Human acellular dermal matrix for closure of a contaminated gynecologic wound

A critical review of biologic mesh use in ventral hernia repairs under contaminated conditions

PURPOSE

We used an evidence-based approach to determine whether the promotions and claims of superiority of biologic mesh over synthetic mesh use in ventral hernia repairs (VHRs) under contaminated conditions were sound and valid.

METHODS

We searched the Medline database to specifically identify review articles relating to biologic mesh and VHR and critically reviewed these studies using an evidence-based approach.

RESULTS

For the past 45 years, four clinical reviews and one systematic review have included biologic meshes as part of a larger discussion on available prosthetics for VHR. All reviews supported biologic mesh use, especially in the setting of contaminated fields. Yet, the primary literature included in these reviews and served as the basis for these conclusions consisted entirely of case series and case reports, which have the lowest level of evidence in determining scientific validity. Furthermore, the FDA has neither cleared nor approved this particular use.

CONCLUSIONS

The cumulative data regarding biologic mesh use in VHRs under contaminated conditions does not support the claim that it is better than synthetic mesh used under the same conditions. The highly promoted and at least moderately utilized practice of placing biologic mesh in contamination is being done outside of the original intended use, and a re-evaluation of or possible moratorium on biologic mesh use in hernia surgery is seriously warranted. Alternatively, an industry-sponsored national registry of patients in whom ventral hernia repairs involved biologic mesh would substantively add to our understanding regarding how these intriguing biomaterials are being used and their overall clinical efficacy.

Corneal reinforcement using an acellular dermal matrix for an analysis of biocompatibility, mechanical properties, and transparency

The aim of this study was to analyze the viability of using an acellular dermal matrix (ADM) as a reinforcement material for peripheral corneal thinning disease. The complete removal of cell components was confirmed by hematoxylin and eosin (H&E) and 4',6-diamidino-2-phenylindole (DAPI) staining. Transmission electron microscopy determined that the stromal structure was well preserved. Uniaxial tests revealed that the ADM had strong mechanical properties. After being implanted into rabbit cornea the ADM showed no sign of rejection and even achieved good transparency 24weeks post-surgery. H&E staining demonstrated that keratocytes grew in the ADM and the ADM-cornea interface became blurry. Picrosirius red staining revealed great changes of collagen in the ADM. Uniaxial testing of the reinforced cornea showed better mechanical strength than the normal rabbit cornea, but this did not exhibit statistical significance. These results suggest that ADM is a worthy candidate for future exploration as a reinforcement material for peripheral corneal thinning problems.

Repair of incisional hernias with biological prosthesis: a systematic review of current evidence

BACKGROUND

No consensus has been reached on the use of bioprosthetics to repair abdominal wall defects. The purpose of this systematic review was to summarize the outcomes from studies describing this use of various bioprosthetics for incisional hernia repair.

METHODS

Studies published by October 2011 were identified through literature searches using EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials.

RESULTS

A total of 491 articles were scanned, 60 met eligibility criteria. Most studies were retrospective case studies. The studies ranged considerably in methodologic quality, with a modified Methodological Index of Nonrandomized Studies score from 5 to 12. Many repairs were performed in contaminated surgical sites (47.9%). At least one complication was seen in 87% of repairs. Major complications noted were wound infections (16.9%) and seroma (12.0%). With a mean follow-up period of 13.6 months the hernia recurrence rate was 15.2%.

CONCLUSIONS

There is an insufficient level of high-quality evidence in the literature on the value of bioprosthetics for incisional hernia repair. Randomized controlled trials that use standardized reporting comparing bioprosthetics with synthetic mesh for incisional hernia repair are needed.

High-throughput assay for bacterial adhesion on acellular dermal matrices and synthetic surgical materials

BACKGROUND

There has been increasing use of synthetic and acellular dermal matrix materials in surgery, ranging from breast reconstruction to hernia repairs. There is a paucity of data on how acellular dermal matrix compares with other surgical materials as a substrate for bacterial adhesion, the first step in formation biofilm, which occurs in prosthetic wound infections. The authors have designed a high-throughput assay to evaluate Staphylococcus aureus adherence on various synthetic and biologically derived materials.

METHODS

Clinical isolates of S. aureus (strains SC-1 and UAMS-1) were cultured with different materials, and bacterial adherence was measured using a resazurin cell vitality assay. Four materials that are commonly used in surgery were evaluated: Prolene mesh, Vicryl mesh, and two different acellular dermal matrix preparations (AlloDerm and FlexHD). The authors were able to develop a high-throughput and reliable assay for quantifying bacterial adhesion on synthetic and biologically derived materials.

RESULTS

The resazurin vitality assay can be reliably used to quantify bacterial adherence to acellular dermal matrix material and synthetic material. S. aureus strains SC-1 and UAMS-1 both adhered better to acellular dermal matrix materials (AlloDerm versus FlexHD) than to the synthetic material Prolene. S. aureus also adhered better to Vicryl than to Prolene. Strain UAMS-1 adhered better to Vicryl and acellular dermal matrix materials than did strain SC-1.

CONCLUSIONS

The results show that S. aureus adheres more readily to acellular dermal matrix material than to synthetic material. The resazurin assay provides a standard method for evaluating surgical materials with regard to bacterial adherence and potential propensity for biofilm development.

Are biologic grafts effective for hernia repair?: a systematic review of the literature

Biologic grafts for hernia repair are a relatively new development in the world of surgery. A thorough search of the Medline database for uses of various biologic grafts in hernia shows that the evidence behind their application is plentiful in some areas (ventral, inguinal) and nearly absent in others (parastomal). The assumption that these materials are only suited for contaminated or potentially contaminated surgical fields is not borne out in the literature, with more than 4 times the experience being reported in clean fields and the average success rates being higher (93% vs 87%). Outcomes prove to be highly dependent on material source, processing methods and implant scenarios with failure rates ranging from zero to more than 30%. Small intestinal submucosa (SIS) grafts have an aggregate failure rate of 6.7% at 19 months whereas acellular human dermis (AHD) grafts have a failure rate of 13.6% at 12 months. Chemically cross-linked grafts have much less published data than the non-cross-linked materials. In particular, the search found 33 articles for SIS, 32 for AHD, and 13 for cross-linked porcine dermis. Furthermore, the cumulative level of evidence for each graft material was fairly low (2.6 to 2.9), and only 1 material (SIS) had level 1 evidence reported in any hernia type (inguinal and hiatal). Together, biologic grafts have published evidence showing success rates better than 90% overall and more than 2000 years of cumulative implant time. Improvements in materials, techniques, and patient selection are likely to improve these numbers as this field of surgery matures.