Xenograft use in reconstructive pelvic surgery: a review of the literature

A preliminary evaluation of in vivo response to a filament-wound macroporous collagen midurethral sling in an ovine model

Stress urinary incontinence (SUI) impacts ~1/3 of women over age 50. Negative publicity around PP meshes used in pelvic prolapse repair drives the need for identifying alternative biomaterials for SUI repair. Our study evaluated in vivo response to collagen sling implanted in an ovine model. Electrocompacted collagen threads were filament wound as slings and crosslinked in genipin. Collagen slings were implanted suburethrally mimicking the transvaginal tape technique. Main study groups were: Collagen sling (n = 3, 6 months) and PP sling (n = 3, 6 months). Collagen sling was also tested at 3-weeks (n = 1) to observe early-stage tissue response and 1-year (n = 2) to assess biomaterial longevity in a preliminary capacity. Collagen slings healed to a fibrous ligament texture at 6 months and maintained such texture to 1 year. Histological scoring indicated biocompatible responses to collagen slings with no adverse events. All study groups exhibited complete tissue ingrowth and interstitial de novo collagen deposition at all time points. Collagen threads induced orderly de novo collagen deposition that was aligned along long axes of threads. Tissue infiltrated collagen slings that were explanted at 6 and 12 months presented similar structural strength with native tissues such as vagina and fascia, and PP (Lynx) slings (p > .05). With the limitation of low number of animals per time point in hindsight, this preliminary study justifies evaluation of collagen slings in a larger sample size of animals, particularly to assess persistence of ligamentous tissue response over longer durations than 1-year.

Repair of bone defects in rhesus monkeys with α1,3-galactosyltransferase-knockout pig cancellous bone

Introduction: Since xenografts offer a wide range of incomparable advantages, they can be a better option than allografts but only if the possibility of immunological rejection can be eliminated. In this study, we investigated the ability of α1,3-galactosyltransferase (α1,3-GT) gene knockout (GTKO) pig cancellous bone to promote the repair of a femoral condyle bone defect and its influence on heterologous immune rejection.

Materials and methods: Cylindrical bone defects created in a rhesus monkey model were transplanted with GTKO bone, WT bone or left empty. For immunological evaluation, T lymphocyte subsets CD4⁺ and CD8⁺ in peripheral blood were assayed by flow cytometry, and the IL-2 and IFN-γ contents of peripheral blood serum were analyzed by ELISA at 2, 5, 7, 10, and 14 days post-surgery. Micro-CT scans and histological assessment were conducted at 4 and 8 weeks after implantation.

Results: Compared with WT-pig bone, the heterologous immunogenicity of GTKO-pig bone was reduced. The defect filled with fresh GTKO-pig bone was tightly integrated with the graft. Histological analysis showed that GTKO-pig cancellous bone showed better osseointegration and an appropriate rate of resorption. Osteoblast phenotype progression in the GTKO group was not affected, which revealed that GTKO-pig bone could not only fill and maintain the bone defect, but also promote new bone formation.

Conclusion: GTKO-pig cancellous bone decreased the ratio of CD4⁺ to CD8⁺ T cells and cytokines (IFN-γ and IL-2) to inhibit xenotransplant rejection. Moreover, GTKO group increased more bone formation by micro-CT analysis and osteoblastic markers (Runx2, OSX and OCN). Together, GTKO-pig cancellous bone showed better bone repair than WT-pig cancellous bone.

Effect of Mammalian Tissue Source on the Molecular and Macroscopic Characteristics of UV-Cured Type I Collagen Hydrogel Networks

The tissue source of type I collagen is critical to ensure scalability and regulation-friendly clinical translation of new medical device prototypes. However, the selection of a commercial source of collagen that fulfils both aforementioned requirements and is compliant with new manufacturing routes is challenging. This study investigates the effect that type I collagen extracted from three different mammalian tissues has on the molecular and macroscopic characteristics of a new UV-cured collagen hydrogel. Pepsin-solubilised bovine atelocollagen (BA) and pepsin-solubilised porcine atelocollagen (PA) were selected as commercially available raw materials associated with varying safety risks and compared with in-house acid-extracted type I collagen from rat tails (CRT). All raw materials displayed the typical dichroic and electrophoretic characteristics of type I collagen, while significantly decreased lysine content was measured on samples of PA. Following covalent functionalisation with 4-vinylbenzyl chloride (4VBC), BA and CRT products generated comparable UV-cured hydrogels with significantly increased averaged gel content (G ≥ 97 wt.%), while the porcine variants revealed the highest swelling ratio (SR = 2224 ± 242 wt.%) and an order of magnitude reduction in compression modulus (Ec = 6 ± 2 kPa). Collectively, these results support the use of bovine tissues as a chemically viable source of type I collagen for the realisation of UV-cured hydrogels with competitive mechanical properties and covalent network architectures.

Mammalian Pericardium-Based Bioprosthetic Materials in Xenotransplantation and Tissue Engineering

Bioprosthetic materials based on mammalian pericardium tissue are the gold standard in reconstructive surgery. Their application range covers repair of rectovaginal septum defects, abdominoplastics, urethroplasty, duraplastics, maxillofacial, ophthalmic, thoracic and cardiovascular reconstruction, etc. However, a number of factors contribute to the success of their integration into the host tissue including structural organization, mechanical strength, biocompatibility, immunogenicity, surface chemistry, and biodegradability. In order to improve the material's properties, various strategies are developed, such as decellularization, crosslinking, and detoxification. In this review, the existing issues and long-term achievements in the development of bioprosthetic materials based on the mammalian pericardium tissue, aimed at a wide-spectrum application in reconstructive surgery are analyzed. The basic technical approaches to preparation of biocompatible forms providing continuous functioning, optimization of biomechanical and functional properties, and clinical applicability are described.

The Rise and Fall of Mesh in Pelvic Surgery and the Shortcomings of Medical Device Regulation

Two U.S. Food and Drug Administration public health warnings regarding the use of mesh in stress incontinence and prolapse repairs have had far-reaching clinical and legal consequences. In this commentary, we explore the drastically distinct results from these mesh-based procedures, which revealed systemic flaws with the medical device approval process across specialties and affected thousands of patients.

Surgical perspectives regarding application of biomaterials for the management of large congenital diaphragmatic hernia defects

This review focuses on the surgical viewpoints on patch repairs in neonates with large congenital diaphragmatic hernia defects. The main focus  is on the various biomaterials that have been employed to date with regard to their source of origins, degradation properties as well as tissue integration characteristics. Further focus  is on the present knowledge on patch integration when biomaterials are placed in the diaphragmatic defect. The review will also look at the present evidence on the biomechanical characteristics of the most commonly used biomaterials and compares these materials to diaphragmatic tissue to offer more  insight on the present practice of patch repairs in large defects. Since tissue engineering and regenerative medicine has offered another dimension to diaphragmatic replacement, a detailed overview of this technology will be undertaken with regard to cell sourcing, scaffolds, in vitro versus in vivo implants as well as quality of tissue produced, to explore the limitations and the feasibility facing the scientific community in its clinical implementation of skeletal muscle-engineered tissue beyond laboratory research for diaphragmatic replacement.

Biomimetic implants for pelvic floor repair

BACKGROUND

Polypropylene implants are used for the reconstructive surgery of urogynaecological disorders like pelvic organ prolapse, but severe complications associated with their use have been reported. There is evidence that surface properties and a difference in mechanical stiffness between the implant and the host tissue contribute to these adverse events. Electrospinning is an innovative engineering alternative that provides a biomimetic microstructure for implants, resulting in a different mechano-biological performance.

AIM

The main objective of this review is to inform about the potential of electrospun matrices as an alternative modality for pelvic floor repair.

METHODS

Publications with the following studies of electrospun matrices were reviewed: (i) the technique; (ii) in vitro use for soft tissue engineering; (iii) in vivo use for reconstruction of soft tissues in animals; and (iv) clinical use in humans.

RESULTS

Electrospun matrices provide a synthetic mimic of natural extracellular matrix (ECM), favoring cellular attachment, proliferation and matrix deposition, through which a proper, low-inflammatory tissue-implant interaction can be established. Electrospun sheets can also be created with sufficient mechanical strength and stiffness for usage in prolapse surgery.

CONCLUSION

Electrospun matrices mimic the structural topography of the extracellular matrix and can be functionalized for better biological performance. As such, they have great potential for the next generation of urogynecological implants. However, their long-term safety and efficacy must still be established in vivo.

Surgical Management of the Constricted or Obliterated Vagina

Management of the constricted or obliterated vagina demands an understanding and recognition of the potential etiologies leading to this presentation. A thorough and comprehensive medical and surgical review is required to arrive at an accurate diagnosis, which then will guide medical or surgical intervention. It is paramount to recognize when underlying medical conditions are contributing to these conditions and to begin medical therapy; failure to do so will often yield suboptimal results. When these conditions arise after surgical interventions, compensatory surgical techniques that correct upper and lower vaginal strictures or obliteration include incision through the stricture, vaginal advancement, Z-plasty, skin grafts, perineal flaps, and abdominal flaps and grafts. Postoperative surveillance and dilation are critical to optimize long-term success.

Transforming surgery through biomaterial template technology

Templates inserted into surgical wounds strongly influence the healing responses in humans. The science of these templates, in the form of extracellular matrix biomaterials, is rapidly evolving and improving as the natural interactions with the body become better understood.

Glycerolized Reticular Dermis as a New Human Acellular Dermal Matrix: An Exploratory Study

Human Acellular Dermal Matrices (HADM) are employed in various reconstructive surgery procedures as scaffolds for autologous tissue regeneration. The aim of this project was to develop a new type of HADM for clinical use, composed of glycerolized reticular dermis decellularized through incubation and tilting in Dulbecco's Modified Eagle's Medium (DMEM). This manufacturing method was compared with a decellularization procedure already described in the literature, based on the use of sodium hydroxide (NaOH), on samples from 28 donors. Cell viability was assessed using an MTT assay and microbiological monitoring was performed on all samples processed after each step. Two surgeons evaluated the biomechanical characteristics of grafts of increasing thickness. The effects of the different decellularization protocols were assessed by means of histological examination and immunohistochemistry, and residual DNA after decellularization was quantified using a real-time TaqMan MGB probe. Finally, we compared the results of DMEM based decellularization protocol on reticular dermis derived samples with the results of the same protocol applied on papillary dermis derived grafts. Our experimental results indicated that the use of glycerolized reticular dermis after 5 weeks of treatment with DMEM results in an HADM with good handling and biocompatibility properties.

Preparation of a small intestinal submucosa modified polypropylene hybrid mesh via a mussel-inspired polydopamine coating for pelvic reconstruction

Pelvic organ prolapse (POP) is a serious health issue that affects many adult women. Surgical treatments for POP patients comprise a common strategy in which scaffold materials are used to reconstruct the prolapsed pelvic. However, the existing materials for pelvic reconstruction cannot meet clinical requirements in terms of biocompatibility, mechanics and immunological rejection. To address these concerns, polypropylene (PP) mesh was selected because of its strong mechanical properties. Small intestinal submucosa (SIS) was used to modify the PP mesh via a mussel-inspired polydopamine coating to enhance its biocompatibility. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) results demonstrated that SIS was successfully conjugated on the surface of the PP mesh. Moreover, the cytotoxicity results indicated that the PP mesh and SIS-modified PP mesh were safe to use. Furthermore, in vivo tests demonstrated that the fibroplasia around the implanted site in the SIS-modified PP mesh group was significantly less than the fibroplasia around the PP mesh group. In addition, the immunohistochemistry staining results indicated that the expression of pro-inflammatory macrophages (M1) was substantially lower and that the expression of pro-healing macrophages (M2) was higher in the SIS-modified PP mesh group. Furthermore, ELISA detection indicated that the expression of IL-1β and IL-6 in the SIS-modified PP mesh group was reduced compared with the PP mesh group. These findings suggest that a SIS-modified polypropylene hybrid mesh via a mussel-inspired polydopamine coating is a promising approach in pelvic reconstruction.

Comparison of graft-reinforced repairs and suture repair using a novel biomechanical test

INTRODUCTION AND HYPOTHESIS

The aim of this study was to determine the feasibility of a novel biomechanical test for evaluating mesh-reinforced repair compared to suture-reinforced repair using an animal model. We hypothesized that the fatigue life of a mesh reinforced repair would be greater than that of xenograft reinforced repair and suture-only repair.

METHODS

Wistar rats were randomly assigned to undergo a ventral hernia repair using sutures or one of the three mesh materials representative of incorporation, encapsulation and resorption host responses (Gynemesh, Pelvisoft and Surgisis®, respectively). All surviving animals were killed at 90 days and specimens containing the prosthesis-tissue interface were exposed to cyclic forces. The number of cycles to failure (fatigue life) was compared between groups using a Cox regression model.

RESULTS

Of 40 randomly assigned animals, 11 died before 90 days. After randomizing an additional 5 rats, a total of 34 rats were killed at 90 days. The proportions of specimens that failed before 10,000 cycles were 25% (2/8), 50% (4/8), 62.5% (5/8) and 70% (7/10) in the Gynemesh, Surgisis, Pelvisoft, and suture control groups, respectively. In addition, the median number of cycles to failure was >10,000 in the Gynemesh group, >6,923 in the Surgisis group, 1133 in the Pelvisoft group and 741 in the control group. After adjustment for cross-sectional area, the risk of failure in the suture control group was higher than in all of the reinforced repair groups combined with an adjusted hazard ratio of 2.58 (95% CI 0.96 - 6.97), and was statistically significantly higher than in the Gynemesh group with an adjusted hazard ratio of 6.67 (95% CI 1.30 - 34.48).

CONCLUSION

We present a novel biomechanical test that can be used to compare mesh materials in an animal model prior to use in humans. In this animal model, after adjusting for cross-sectional area, suture reinforced repair has a higher risk of failure than graft reinforced repair.

Integration of nondegradable polystyrene and degradable gelatin in a core-sheath nanofibrous patch for pelvic reconstruction

Pelvic organ prolapse (POP) is a serious health issue affecting many adult women. Complications of POP include pelvic pressure, pelvic pain, and problems in emptying their bowels or bladder. Sometimes, POP may even cause urinary outflow obstruction and lead to bladder or kidney infections. Currently, synthetic and naturally derived materials have been chosen for treatment of POP to reduce the high recurrence rates after surgical interventions. However, existing materials for POP treatment cannot meet the clinical requirements in terms of biocompatibility, mechanics, and minimal risk of rejection. Especially, erosion in synthetic polymers and rapid degradation in natural polymers limit their further applications in clinics. To address these concerns, we report a novel POP replacement using core-sheath polystyrene/gelatin electrospun nanofiber mesh. The outside gelatin sheath provides a hydrophilic surface and implantable integrity between host and guest, while the inner PS core offers the necessary mechanical support. The composite mesh shows graft accommodation in pelvic submucosa after implantation in vivo, as shown in hematoxylin-eosin staining and T helper cell phenotype and macrophage phenotype stainings. Qualitative analysis of inducible nitric oxide synthase, arginase, interferon-γ, and interleukin-10 gene expressions also indicates that the implanted composite mesh switches to accommodation mode 2 weeks postimplantation. Thus, these novel core-sheath polystyrene/gelatin nanofibrous membranes are promising in pelvic reconstruction.

Full thickness abdominal wall defect in growing rats as a model for congenital diaphragmatic hernia prosthetic repair

BACKGROUND

Large congenital diaphragmatic hernia may require prosthetic correction. Acellular collagen matrices were introduced to avoid complications owing to the use of synthetic patches. We tested 3 different ACM for reconstruction of an abdominal wall defect in an animal model that mimics the fast growth during infancy.

METHODS

Pelvisoft® (CR Bard, Covington, GA) and 2 investigational ACM were used for primary reconstruction of a full thickness abdominal wall defect. 3months-old rats (n=26) were allowed to survive for 90days after implantation. Anatomical, tensiometric and histological analyses were performed. Based on good outcomes, we did the same with 1month-old rats (n=54). Unoperated rats were used for obtaining reference tensiometric values of selected native tissues.

RESULTS

Major wound complications were exclusively observed in 1month-old rats. All explants in both groups thinned significantly (p<0.03) and had an elastic modulus increasing over time, far above that from native tissues at 90days of life. Both investigational ACM induced a more vigorous foreign body reaction than Pelvisoft(®).

CONCLUSIONS

The shift from 3 to 1month-old rats was associated with wound complications. Pelvisoft® showed a better biocompatibility than the 2 investigational ACM. Passive biomechanical properties of all explants were still not comparable to that of native tissues.

Evaluation of an established pericardium patch for delivery of mesenchymal stem cells to cardiac tissue

The present study has evaluated a commercial pericardial material for its capacity to assist as a natural extracellular matrix (ECM) patch for the delivery and retention of mesenchymal stem cells for cardiac repair. The repair of cardiac tissue with cells delivered by an appropriate bioscaffold is expected to offer a superior, long-lasting treatment strategy. The present material, CardioCel®, is based on acellular pericardium that has been stabilized by treatments, including a low concentration of glutaraldehyde, that eliminate calcification after implantation. In the present study, we have assessed this material using human bone marrow mesenchymal stem cells at various cell densities under standard, static cell culture conditions. The initial seeding densities were monitored to evaluate the extent of cell attachment and cell viability, with subsequent cell proliferation assessed up to 4 weeks using an MTS assay. Cell morphology, infiltration, and spreading were tracked using scanning electron microscopy and phalloidin staining. The efficacy of long-term cell survival was further assessed by examining the extent and type of new tissue formation on seeded scaffolds at 70 days; both type I and type III collagens were present in fibrillar structures on these scaffolds indicating that the seeded stem cells had the capacity to differentiate into collagen-producing cells necessary to repair damaged ECM. These data show that the CardioCel® scaffold is an appropriate substrate for the stem cells and has the potential to both retain seeded stem cells and to act as a template for cell propagation and new tissue formation.

The outcome of transobturator anterior vaginal wall prolapse repair using porcine dermis graft: intermediate term follow-up

INTRODUCTION AND HYPOTHESIS

We evaluated the anatomical success and complications of Perigee® with porcine dermis Graft in the repair of anterior vaginal wall prolapse (AVWP) MATERIALS AND METHODS: After Institutional Review Board (IRB) approval, the charts of all patients who underwent AVWP repair using the Perigee/InteXen® kit from July 2005 to July 2009 were reviewed. Patients who had less than 6-month follow-up were excluded. Preoperative data including patient age, previous AVWP repairs, hysterectomy status, preoperative dyspareunia and pertinent physical findings were collected and recorded. Postoperative success was defined as anatomical stage 0 or I using the Pelvic Organ Prolapse Quantification (POP-Q) scoring system. Graft related complications were also recorded.

RESULTS

Out of 89 patients, 69 completed at least 6-month follow-up. Median follow-up was 13 (6-48) months. Seventeen patients (25%) had previous AVWP repair and 32 (46%) had previous hysterectomy. Preoperatively, AVWP stage II was found in 9 (13%), stage III in 27 (39%) and stage IV in 33 (48%) patients. Anatomic success was found in 48 (69%) patients, with 23 (33%) having stage 0 and 25 (36%) stage I AVWP. Intraoperative complications included incidental cystotomy in one patient and bladder perforation in one. Postoperative complications included vaginal exposure and dyspareunia in one case, wound dehiscence in one and tenderness over the graft arm with dyspareunia in one.

CONCLUSIONS

The use of porcine dermis in AVWP repair is safe with minimal graft related complications; however, anatomical success is lower than that reported with the use of synthetic grafts.

Collagen--emerging collagen based therapies hit the patient

The choice of biomaterials available for regenerative medicine continues to grow rapidly, with new materials often claiming advantages over the short-comings of those already in existence. Going back to nature, collagen is one of the most abundant proteins in mammals and its role is essential to our way of life. It can therefore be obtained from many sources including porcine, bovine, equine or human and offer a great promise as a biomimetic scaffold for regenerative medicine. Using naturally derived collagen, extracellular matrices (ECMs), as surgical materials have become established practice for a number of years. For clinical use the goal has been to preserve as much of the composition and structure of the ECM as possible without adverse effects to the recipient. This review will therefore cover in-depth both naturally and synthetically produced collagen matrices. Furthermore the production of more sophisticated three dimensional collagen scaffolds that provide cues at nano-, micro- and meso-scale for molecules, cells, proteins and bulk fluids by inducing fibrils alignments, embossing and layered configuration through the application of plastic compression technology will be discussed in details. This review will also shed light on both naturally and synthetically derived collagen products that have been available in the market for several purposes including neural repair, as cosmetic for the treatment of dermatologic defects, haemostatic agents, mucosal wound dressing and guided bone regeneration membrane. There are other several potential applications of collagen still under investigations and they are also covered in this review.

Ureteral injury during vaginal mesh excision: role of prevention and treatment options

Vaginal mesh kits are increasingly used in vaginal prolapse repair. Mesh erosion, infection, and pain may necessitate removal, which can lead to urinary tract injury. We describe 2 cases of ureteral injury at the time of mesh excision. Surgeons must recognize the possibility of ureteral injury and treatment modalities available.

Biologic grafts for ventral hernia repair: a systematic review

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Abdominal rectopexy with absorbable and non-absorbable materials in the treatment for rectal prolapse

THE AIM OF THE STUDY was to present and compare own results of abdominal rectopexy performed with absorbable and nonabsorbable materials used in surgical repair of rectal prolapse.

MATERIAL AND METHODS

In the years 1991-2009, 50 patients were operated on for rectal prolapse. The first 8 patients (group I) were operated using absorbale polyglycolic acid mesh. The next 42 patients were operated using non-absorbable polypropylene mesh (group II). 12 patients with chronic, incurable constipation had sigmoidectomy and rectopexy performed at the same operation. Rectopexy was performed with the mesh and fixed to the pelvic fascia and periosteum and mesorectum, leaving the anterior one third of the rectum free. 6 months after surgery functional outcomes were evaluated. Statistic analysis with the level of statistical significance p < 0.005 was applied to obtained functional results.

RESULTS

On the follow up visits, there were no symptoms of the recurrence of rectal prolapse in 5 patients (62.5%) from group I and in 25 patients (92.6%) from group II. Patients relapsing were reoperated 24 to 98 months after primary surgery. In all patients from group I (absorbable mesh), prosthetic material was not found at reoperation. In redo surgery only non-absorbable mesh was used.

CONCLUSIONS

The effectiveness of rectal fixation depends on the on the durability of the prosthetic material. In the studied group polypropylene mesh was superior in rectopexy to absorbable mesh.

Use of surgisis for treatment of anterior and posterior vaginal prolapse

Aim. To evaluate the anatomical success and complication rate of Surgisis in the repair of anterior and posterior vaginal wall prolapse. Methods. A retrospective review of 65 consecutive Surgisis prolapse repairs, involving the anterior and/or posterior compartment, performed between 2003 and 2009, including their objective and subjective success rates using the pelvic organ prolapse quantification (POPQ) system. Results. The subjective success rate (no symptoms and no bulge beyond the hymen) was 92%, and the overall objective success rate (no subsequent prolapse in any compartment) was 66% (43 of 65). The overall reoperation rate for de novo and recurrent prolapse was 7.7% with 3 women undergoing repeat surgery at the same site (anterior compartment). No long-term complications occurred. Conclusions. Surgisis has a definite role in the surgical treatment of prolapse. It may decrease recurrences seen with native tissue repair and long-term complications of synthetic mesh. Its use in posterior compartment repair in particular is promising.

Long-term outcomes after native tissue vs. biological graft-augmented repair in the posterior compartment

INTRODUCTION AND HYPOTHESIS

We aimed to compare the outcomes of native tissue vs. biological graft-augmented repair in the posterior compartment. We hypothesized that the addition of graft would result in superior anatomic and functional outcomes.

METHODS

A retrospective review of posterior repairs between 2001 and 2008 was performed to compare the anatomic and functional outcomes between native tissue and graft-augmented techniques. Mann-Whitney and chi-square tests were used. Power calculation determined that 32 subjects were needed in each group.

RESULTS

One hundred twenty-four native tissue and 69 graft-augmented repairs were performed with a median follow-up of 35.8 months (range, 6 to 157 months). Anatomic success was similar for native tissue vs. graft (Bp < -1, 86% vs. 80% and Bp ≤ 0, 97% vs. 97%; all p > 0.05). Postoperative splinting and incomplete evacuation was greater in the graft group (splinting, 85% vs. 68%; p = 0.04 and incomplete evacuation, 85% vs. 64%; p = 0.03).

CONCLUSION

Long-term success of posterior repair is high. Graft augmentation does not appear to improve anatomic or functional outcomes.

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.

Site-specific prolapse surgery. II. Vaginal paravaginal repair augmented with either synthetic mesh or remodelling xenograft

INTRODUCTION AND HYPOTHESIS

This study aims to answer the question, "Does tissue augmentation improve the mechanical repair of displacement cystourethrocoele?"

METHODS

A retrospective cohort study comparing 108 bridging graft vaginal paravaginal repairs (89 tissue-inductive xenografts and 19 polypropylene mesh) to 59 native tissue historical controls was conducted. Main outcome measures were same-site prolapse recurrence and time to failure. Initial reliability was evaluated by chi-squared test, 10-year durability by Kaplan-Meier survival analysis and risk factors by Cox regression.

RESULTS

Late recurrence was 17.7% lower with augmentation (logrank test χ (2) = 8.4, p value = 0.0038 < 0.05, adjusted regression analysis χ (2) = 2.94; p value = 0.0866 <0.10), implicating collagen degeneration in repair failure.

CONCLUSIONS

Rebuilding the pubocervical septum, from arcus to arcus and pubic ramus to pericervical ring, satisfies the mechanical but not the metabolic hernia principles. Bridging grafts simplify technical repair (reducing prolapse persistence from 10.2% to 4.6%), and also rejuvenate adjacent connective tissue (reducing late recurrence from 22.6% to 4.9%).

Use of Surgisis mesh in the management of polypropylene mesh erosion into the vagina

INTRODUCTION AND HYPOTHESIS

mesh in pelvic reconstructive surgery is being used increasingly in clinical practice. Complications such as mesh erosion and dyspareunia can cause significant patient morbidity. In cases where vaginal mesh erosions are large or multifocal resulting in inadequate healthy epithelium for repair, this may lead to recurrent mesh erosion or vaginal stenosis.

METHOD

nine patients with synthetic mesh erosion who failed to respond to conservative measures were managed surgically with Surgisis.

RESULTS

the median time at which patients presented with mesh erosion was 12 weeks. The size of erosion ranged from 1 to 4 cm in diameter. At follow-up, five patients were cured, three still had evidence of mesh erosion although the overall defects were smaller, and one patient required further surgery.

CONCLUSION

with mesh erosion being a troublesome reality following insertion of synthetic mesh repairs, Surgisis may prove to be a useful option in the treatment of large vaginal mesh defects.

Evaluation of fenestrated and non-fenestrated biologic grafts in a porcine model of mature ventral incisional hernia repair

INTRODUCTION

The purpose of this study is to compare the tissue incorporation of a novel fenestrated and non-fenestrated crosslinked porcine dermal matrix (CPDM) (CollaMend™, Davol Inc., Warwick, RI) in a porcine model of ventral hernia repair.

METHODS

Bilateral abdominal wall defects were created in 12 Yucatan minipigs and repaired with a preperitoneal or intraperitoneal technique 21 days after hernia creation. Animals were randomized to fenestrated or non-fenestrated CPDM for n = 6 pieces of each graft in the preperitoneal or intraperitoneal location. All animals were sacrificed at 1 month. Adhesion characteristics and graft contraction/growth were measured by the Garrard adhesion grading scale and transparent grid overlay. Histological analysis of hematoxylin and eosin (H&E)-stained slides was performed to assess graft incorporation. Tissue incorporation strength was measured by a T-peel tensile test. The strength of explanted CPDM alone and de novo CPDM was measured by a uniaxial tensile test using a tensiometer (Instron, Norwood, MA) at a displacement rate of 0.42 mm/s. Statistical significance (P < 0.05) was determined for histological analysis using a Kruskal-Wallis non-parametric test with a Bonferroni correction, and for all other analyses using a two-way analysis of variance (ANOVA) with a Bonferroni post-test or a Kruskal-Wallis non-parametric test with a Dunn's post-test.

RESULTS

Intraperitoneal placement of fenestrated CPDM resulted in a significantly higher area of adhesions and adhesion score compared to the preperitoneal placement of fenestrated CPDM (P < 0.05). For both preperitoneal and intraperitoneal placement, histological findings demonstrated greater incorporation of the graft due to the fenestrations. No significant differences were detected in the uniaxial tensile strengths of the graft materials alone, either due to the graft type (non-fenestrated vs. fenestrated) or due to the placement location (preperitoneal vs. intraperitoneal). The incorporation strength (T-peel force) was significantly greater for fenestrated compared to non-fenestrated CPDM when placed in the preperitoneal location (P < 0.01). The incorporation strength was also significantly greater for fenestrated CPDM placed in the preperitoneal location compared to fenestrated CPDM placed in the intraperitoneal location (P < 0.05).

CONCLUSIONS

Fenestrations in CPDM result in greater tissue incorporation strength and lower adhesion area and score when placed in the preperitoneal location. Fenestrations in CPDM allow for greater tissue incorporation without accelerating graft degradation. Fenestrations may be placed in CPDM while still allowing adequate graft strength for intraperitoneal and preperitoneal hernia repairs at 1 month in a porcine model.

Long-term results of vaginal repairs with and without xenograft reinforcement

INTRODUCTION AND HYPOTHESIS

The aim of this paper is to study if xenograft reinforcement of vaginal repair reduces recurrence of prolapse.

METHODS

Results 1-5 years after vaginal repair were studied in 41 cases with xenograft and in 82 matched controls without. Symptoms were evaluated by a validated questionnaire and anatomy by pelvic organ prolapse quantification (POPQ).

RESULTS

Significant more cases, 97% versus 81% controls, felt cured or much improved (p = 0.02); 11% of cases and 19% of controls had POP symptoms, POPQ > -1 was found in 31% cases and 24% controls. Defining recurrence as POPQ > -1 plus symptoms revealed recurrence in 3% of cases and 12% controls. None of the recurrence rates was significantly different for cases versus controls. No vaginal erosions were seen. Previous surgery was a significant risk factor with odds ratio 7.3 for another recurrence.

CONCLUSIONS

Recurrence rates defined by POPQ plus symptoms were low compared to literature. Xenograft reinforcement might improve results.

Long-term histologic response to synthetic and biologic graft materials implanted in the vagina and abdomen of a rabbit model

OBJECTIVE

We sought to evaluate the effects of graft type, site of implantation, and ovariectomy on the long-term histologic response to graft materials used in pelvic reconstructive surgery.

STUDY DESIGN

In all, 45 rabbits underwent ovariectomy or sham laparotomy and were implanted with polypropylene (PP) mesh (n = 23) or cross-linked porcine dermis (PS) (n = 22) in the vagina and abdomen. Grafts were harvested 9 months later and were processed for histology to evaluate the host inflammatory response and degree of tissue incorporation within the grafts.

RESULTS

Polypropylene induced a milder (P < .007), more uniform response than PS, whereas PS elicited a more variable response and degraded by 9 months. Vaginal grafts had higher scores for inflammation (P = .005) and neovascularization (P < .001), and had lower scores for fibroblastic proliferation (P < .001) than abdominal grafts. Ovariectomy had no effect (P > .05).

CONCLUSION

Synthetic and biologic grafts evoke different foreign body responses, which may have implications for surgical outcomes in women.

Biomechanical properties of synthetic and biologic graft materials following long-term implantation in the rabbit abdomen and vagina

OBJECTIVE

We sought to evaluate the effects of anatomic location and ovariectomy on biomechanical properties of synthetic and biologic graft materials after long-term implantation.

STUDY DESIGN

A total of 35 rabbits underwent ovariectomy or sham laparotomy and were implanted with polypropylene (PP) mesh (n = 17) or cross-linked porcine dermis (PS) (n = 18) in the vagina and abdomen. Grafts were harvested 9 months later and underwent mechanical properties testing.

RESULTS

After implantation, PS was similar in strength (P = .52) but was twice as stiff as PP (P = .04) and had a maximal elongation only half that of PP (P < .001). Degradation of PS was associated with decreased ultimate tensile strength (P = .03) and elastic modulus (P = .046). Vaginal PP grafts shrunk more (P < .001) and were less stiff than abdominal PP grafts (P = .049) but were not different in strength (P = .19). Ovariectomy had no effect (P > .05).

CONCLUSION

Cross-linked PS undergoes long-term degradation resulting in compromised biomechanical properties and thus is likely inferior to lightweight PP meshes for pelvic organ prolapse and incontinence procedures.

Development of vaginal erosion and vesicocutaneous fistula following midurethral transvaginal tape with PelviLace for treatment of stress urinary incontinence

Stress urinary incontinence (SUI) is a common diagnosis that greatly impacts quality of life for many women. Current therapies implement the use of suburethral slings, either synthetic or xenografts, to remedy this condition. In this study, we report on a patient with SUI, treated with PelviLace Biourethral Support, who suffered multiple issues postoperatively.

Effect of host response (incorporation, encapsulation, mixed incorporation and encapsulation, or resorption) on the tensile strength of graft-reinforced repair in the rat ventral hernia model

OBJECTIVE

The objective of the study was to determine whether the elicited histologic response to synthetic and xenograft materials affected the tensile strength of mesh-reinforced repairs in the rat ventral hernia model.

STUDY DESIGN

Hernias were repaired with Gynemesh, Pelvicol, Pelvisoft, or Surgisis (representing incorporation, encapsulation, mixed incorporation and encapsulation, or resorption responses) and were compared with a suture-plicated control. Six animals per group were killed at 1 and 3 months after graft implantation. Preimplantation tensile strength was also measured for each graft material and native rat abdominal wall.

RESULTS

Before implantation, Pelvicol had significantly higher adjusted tensile strength when compared with the rat abdominal wall (P < .001) or the other graft materials (P <or= .05). However, no difference in adjusted tensile strength was observed among the groups at 1 and 3 months after implantation.

CONCLUSION

The elicited histologic response did not affect the adjusted tensile strength of xenograft or synthetic mesh-reinforced repairs when compared with suture controls.

Update on the utilization of grafts in pelvic reconstruction surgeries

PURPOSE OF REVIEW

Implanted grafts are increasingly used by pelvic reconstructive surgeons and gynecologists. In addition, the marketing of a variety of grafts has been aggressively expanded without scientific evidence to support their use. This review aims to provide an update of the current status and role of grafts in reconstructive pelvic surgery and to review the current knowledge of the biology of currently marketed synthetic and biologic grafts.

RECENT FINDINGS

Xenografts are preferable to human tissue-banked grafts due to more predictable integrity. How these biomaterials compare to synthetics in terms of surgical outcomes has not been well studied, however. Absorbable materials that mimic some behaviors of synthetic and biological materials have been developed. Furthermore, several new techniques have been advocated with limited studies.

SUMMARY

While the reduction of surgical failure rates in vaginal surgery is desirable, the addition of graft materials must demonstrate improvement in anatomical, functional, and quality of life outcomes over time. Furthermore, future complications due to improper placement or movement of a graft and the possible shrinkage of the graft are of concern. Therefore, significant research is necessary for the preclinical testing of materials, and expertise needs to be developed for the management of complications.