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

The use of a polyglycolic acid polymer graft in Peyronie's disease - preliminary outcomes

OBJECTIVE

Plaque incision and grafting is indicated for patients with Peyronie's Disease [PD] and severe curvature, complex deformities or for patients with significant penile shortening. To date, no graft studied has been considered ideal. The aim of this study is to conduct a descriptive analysis about functional results with the use of a bioabsorbable graft for PD treatment.

MATERIALS AND METHODS

A single-center, retrospective evaluation of a cohort of patients who were treated by plaque incision and grafting with a polyglycolic acid polymer graft (Gore® Bio-A®) between 2018 and 2021 was conducted. Correction of penile curvature was the main outcome. Loss of penile sensitivity, de novo erectile dysfunction and any other adverse event were the secondary endpoints.

RESULTS

14 patients were included in this study (mean age 59.5 ± 7.2 years). The median follow-up time was 12 months (range 3-12). The curvature correction rate was 78.5%. Glans hypoesthesia was present in one of 14 patients (7.1%) and refractory erectile dysfunction was reported in 64.2%. None of the patients presented any major adverse event based on Clavien-Dindo classification.

CONCLUSIONS

Curvature correction and changes in penile sensitivity rates were similar to those found in the literature. No major surgical complications, such as graft rejection, infection, and extrusion, occurred in this sample. Although a population with a higher prevalence of erectile dysfunction was included in this sample, higher rates of refractory erectile dysfunction were observed and these findings should be confirmed in further studies.

Demineralized Freeze-Dried Bovine Cortical Bone: Its Potential for Guided Bone Regeneration Membrane

BACKGROUND

Bovine pericardium collagen membrane (BPCM) had been widely used in guided bone regeneration (GBR) whose manufacturing process usually required chemical cross-linking to prolong its biodegradation. However, cross-linking of collagen fibrils was associated with poorer tissue integration and delayed vascular invasion.

OBJECTIVE

This study evaluated the potential of bovine cortical bone collagen membrane for GBR by evaluating its antigenicity potential, cytotoxicity, immune and tissue response, and biodegradation behaviors.

MATERIAL AND METHODS

Antigenicity potential of demineralized freeze-dried bovine cortical bone membrane (DFDBCBM) was done with histology-based anticellularity evaluation, while cytotoxicity was analyzed using MTT Assay. Evaluation of immune response, tissue response, and biodegradation was done by randomly implanting DFDBCBM and BPCM in rat's subcutaneous dorsum. Samples were collected at 2, 5, and 7 days and 7, 14, 21, and 28 days for biocompatibility and tissue response-biodegradation study, respectively.

RESULT

DFDBCBM, histologically, showed no retained cells; however, it showed some level of in vitro cytotoxicity. In vivo study exhibited increased immune response to DFDBCBM in early healing phase; however, normal tissue response and degradation rate were observed up to 4 weeks after DFDBCBM implantation.

CONCLUSION

Demineralized freeze-dried bovine cortical bone membrane showed potential for clinical application; however, it needs to be optimized in its biocompatibility to fulfill all requirements for GBR membrane.

Bioprosthetic mesh of bacterial cellulose for treatment of abdominal muscle aponeurotic defect in rat model

The use of meshes for treatment of hernias continues to draw attention of surgeons and the industry in the search of an ideal prosthesis. The purpose of this work is to use meshes manufactured from bacterial cellulose, evaluate their organic tissue interaction and compare with an expanded polytetrafluorethylene (ePTFE's) prosthesis used to repair acute defect of muscle aponeurotic induced in rats. Forty-five male Wistar rats were classified using the following criteria: (1) surgical repair of acute muscle aponeurotic defect with perforated bacterial cellulose film (PBC; n = 18); (2) compact bacterial cellulose film (CBC; n = 12) and (3) ePTFE; (n = 15). After postoperative period, rectangles (2 × 3 cm) including prosthesis, muscles and peritoneum were collected for biomechanical, histological and stereological analysis. In all cases, the maximum acceptable error probability for rejecting the null hypothesis was 5 %. Between PBC and CBC samples, the variables of strain (P = 0.011) and elasticity (P = 0.035) were statistically different. The same was found between CBC and ePTFE (elasticity, P = 0.000; strain, P = 0.009). PBC differed from CBC for giant cells (P = 0.001) and new blood vessels (P = 0.000). In conclusion, there was biological integration and biomechanical elasticity of PBC; therefore, we think this option should be considered as a new alternative biomaterial for use as a bio prosthesis.

Prosthetics and Techniques in Repair of Animal's Abdominal Wall

The management of abdominal wall repair continues to present a challenging problem, especially in the repair of major defects. Many abdominal wall defects can be repaired by primary closure; however, if the defect is large and there is a tension on the closure of the wound, the use of prosthetic materials becomes indispensable. Many studies have been performed with various materials and implant techniques, without the comparison of their degrees of success, based on sound meta-analysis and/or inclusive epidemiologic studies. This review covered the effectiveness of recent advances in prosthetic materials and implant procedures used in repair of abdominal wall, based on biomechanical properties and economic aspects of reconstructed large abdominal wall defects and hernias in animals. The presented results in this review helped to reach treatment algorithms that could maximize outcomes and minimize morbidity.

In vivo biomechanical properties of heavy versus light weight monofilament polypropylene meshes. Does the knitting pattern matter?

AIMS

This work evaluated the post-implant biomechanical properties of light-weight (LW) and heavy-weight (HW) monofilament polypropylene (PP) meshes with different knitting patterns in an animal model in vivo.

METHODS

Forty-five adult female Wistar rats were divided into three groups and randomly implanted with 32 × 32 mm HW-PP (62 gm^-2 ) orLW-PP (16 gm^-2 ) in the lower abdomen. LW-PPwas tested orthogonally (called LWL and LWT) to reproduce the longitudinal and transverse planes of the vaginal wall, respectively. Abdominal walls were removed at 7, 30, and 60 days, and then tested for tensile load (maximum load until avulsion from the tissue), deflection, and stiffness to maximum load. Explants were compared over time and between groups.

RESULTS

LW-PP meshes implanted in the LWT fashion (vaginal transverse plane) showed comparable maximum load and stiffness to HW-PP meshes, and LW-PP meshes implanted in the LWL fashion (vaginal longitudinal plane) presented lower maximum load and stiffness than the HW-PP meshes. There were no significant differences in the values of deflection at maximum load between the studied meshes as a function of time.

CONCLUSIONS

The final mechanical behavior of PP mesh can be changed by its weight and knitting pattern. These properties may be useful in making more biocompatible prostheses for pelvic organ prolapse (POP) with less foreign material to maintain longitudinal vaginal elasticity and minimize sexual symptoms while maintaining transverse resistance (i.e., between vaginal fornixes) to prevent POP recurrence. Neurourol. Urodynam. 36:73-79, 2017. © 2015 Wiley Periodicals, Inc.

Spondylodiscitis following sacral colpopexy procedure: is it an infection or graft rejection?

Spondylodiscitis is a rare but severe complication of sacral colpopexy (SC) procedure. Although the term 'spondylodiscitis' refers to infection of vertebral body and intervertebral disc space, neither the infecting microorganism could be isolated nor any purulent material could be observed during the second surgery and there was failure of different regimens of antibiotherapy. This type of spondylodiscitis cases might be explained by the graft rejection hypothesis. We hypothesize that the initiator of the rejection process is the host response solely and infection is just a co-incidence. In this situation, infection is neither a cause of this reaction, nor a promoter. There might be no infection at all. We presented two spondylodiscitis cases most probably secondary to graft rejection reaction and reviewed the literature in order to increase the awareness of this destructive complication of SC, which can only be ameliorated by surgical mesh removal.

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.

Porcine dermis compared with polypropylene mesh for laparoscopic sacrocolpopexy: a randomized controlled trial

OBJECTIVE

To compare the surgical outcomes 12 months after laparoscopic sacrocolpopexy performed with porcine dermis and the current gold standard of polypropylene mesh.

METHODS

Patients scheduled for laparoscopic sacrocolpopexy were eligible for this randomized controlled trial. Both our clinical research nurse and the patients were blinded as to which material was used. Our primary end point was objective anatomic cure defined as no pelvic organ prolapse quantification (POP-Q) points Stage 2 or greater at any postoperative interval. Our sample size calculation called for 57 patients in each group to achieve 90% power to detect a 23% difference in objective anatomic cure at 12 months (α=0.05). Our secondary end point was clinical cure. Any patient with a POP-Q point greater than zero, or Point C less than or equal to -5, or any complaints of prolapse symptoms whatsoever on Pelvic Floor Distress Inventory-20 or Pelvic Floor Impact Questionnaire, Short Form 7, or reoperation for prolapse were considered "clinical failures"; the rest were "clinical cures." Statistical comparisons were performed using the χ or independent samples t test as appropriate.

RESULTS

As expected, there were no preoperative differences between the porcine (n=57) and mesh (n=58) groups. The 12-month objective anatomic cure rates for the porcine and mesh groups were 80.7% and 86.2%, respectively (P=.24), and the "clinical cure" rates for the porcine and mesh groups were 84.2% and 89.7%, respectively (P=.96). Pelvic Floor Distress Inventory-20 and Pelvic Floor Impact Questionnaire, Short Form 7 score improvements were significant for both groups with no differences found between groups. There were no major operative complications.

CONCLUSIONS

There were similar outcomes in subjective or objective results 12 months after laparoscopic sacrocolpopexy performed with either porcine dermis or polypropylene mesh.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT00564083.

LEVEL OF EVIDENCE

I.

Abdominal ventral hernia repair with current biological prostheses: an experimental large animal model

Biologic prostheses have emerged to address the limitations of synthetic materials for ventral hernia repairs; however, they lack experimental comparative data. Fifteen swine were randomly assigned to 1 of 3 bioprosthetic groups (DermaMatrix, AlloDerm, and Permacol) after creation of a full thickness ventral fascial defect. At 15 weeks, host incorporation, hernia recurrence, adhesion formation, neovascularization, inflammation, and biomechanical properties were assessed. No animals had hernia recurrence or eventration. DermaMatrix and Alloderm implants demonstrated more adhesions, greater inflammatory infiltration, and more longitudinal laxity, but near identical neovascularization and tensile strength to Permacol. We found that porcine acellular dermal products (Permacol) contain following essential properties of an ideal ventral hernia repair material: low inflammation, less elastin and stretch, lower adhesion rates and cost, and more contracture. The addition of lower cost xenogeneic acellular dermal products to the repertoire of available acellular dermal products demonstrates promise, but requires long-term clinical studies to verify advantages and efficacy.

Is biocompatibility affected by constant shear stress?--comparison of three commercially available meshes in a rabbit model

Mesh implants as standard treatment for tissue defects can be adapted to patient's needs by specific bioactive coatings. The biophysical interaction with the surrounding tissue must be understood to describe the influence of coatings qualitatively and quantitatively. This study investigates the use of meshes to repair diaphragmatic defects. The physical stress in this tissue is high in comparison to other applications. Therefore, knowledge gained from this experimental model can be applied to other locations. Meshes were implanted on surgically created diaphragmatic defects in growing rabbits. A standardized load model was used to investigate 33 rabbits. The commercial products Ultrapro®, Surgisis®, and Proceed® were implanted. The adhesive properties of the meshes as well as the defect size were determined macroscopically at explantation after 4 months. Sections of the explanted meshes and diaphragms were examined histologically and immunohistochemically. The median defect size for all mesh groups decreased from the initial size of 10 mm down to 4.5 mm at explantation. No statistically significant differences were seen between the three mesh groups. Surgisis® was found to be completely disintegrated after 4 months. Ultrapro® and Proceed® showed no macroscopic differences compared to their original appearance. Both sealed the original diaphragmatic defect as tightly as at time of implantation. Histological and immunohistochemical analyses showed significant differences between the three mesh groups. Proceed® caused stronger inflammatory reaction in the surrounding tissue and inferior connective tissue formation. Regarding the composition of the newly generated tissue within the defect area, Ultrapro® and Surgisis® were found superior. This can sufficiently be explained by the different gradient of inflammatory reaction in the surrounding tissue. Because Surgisis® offers no sufficiently lasting support for the diaphragmatic defect, our future main focus for mesh modification is laid on Ultrapro®.

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.

Inguinal hernia repair with porcine small intestine submucosa: 3-year follow-up results of a randomized controlled trial of Lichtenstein's repair with polypropylene mesh versus Surgisis Inguinal Hernia Matrix

BACKGROUND

The aim of this study was to evaluate the safety and efficacy of Lichtenstein's hernioplasty using Surgisis Inguinal Hernia Matrix (SIHM; Cook, Bloomington, Indiana) compared with polypropylene (PP; Angiologica, Pavia, Italy).

METHODS

This was a prospective, randomized, double-blind trial comparing Lichtenstein's inguinal hernioplasty using SIHM versus PP.

RESULTS

Seventy male patients underwent Lichtenstein's hernioplasty (n = 35 in the SIHM group and n = 35 in the PP group). At 3 years after surgery, there were 2 deaths (5.7%) in the PP group and 1 death (2.9%) in the SIHM group (not significant [NS]). Although the study was underpowered to evaluate the recurrence rate, only 1 recurrence (2.9%) was seen in the PP group (NS). Although a significant decrease in postsurgical pain incidence was never observed among patients in the SIHM group, a significantly lower degree of pain was detected at rest and on coughing at 1, 3, and 6 months and on movement at 1, 3, and 6 months and 1, 2, and 3 years. A significant decrease in postsurgical incidence and degree of discomfort when coughing and moving were observed among patients in the SIHM group at 3 and 6 months and at 1, 2, and 3 years after surgery.

COMMENTS

SIHM hernioplasty seems to be a safe and effective procedure.