tissue after remodeling. Spontaneous differentiation of mesenchymal stromal cells on the decellularized material would be undesirable. Conversely, induced differentiation of mesenchymal stem cells (MSC) on the material would suggest that these materials may have promise as scaffold materials for bone, cartilage, or adipocyte formation. Two sources of mesenchymal cells were evaluated for induced differentiation in control wells. These MSCs were also evaluated for spontaneous or induced differentiation on decellularized porcine dermis and mesothelium materials. Primarily harvested bone marrow MSCs and commercially obtained MSCs were induced into osteoblasts and adipocytes on decellularized dermis and mesothelium materials. The MSCs were able to be induced into chondrocytes in pellet form but not when grown as a monolayer on the materials. The MSCs did not undergo spontaneous differentiation when grown on the materials for up to four weeks. MSC grown on decellularized porcine dermis or mesothelium do not spontaneously differentiate and may serve as a source of autologous cells for preseeding these extracellular matrix materials prior to implantation.

Long-term outcomes (>5-year follow-up) with porcine acellular dermal matrix (Permacol) in incisional hernias at risk for infection

PURPOSE

We reviewed retrospectively all patients undergoing abdominal wall reconstruction using porcine acellular dermal matrix (PADM) from 2004 to 2008 with follow-up assessment in 2012. Technique, short-term (infection, seroma, wound dehiscence), and long-term (mesh infection, recurrence) complications, and hernia recurrences were evaluated by physician examination ≥5 years postoperatively.

RESULTS

56 patients at high risk for infection had elective operation; nine had non-elective operation for complications of prior incisional hernia/hernia repair. Operations were clean, clean-contaminated, contaminated, or grossly infected in 49, 32, 12, and 6%, respectively. Techniques of repair included 10 onlay (six reinforced primary closures, four bridging patches), 47 sublay (20 reinforced primary closures, 27 bridging patches), six inlay, and two sandwich (sublay and onlay). Early complications (≤30 days postoperatively) occurred in 19 of the 65 patients (29%), including two prosthetic dehiscences from fascial attachment, 13 wound infections, and 4 seromas. After a mean follow-up of ≥5 years in 59 of 65 patients, physician-reported incidences of infection requiring removal of mesh or hernia recurrence were 25 and 66%, respectively. Hernia recurrence occurred in 12 of 26 (46%) patients with a reinforced repair and 27 of 33 (82%) with patched repairs. Mesh infection occurred in 7 of 24 patients with sublay patch and in 4 of 19 sublay reinforcement. The greatest recurrence rate was in contaminated (71%) and grossly infected wounds (100%), while recurrence rate was 63% in clean and 63% in clean-contaminated wounds.

CONCLUSIONS

At ≥5 years of follow-up, use of PADM as a bioprosthesis in ventral hernia in high-risk patients is unreliable as a definitive repair in the majority of patients, but may provide satisfactory outcomes in some patients.

Outcome of Abdominal Wall Hernia Repair with Permacol™ Biologic Mesh

The use of biologic mesh in abdominal wall operations has gained popularity despite a paucity of outcome data. We aimed to review the experience of a large healthcare organization with Permacol™. A retrospective study was conducted of patients who underwent abdominal hernia repair with Permacol™ in 14 Southern California hospitals. One hundred ninety-five patients were analyzed over a 4-year period. Operations included ventral/incisional hernia repairs, ostomy closures, parastomal hernia repairs, and inguinal hernia repairs. In 50 per cent of the patients, Permacol™ was used to reinforce a primary fascial repair and in 50 per cent as a fascial bridge. The overall complication rate was 39.5 per cent. The complication rate was higher in patients with infected versus clean wounds, body mass index (BMI) 40 kg/m2 or greater versus BMI less than 40 kg/m2, in patients with prior mesh repair, and when mesh was used as a fascial bridge. With a mean follow-up of 2.1 years, morbid obesity was associated with a higher recurrence. To date this is the largest study on the use of Permacol™ in abdominal wall hernia repair. In our patient population undergoing heterogeneous operations with a majority of wounds as Class II or higher, use of Permacol™ did not eliminate wound morbidity or prevent recurrence, especially in morbidly obese patients.

Repair of traumatic muscle herniation with acellular porcine collagen matrix

BACKGROUND

Muscle hernias are uncommon clinical conditions with no uniform solution of repair. Biocompatible mesh allows for repair of hernias without the donor site morbidity and complications from direct repair under tension.

METHODS

Over a 6-month period at a Level 1 Trauma centre, four consecutive symptomatic muscle hernias were identified, two in the forearm and two in the lower limb. Three resulted from high-speed motorbike accidents, one from a mining accident. All patients had hernia repair at a minimum of 4 months post accident. A 10 × 15 cm × 1.0 mm sheet of acellular collagen matrix was fashioned to fit as an underlay of the fascia defect. Patients were clinically followed at the 2-, 6-, 12- and 26-week mark. Final phone contact was made 18 months post-operatively.

RESULTS

All patients were pleased with their cosmetic and functional outcomes. All patients returned to work and sport 3 months after reconstruction.

CONCLUSION

Symptomatic hernias as a result of trauma can be safely reconstructed with a biological mesh implant. This approach can prevent complications from previously described methods and return to active lifestyles with good results.

Interstitial engraftment of adipose-derived stem cells into an acellular dermal matrix results in improved inward angiogenesis and tissue incorporation

Acellular dermal matrices (ADM) are commonly used in reconstructive procedures and rely on host cell invasion to become incorporated into host tissues. We investigated different approaches to adipose-derived stem cells (ASCs) engraftment into ADM to enhance this process. Lewis rat adipose-derived stem cells were isolated and grafted (3.0 × 10(5) cells) to porcine ADM disks (1.5 mm thick × 6 mm diameter) using either passive onlay or interstitial injection seeding techniques. Following incubation, seeding efficiency and seeded cell viability were measured in vitro. In addition, Eighteen Lewis rats underwent subcutaneous placement of ADM disk either as control or seeded with PKH67 labeled ASCs. ADM disks were seeded with ASCs using either onlay or injection techniques. On day 7 and or 14, ADM disks were harvested and analyzed for host cell infiltration. Onlay and injection techniques resulted in unique seeding patterns; however cell seeding efficiency and cell viability were similar. In-vivo studies showed significantly increased host cell infiltration towards the ASCs foci following injection seeding in comparison to control group (p < 0.05). Moreover, regional endothelial cell invasion was significantly greater in ASCs injected grafts in comparison to onlay seeding (p < 0.05). ADM can successfully be engrafted with ASCs. Interstitial engraftment of ASCs into ADM via injection enhances regional infiltration of host cells and angiogenesis, whereas onlay seeding showed relatively broad and superficial cell infiltration. These findings may be applied to improve the incorporation of avascular engineered constructs.

Complications of acellular dermal matrices in abdominal wall reconstruction

BACKGROUND

Acellular dermal matrices have been increasingly used in abdominal wall reconstruction. Unique characteristics of these grafts have allowed surgeons to reconstruct increasingly complex abdominal wall defects. This has resulted in a myriad of complications related to the acellular dermal matrix with unique management strategies as compared with synthetic mesh.

METHODS

A review of the literature was performed to identify studies evaluating the use and efficacy of acellular dermal matrices in abdominal wall reconstruction. Complication profiles were identified and are compared. Differences between porcine and human derivatives were identified.

RESULTS

Hernia recurrence, infection, skin necrosis, and fluid collections were among the most common complications following abdominal wall reconstruction identified in the literature. Differences among various acellular dermal matrix products make certain types more suitable for abdominal wall reconstruction.

CONCLUSIONS

Complications are frequent in abdominal wall reconstruction. Many acellular dermal matrices have properties that allow for conservative management and maintenance of reconstruction when complications occur. With traditional synthetic mesh reconstruction, complications likely result in mesh explantation and prolonged morbidity. With acellular dermal matrix reconstruction, however, more conservative treatment strategies will allow for mesh salvage.

Acellular dermal matrices in abdominal wall reconstruction: a systematic review of the current evidence

BACKGROUND

Reconstruction of the anterior abdominal wall is a complex procedure that can be complicated by contamination, loss of domain, previous scarring or radiotherapy, and reduced availability of local tissues. With the introduction of acellular dermal matrices to clinical use, it was hoped that many of the problems associated with previous synthetic materials could be overcome. With their enhanced biocompatibility, acellular dermal matrices are believed to integrate with surrounding tissues while demonstrating resistance to infection, extrusion, erosion, and adhesion formation.

METHODS

The MEDLINE database was reviewed, including all publications as of December 31, 2011, using the search terms "dermal matrix" or "human dermis" or "porcine dermis" or "bovine dermis," applying the limits "human" and "English language." Prospective and retrospective clinical articles were identified.

RESULTS

A total of 40 eligible articles were identified and included in this review. Thirty-five of the studies were level IV; the remaining studies were level III. Acellular dermal matrix was used to reconstruct the abdominal wall in a wide range of clinical settings, including trauma, tumor resection, sepsis, and hernia repairs. The operative methods varied widely among clinical studies. While the heterogeneity of the patient populations and techniques limited interpretation of the data, concerns were identified regarding high rates of hernia recurrence with acellular dermal matrix use.

CONCLUSION

High-quality data derived from level I, II, and III studies are necessary to determine the indications for acellular dermal matrix use and the optimal surgical techniques to maximize outcomes in abdominal wall reconstruction.

A decade of ventral incisional hernia repairs with biologic acellular dermal matrix: what have we learned?

BACKGROUND

Innovative types of biologic mesh have provided new alternatives to ventral incisional hernia repair, especially in the face of contamination. The authors studied the experience and outcomes of patients who underwent repair of a ventral incisional hernia with biologic mesh.

METHODS

Online database and detailed reference searches were conducted. Studies chosen for review had a sample size of at least 40 patients, level IV evidence at most, and a Methodological Index for Nonrandomized Studies index of at least 10. Indications for use of biologic mesh, type of mesh, patient comorbidities, and surgical techniques were also noted.

RESULTS

Eight studies fulfilled the search criteria and included 635 patients using AlloDerm, Surgisis, and Strattice biologic tissue matrices. In one study, indications and surgical techniques were standardized, and follow-up was prospective. In the other seven studies, indications, surgical techniques, and follow-up were assessed retrospectively. The mean patient age, when reported, was 55.7 years. Body mass index ranged from 30 to 35 kg/m2 in 44 percent of the reported patients. In seven of the eight studies [565 patients (89 percent)], the mean follow-up was 25.8 months and the mean hernia recurrence rate was 21 percent. Complication rate exceeded 20 percent in most studies.

CONCLUSIONS

Biologic tissue matrices are mostly used in contaminated fields, which has allowed for a one-stage repair with no or little subsequent mesh removal. Ventral incisional hernia repair with these matrices continues to be plagued by a high recurrence rate and complications. Prospective randomized trials are needed to properly direct practice in the use of these meshes and evaluate their ultimate value.

The role of biologic mesh in abdominal wall reconstruction: a systematic review of the current literature

BACKGROUND

Biologic mesh in the form of allograft or xenograft products have been used in complicated abdominal hernia repair, but few comparative studies exist.

METHODS

A systematic review of original incisional hernia studies was conducted to include 2 primary end points: hernia recurrence and surgical site occurrence. Analysis of variance and a Satterthwaite t test compared the devices.

RESULTS

Twenty-nine studies were included in this analysis, which included 1,257 patients. The total number of studies and the total subjects for each device include the following: Permacol (Tissue Science Laboratories, Hampshire, UK) (4/64), Surgisis (Cook Medical, Bloomington, IN) (3/87), and Alloderm (LifeCell, Corp, Branchburg, NJ) (23/1,106). Device-specific recurrence rates and surgical site occurrence rates, respectively, were as follows: Alloderm (20.8%, 31.4%), Permacol (10.9%, 25%), and Surgisis (8.0%, 40.2%). A Satterthwaite t test comparison revealed significantly higher numbers of hernia recurrence (P = .006) and surgical site occurrence (P = .04) when comparing Alloderm with Permacol.

CONCLUSIONS

Biologic mesh does play a beneficial role in abdominal wall reconstruction although allograft acellular dermal matrix does have a higher recurrence rate as compared with xenograft products, which limits its current role in hernia repair.

Biologic grafts for ventral hernia repair: a systematic review

BACKGROUND

Biologic grafts hold promise of a durable repair for ventral hernias with the potential for fewer complications than synthetic mesh. This systematic review was performed to evaluate the effectiveness and safety of biologic grafts for ventral hernia repair.

METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched for studies on biologic grafts for the repair of ventral hernias. Outcomes are presented as weighted pooled proportions.

RESULTS

Twenty-five retrospective studies were included. Recurrence depended on wound class, with an overall rate of 13.8% (95% confidence interval [CI], 7.6-21.3). The recurrence rate in contaminated/dirty repairs was 23.1% (95% CI, 11.3-37.6). Abdominal wall laxity occurred in 10.5% (95% CI, 3.7-20.3) of patients. The surgical morbidity rate was 46.3% (95% CI, 33.3-59.6). Infection occurred in 15.9% (95% CI, 9.8-23.2) of patients but only led to graft removal in 4.9% of cases.

CONCLUSIONS

No randomized trials are available to properly evaluate biologic grafts for ventral hernia repair. The current evidence suggests that biologic grafts perform similarly to other surgical options. Biologic grafts are associated with a high salvage rate when faced with infection.

A review of available prosthetic material for abdominal wall repair

Abdominal wall incisional and inguinal hernia repair can call for utilization of implants or prostheses as an alternative to simple suture techniques. The various implants can be synthetic, biologic or mixed: their physicochemical properties condition the mechanical results and the long-term outcome of the repair. The increasing number of available materials allows the surgeon to choose between a wide variety depending on the indication, the site of implantation, the surgical approach and whether the operative field is contaminated or not. With regard to evidence-based medicine, while several synthetic implants have been shown to be superior in efficacy to simple suture, other studies are underway to develop the indications for bioprostheses, in particular in contaminated fields. This review of the literature summarizes the current knowledge on synthetic and biologic implants (physicochemical characteristics, forms, indications).

Repair of incisional hernias with biological prosthesis: a systematic review of current evidence

BACKGROUND

No consensus has been reached on the use of bioprosthetics to repair abdominal wall defects. The purpose of this systematic review was to summarize the outcomes from studies describing this use of various bioprosthetics for incisional hernia repair.

METHODS

Studies published by October 2011 were identified through literature searches using EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials.

RESULTS

A total of 491 articles were scanned, 60 met eligibility criteria. Most studies were retrospective case studies. The studies ranged considerably in methodologic quality, with a modified Methodological Index of Nonrandomized Studies score from 5 to 12. Many repairs were performed in contaminated surgical sites (47.9%). At least one complication was seen in 87% of repairs. Major complications noted were wound infections (16.9%) and seroma (12.0%). With a mean follow-up period of 13.6 months the hernia recurrence rate was 15.2%.

CONCLUSIONS

There is an insufficient level of high-quality evidence in the literature on the value of bioprosthetics for incisional hernia repair. Randomized controlled trials that use standardized reporting comparing bioprosthetics with synthetic mesh for incisional hernia repair are needed.