Lora Melman

Histologic and Biomechanical Evaluation of Crosslinked and Non-Crosslinked Biologic Meshes in a Porcine Model of Ventral Incisional Hernia Repair

BACKGROUND The objective of this study was to evaluate the biomechanical characteristics and histologic remodeling of crosslinked (Peri-Guard, Permacol) and non-crosslinked (AlloDerm, Veritas) biologic meshes over a 12 month period using a porcine model of incisional hernia repair. STUDY DESIGN Bilateral incisional hernias were created in 48 Yucatan minipigs and repaired after 21 days using an underlay technique. Samples were harvested at 1, 6, and 12 months and analyzed for biomechanical and histologic properties. The same biomechanical tests were conducted with de novo (time 0) meshes as well as samples of native abdominal wall. Statistical significance (p < 0.05) was determined using 1-way analysis of variance with a Fishers least significant difference post-test. RESULTS All repair sites demonstrated similar tensile strengths at 1, 6, and 12 months and no significant differences were observed between mesh materials (p > 0.05 in all cases). The strength of the native porcine abdominal wall was not augmented by the presence of the mesh at any of the time points, regardless of de novo tensile strength of the mesh. Histologically, non-crosslinked materials showed earlier cell infiltration (p < 0.01), extracellular matrix deposition (p < 0.02), scaffold degradation (p < 0.05), and neovascularization (p < 0.02) compared with crosslinked materials. However, by 12 months, crosslinked materials showed similar results compared with the non-crosslinked materials for many of the features evaluated. CONCLUSIONS The tensile strengths of sites repaired with biologic mesh were not impacted by very high de novo tensile strength/stiffness or mesh-specific variables such as crosslinking. Although crosslinking distinguishes biologic meshes in the short-term for histologic features, such as cellular infiltration and neovascularization, many differences diminish during longer periods of time. Characteristics other than crosslinking, such as tissue type and processing conditions, are likely responsible for these differences.

Elastic Fiber Depletion in the Supporting Ligaments of the Gastroesophageal Junction: A Structural Basis for the Development of Hiatal Hernia

BACKGROUND The position of the gastroesophageal junction is maintained by a complex of fibroelastic ligaments. The purpose of this study was to characterize and compare the histology of these ligaments in patients with gastroesophageal reflux disease (GERD) and hiatal hernia (HH) versus GERD alone, with emphasis on the elastin morphology. STUDY DESIGN Thirteen patients were examined at the time of laparoscopic fundoplication for symptomatic GERD; nine had no significant HH and four had large diaphragmatic hernias (GERD/HH). Tissue biopsies were obtained from the gastrohepatic ligament (GHL, n=5 and n=3, GERD and GERD/HH, respectively), the phrenoesophageal ligament (n=7 and n=4, respectively), and the gastrophrenic ligament (n=6 and n=4, respectively). Sections of fixed tissue were stained with hematoxylin and eosin, Massons trichrome, and resorcin-fuchsin for analysis of elastic fibers by light microscopy, and elastin area was quantified and expressed as a percentage of the imaged tissue. RESULTS Elastin and collagen fibers were prominent in all ligaments in patients with GERD alone. In patients with GERD/HH, there was fragmentation and distortion of elastin in the phrenoesophageal ligament and gastrohepatic ligament, and to a lesser degree, in the gastrophrenic ligament. Compared with patients with GERD alone, the presence of hiatal hernia was associated with a reduction in elastin area by more than 50% in the phrenoesophageal ligament ([mean +/- SEM] 31.0%+/-3.3% versus 15.1%+/-1.3%, p < 0.01) and gastrohepatic ligament (26.9% +/- 0.5% versus 12.5%+/-0.1%, p < 0.008). There was no decrease with respect to elastin in the gastrophrenic ligament. CONCLUSIONS The periesophageal ligaments in patients with GERD are characterized by prominent elastic fibers. In contrast, GERD/HH is associated with depletion of elastic fibers in two of three ligaments supporting the gastroesophageal junction. Elastic fiber depletion in the periesophageal ligaments thereby provides a structural basis for the development of HH. It remains unclear if this represents a primary (etiologic) alteration or if it is a secondary phenomenon.

Informed Consent: Cultural and Religious Issues Associated with the Use of Allogeneic and Xenogeneic Mesh Products

BACKGROUND Our aim was to investigate the views of major religions and cultural groups regarding the use of allogeneic and xenogeneic mesh for soft tissue repair. STUDY DESIGN We contacted representatives from Judaism, Islam, Buddhism, Hinduism, Scientology, and Christianity (Baptists, Methodists, Seventh-Day Adventists, Catholics, Lutherans, Church of Jesus Christ of Latter-Day Saints, Evangelical, and Jehovahs Witnesses). We also contacted American Vegan and People for the Ethical Treatment of Animals (PETA). Standardized questionnaires were distributed to the religious and cultural authorities. Questions solicited views on the consumption of beef and pork products and the acceptability of human-, bovine-, or porcine-derived acellular grafts. RESULTS Dietary restrictions among Jews and Muslims do not translate to tissue implantation restriction. Approximately 50% of Seventh-day Adventists and 40% of Buddhists practice vegetarianism, which may translate into a refusal of the use of xenogeneic tissue. Some Hindus categorically prohibit the use of human tissue and animal products; others allow the donation and receipt of human organs and tissues. PETA is opposed to all uses of animals, but not to human acellular grafts or organ transplantation. Some vegans prefer allogeneic to xenogeneic tissue. Allogeneic and xenogeneic acellular grafts are acceptable among Scientologists, Baptists, Lutherans, Evangelicals, and Catholics. Methodists, Jehovahs Witnesses, and The Church of Jesus Christ of Latter-Day Saints leave the decision up to the individual. CONCLUSIONS Knowledge of religious and cultural preferences regarding biologic mesh assists the surgeon in obtaining a culturally sensitive informed consent for procedures involving acellular allogeneic or xenogeneic grafts.

Evaluation of Acute Fixation Strength for Mechanical Tacking Devices and Fibrin Sealant Versus Polypropylene Suture for Laparoscopic Ventral Hernia Repair

Background: The purpose of this comparative study is to evaluate the acute fixation strength of mechanical tacking devices and fibrin sealant against polypropylene suture for laparoscopic ventral hernia repair. Methods: Three metallic mechanical tacking devices (ProTack, Salute, EndoANCHOR), 4 absorbable tacking devices (AbsorbaTack, PermaSorb, I-Clip, and SorbaFix), and 2 types of fibrin sealant (Tisseel, Artiss) were compared with 0-polypropylene suture. Three constructs from each device or an amount of sealant sufficient to cover a 3 × 3 cm2 area were used to affix a 4 × 3 cm piece of absorbable barrier-coated mesh (Proceed, Ethicon, Inc) to the peritoneal surface of porcine abdominal wall. Ten samples were completed for each fixation modality. Acute fixation strength was measured via a lap shear test on an Instron tensiometer. Results: Acute fixation strength was significantly greater for suture (59.7 7.2 N) compared with all laparoscopic tacking devices and to fibrin sealant (P < .001 for all comparisons). Protack (29.5 ± 2.8 N) was stronger than Absorbatack (13.2 ± 3.7 N; P = .029). Protack, Permasorb, SorbaFix, and I-clip were stronger than fibrin sealant (P < .05 for all comparisons). Conclusions: The acute fixation strengths of metallic or absorbable tacks as well as fibrin sealant are all significantly less than that achieved with polypropylene suture. These factors should be considered in selecting the type of mechanical fixation for patients undergoing laparoscopic ventral hernia repair.

Biomechanical and Histologic Evaluation of Fenestrated and Nonfenestrated Biologic Mesh in a Porcine Model of Ventral Hernia Repair

BACKGROUND The purpose of this study was to compare tissue incorporation and adhesion characteristics of a novel fenestrated versus nonfenestrated crosslinked porcine dermal matrix (CPDM) (Bard CollaMend) in a porcine model of ventral hernia repair. STUDY DESIGN Bilateral abdominal wall defects were created in 24 Yucatan minipigs, resulting in 48 defects, which were allowed to mature for 21 days. Twelve defects were repaired with fenestrated CPDM using a preperitoneal technique, 12 with fenestrated CPDM using an intraperitoneal technique, 12 with nonfenestrated CPDM using a preperitoneal technique, and 12 with nonfenestrated CPDM using an intraperitoneal technique. Half of the animals in the intraperitoneal group were euthanized after 1 month, and the other half after 3 months. Similarly, half of the animals in the preperitoneal group were euthanized after 1 month, and the other half after 6 months. Biomechanical testing and histologic evaluation were performed. RESULTS Intraperitoneal placement of the CPDM products resulted in significantly greater adhesed area compared with preperitoneal placement (p < 0.05). Tissue ingrowth into preperitoneal fenestrated and nonfenestrated CPDM resulted in significantly greater incorporation strengths after 6 months compared with 1 month (p = 0.03 and p < 0.0001). Histologic analysis showed significantly greater cellular infiltration, extracellular matrix deposition, and neovascularization, with less fibrous encapsulation through the center of the fenestrations compared with all other sites evaluated, including nonfenestrated grafts. CONCLUSIONS Histologic findings revealed increased tissue incorporation at fenestration sites compared with nonfenestrated grafts regardless of implant location or time in vivo. However, preperitoneal placement resulted in greater incorporation strength, less adhesed area, and lower adhesion scores compared with intraperitoneal placement for both fenestrated and nonfenestrated CPDM.

Current Trends in Laparoscopic Solid Organ Surgery: Spleen, Adrenal, Pancreas, and Liver

Laparoscopic procedures are becoming increasingly preferred by both surgeons and patients owing to decreased pain, reduced perioperative morbidity, and an earlier return to self-reliance. Laparoscopy for solid organ surgery has been slower to evolve when compared with procedures such as laparoscopic cholecystectomy owing to factors involving lower case volume and refinement of technologies specific to operations involving the spleen, adrenal, pancreas, and liver. Future integration of technology will allow surgeons to offer increasingly less morbid therapies aimed at the patients best clinical outcome.