Prospective evaluation of poly-4-hydroxybutyrate mesh in CDC class I/high-risk ventral and incisional hernia repair: 18-month follow-up.

BACKGROUND: Long-term resorbable mesh represents a promising technology for complex ventral and incisional hernia repair (VIHR). Preclinical studies indicate that poly-4-hydroxybutyrate (P4HB) resorbable mesh supports strength restoration of the abdominal wall. This study evaluated outcomes of high-risk subjects undergoing VIHR with P4HB mesh. METHODS: This was a prospective, multi-institutional study of subjects undergoing retrorectus or onlay VIHR. Inclusion criteria were CDC Class I, defect 10-350 cm2, ≤ 3 prior repairs, and ≥ 1 high-risk criteria (obesity (BMI: 30-40 kg/m2), active smoker, COPD, diabetes, immunosuppression, coronary artery disease, chronic corticosteroid use, hypoalbuminemia, advanced age, and renal insufficiency). Physical exam and/or quality of life surveys were performed at regular intervals through 18 months (to date) with longer-term, 36-month follow-up ongoing. RESULTS: One hundred and twenty-one subjects (46M, 75F) with an age of 54.7 ± 12.0 years and BMI of 32.2 ± 4.5 kg/m2 (mean ± SD), underwent VIHR. Comorbidities included the following: obesity (n = 95, 78.5%), hypertension (n = 72, 59.5%), cardiovascular disease (n = 42, 34.7%), diabetes (n = 40, 33.1%), COPD (n = 34, 28.1%), malignancy (n = 30, 24.8%), active smoker (n = 28, 23.1%), immunosuppression (n = 10, 8.3%), chronic corticosteroid use (n = 6, 5.0%), advanced age (n = 6, 5.0%), hypoalbuminemia (n = 3, 2.5%), and renal insufficiency (n = 1, 0.8%). Hernia types included the following: primary ventral (n = 17, 14%), primary incisional (n = 54, 45%), recurrent ventral (n = 15, 12%), and recurrent incisional hernia (n = 35, 29%). Defect and mesh size were 115.7 ± 80.6 and 580.9 ± 216.1 cm2 (mean ± SD), respectively. Repair types included the following: retrorectus (n = 43, 36%), retrorectus with additional myofascial release (n = 45, 37%), onlay (n = 24, 20%), and onlay with additional myofascial release (n = 8, 7%). 95 (79%) subjects completed 18-month follow-up to date. Postoperative wound infection, seroma requiring intervention, and hernia recurrence occurred in 11 (9%), 7 (6%), and 11 (9%) subjects, respectively. CONCLUSIONS: High-risk VIHR with P4HB mesh demonstrated positive outcomes and low incidence of hernia recurrence at 18 months. Longer-term 36-month follow-up is ongoing.

Type I/type III collagen ratio associated with diverticulitis of the colon in young patients.

BACKGROUND: The incidence of diverticulitis in young patients is rising, whereas the type I:III collagen ratio of the colon decreases with age. Perhaps a lower type I:III collagen ratio in younger patients may predispose these patients to the development of the disease. METHOD: The purpose of this study was to evaluate the collagen content and type I:III collagen ratio in patients with diverticulitis versus a control group. Patients who underwent a colon resection were identified. Three groups of patients were created for analysis: those with diverticulitis aged <50 y, >50 y, and a control group. Tissue samples were stained with Sirius red/fast green and photographed. Photos analysis was performed to quantify the amount of type I collagen and type III collagen. The type I:III collagen ratio was calculated for each patient and compared. RESULTS: The quantity of type I collagen and type III collagen was higher in patients with diverticulitis aged >50 y (P = 0.04 and P < 0.0001, respectively); however, the collagen ratio was greatest in those patients with diverticulitis aged <50 y (P = 0.01). Further analysis demonstrated a significant higher type I:III ratio in all patients aged less than 50 y compared with all patients aged over 50 y (P = 0.04). CONCLUSIONS: Our study demonstrated that diverticulitis in the younger patient was not associated with a lower type I:III collagen ratio. It appears that the decrease in collagen ratio of the colon with age is associated with an increase in type III collagen deposition.

Evaluation of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh in a porcine model of ventral hernia repair.

BACKGROUND: The objective of this study was to evaluate the mechanical and histological properties of a fully absorbable poly-4-hydroxybutyrate/absorbable barrier composite mesh (Phasix™ ST) compared to partially absorbable (Ventralight™ ST), fully absorbable (Phasix™), and biologically derived (Strattice™) meshes in a porcine model of ventral hernia repair. METHODS: Bilateral abdominal surgical defects were created in twenty-four Yucatan pigs, repaired with intraperitoneal (Phasix™ ST, Ventralight™ ST) or retromuscular (Phasix™, Strattice™) mesh, and evaluated at 12 and 24 weeks (n = 6 mesh/group/time point). RESULTS: Prior to implantation, Strattice™ demonstrated significantly higher (p < 0.001) strength (636.6 ± 192.1 N) compared to Ventralight™ ST (324.3 ± 37.1 N), Phasix™ ST (206.9 ± 11.3 N), and Phasix™ (200.6 ± 25.2 N). At 12 and 24 weeks, mesh/repair strength was significantly greater than NAW (p < 0.01 in all cases), and no significant changes in strength were observed for any meshes between 12 and 24 weeks (p > 0.05). Phasix™ mesh/repair strength was significantly greater than Strattice™ (p < 0.001) at 12 and 24 weeks, and Ventralight™ ST mesh/repair strength was significantly greater than Phasix™ ST mesh (p < 0.05) at 24 weeks. At 12 and 24 weeks, Phasix™ ST and Ventralight™ ST were associated with mild inflammation and minimal-mild fibrosis/neovascularization, with no significant differences between groups. At both time points, Phasix™ was associated with minimal-mild inflammation/fibrosis and mild neovascularization. Strattice™ was associated with minimal inflammation/fibrosis, with minimal neovascularization at 12 weeks, which increased to mild by 24 weeks. Strattice™ exhibited significantly less neovascularization than Phasix™ at 12 weeks and significantly greater inflammation at 24 weeks due to remodeling. CONCLUSIONS: Phasix™ ST demonstrated mechanical and histological properties comparable to partially absorbable (Ventralight™ ST) and fully resorbable (Phasix™) meshes at 12 and 24 weeks in this model. Data also suggest that fully absorbable meshes with longer-term resorption profiles may provide improved mechanical and histological properties compared to biologically derived scaffolds.

Remodeling characteristics and collagen distribution in biological scaffold materials explanted from human subjects after abdominal soft tissue reconstruction: an analysis of scaffold remodeling characteristics by patient risk factors and surgical site classifications.

OBJECTIVE: The study purpose was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of biologic meshes biopsied from abdominal soft tissue repair sites in the first attempt to generate a multivariable risk-prediction model of nonconstructive remodeling. BACKGROUND: Host characteristics and surgical site assessments may predict remodeling degree for biologic meshes used to reinforce abdominal tissue repair sites. METHODS: Biologic meshes were biopsied from the abdominal tissue repair sites of n = 40 patients during an abdominal reexploration, stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell types, cell infiltration, extracellular matrix deposition, scaffold degradation, fibrous encapsulation, and neovascularization) and a mean composite score. Biopsies were stained with Sirius Red and Fast Green and analyzed to determine the collagen I:III ratio. On the basis of univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using P ≤ 0.200. RESULTS: The model selection process for cell infiltration score yielded 2 variables: age at mesh implantation and mesh classification (C statistic = 0.989). For the mean composite score, the model selection process yielded 2 variables: age at mesh implantation and mesh classification (r = 0.449). CONCLUSIONS: These preliminary results constitute the first steps in generating a risk-prediction model that predicts the patients and clinical circumstances most likely to experience nonconstructive remodeling of abdominal tissue repair sites with biologic mesh reinforcement.

Evaluation of absorbable mesh fixation devices at various deployment angles.

BACKGROUND: Hernia repair failure may occur due to suboptimal mesh fixation by mechanical constructs before mesh integration. Construct design and acute penetration angle may alter mesh-tissue fixation strength. We compared acute fixation strengths of absorbable fixation devices at various deployment angles, directions of loading, and construct orientations. METHODS: Porcine abdominal walls were sectioned. Constructs were deployed at 30°, 45°, 60°, and 90° angles to fix mesh to the tissue specimens. Lap-shear testing was performed in upward, downward, and lateral directions in relation to the abdominal wall cranial-caudal axis to evaluate fixation. Absorbatack™ (AT), SorbaFix™ (SF), and SecureStrap™ in vertical (SSV) and horizontal (SSH) orientations in relation to the abdominal wall cranial-caudal axis were tested. Ten tests were performed for each combination of device, angle, and loading direction. Failure types and strength data were recorded. ANOVA with Tukey-Kramer adjustments for multiple comparisons and χ (2) tests were performed as appropriate (p < 0.05 considered significant). RESULTS: At 30°, SSH and SSV had greater fixation strengths (12.95, 12.98 N, respectively) than SF (5.70 N; p = 0.0057, p = 0.0053, respectively). At 45°, mean fixation strength of SSH was significantly greater than SF (18.14, 11.40 N; p = 0.0002). No differences in strength were identified at 60° or 90°. No differences in strength were noted between SSV and SSH with different directions of loading. No differences were noted between SS and AT at any angle. Immediate failure was associated with SF (p < 0.0001) and the 30° tacking angle (p < 0.01). CONCLUSIONS: Mesh-tissue fixation was stronger at acute deployment angles with SS compared to SF constructs. The 30° angle and the SF device were associated with increased immediate failures. Varying construct and loading direction did not generate statistically significant differences in the fixation strength of absorbable fixation devices in this study.

Effect of acellular human dermis buttress on laparoscopic hiatal hernia repair.

PURPOSE: The objective of this study was to evaluate the performance of acellular human dermis reinforcement during laparoscopic hiatal hernia repair. METHODS: A prospective non-randomized, single institution study enrolled patients undergoing laparoscopic hiatal hernia repair. Acellular human dermis, FlexHD (Musculoskeletal Transplant Foundation, Edison, NJ) or AlloDerm (LifeCell Inc., Branchburg, NJ) were used to buttress the repair after primary closure. A protocol barium swallow (BAS) was performed at 6 months and then as needed due to clinical indications. Primary outcome measure was recurrence. Patients completed preoperative and postoperative GERD symptom questionnaires and quality of life surveys (SF-36). Kruskal-Wallis ANOVA, Student's t test, Fisher's exact test, or Wilcoxon signed-rank test were utilized as appropriate (p < 0.05 considered statistically significant). RESULTS: Fifty-four patients (10 men and 44 women) with a mean age of 62 ± 10 years underwent laparoscopic hiatal hernia repair using Flex HD (n = 37) or AlloDerm (n = 17). Both groups were similar with respect to gender, age, hiatus size, hernia type [sliding/Type I (n = 14) or paraesophageal/Type III/IV (n = 40)], esophageal motor function (manometry), preoperative SF-36 quality of life surveys, and GERD symptom questionnaires. Forty-seven patients (87 %) completed the BAS at 6 months; each group had two recurrences (p = 0.597). At median follow-up of 33 months, there were 3 recurrences (18 %) in the AlloDerm group and 5 recurrences (14 %) in the Flex HD group (p = 0.365). Minimal differences in GERD symptoms or SF-36 scores were detected between groups. However, anti-reflux medication usage, GERD symptoms, and quality of life significantly improved for both groups after laparoscopic hiatal hernia repair. CONCLUSIONS: Laparoscopic hiatal hernia repair with acellular human dermis reinforcement results in improvement of GERD-related symptoms and quality of life without mesh-associated complications. The type of acellular human dermis did not influence recurrence rate.

Remodeling Characteristics and Collagen Distributions of Biologic Scaffold Materials Biopsied From Postmastectomy Breast Reconstruction Sites.

OBJECTIVE: The study purpose was to evaluate the associations between patient characteristics and the histologic remodeling scores of acellular dermal matrices (ADMs) biopsied from breast reconstruction sites in the first attempt to generate a multivariable risk prediction model of nonconstructive remodeling. It was hypothesized that host characteristics and surgical site assessments predict the degree of graft remodeling for ADMs used during breast reconstruction. METHODS: The ADMs were biopsied from the breast reconstruction sites of n = 62 patients during a subsequent breast procedure, stained with hematoxylin-eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell types, cell infiltration, extracellular matrix deposition, scaffold degradation, fibrous encapsulation, and neovascularization) and a mean composite score. Biopsies were stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a P value of 0.20 or less. RESULTS: The composite score model yielded 3 variables: pack-year history, corticosteroid use, and radiation timing (r pseudo = 0.81). The model for collagen I yielded 2 variables: corticosteroid use and reason for reoperation (r pseudo = 0.78). The model for collagen III yielded 1 variable: reason for reoperation (r pseudo = 0.35). CONCLUSIONS: These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances most likely to experience nonconstructive remodeling of biologic grafts used to reconstruct the breast.

Remodeling characteristics and collagen distribution in synthetic mesh materials explanted from human subjects after abdominal wall reconstruction: an analysis of remodeling characteristics by patient risk factors and surgical site classifications.

BACKGROUND: The purpose of this study was to evaluate the associations between patient characteristics or surgical site classifications and the histologic remodeling scores of synthetic meshes biopsied from their abdominal wall repair sites in the first attempt to generate a multivariable risk prediction model of non-constructive remodeling. METHODS: Biopsies of the synthetic meshes were obtained from the abdominal wall repair sites of 51 patients during a subsequent abdominal re-exploration. Biopsies were stained with hematoxylin and eosin, and evaluated according to a semi-quantitative scoring system for remodeling characteristics (cell infiltration, cell types, extracellular matrix deposition, inflammation, fibrous encapsulation, and neovascularization) and a mean composite score (CR). Biopsies were also stained with Sirius Red and Fast Green, and analyzed to determine the collagen I:III ratio. Based on univariate analyses between subject clinical characteristics or surgical site classification and the histologic remodeling scores, cohort variables were selected for multivariable regression models using a threshold p value of ≤0.200. RESULTS: The model selection process for the extracellular matrix score yielded two variables: subject age at time of mesh implantation, and mesh classification (c-statistic = 0.842). For CR score, the model selection process yielded two variables: subject age at time of mesh implantation and mesh classification (r (2) = 0.464). The model selection process for the collagen III area yielded a model with two variables: subject body mass index at time of mesh explantation and pack-year history (r (2) = 0.244). CONCLUSION: Host characteristics and surgical site assessments may predict degree of remodeling for synthetic meshes used to reinforce abdominal wall repair sites. These preliminary results constitute the first steps in generating a risk prediction model that predicts the patients and clinical circumstances for which non-constructive remodeling of an abdominal wall repair site with synthetic mesh reinforcement is most likely to occur.

Reinforced tissue matrix to strengthen the abdominal wall following reversal of temporary ostomies or to treat incisional hernias.

BACKGROUND: Abdominal wall deficiencies or weakness are a common complication of temporary ostomies, and incisional hernias frequently develop after colostomy or ileostomy takedown. The use of synthetic meshes to reinforce the abdominal wall has reduced hernia occurrence. Biologic meshes have also been used to enhance healing, particularly in contaminated conditions. Reinforced tissue matrices (RTMs), which include a biologic scaffold of native extracellular matrix and a synthetic component for added strength/durability, are designed to take advantage of aspects of both synthetic and biologic materials. To date, RTMs have not been reported to reinforce the abdominal wall following stoma reversal. AIM: To evaluate the effectiveness of using an RTM to reinforce the abdominal wall at stoma takedown sites. METHODS: Twenty-eight patients were selected with a parastomal and/or incisional hernia who had received a temporary ileostomy or colostomy for fecal diversion after rectal cancer treatment or trauma. Following hernia repair and proximal stoma closure, RTM (OviTex® 1S permanent or OviTex® LPR) was placed to reinforce the abdominal wall using a laparoscopic, robotic, or open surgical approach. Post-operative follow-up was performed at 1 month and 1 year. Hernia recurrence was determined by physical examination and, when necessary, via computed tomography scan. Secondary endpoints included length of hospital stay, time to return to work, and hospital readmissions. Evaluated complications of the wound/repair site included presence of surgical site infection, seroma, hematoma, wound dehiscence, or fistula formation. RESULTS: The observational study cohort included 16 male and 12 female patients with average age of 58.5 years ± 16.3 years and average body mass index of 26.2 kg/m2 ± 4.1 kg/m2. Patients presented with a parastomal hernia (75.0%), incisional hernia (14.3%), or combined parastomal/incisional hernia (10.7%). Using a laparoscopic (53.6%), robotic (35.7%), or open (10.7%) technique, RTMs (OviTex® LPR: 82.1%, OviTex® 1S: 17.9%) were placed using sublay (82.1%) or intraperitoneal onlay (IPOM; 17.9%) mesh positioning. At 1-month and 1-year follow-ups, there were no hernia recurrences (0%). Average hospital stays were 2.1 d ± 1.2 d and return to work occurred at 8.3 post-operative days ± 3.0 post-operative days. Three patients (10.7%) were readmitted before the 1-month follow up due to mesh infection and/or gastrointestinal issues. Fistula and mesh infection were observed in two patients each (7.1%), leading to partial mesh removal in one patient (3.6%). There were no complications between 1 month and 1 year (0%). CONCLUSION: RTMs were used successfully to treat parastomal and incisional hernias at ileostomy reversal, with no hernia recurrences and favorable outcomes after 1-month and 1-year.

Fully resorbable poly-4-hydroxybutyrate (P4HB) mesh for soft tissue repair and reconstruction: A scoping review.

Background: Poly-4-hydroxybutyrate (P4HB) is a fully resorbable, biologically-produced polymer with a strength and flexibility comparable to permanent synthetic polymers. The objective was to identify/summarize all peer-reviewed publications involving P4HB mesh. Methods: A scoping review was conducted within PubMed and included articles published through October 2022. Results: A total of n = 79 studies were identified (n = 12 in vitro/bench; n = 14 preclinical; n = 6 commentaries; n = 50 clinical). Of the clinical studies, n = 40 reported results applicable to hernia and n = 10 to plastic/reconstructive surgery and involved patients of all Centers for Disease Control (CDC) wound classes and Ventral Hernia Working Group (VHWG) grades. Conclusion: P4HB mesh provides long-term hernia repair strength and exhibits promising clinical outcomes beyond its resorption period. Future studies should include randomized controlled trials comparing P4HB to other biomaterials, as well as optimal patient selection, operative technique, long-term outcomes, minimization of potential mesh-related complications, and potential contraindications/complications for P4HB in hernia/abdominal wall reconstruction.

Efficacy of Flowable Collagen Hemostat Evaluated in Preclinical Models of Liver Injury and Spinal Cord Exposure.

Introduction: Excessive bleeding in trauma and surgical settings leads to increased operative time, reoperation rates, and overall healthcare costs. A wide range of hemostatic agents have been developed to control bleeding that can vary considerably in type of hemostatic action, ease of application, cost, risk of infection, and dependence on patient coagulation. Microfibrillar collagen-based hemostatic materials (MCH) have yielded beneficial results in a variety of applications. Methods: A new flowable collagen product, containing a modified MCH flour, but in a more convenient flowable delivery system, was evaluated for hemostatic efficacy in preclinical models of solid organ injury and spinal cord exposure. The primary objective of this study was to compare the hemostatic potential and local tissue responses to this novel, flowable collagen-based hemostatic agent to the original flour formulation to confirm that the new method of delivery did not interfere with the hemostatic properties of the MCH flour. Results: When observed visually, the flowable MCH flour mixed with saline (FL) provided more precise application and uniform coverage to injured tissues compared to the dry MCH flour alone (F0). All of the treatments (FL, F0, and gauze) exhibited comparable Lewis bleed grade at all three time points evaluated in the capsular resection liver injury model (bleed grade: 1.0-1.3; p> 0.05 in all cases). FL and F0 exhibited comparable 100% acute hemostatic efficacy and similar long-term histomorphological properties (up to 120 days) in a capsular resection liver injury in pigs, while gauze resulted in significantly lower rates of acute hemostatic efficacy (8-42%, p<0.05 in all cases). In an ovine model of dorsal laminectomy and durotomy, FL and F0 again exhibited comparable results without any neurological effects. Conclusion: Flowable microfibrillar collagen was shown to yield favorable short- and long-term outcomes in two representative applications where hemostatic efficacy is critical to surgical success.

Early wound morbidity and clinical outcomes associated with P4HB mesh compared to permanent synthetic mesh in umbilical and small to medium, routine ventral hernia repairs.

Background: Permanent synthetic meshes such as polypropylene (PP) have been utilized for hernia repair for decades, but concerns remain regarding potential long-term, mesh-related complications. A resorbable polymer such as poly-4-hydroxybutyrate (P4HB) represents an alternative with high initial strength, that gradually resorbs, leaving an abdominal wall that is at least as strong as it would be in its native state. We aimed to compare early wound morbidity and clinical outcomes associated with P4HB to traditional, permanent PP in umbilical and small to medium, routine ventral hernias using data from the Abdominal Core Health Quality Collaborative (ACHQC). Methods: Inclusion criteria for the umbilical cohort included: all Centers for Disease Control and Prevention (CDC) wound classes, all Ventral Hernia Working Group (VHWG) hernia grades, and hernia defects <3 cm. The small to medium, routine ventral hernia cohort was limited to CDC class I wounds, VHWG hernia grades I and II, and hernia defects <5 cm. The study group was comprised of P4HB meshes; the comparator group was an aggregate of PP meshes. Clinical outcomes were assessed at 30 days. Results: There was no significant difference in early wound morbidity, readmission, or reoperation between the P4HB and PP cohorts. A small number of patients experienced SSO, with ≤4% requiring procedural intervention. None of the patients (0% in all cases) experienced skin/soft tissue necrosis, infected seroma, infected hematoma, exposed/contaminated/infected mesh, enterocutaneous fistula, graft failure, or pain requiring intervention at 30-days. However, P4HB was associated with significantly greater operative time, length of stay, and use of myofascial release compared to PP (p < 0.05 in all cases). Conclusions: Short-term clinical outcomes associated with resorbable P4HB mesh are comparable to permanent synthetic PP mesh in umbilical and small to medium, routine ventral hernia repairs, despite significant differences in operative time and length of stay. Longer-term follow-up is needed to expand on the clinical relevance of these short-term findings.

Prospective, multicenter study of antimicrobial-coated, noncrosslinked, acellular porcine dermal matrix (XenMatrix™ AB Surgical Graft) for hernia repair in all centers for disease control and prevention wound classes: 24-month follow-up cohort.

Prospective, multicenter, single-arm study of antimicrobial-coated, noncrosslinked, acellular porcine dermal matrix (AC-PDM) in a cohort involving all centers for disease control and prevention wound classes in ventral/incisional midline hernia repair (VIHR). Materials and methods: Seventy-five patients (mean age 58.6±12.7 years; BMI 31.3±4.9 kg/m2) underwent ventral/incisional midline hernia repair with AC-PDM. Surgical site occurrence (SSO) was assessed in the first 45 days post-implantation. Length of stay, return to work, hernia recurrence, reoperation, quality of life, and SSO were assessed at 1, 3, 6, 12, 18, and 24 months. Results: 14.7% of patients experienced SSO requiring intervention within 45 days post-implantation, and 20.0% thereafter (>45 d post-implantation). Recurrence (5.8%), definitely device-related adverse events (4.0%), and reoperation (10.7%) were low at 24 months; all quality-of-life indicators were significantly improved compared to baseline. Conclusion: AC-PDM exhibited favourable results, including infrequent hernia recurrence and definitely device-related adverse events, with reoperation and SSO comparable to other studies, and significantly improved quality of life.

Differentiation of biologic scaffold materials through physicomechanical, thermal, and enzymatic degradation techniques.

OBJECTIVE: The objective of this study was to characterize the physicomechanical, thermal, and degradation properties of several types of biologic scaffold materials to differentiate between the various materials. BACKGROUND: As more biologic scaffold materials arrive on the market, it is critical that surgeons understand the properties of each material and are provided with resources to determine the suitability of these products for specific applications such as hernia repair. METHODS: Twelve biologic scaffold materials were evaluated, including crosslinked and non-crosslinked; those of bovine, human, and porcine origin; and derivatives of pericardium, dermis, and small intestine submucosa. Physicomechanical, thermal, and degradation properties were evaluated through biomechanical testing, modulated differential scanning calorimetry, and collagenase digestion assays, respectively. Biomechanical testing included suture retention, tear strength, uniaxial tensile, and ball burst techniques. RESULTS: All scaffolds exhibited suture retention strengths greater than 20 N, but only half of the scaffolds exhibited tear resistance greater than 20 N, indicating that some scaffolds may not provide adequate resistance to tearing. A wide range of burst strengths were observed ranging from 66.2 ± 10.8 N/cm for Permacol to 1,028.0 ± 199.1 N/cm for X-Thick AlloDerm, and all scaffolds except SurgiMend, Strattice, and CollaMend exhibited strains in the physiological range of 10% to 30% (at a stress of 16 N/cm). Thermal analysis revealed differences between crosslinked and non-crosslinked materials with crosslinked bovine pericardium and porcine dermis materials exhibiting a higher melting temperature than their non-crosslinked counterparts. Similarly, the collagenase digestion assay revealed that crosslinked bovine pericardium materials resisted enzymatic degradation significantly longer than non-crosslinked bovine pericardium. CONCLUSIONS: Although differences were observed because of cross-linking, some crosslinked and non-crosslinked materials exhibited very similar properties. Variables other than cross-linking, such as decellularization/sterilization treatments or species/tissue type also contribute to the properties of the scaffolds.

A review of the composition, characteristics, and effectiveness of barrier mesh prostheses utilized for laparoscopic ventral hernia repair.

BACKGROUND: The objective of this review was to provide an overview of the components that comprise each of the eight barrier mesh prostheses commonly utilized for LVHR and to review the current literature related to the characteristics and effectiveness of these materials to guide the general surgeon in selecting the most appropriate material for LVHR. METHODS: Composite prostheses with permanent barriers (Bard™ Composix™ E/X, Bard™ Composix™ L/P, and DUALMESH(®) Biomaterial) were compared to composite prostheses with absorbable barriers (C-QUR™ Mesh, PROCEED™ Surgical Mesh, Bard™ Sepramesh™ IP Composite, Parietex™ Composite, and PHYSIOMESH™) using scanning electron microscopy and a review of the current preclinical and clinical literature. RESULTS: Clinical studies and preclinical animal models have attempted to determine the adhesion characteristics and effectiveness of barrier mesh prostheses available for ventral hernia repair applications. However, it is difficult to make any definitive statements about the adhesion characteristics and effectiveness of these materials because all meshes were not included in all studies and likewise not compared under identical conditions. Overall, Parietex™ Composite and DUALMESH(®) Biomaterial were cited most frequently for improvement of adhesion characteristics, followed closely by Bard™ Sepramesh™ IP Composite and C-QUR™ Mesh. Bard™ Composix™, PROCEED™ Surgical Mesh, and uncoated polypropylene were cited most frequently as having the most tenacious and extensive adhesions. CONCLUSIONS: Differences observed between the various barrier prostheses are likely attributable to the chemical composition of the barrier or the conditions required for resorption and metabolism of the barrier components. It is likely that the components of these barriers incite a wide range of inflammatory responses resulting in the range of adhesion coverage and tenacity observed in the preclinical and clinical studies reviewed. Clinical trials are needed to more appropriately define the clinical effectiveness of these barriers.

Development of novel electrospun absorbable polycaprolactone (PCL) scaffolds for hernia repair applications.

INTRODUCTION: Permanent/nonresorbable hernia repair materials rely on profibrotic wound healing, and repair sites are commonly composed of disorganized tissue with inferior mechanical strength and risk of reherniation. Resorbable electrospun scaffolds represent a novel class of biomaterials, which may provide a unique platform for the design of advanced soft tissue repair materials. These materials are simple, inexpensive, nonwoven materials composed of polymer fibers that readily mimic the natural extracellular matrix. The primary goal of the present study was to evaluate the physiomechanical properties of novel electrospun scaffolds to determine their suitability for hernia repair. Based on previous experimentation, scaffolds possessing ≥ 20 N suture retention strength, ≥ 20 N tear resistance, and ≥ 50 N/cm tensile strength are appropriate for hernia repair. METHODS: Six novel electrospun scaffolds were fabricated by varying combinations of polymer concentration (10-12 %) and flow rate (3.5-10 mL/h). Briefly, poly(ε-caprolactone) (PCL) was dissolved in a solvent mixture and electrospun onto a planar metal collector, yielding sheets with randomly oriented fibers. Physiomechanical properties were evaluated through scanning electron microscopy, laser micrometry, and mechanical testing. RESULTS: Scanning electron micrographs demonstrated fiber diameters ranging from 1.0 ± 0.1 µm (10 % PCL, 3.5 mL/h) to 1.5 ± 0.2 µm (12 % PCL, 4 mL/h). Laser micrometry demonstrated thicknesses ranging from 0.72 ± 0.07 mm (12 % PCL, 10 mL/h) to 0.91 ± 0.05 mm (10 % PCL, 3.5 mL/h). Mechanical testing identified two scaffolds possessing suture retention strengths ≥ 20 N (12 % PCL, 10 mL/h and 12 % PCL, 6 mL/h), and no scaffolds possessing tear resistance values ≥ 20 N (range, 4.7 ± 0.9 N to 10.6 ± 1.8 N). Tensile strengths ranged from 35.27 ± 2.08 N/cm (10 % PCL, 3.5 mL/h) to 81.76 ± 15.85 N/cm (12 % PCL, 4 mL/h), with three scaffolds possessing strengths ≥ 50 N/cm (12 % PCL, 10 mL/h; 12 % PCL, 6 mL/h; 12 % PCL, 4 mL/h). CONCLUSIONS: Two electrospun scaffolds (12 % PCL, 10 mL/h and 12 % PCL, 6 mL/h) possessed suture retention and tensile strengths appropriate for hernia repair, justifying evaluation in a large animal model. Additional studies examining advanced methods of fabrication may further improve the unique properties of these scaffolds, propelling them into applications in a variety of clinical settings.

Effect of enzymatic degradation on the mechanical properties of biological scaffold materials.

BACKGROUND: Biological scaffolds must support a complex balance of resisting enzymatic degradation while promoting tissue remodeling. Thus, the purpose of this study was to evaluate the effects of in vitro enzymatic exposure on the mechanical properties of biological scaffolds. It was hypothesized that exposure to an enzyme solution would result in decreased tensile strength and that crosslinked scaffolds would resist enzymatic degradation more effectively than noncrosslinked scaffolds. METHODS: Nine scaffolds were evaluated (four porcine dermis: Permacol™, CollaMend™, Strattice™, XenMatrix™; two human dermis: AlloMax™, FlexHD(®); two bovine pericardium: Veritas(®), PeriGuard(®); and one porcine small intestine submucosa: Surgisis™). Ten specimens (n = 10) were hydrated in saline at 37 °C and subjected to uniaxial testing to establish baseline properties. 50 specimens (n = 50) were incubated in collagenase solution at 37 °C for 2, 6, 12, 24, or 30 h (n = 10 each group) followed by uniaxial tensile testing. RESULTS: Tensile strength was significantly reduced after 30 h for CollaMend™, AlloMax™, Veritas(®), Strattice™, XenMatrix™, Permacol™, and FlexHD(®) (p < 0.01), while PeriGuard(®) demonstrated a slight increase in tensile strength (p = 0.0188). Crosslinked bovine pericardium (PeriGuard(®)) maintained greater tensile strength than noncrosslinked bovine pericardium (Veritas(®)) throughout all exposure periods (p < 0.0001). Similarly, crosslinked porcine dermis (Permacol™) maintained greater tensile strength than noncrosslinked porcine dermis (Strattice™ and XenMatrix™) throughout all exposure periods (p < 0.0001). CONCLUSIONS: Materials that deteriorate rapidly after in vitro enzymatic exposure may also deteriorate rapidly in vivo, particularly when exposed to a wound environment with elevated levels of matrix metalloproteinases. Permacol™, CollaMend™, Strattice™, FlexHD(®), and PeriGuard(®) survived the longest incubation period (30 h) and withstood mechanical testing. XenMatrix™, AlloMax™, Veritas(®), and Surgisis™ degraded more quickly and did not survive the longer exposure periods. Scaffolds that maintain strength characteristics after in vitro collagenase exposure may be advantageous for long-term hernia repair scenarios where elevated enzyme levels are expected.

Characterization of bionanocomposite scaffolds comprised of mercaptoethylamine-functionalized gold nanoparticles crosslinked to acellular porcine tissue.

Bionanocomposite scaffolds comprised of nanomaterials and the extracellular matrix (ECM) of porcine diaphragm tissue capitalizes on the benefits of utilizing a natural ECM material, while also potentially enhancing physicomechanical properties and biocompatibility through nanomaterials. Gold nanoparticle (AuNP) bionanocomposite scaffolds were subjected to a number of characterization techniques to determine whether the fabrication process negatively impacted the properties of the porcine diaphragm tissue and whether the AuNP improved the properties of the tissue. Tensile testing and differential scanning calorimetry demonstrated that the bionanocomposite possessed improved tensile strength and thermal stability relative to natural tissue. The collagenase assay and Fourier transform infrared spectroscopy additionally confirmed that denaturation of the collagen of the ECM did not occur. The novel bionanocomposite scaffold possessed properties similar to commercially available scaffolds and will be further developed for soft tissue applications such as hernia repair through in vivo studies in an animal model.

Mechanical and Histological Characteristics of Phasix™ ST Mesh in a Porcine Model of Hernia Repair.

PURPOSE: The objective of this study was to determine mechanical and histological properties of Phasix™ ST Mesh in various defect sizes and characterize the tissue replacing Phasix™ ST Mesh in a porcine model of ventral hernia repair. METHODS: Simulated hernia defects were surgically created in the midline of twenty-four (n = 24) Yucatan pigs. Treatment groups included 8 cm defect sutured closed (buttress) and unclosed 4 cm and 8 cm defect groups. Phasix™ ST Mesh (15 cm diameter circle) was implanted laparoscopically and fixated circumferentially with SorbaFix™ Absorbable Fixation System fasteners. The repair sites underwent mechanical, molecular weight, and histological evaluation at 48 and 72 weeks postimplantation. RESULTS: Mechanical testing of Phasix™ ST Mesh-repaired sites revealed similar strengths at both time points for all three repair types, p > 0.05 in all cases (48 weeks: 142.4 ± 6.0 N, 142.3 ± 16.5 N, and 168.8 ± 38.5 N; 72 weeks: 110.0 ± 18.3 N, 138.6 ± 42.2 N, and 160.6 ± 42.0 N for 4 cm defect, 8 cm defect, and 8 cm buttress, respectively. mean ± SEM) No significant differences were observed over time except at 72 weeks postimplantation when the 4 cm defect group exhibited significantly lower strength than the T0 strength of Phasix™ ST Mesh (204.6 ± 5.0 N, p < 0.05). The molecular weight of Phasix™ ST Mesh decreased over time, regardless of repair type. Histological analysis showed comparable mature collagen/fibrovascular tissue around and within the Phasix™ ST Mesh interstices, including the segment of mesh overlying the defect. CONCLUSION: Phasix™ ST Mesh-repaired sites exhibited similar mechanical strengths and histological properties across all defect sizes in this porcine model.

Antimicrobial performance of two preoperative skin preparation solutions containing iodine and isopropyl alcohol.

BACKGROUND: Healthcare-associated infections (HAIs) are a persistent clinical challenge caused primarily by bacteria on the skin. Proper utilization of optimized antiseptic skin preparation solutions helps reduce the prevalence and impact of HAIs by decreasing patient skin microorganisms preoperatively. The purpose of this study was to evaluate the efficacy of 2 antimicrobial solutions containing iodine and isopropyl alcohol (IPA): Povidone iodine (PVP-I) with IPA (ie, PVP-I+IPA, PurPrep) and Iodine Povacrylex+IPA (DuraPrep). METHODS: The antimicrobial activity of the test solutions was evaluated in vitro by determinations of minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) against 1105 diverse microbial isolates and a time-kill assay to evaluate efficacy against 120 strains of Gram-positive and Gram-negative bacteria and yeasts. Peel tests were performed between skin samples treated with test solutions and representative drape/dressing materials to determine effects of test solutions on the biomechanical adhesion properties. Finally, an Institutional Review Board (IRB)-approved, randomized, controlled, single-center, partially blinded in vivo study was performed to assess the immediate and persistent antimicrobial activity of the test solutions on the abdomen and groin. RESULTS: Both PVP-I+IPA and Iodine Povacrylex+IPA solutions demonstrated broad-spectrum antimicrobial activity with MIC and MBC at less than 1% of the full-strength concentration of each product against a wide variety of microorganisms. In the time-kill tests, both solutions were able to successfully reduce all microbial populations by 99.99% (ie, 4 log10) at the contact times of 30 seconds, 2 minutes and 10 minutes. The 2 solutions showed relatively similar adhesion results when tested with 3 representative operating room materials. Both PVP-I+IPA and Iodine Povacrylex+IPA met the expected Food and Drug Administration (FDA) efficacy requirements at 10 minutes and 6 hours post-treatment for both anatomic sites (ie, groin, and abdomen) in the clinical study, with no safety issues or adverse events. CONCLUSIONS: Analysis of the in vitro antimicrobial activity, biomechanical adhesive strength, and in vivo efficacy of PVP-I+IPA demonstrated similar results compared to Iodine Povacrylex+IPA. Both products were efficacious at reducing or eliminating a wide range of clinically-relevant microorganisms in lab-based and clinical settings, supporting their use as antiseptic skin preparation solutions to reduce bacteria on the skin that can cause infection.