Non–Cross-Linked Porcine Acellular Dermal Matrices for Abdominal Wall Reconstruction:

Mesh Selection in Abdominal Wall Reconstruction: An Update on Biomaterials

A wide array of mesh choices is available for abdominal wall reconstruction, making mesh selection confusing. Understanding mesh properties can make mesh choice simpler. Each mesh has characteristics that determine its durability, ability to clear an infection, and optimal position of placement in the abdominal wall. For clean retromuscular hernia repairs, we prefer bare, heavy weight, permanent synthetic mesh. For contaminated retromuscular abdominal wall reconstruction cases, such as parastomal hernia repairs, we typically use bare, medium weight, permanent synthetic mesh. Biologic and biosynthetic meshes also have acceptable wound event and hernia recurrence rates when used in contaminated cases.

Efficacy of Supercritical Fluid Decellularized Porcine Acellular Dermal Matrix in the Post-Repair of Full-Thickness Abdominal Wall Defects in the Rabbit Hernia Model

Damage to abdominal wall integrity occurs in accidents, infection and herniation. Repairing the hernia remains to be one of the most recurrent common surgical techniques. Supercritical carbon dioxide (SCCO2) was used to decellularize porcine skin to manufacture acellular dermal matrix (ADM) for the reparation of full-thickness abdominal wall defects and hernia. The ADM produced by SCCO2 is chemically equivalent and biocompatible with human skin. The ADM was characterized by hematoxylin and eosin (H&E) staining, 4,6-Diamidino-2-phenylindole, dihydrochloride (DAPI) staining, residual deoxyribonucleic acid (DNA) contents and alpha-galactosidase (α-gal staining), to ensure the complete decellularization of ADM. The ADM mechanical strength was tested following the repair of full-thickness abdominal wall defects (4 × 4 cm) created on the left and right sides in the anterior abdominal wall of New Zealand White rabbits. The ADM produced by SCCO2 technology revealed complete decellularization, as characterized by H&E, DAPI staining, DNA contents (average of 26.92 ng/mg) and α-gal staining. In addition, ADM exhibited excellent performance in the repair of full-thickness abdominal wall defects. Furthermore, the mechanical strength of the reconstructed abdominal wall after using ADM was significantly (p < 0.05) increased in suture retention strength (30.42 ± 1.23 N), tear strength (63.45 ± 7.64 N and 37.34 ± 11.72 N) and burst strength (153.92 ± 20.39 N) as compared to the suture retention (13.33 ± 5.05 N), tear strength (6.83 ± 0.40 N and 15.27 ± 3.46 N) and burst strength (71.77 ± 18.09 N) when the predicate device materials were concomitantly tested. However, the efficacy in hernia reconstruction of ADM is substantially equivalent to that of predicate material in both macroscopic and microscopic observations. To conclude, ADM manufactured by SCCO2 technology revealed good biocompatibility and excellent mechanical strength in post-repair of full-thickness abdominal wall defects in the rabbit hernia model.

Outcomes of biologic versus synthetic mesh in CDC class 3 and 4 open abdominal wall reconstruction

INTRODUCTION

Abdominal wall reconstruction (AWR) in a contaminated field is associated with an increased risk of wound complications, infection, and reoperation. The best method of repair and mesh choice in these operations have generated marked controversy. Our aim was to compare outcomes of patients who underwent AWR with biologic versus synthetic mesh in CDC class 3 and 4 wounds.

METHODS

A prospective, single-institution database was queried for AWR using biologic or synthetic mesh in CDC Class 3 and 4 wounds. Hernia recurrence and complications were measured. Multivariable logistic regression was performed to identify factors predicting both.

RESULTS

In total, 386 patients with contaminated wounds underwent AWR, 335 with biologic and 51 with synthetic mesh. Groups were similar in age, sex, BMI, and rate of diabetes. Biologic mesh patients had larger hernia defects (298 ± 233cm² vs. 208 ± 155cm²; p = 0.004) and a higher rate of recurrent hernias (72.2% vs 47.1%; p < 0.001), comorbidities(5.8 ± 2.7 vs. 4.2 ± 2.4, p < 0.01), and a nearly fivefold increase in Class 4 wounds (47.8% vs. 9.8%, p < 0.001), while fascial closure trended to being less common (90.7% vs 96.1%; p = 0.078). Hernia recurrence was comparable between biologic and synthetic mesh (10.4% vs. 17.6%, p = 0.132). Wound complication rates were similar (36.1% vs. 33.3%, p = 0.699), but synthetic mesh had higher rates of mesh infection (1.2% vs 11.8%; p < 0.001) and infection-related resection (0% vs 7.8%, p < 0.001), with 66% of those synthetic mesh infections requiring excision. On logistic regression, wound complications (OR 5.96 [CI 1.60-22.17]; p = 0.008) and bridging mesh (OR 13.10 [CI 2.71-63.42];p = 0.030) predicted of hernia recurrence (p < 0.05), while synthetic mesh (OR 18.6 [CI 2.35-260.4] p = 0.012) and wound complications (OR 20.6 [CI 3.15-417.7] p = 0.008) predicted mesh infection.

CONCLUSIONS

Wound complications in AWR with CDC class 3 and 4 wounds significantly increased mesh infection and hernia recurrence; failure to achieve fascial closure also increased hernia recurrence. Use of synthetic versus biologic mesh increased the mesh infection rate by 18.6 times.

Immunomodulation of Acellular Dermal Matrix Through Interleukin 4 Enhances Vascular Infiltration

BACKGROUND

Acellular dermal matrix (ADM) supported implant-based reconstruction remains the most commonly performed mode of reconstruction after breast cancer. Acellular dermal matrix clinical usage has reported benefits but requires rapid and efficient vascular and cellular incorporation into the recipient to have the best outcomes. Orderly transition from M1 to M2 macrophage phenotypic profile, coordinated in part by interleukin 4 (IL-4), is an important component of vascular stabilization and remodeling. Using the ADM substrate as a delivery device for immunomodulation of macrophage phenotype holds the potential to improve integration.

METHODS

Interleukin 4 was adsorbed onto ADM samples and drug elution curves were measured. Next, experimental groups of 8 C57BL/6 mice had 5-mm ADM discs surgically placed in a dorsal window chamber with a vascularized skin flap on one side and a plastic cover slip on the other in a model of implant-based breast reconstruction. Group 1 consisted of IL-4 (5 μg) adsorbed into the ADM preoperatively and group 2 consisted of an untreated ADM control. Serial gross examinations were performed with histology at day 21 for markers of vascularization, mesenchymal cell infiltration, and macrophage lineage.

RESULTS

Drug elution curves showed sustained IL-4 release for 10 days after adsorption. Serial gross examination showed similar rates of superficial vascular investment of the ADM beginning at the periphery by day 14 and increasing through day 21. Interleukin-4 treatment led to significantly increased CD31 staining of vascular endothelial cells within the ADM over the control group (P < 0.05) at 21 days. Although vimentin staining did not indicate a significant increase in fibroblasts overall, IL-4 did result in a significant increase in expression of α-smooth muscle actin. The expression of macrophage phenotype markers Arginase1 and iNOS present within the ADM were not significantly affected by IL-4 treatment at the day 21 time point.

CONCLUSIONS

Acellular dermal matrix has the potential to be used for immunomodulatory cytokine delivery during the timeframe of healing. Using implanted ADM as a delivery vehicle to drive IL-4 mediated angiogenesis and vascular remodeling significantly enhanced vascularity within the ADM substrate.

Bovine versus porcine acellular dermal matrix for abdominal wall herniorrhaphy or bridging

BACKGROUND

The management of complicated ventral hernias (CVH), namely ventral hernias in actively or recently infected/contaminated operative fields, and open abdomens in which the native fascia cannot be primarily reapproximated, pose a surgical challenge. Fetal Bovine and Porcine Acellular Dermal Matrix (BADM and PADM) biologic meshes are being increasingly used in these scenarios. A comparison, however, of clinically relevant outcomes between the two is lacking. With this investigation, we aim to review and compare clinically relevant outcomes in patients that underwent abdominal wall herniorrhaphy with either BADM or PADM at a tertiary urban academic institution over a 5-year period.

METHODS

Patients who had a BADM or PADM implanted during CVH over a 5-year period at a tertiary urban academic hospital were identified. Baseline clinical and hernia characteristics, as well as postoperative outcomes were compared after a retrospective chart review. Phone interviews were also conducted to assess for recurrence, followed by in-person visits as indicated. Cox Proportional Hazard regression was fitted to identify risk factors for recurrence.

RESULTS

Of the 140 patients who underwent biologic mesh implantation for CVH, 109 were for ventral hernia repair and 31 for open abdomen bridging. Mean age was 52.7 ± 14.2 and males constituted 57.9% of our sample, while 25.1% had undergone > 5 prior abdominal operations. Thirty percent were active smokers, and another 30% required emergency surgery. Only immunosuppression was a risk factor for recurrence [HR 13.3 (1.04-169.2), p = 0.047] on Cox Proportional Hazard regression, while mesh selection had no effect.

CONCLUSIONS

Both BADM and PADM meshes perform well in CVH, with satisfactory recurrence rates, only slightly higher compared to traditional synthetic mesh repairs.

VERSATILITY OF POLY-4-HYDROXYBUTYRATE (PHASIX™) MESH IN ABDOMINAL WALL SURGERY

BACKGROUND

Poly-4-hydroxybutyrate (P4HB) is a naturally occurring polymer derived from transgenic E. coli bacteria with the longest degradation rate when compared to other available products. This polymer has been manufactured as a biosynthetic mesh to be used as reinforcement when repairing a variety of abdominal wall defects.

OBJECTIVE

We aim to describe our center initial experience with this mesh and discuss the possible indications that may benefit from the use of P4HB mesh.

METHODS

This is a descriptive retrospective study of patients who underwent abdominal wall repair with a P4HB mesh from October 2018 to December 2020 in a single, large volume, academic center.

RESULTS

A total of 51 patients (mean age 54.4 years, range 12-89) underwent abdominal wall reconstruction with a P4HB mesh between October 2018 and December 2020. The mean BMI was 30.5 (range 17.2-50.6). Twenty-three (45%) patients had a prior hernia repair at the site. We grouped patients into six different indications for the use of P4HB mesh in our cohort: clean-contaminated, contaminated or infected field (57%), patient refusal for permanent meshes (14%), those with high risk for post-operative infection (12%), visceral protection of second mesh (10%), recurrence with related chronic pain from mesh (6%), and children (2%). Median follow-up was 105 days (range 8-648). Two patients had hernia recurrence (4%) and 8 (16%) patients developed seroma.

CONCLUSION

P4HB mesh is a safe and a viable alternative for complex hernias and high-risk patients with a low complication rate in the short-term.

Low Concentrated Fractionalized Nanofibers as Suitable Fillers for Optimization of Structural–Functional Parameters of Dead Space Gel Implants after Rectal Extirpation

Dead space after rectal resection in colorectal surgery is an area with a high risk of complications. In this study, our goal was to develop a novel 3D implant based on composite hydrogels enriched with fractionalized nanofibers. We employed, as a novel approach in abdominal surgery, the application of agarose gels functionalized with fractionalized nanofibers on pieces dozens of microns large with a well-preserved nano-substructure. This retained excellent cell accommodation and proliferation, while nanofiber structures in separated islets allowed cells a free migration throughout the gel. We found these low-concentrated fractionalized nanofibers to be a good tool for structural and biomechanical optimization of the 3D hydrogel implants. In addition, this nano-structuralized system can serve as a convenient drug delivery system for a controlled release of encapsulated bioactive substances from the nanofiber core. Thus, we present novel 3D nanofiber-based gels for controlled release, with a possibility to modify both their biomechanical properties and drug release intended for 3D lesions healing after a rectal extirpation, hysterectomy, or pelvic exenteration.

Comparison of porcine and human acellular dermal matrix outcomes in wound healing: a deep dive into the evidence

Acellular dermal matrices (ADM) are a novel graft. The goal of this systematic review is to evaluate the evidence behind differences in human and porcine ADM, irrelevant of manufacturing method, and to determine if there is enough of an evidence base to change clinical practice. An extensive literature search was performed through MEDLINE and Embase with search terms defining a population, intervention and outcome. Title and abstract exclusion were performed with other exclusion criteria. In 191 articles were found after exclusion of duplicates, with only 29 remaining following exclusions. Ten studies were found to have level I and II evidence (I=3, II=8), of which two were histopathological, one was an animal model, one was a systematic review, and six were clinical. The remaining studies were reviewed and considered for discussion, but did not hold high enough standards for medical evidence. Strong clinical evidence already exists for the use of human ADM, but questions of access, cost, and ethics require consideration of a xenograft. Histopathologically, evidence suggests minimal long-term differences between human and porcine ADM, although there is a short acute immune response with porcine ADM. Clinically, there is limited difference in outcomes, with a small range in effect of different ADM preparations. Considering the effectiveness of ADM in wound healing, more high-level research with appropriate statistical analysis to facilitate a future meta-analysis is recommended to justify a transition from human to porcine ADM.

Meta-analysis of biological mesh reconstruction versus primary perineal closure after abdominoperineal excision of rectal cancer

BACKGROUND

Extralevator abdominoperineal excision (ELAPE) of rectal cancer has been proposed to achieve better oncological outcomes. The resultant wide perineal wound, however, presents a challenge for primary closure and subsequent wound healing. This meta-analysis compared the outcomes of primary perineal closure with those of biological mesh reconstruction.

METHODS

The Medline and Embase search was performed for the publications comparing primary perineal closure to biological mesh reconstruction. Early perineal wound complications (seroma, infection, dehiscence) and late perineal wound complications (perineal hernia, chronic pain, and chronic sinus) were analyzed as primary endpoints. Intraoperative blood loss, operation time, and hospital stay were compared as secondary endpoints.

RESULTS

There was no significant difference in the overall early wound complications after primary closure or biological mesh reconstruction (odds ratio (OR) of 0.575 with 95% confidence interval (CI) of 0.241 to 1.373 and a P value of 0.213). The incidence of perineal hernia after 1 year was significantly high after primary closure of the perineal wounds (OR of 0.400 with 95% CI of 0.240 to 0.665 and a P value of 0.001). No significant differences were observed among other early and late perineal wound complications. The operation time and hospital stay were shorter after primary perineal closure (p 0.001).

CONCLUSION

A lower incidence of perineal hernia and comparable early perineal wound complications after biological mesh reconstruction show a relative superiority over primary closure. More randomized studies are required before a routine biological mesh reconstruction can be recommended for closure of perineal wounds after ELAPE.

Outcomes of Poly-4-hydroxybutyrate Mesh in Ventral Hernia Repair: A Systematic Review and Pooled Analysis

Within the past decade, poly-4-hydroxybutyrate (P4HB) biosynthetic mesh has been introduced as a potential alternative to traditional biologic and synthetic mesh in ventral hernia repair (VHR). The aim of this study was to systematically assess clinical outcomes with the P4HB in VHR.

Methods

A literature search identified all articles published in 2000 involving the use of P4HB in VHR. Descriptive statistics were used to synthesize collective data points, including postoperative outcomes. A pooled analysis of postoperative outcomes was performed using chi-square test and Fisher exact test.

Results

Across 7 studies, the P4HB was used in 453 patients. The mean rate of surgical site infection (SSI) was 6.8% (31/453), reoperation 10.7% (30/281), and recurrence 9.1% (41/453). At an average follow-up of 26.8 months, the incidence of recurrence was 10.4% (28/270). Onlay was significantly associated with increased recurrence (14.2% versus 4.4%, P = 0.001). Among sublay placements, there was no difference in recurrence in clean (Center for Disease Control [CDC] 1) or contaminated (CDC >1) wounds (2.7% versus 6.1%, P = 0.585), but contaminated wounds were associated with increased SSI (2.7% versus 15.2%, P = 0.028). Ventral Hernia Working Group grade 2 and 3 did not have different incidences of recurrence (8.0% versus 5.1%, P = 0.526) nor SSI (5.1% versus 14.6%, P = 0.265).

Conclusions

Overall, clinical outcomes of the P4HB mesh in VHR are acceptable. The P4HB mesh serves as a reliable alternative to traditional synthetic and biologic mesh across a range of defect characteristics and patient health conditions. Further research is needed to better understand the conditions in which it may provide a clinical benefit over traditional mesh types.

Pulley Release and Reconstruction With Acellular Dermal Matrix After Zone 2 Flexor Tendon Injury

Zone 2 flexor tendon repair has been historically associated with poor outcomes, mainly due to stiffness. In an effort to minimize adhesions, accommodate flexor digitorum profundus and flexor digitorum superficialis bulk, and prevent bowstringing, we have developed a novel approach to flexor tendon repair that relies on aggressive flexor tendon pulley release and pulley reconstruction with acellular dermal matrix. This technique leverages the antiadhesive properties and high tensile strength of acellular dermal matrix to maximize gliding and prevent bowstringing. Here we describe the details of our technique and illustrate a case where this technique was employed.

Component Separation with Porcine Acellular Dermal Reinforcement is Superior to Traditional Bridged Mesh Repairs in the Open Repair of Significant Midline Ventral Hernia Defects

The optimal technique for complex ventral hernia repair (VHR) remains controversial. Component separation (CS) reinforced with porcine acellular dermal matrix (PADM) has shown favorable results compared with series of conventional bridged VHR, but few comparative studies exist. We conducted a retrospective cohort study comparing 40 randomly selected patients who underwent CS/PADM reinforcement against an identical number of patients who underwent conventional open VHR with mesh at our institution. Patient characteristics, operative findings, outcomes, complications, reoperations, and recurrences were obtained by chart review. Fisher's exact/ t test compared outcomes between the two cohorts. Statistical significance was set as P < 0.05. Mean follow-up was 33.1 months. Patient groups did not differ significantly in race ( P = 1.00), age ( P = 0.82), body mass index ( P = 0.14), or comorbid conditions (smoking, chronic obstructive pulmonary disease, obesity, steroid use; P values 0.60, 0.29, 0.08, and 0.56, respectively). Defect size was greater in the CS/PADM group (mean, 372.5 vs 283.7 cm2, P = 0.01) as was the percentage Ventral Hernia Working Group Grade III/IV hernias (65.0 vs 30.0%, P = 0.03). Recurrences were lower in the CS/PADM group (13.2 vs 37.5%, P = 0.02). Mesh infection was lower in the CS/PADM group (0 vs 23% in the bridged group, P = 0.002), all of which occurred with synthetic mesh. Indications for reoperation (recurrence or complications requiring reoperation) were also lower in the CS/PADM group (17.5 vs 52.5%, P = 0.002). Superior results are achieved with CS/PADM reinforcement over traditional bridged VHR. This is evidenced by lower recurrence rates and overall complications requiring reoperation, particularly mesh infection. This is despite the greater use of CS in larger defects and contaminated hernias (VHWG Grade III and IV). CS/PADM reinforcement should be strongly considered for the repair of significant midline ventral hernia defects.

Stoma closure and reinforcement (SCAR): A study protocol for a pilot trial

A quality metric for centers performing rectal cancer surgery is a high percentage of sphincter sparing procedures. These procedures often involve temporary bowel diversion to minimize the complications of an anastomotic leak. The most common strategy is a diverting loop ileostomy which is then closed after completion of adjuvant therapy or the patient recovers from surgery. Loop ileostomy is not without complications and the closure is complicated by a one in three chance of incisional hernia development. Strategies to prevent this problem have been designed using a variety of techniques with and without mesh placement. This proposed pilot study will test the safety and efficacy of a novel stoma closure technique involving permanent mesh in the retro rectus position during ileostomy closure. The study will prospectively follow 20 patients undergoing ileostomy closure using this technique and evaluate for safety of the procedure, quality of life, and feasibility for a larger randomized controlled trial. Patients will be followed post procedurally and evaluated for 30-day complications, as well as followed up with routine cancer surveillance computed tomography every 6 months in which the presence of stoma site incisional hernias will be evaluated. The results of this pilot study will inform the design of a multiple center, blinded randomized controlled trial to evaluate the utility of permanent mesh placement to decrease the incidence of prior stoma site incisional hernias.

Further insights into the treatment of perineal hernia based on a the experience of a single tertiary centre

AIM

There is little evidence concerning the optimal surgical technique for the repair of perineal hernia. This study aimed to report on the evolution of a technique for repair of perineal hernia by analysing the experience in a tertiary referral centre.

METHOD

This was a retrospective review of consecutive patients who underwent perineal hernia repair after abdominoperineal excision in a tertiary referral centre. The main study end-points were rate of recurrent perineal hernia, perineal wound complications and related re-intervention.

RESULTS

Thirty-four patients were included: in 18 patients a biological mesh was used followed by 16 patients who underwent synthetic mesh repair. Postoperative perineal wound infection occurred in two patients (11%) after biological mesh repair compared with four (25%) after synthetic mesh repair (P = 0.387). None of the meshes were explanted. Recurrent perineal hernia following biological mesh was found in 7 of 18 patients (39%) after a median of 33 months. The recurrence rate with a synthetic mesh was 5 of 16 patients (31%) after a median of 17 months (P = 0.642). Re-repair was performed in four (22%) and two patients (13%), respectively (P = 0.660). Eight patients required a transposition flap reconstruction to close the perineum over the mesh, and no recurrent hernias were observed in this subgroup (P = 0.030). No mesh-related small bowel complications occurred.

CONCLUSION

Recurrence rates after perineal hernia repair following abdominoperineal excision were high, and did not seem to be related to the type of mesh. If a transposition flap was added to the mesh repair no recurrences were observed, but this finding needs confirmation in larger studies.

Outcomes of Open Complex Ventral Hernia Repairs With Retromuscular Placement of Poly-4-Hydroxybutyrate Bioabsorbable Mesh

Purpose. Optimal technique and mesh selection still debated for complex ventral hernias. Limited data exists on bioabsorbable meshes in high-risk patients. We evaluated our experience. Methods. Retrospective review was conducted following institutional review board approval for ventral hernia repairs using a single bioabsorbable mesh between February 2014 and November 2017. Patient and hernia details characterized. Outcomes evaluated. Results. 20 ventral hernia repairs identified, 10 males, 10 females. Mean body mass index was 35 ± 7.4 kg/m², and mean age 47 ± 13 years. Comorbid conditions were diabetes 35% and hypertension 40%. Fifty-five percent had American Society of Anesthesiologist scores of 3. Hernia Characteristics: Ventral Hernia Working Group Grade 3 hernias were 80%, and remainder grade 2. Forty percent of hernias were Centers for Disease Control class III, and remainder were class I and II. The mean defect size was 533 cm² ± 500. Repair for prior open abdomens was 45%, recurrent hernias 20%, incisional 15%, incarcerated 10%, incisional with parastomal 5%, and primary ventral 5%. Concomitant bowel procedures in 8, (40%). All cases had retromuscular mesh placement (transversus abdominus release 65%, Rives-Stoppa 35%). Surgical site occurrences were 20% (surgical site infection 10%, seroma 10%). Overall hospital stay 5 ± 3 days. Ileus occurred in 20%. One postoperative death due to fatal arrhythmia. There were no recurrences with mean follow-up 21.1 months. Conclusions. Complex hernia repairs using bioabsorbable mesh were conducted in a small cohort of high-risk patients. These data demonstrate good outcomes with limited morbidity and mortality. There were no recurrences.

Short-term influences of radiation on musculofascial healing in a laparotomy rat model

Preoperative radiation is associated with an increased risk of wound complications. However, the influences of radiation on musculofascial wound healing remains unclear. The purpose of the study was to investigate the short-term effects of preoperative local radiation on the musculofascial healing of laparotomy incisions in a rat model. Eighteen Fischer 344 rats received radiation doses of 0, 10, or 20 Gy to the abdominal wall and underwent laparotomy 4 weeks later. Two weeks after laparotomy, samples of irradiated muscle were harvested for mechanical tests, histological (Hematoxylin & Eosin, and Masson's Trichrome) and immunohistochemical analyses using KI67, CD31, TGF-β, and MYOD1 antibodies. The elastic modulus (EM), maximum strain (MS), and ultimate tensile strength (UTS) in the 20-Gy group were significantly weaker than those in the 0-Gy group. The EM and UTS in the 20-Gy group were significantly lower than those in the 10-Gy group. The UTS and MS in the 10-Gy group were significantly lower than those in the 0-Gy group. The mean number of inflammatory cells per mm² in the 20-Gy group was significantly larger than those in the 10- and 0-Gy groups. The mean numbers of CD31-, KI67-, and MYOD1-positive cells, the optical density of TGF-β, and the microvessel density in the 20-Gy group were significantly smaller than those in the 10- and 0-Gy groups. These results indicated that radiation delays musculofascial healing and decreases mechanical strength of the laparotomy incision by creating a chronic inflammatory environment, inhibiting cell proliferation, angiogenesis, granulation maturation, collagen deposition, and muscular regeneration in a dose-dependent manner. The impaired biomechanical, histological and molecular properties may be associated with the higher risk of wound complications in patients who undergo radiotherapy prior to laparotomy.

"Complex abdominal wall" management: evidence-based guidelines of the Italian Consensus Conference

To date, there is no shared consensus on a definition of a complex abdominal wall in elective surgery and in the emergency, on indications, technical details, complications, and follow-up. The purpose of the conference was to lay the foundations for a homogeneous approach to the complex abdominal wall with the primary intent being to attain the following objectives: (1) to develop evidence-based recommendations to define “complex abdominal wall”; (2) indications in emergency and in elective cases; (3) management of “complex abdominal wall”; (4) techniques for temporary abdominal closure. The decompressive laparostomy should be considered in a case of abdominal compartment syndrome in patients with critical conditions or after the failure of a medical treatment or less invasive methods. In the second one, beyond different mechanism, patients with surgical emergency diseases might reach the same pathophysiological end point of trauma patients where a preventive “open abdomen” might be indicated (a temporary abdominal closure: in the case of a non-infected field, the Wittmann patch and the NPWT had the best outcome followed by meshes; in the case of an infected field, NPWT techniques seem to be the preferred). The second priority is to create optimal both general as local conditions for healing: the right antimicrobial management, feeding—preferably by the enteral route—and managing correctly the open abdomen wall. The use of a mesh appears to be—if and when possible—the gold standard. There is a lot of enthusiasm about biological meshes. But the actual evidence supports their use only in contaminated or potentially contaminated fields but above all, to reduce the higher rate of recurrences, the wall anatomy and function should be restored in the midline, with or without component separation technique. On the other site has not to be neglected that the use of monofilament and macroporous non-absorbable meshes, in extraperitoneal position, in the setting of the complex abdomen with contamination, seems to have a cost effective role too. The idea of this consensus conference was mainly to try to bring order in the so copious, but not always so “evident” literature utilizing and exchanging the expertise of different specialists.

A Current Review of Hybrid Meshes in Abdominal Wall Reconstruction

Complex abdominal wall defects remain a common problem, though there has been significant advancement in technique and biomaterials over the last decade. The newly developed hybrid meshes are targeted to address several shortcomings of other meshes. Specifically, the marriage of biosynthetic or biologic materials with permanent prosthetic material is designed so that each will counteract the other's negative attributes. There are reports of permanent meshes having been associated with chronic pain, stiffness, and inflammation. However, their utility in maintaining biomechanical strength, thus limiting recurrence, makes them of value. In hybrid meshes, biosynthetic or biologic materials are coupled with permanent prosthetics, potentially protecting them from exhibiting deleterious effects by promoting and hastening tissue ingrowth. The various hybrid meshes currently available and investigational data are reviewed.

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.

Use of Acellular Dermal Matrix in Craniosynostosis

In craniofacial surgery, a wide spectrum of pathological conditions are usually treated. The aetiology of these could be congenital, traumatic, infective, post-tumor resection, postradiation, autoimmune, iatrogenic, or other miscellaneous conditions. The surgical approach for the procedures is usually via a coronal incision. In a large proportion of the patients, the frontal bone is removed to obtain intracranial access. The frontal bone is then replaced either in its original form or in a remodeled state. In congenital conditions the supraorbital bar and frontal bone is often also removed, remodeled, and replaced. One of the common late sequelae following craniofacial surgery is contour irregularities of the frontal region. These irregularities can vary in their extent. They are invariably palpable and often visible. Surgeons have attempted various methods to improve the contour irregularities. Despite these measures contour irregularities can still ensue. In the authors' unit, the authors have been using acellular dermal matrix in an attempt to diminish the contour irregularities in the frontal region following craniofacial reconstruction for craniosynostosis. This has been used in 35 patients undergoing craniosynostosis correction. Of the 35 patients, 12 were for plagiocephaly, 7 for brachycephaly, 10 for scaphocephaly, 4 for trigonocephaly, and 2 for combined coronal and metopic synostosis. The age of the patients ranged from 5 months to 12 years (mean 20.5 months). There were 21 males and 14 females. The follow-up ranged from 10 to 48 months (mean 23 months).

Multicenter, Prospective, Longitudinal Study of the Recurrence, Surgical Site Infection, and Quality of Life After Contaminated Ventral Hernia Repair Using Biosynthetic Absorbable Mesh: The COBRA Study

OBJECTIVE

The aim of the study was to evaluate biosynthetic absorbable mesh in single-staged contaminated (Centers for Disease Control class II and III) ventral hernia (CVH) repair over 24 months.

BACKGROUND

CVH has an increased risk of postoperative infection. CVH repair with synthetic or biologic meshes has reported chronic biomaterial infections and high hernia recurrence rates.

METHODS

Patients with a contaminated or clean-contaminated operative field and a hernia defect at least 9 cm had a biosynthetic mesh (open, sublay, retrorectus, or intraperitoneal) repair with fascial closure (n = 104). Endpoints included overall Kaplan-Meier estimates for hernia recurrence and postoperative wound infection rates at 24 months, and the EQ-5D and Short Form 12 Health Survey (SF-12). Analyses were conducted on the intent-to-treat population, and health outcome measures evaluated using paired t tests.

RESULTS

Patients had a mean age of 58 years, body mass index of 28 kg/m, 77% had contaminated wounds, and 84% completed 24-months follow-up. Concomitant procedures included fistula takedown (n = 24) or removal of infected previously placed mesh (n = 29). Hernia recurrence rate was 17% (n = 16). At the time of CVH repair, intraperitoneal placement of the biosynthetic mesh significantly increased the risk of recurrences (P ≤ 0.04). Surgical site infections (19/104) led to higher risk of recurrence (P < 0.01). Mean 24-month EQ-5D (index and visual analogue) and SF-12 physical component and mental scores improved from baseline (P < 0.05).

CONCLUSIONS

In this prospective longitudinal study, biosynthetic absorbable mesh showed efficacy in terms of long-term recurrence and quality of life for CVH repair patients and offers an alternative to biologic and permanent synthetic meshes in these complex situations.

Abdominal Wall Allograft: Preclinical Biomechanical Investigation of a Novel Reconstructive Adjunct

INTRODUCTION

Acellular dermal matrices have revolutionized abdominal wall reconstruction; however, device failure and hernia recurrence remain significant problems. Fascia grafts are a reconstructive adjunct with increased tensile strength compared with acellular dermal matrices; however, clinical use is limited by insufficient donor material and donor site morbidity. To this end, we investigate the biomechanical properties of human abdominal wall allografts (AWAs) consisting of the anterior rectus sheath from xiphoid to pubis.

METHODS

After cadaveric procurement of 6 human AWAs, the tissue was divided horizontally and a matched-sample study was performed with specimens randomized to 2 groups: fresh, unprocessed versus processed with gamma irradiation and decellularization. Specimens were evaluated for physical properties, DNA content, tensile strength, and electron microscopy.

RESULTS

All AWA donors were male, with a mean age of 55.2 years (range, 35-74 years). Procured AWAs had a mean length of 21.70 ± 1.8 cm, width of 14.30 ± 1.32 cm, and area of 318.50 cm, and processing resulted in a 98.3% reduction in DNA content. Ultimate tensile strength was significantly increased after tissue processing, and after subcutaneous implantation, processed AWA demonstrated 4-fold increased tensile strength compared with unprocessed AWAs.

CONCLUSIONS

Acellular AWAs represent a novel reconstructive adjunct for abdominal wall reconstruction with the potential of replacing "like with like" without additional donor site morbidity or antigenicity.

Complex Ventral Hernia Repair with Acellular Dermal Matrices: Clinical and Quality of Life Outcomes

Acellular dermal matrices (ADMs) are used in conjunction with complex hernia repair, but their efficacy is often debated. This study assesses clinical and quality of life (QOL) outcomes in multiply comorbid patients undergoing complex ventral hernia repair using ADMs. After obtaining institutional review board approval, a prospective study was conducted evaluating patients undergoing complex ventral incisional hernia repair with abdominal wall reconstruction (AWR) using either human (Flex HD) or porcine ADM (Strattice). Patient accrual occurred over three years. Demographics, comorbid conditions, and operative details were recorded. Postoperative two-week, six-week, six-month, and one-year follow-up occurred. Primary outcomes measures include wound occurrence, QOL parameters using the Short Form-12 health survey, and hernia recurrence. Groups were compared using chi-squared, Fisher's exact, Mann-Whitney U, or t tests as appropriate. Significance was set at P < 0.05. Thirty-five patients underwent hernia repair using ADM: mean age = 58 years, mean body mass index = 34 kg/m2, >50 per cent Centers for Disease Control and Prevention Wound Class II and above, >50 per cent recurrent hernia repair, and 25 per cent current or previous mesh infection. Twenty patients (57%) experienced surgical site occurrences, 15 (43%) wound infections, and 5 (14%) recurrences with a median follow-up of one year. All Short Form-12 QOL indicators improved at 12 months compared with baseline (NS). Outcomes were similar between mesh types. In conclusion, abdominal wall reconstruction for complex hernias using biologic materials is safe but has significant morbidity. Wound complications occur in over half of all patients and are not impacted by ADM type. There is no decrement in QOL one year after hernia repair despite associated morbidity.

Xenograft biologic mesh in parietal and general surgery: Technical assessment and review of clinical effectiveness and safety data

STUDY AIM

To describe the main technical characteristics of biologic prostheses used for parietal reinforcement and to present the state of the art on their risk/benefit ratio.

METHODS

We conducted a technical analysis of manufacturer specifications of the biologic prostheses that are currently available in France accompanied by a literature review by selecting meta-analyses and systematic reviews, randomized controlled trials and publications of health technology rating agencies.

RESULTS

Biological implants for parietal reinforcement are mainly intended for use in a contaminated environment where the use of synthetic prostheses is contra-indicated. We identified fourteen systematic reviews and meta-analyses and one randomized controlled trial. Six ongoing clinical trials were identified as well as two clinical trials that had been interrupted. In the current state of knowledge, there are no high-level evidence data on the therapeutic contribution of biologic prostheses that allow prioritization of the various biologic prostheses according to their characteristics or their different manufacturing processes.

CONCLUSION

Pending the results of current randomized controlled trials to validate the indications and an eventual specific reimbursement, indications for the use of biologic parietal reinforcement prostheses seems to be limited to rare clinical situations and only after collegial discussion.

Is there a place for a biological mesh in perineal hernia repair?

Purpose

This study aimed to determine the outcome of perineal hernia repair with a biological mesh after abdominoperineal resection (APR).

Method

All consecutive patients who underwent perineal hernia repair with a porcine acellular dermal mesh between 2010 and 2014 were included. Follow-up was performed by clinical examination and MRI.

Results

Fifteen patients underwent perineal hernia repair after a median of 25 months from APR. Four patients had a concomitant contaminated perineal defect, for which a gluteal fasciocutaneous flap was added in three patients. Wound infection occurred in three patients. After a median follow-up of 17 months (IQR 12–24), a clinically recurrent perineal hernia developed in 7 patients (47 %): 6 of 11 patients after a non-cross-linked mesh and 1 of 4 patients after a cross-linked mesh (p = 0.57). Routine MRI at a median of 17 months revealed a recurrent perineal hernia in 7 of 10 evaluable patients, with clinical confirmation of recurrence in 5 of these 7 patients. No recurrent hernia was observed in the three patients with combined flap reconstruction for contaminated perineal defects.

Conclusion

A high recurrence rate was observed after biological mesh repair of a perineal hernia following APR.

Non-cross-linked porcine acellular dermal matrix (Strattice Tissue Matrix) in pediatric reconstructive surgery

BACKGROUND

A variety of prosthetic materials are used in the pediatric population for abdominal and chest wall reconstruction. Pediatric experience of non-cross-linked porcine acellular dermal matrix is limited to patients following liver transplantation. We review our outcomes in patients in whom this matrix was used.

METHODS

A retrospective analysis of patients who underwent abdominal and chest wall reconstruction with a non-cross-linked porcine acellular dermal matrix (Strattice TM) was performed to assess clinical outcomes.

RESULTS

The tissue matrix was used in thirteen patients over a three-year period. Eleven had abdominal wall reconstruction and two underwent chest wall reconstruction. Seven procedures were contaminated at the time of surgery. Median age at insertion was 8.1years (5days-18years) with a median weight of 20.6kg (1.9kg-99kg). The tissue matrix failed in one patient with no unanticipated adverse events.

CONCLUSION

Future growth and need for reoperation requires special consideration in pediatric patients undergoing abdominal or thoracic wall reconstruction. Non-cross-linked porcine acellular dermal matrix can be safely used for abdominal and chest wall reconstruction in the pediatric population with a number of advantages over previously utilized materials. In our study, children have a favorable risk profile as compared to published adult series.

Development and preparation of a low-immunogenicity porcine dermal scaffold and its biocompatibility assessment

Acellular dermal matrix (ADM) has been widely used in repair and reconstruction of tissue defect. Therapeutic effect of porcine ADM (PADM) is inferior to that of human ADM (HADM). Relatively high immunogenicity and the resulting strong inflammatory response are major issue in application of PADM. We therefore treated reticular layer PADM (Rl-PADM) with matrix metalloproteinase-7 (MMP-7) and obtained a low-immunogenicity porcine dermal scaffold (LIPDS). Highly immunogenic components, tissue structure, cytocompatibility, and postgrafting histological changes of LIPDS were further investigated. Compared with Rl-PADM, LIPDS showed that the epithelial root sheath, cell debris, laminin, and type IV collagen were almost entirely removed, the structure remained normal, and the interfibrous space was relatively enlarged. Cytocompatibility of LIPDS was similar to that of HADM but superior to Rl-PADM. With regard to the extent of tissue ingrowth in terms of host fibroblasts infiltration and vascularization, LIPDS exhibited clear advantages over Rl-PADM after they had been subcutaneously transplanted in a rat model. In addition, no excessive inflammatory response was observed in LIPDS group up to 28 days postgraft, and the morphosis of collagenous fibers kept essentially normal. However, there were stronger inflammatory response and obvious collagen spallation in Rl-PADM group. The processes of integration and remodeling after the LIPDS grafting were similar to those of a normal wound healing response. The LIPDS graft was vascularized at a relatively high speed. Thus, as an implantable scaffold material, LIPDS is a superior template for guiding tissue regeneration and remodeling.

Novel superhydrophilic poly(l-lactic acid-co-ε-caprolactone)/fibrinogen electrospun patch for rat abdominal wall reconstruction

A novel superhydrophilic hybrid scaffold was created by electrospinning a mixture of poly(l-lactic acid-co-ε-caprolactone) and formulated fibrinogen. The hybrid scaffolds possess the combined benefits of each individual component, such as moderate mechanical strength and excellent biocompatibility. In vitro studies also revealed that endothelial cells seeded on the hybrid scaffolds achieved a relatively high level of cell attachment after three days of culture and a significant increase in the proliferation rate after seven days of culture, compared with pure fibrinogen or poly(l-lactic acid-co-ε-caprolactone) scaffolds. A comparative study of hybrid and pure poly(l-lactic acid-co-ε-caprolactone) patches was performed in an abdominal wall defect model in rats. In both groups, implants degraded by six months, but muscle reconstruction was only observed in the hybrid patch group.

Differentiation of mesenchymal stem cells into neuronal cells on fetal bovine acellular dermal matrix as a tissue engineered nerve scaffold

The purpose of this study was to assess fetal bovine acellular dermal matrix as a scaffold for supporting the differentiation of bone marrow mesenchymal stem cells into neural cells following induction with neural differentiation medium. We performed long-term, continuous observation of cell morphology, growth, differentiation, and neuronal development using several microscopy techniques in conjunction with immunohistochemistry. We examined specific neuronal proteins and Nissl bodies involved in the differentiation process in order to determine the neuronal differentiation of bone marrow mesenchymal stem cells. The results show that bone marrow mesenchymal stem cells that differentiate on fetal bovine acellular dermal matrix display neuronal morphology with unipolar and bi/multipolar neurite elongations that express neuronal-specific proteins, including βIII tubulin. The bone marrow mesenchymal stem cells grown on fetal bovine acellular dermal matrix and induced for long periods of time with neural differentiation medium differentiated into a multilayered neural network-like structure with long nerve fibers that was composed of several parallel microfibers and neuronal cells, forming a complete neural circuit with dendrite-dendrite to axon-dendrite to dendrite-axon synapses. In addition, growth cones with filopodia were observed using scanning electron microscopy. Paraffin sectioning showed differentiated bone marrow mesenchymal stem cells with the typical features of neuronal phenotype, such as a large, round nucleus and a cytoplasm full of Nissl bodies. The data suggest that the biological scaffold fetal bovine acellular dermal matrix is capable of supporting human bone marrow mesenchymal stem cell differentiation into functional neurons and the subsequent formation of tissue engineered nerve.

Clinical application of a silk fibroin protein biologic scaffold for abdominal wall fascial reinforcement

Background:

Preclinical studies have demonstrated that macroporous silk fibroin protein scaffolds are capable of promoting physiologically durable supportive tissue, which favors application of these engineered tissues for clinical implantation. The safety and effectiveness of a long-lasting, transitory, 510(k)-cleared purified silk fibroin biologic scaffold (SBS) are investigated for soft-tissue support and repair of the abdominal wall.

Methods:

We conducted a multicenter retrospective review of all consecutive patients who underwent abdominal wall soft-tissue reinforcement with an SBS device between 2011 and 2013. Indications, comorbid conditions, surgical technique, complications, and outcomes were evaluated.

Results:

We reviewed the records of 172 consecutive patients who received an SBS for soft-tissue support. Of those, 77 patients underwent abdominal wall fascial repair, with a mean follow-up of 18.4 ± 7.5 months. Procedures using an SBS included reinforcement of an abdominal-based flap donor site (31.2%), ventral hernia repair (53.2%), and abdominoplasty (15.6%). The overall complication rate was 6.5%, consisting of 2 wound dehiscences, 1 with device exposure, 1 seroma, 1 infection with explantation, and a perioperative bulge requiring reoperation. There were no reports of hernia.

Conclusions:

Postoperative complication rates after 18 months were low, and most surgical complications were managed nonoperatively on an outpatient basis without mesh removal. To our knowledge, this is the only series to report on a long-lasting, transitory SBS for abdominal wall repair and reinforcement. Procedure-specific outcome studies are warranted to delineate optimal patient selection and define potential device characteristic advantages.

Adipose-derived stem-cell-seeded non-cross-linked porcine acellular dermal matrix increases cellular infiltration, vascular infiltration, and mechanical strength of ventral hernia repairs

Adipose-derived stem cells (ASCs) facilitate wound healing by improving cellular and vascular recruitment to the wound site. Therefore, we investigated whether ASCs would augment a clinically relevant bioprosthetic mesh-non-cross-linked porcine acellular dermal matrix (ncl-PADM)-used for ventral hernia repairs in a syngeneic animal model. ASCs were isolated from the subcutaneous adipose tissue of Brown Norway rats, expanded, and labeled with green fluorescent protein. ASCs were seeded (2.5×10(4) cells/cm(2)) onto ncl-PADM for 24 h before surgery. In vitro ASC adhesion to ncl-PADM was assessed at 0.5, 1, and 2 h after seeding, and cell morphology on ncl-PADM was visualized by scanning electron microscopy. Ventral hernia defects (2×4 cm) were created and repaired with ASC-seeded (n=31) and control (n=32) ncl-PADM. Explants were harvested at 1, 2, and 4 weeks after surgery. Explant remodeling outcomes were evaluated using gross evaluation (bowel adhesions, surface area, and grade), histological analysis (hematoxylin and eosin and Masson's trichrome staining), immunohistochemical analysis (von Willebrand factor VIII), fluorescent microscopy, and mechanical strength measurement at the tissue-bioprosthetic mesh interface. Stem cell markers CD29, CD90, CD44, and P4HB were highly expressed in cultured ASCs, whereas endothelial and hematopoietic cell markers, such as CD31, CD90, and CD45 had low expression. Approximately 85% of seeded ASCs adhered to ncl-PADM within 2 h after seeding, which was further confirmed by scanning electron microcopy examination. Gross evaluation of the hernia repairs revealed weak omental adhesion in all groups. Ultimate tensile strength was not significantly different in control and treatment groups. Conversely, elastic modulus was significantly greater at 4 weeks postsurgery in the ASC-seeded group (p<0.001). Cellular infiltration was significantly higher in the ASC-seeded group at all time points (p<0.05). Vascular infiltration was significantly greater at 4 weeks postsurgery in the ASC-seeded group (p<0.001). The presence of ASCs improved remodeling outcomes by yielding an increase in cellular infiltration and vascularization of ncl-PADM and enhanced the elastic modulus at the ncl-PADM-tissue interface. With the ease of harvesting adipose tissues that are rich in ASCs, this strategy may be clinically translatable for improving ncl-PADM ventral hernia repair outcomes.

Outcomes of abdominal wall reconstruction with acellular dermal matrix are not affected by wound contamination

BACKGROUND

The optimal type of mesh for complex abdominal wall reconstruction has not been elucidated. We hypothesized that AWRs using acellular dermal matrix (ADM) experience low rates of surgical site occurrence (SSO) and surgical site infection, despite increasing degrees of wound contamination.

STUDY DESIGN

We retrospectively reviewed prospectively collected data from consecutive abdominal wall reconstructions with ADM over a 9-year period. Outcomes of abdominal wall reconstructions were compared between patients with different CDC wound classifications. Univariate and multivariate logistic regression and Cox proportional hazard regression analyses identified potential associations and predictive/protective factors.

RESULTS

The 359 patients had a mean follow-up of 28.3 ± 19.0 months. Reconstruction of clean wounds (n = 171) required fewer reoperations than that of combined contaminated (n = 188) wounds (2.3% vs 11.2%; p = 0.001) and trended toward experiencing fewer SSOs (19.9% vs 28.7%, p = 0.052). There were no significant differences between clean and combined contaminated cases in 30-day SSI (8.8% vs 8.0%), hernia recurrence (9.9% vs 10.1%), and mesh removal (1.2% vs 1.1%) rates. Independent predictors of SSO included body mass index ≥30 kg/m(2) (odds ratio [OR] 3.6; p < 0.001), 1 or more comorbidities (OR 2.5; p = 0.008), and defect width ≥15 cm (OR 1.8; p = 0.02).

CONCLUSIONS

Complex abdominal wall reconstructions using ADM demonstrated similar rates of complications between the different CDC wound classifications. This is in contradistinction to published outcomes for abdominal wall reconstruction using synthetic mesh that show progressively higher complication rates with increasing degrees of contamination. These data support the use of ADM rather than synthetic mesh for complex abdominal wall reconstruction in the setting of wound contamination.

Complete horizontal skin cell resurfacing and delayed vertical cell infiltration into porcine reconstructive tissue matrix compared to bovine collagen matrix and human dermis

BACKGROUND

Xenogenous dermal matrices are used for hernia repair and breast reconstruction. Full-thickness skin replacement is needed after burn or degloving injuries with exposure of tendons or bones. The authors used a human skin organ culture model to study whether porcine reconstructive tissue matrix (Strattice) is effective as a dermal tissue replacement.

METHODS

Skin cells or split-thickness skin grafts were seeded onto human deepidermized dermis, Strattice, and Matriderm. Cellular resurfacing and matrix infiltration were monitored by live fluorescence imaging, histology, and electron microscopy. Proliferation, apoptosis, cell differentiation, and adhesion were analyzed by immunohistochemistry.

RESULTS

Epithelial resurfacing and vertical proliferation were reduced and delayed with both bioartificial matrices compared with deepidermized dermis; however, no differences in apoptosis, cell differentiation, or basement membrane formation were found. Vertical penetration was greatest on Matriderm, whereas no matrix infiltration was found on Strattice in the first 12 days. Uncompromised horizontal resurfacing was greatest with Strattice but was absent with Matriderm. Strattice showed no stimulatory effect on cellular inflammation.

CONCLUSIONS

Matrix texture and surface properties governed cellular performance on tissues. Although dense dermal compaction delayed vertical cellular ingrowth for Strattice, it allowed uncompromised horizontal resurfacing. Dense dermal compaction may slow matrix decomposition and result in prolonged biomechanical stability of the graft. Reconstructive surgeons should choose the adequate matrix substitute depending on biomechanical requirements at the recipient site. Strattice may be suitable as a dermal replacement at recipient sites with high mechanical load requirements.

Biology of biological meshes used in hernia repair

Successful repair of most hernias requires the use of a prosthetic implant for reinforcement of the defect. Because of the need for prosthetic implants to resist infections as well to support repairs in contaminated or potentially contaminated fields, biological meshes have been developed to take the place of nondegradable synthetic meshes in cases where mesh infection is of high concern. The ideal is a biological matrix that resists infection while providing durable reinforcement of a hernia repair. This article reviews the validity of assumptions that support the purported notion of the biological behavior of biological meshes.

Bovine versus porcine acellular dermal matrix for complex abdominal wall reconstruction

BACKGROUND

Abdominal wall reconstruction with bioprosthetic mesh is associated with lower rates of mesh infection, fistula formation, and mesh explantation than reconstruction with synthetic mesh. The authors directly compared commonly used bioprosthetic meshes in terms of clinical outcomes and complications.

METHODS

A database of consecutive patients who underwent abdominal wall reconstruction with porcine or bovine acellular dermal matrix and midline musculofascial closure at their institution between January of 2008 and March of 2011 was reviewed. Surgical outcomes were compared.

RESULTS

One hundred twenty patients were identified who underwent a nonbridged, inlay abdominal wall reconstruction with porcine [69 patients (57.5 percent)] or bovine acellular dermal matrix (51 patients (42.5 percent)]. The mean follow-up time was 21.0 ± 9.9 months. The overall complication rate was 36.6 percent; the porcine matrix group had a significantly higher complication rate (44.9 percent) than the bovine matrix group (25.5 percent; p = 0.04) and statistically equivalent surgical complications (29.2 percent versus 21.6 percent; p = 0.34). There were no significant differences in rates of recurrent hernia (2.9 percent versus 3.9 percent; p = 0.99) or bulge (7.2 percent versus 0 percent; p = 0.07). However, the rate of intraoperative adverse events in the porcine matrix group [seven events (10.1 percent)] was significantly higher than that in the bovine matrix group (0 percent; p = 0.02).

CONCLUSIONS

In patients who undergo complex abdominal wall reconstruction, both bovine and porcine acellular dermal matrix are associated with similar rates of postoperative surgical complications and appear to result in similar outcomes. Porcine acellular dermal matrix may be prone to intraoperative device failure.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Abdominal wall reconstruction with mesh and components separation

Incisional hernias in the abdominal wall are a by-product of multiple previous laparotomies. Unfortunately, the incidence of incisional hernias has risen, as we have progressed with new surgical techniques in the treatment of abdominal pathologies. Many methods have been attempted in the past to achieve a better and more durable repair, namely using components separation to bring the fascia into the midline, and reinforce incisional hernias with different mesh materials. The authors review the recent literature regarding the efficacy of these synthetic materials and biomaterials in incisional hernia repair, as well as share their experience in treating complex abdominal wall defects using components separation and biologic mesh.

Bioprosthetic mesh in abdominal wall reconstruction

Mesh materials have undergone a considerable evolution over the last several decades. There has been enhancement of biomechanical properties, improvement in manufacturing processes, and development of antiadhesive laminate synthetic meshes. The evolution of bioprosthetic mesh materials has markedly changed our indications and methods for complex abdominal wall reconstruction. The authors review the optimal properties of bioprosthetic mesh materials, their evolution over time, and their indications for use. The techniques to optimize outcomes are described using bioprosthetic mesh for complex abdominal wall reconstruction. Bioprosthetic mesh materials clearly have certain advantages over other implantable mesh materials in select indications. Appropriate patient selection and surgical technique are critical to the successful use of bioprosthetic materials for abdominal wall repair.

Acellular dermal matrices in hand reconstruction

BACKGROUND

The goal of this article is to review the current literature on the use of acellular dermal matrix in forearm, wrist, and hand reconstruction.

METHODS

A comprehensive literature search was performed using the Cochrane Database of Systematic Reviews, MEDLINE, PubMed, and Web of Knowledge. Articles were categorized as acellular dermal matrix used in soft-tissue repair and in ligament reconstruction. Search terms included "acellular dermal matrix," "biologic dressing," "skin replacement," "dermal allograft," "AlloDerm," "FlexHD," "Permacol," and "Strattice." These were all cross-referenced with "forearm," "wrist," and "hand." Data extraction focused on indications, surgical techniques, clinical outcomes, and complications. Exclusion criteria included regeneration templates, neonatal foreskin, and review articles.

RESULTS

More than 100 articles published between 1994 and 2011 were identified. Upon final review, five prospective case-control studies, three retrospective case-control studies, four case reports, one cross-sectional cohort, one prospective consecutive series, and one study type unknown were evaluated. Matrix was most commonly used in burn reconstruction. It has also been used in ligament and joint reconstruction for first carpometacarpal arthritis. One article illustrated the use of porcine matrix in basal joint arthritis, a practice that was abruptly terminated because of a concern over increased infections.

CONCLUSIONS

The clinical indications for acellular dermal matrix have increased throughout the last 15 years. Hand surgeons have been cautious but diligent in developing alternative treatment options in hand reconstruction, with a focused effort to reduce donor-site morbidity. Although acellular dermal matrices continue to find innovative uses to solve upper extremity surgical problems, more comparative prospective trials are needed.