Porcine dermal collagen graft in abdominal-wall reconstruction

Porcine Dermal Xenograft as Augmentation in the Treatment of Large Rotator Cuff Tears: Clinical and Magnetic Resonance Results at 2-Year Follow-Up

Purpose  The aim of the present retrospective study is to describe the results obtained at 2-year follow-up by using a porcine dermis-derived collagen membrane implanted as augmentation to treat large rotator cuff tears.

Methods  Thirty-five patients in total were included according to the following criteria: large or massive rotator cuff tear, confirmed during surgery, measuring between 3 and 5 cm in width and stage 1 to 2 fatty infiltration documented at magnetic resonance imaging (MRI). Patients underwent arthroscopic repair of the cuff augmented by the implantation of a porcine dermal collagen membrane. Patients were evaluated up to 24 months after surgery by the Constant score and MRI imaging to assess functional outcomes and re-tear rate. The results obtained were compared to those of a matched cohort of 35 patients operated by arthroscopic repair alone by the same surgical team.

Results  The application of the porcine membrane proved to be safe without scaffold-related adverse events documented. A statistically significant difference in the Constant score in favor of the treatment group was documented at the final evaluation ( p  = 0.036 ). Furthermore, a subgroup analysis revealed that patients treated by augmentation and presenting re-tear at MRI showed a significantly higher functional outcome compared with control patients with MRI evidence of re-tear ( p  = 0.0136).

Conclusion  Arthroscopic repair augmented by porcine dermal xenograft for the treatment of chronic and retracted rotator cuff tears with low-grade fatty degeneration proved to be safe and also effective, with higher functional score compared with the arthroscopic repair alone.

Level of Evidence  This is a Level III, retrospective cohort study.

Histological Comparison of Implanted Cadaveric and Porcine Dermal Matrix Grafts

OBJECTIVES: Histological comparison of human-based (AlloDerm) and porcine-based (ENDURAGen) dermal matrices regarding tissue incorporation and neovascularization as potential soft tissue augmentation materials.

STUDY DESIGN: In vivo, rat model.

METHODS: Subcutaneous implantation of 1-mm thick, 1 cm X 1 cm pieces of AlloDerm, ENDURAGen, and meshed ENDURAGen was performed in 24 Sprague Dawley rats. Implant materials were harvested at 4 (n = 12) and 8 weeks (n = 12). Histological quantification of soft tissue ingrowth and microvascular density was performed following hematoxylin-eosin staining and CD34 immunohistochemistry, respectively.

RESULTS: AlloDerm showed significantly greater soft tissue in-growth and microvascular density compared with both ENDURAGen and meshed ENDURAGen at 4 and 8 weeks ( P < 0.001).

CONCLUSIONS: Although these results may differ in human host tissues, AlloDerm seems to be a more suitable dermal matrix implant than ENDURAGen for cases in which tissue incorporation and neovascularization are sought for the optimal outcome based on this animal model.

Clinical application of cultured epithelial autografts on acellular dermal matrices in the treatment of extended burn injuries

Achieving permanent replacement of skin in extensive full-thickness and deep partial-thickness burn injuries and chronic wounds remains one of the fundamental surgical problems. Presently, split-thickness skin grafts are still considered the best material for surgical repair of an excised burn wound. However, in burns that affect greater than 50% of total body surface area, the patient has insufficient areas of unaffected skin from which split-thickness skin grafts can be harvested. The use of cultured epithelial (or epidermal) autografts (CEAs) has achieved satisfactory results. But the take rate of CEAs is poor in full-thickness bed or in chronically infected area. Providing temporary cover with allograft skin, or a more permanent allodermis, may increase clinical take. This review aims to (1) describe the use of CEAs in the regeneration of the epidermis, (2) introduce the application of the acellular dermal matrices (ADMs) in the clinics, and (3) enhance understanding of the CEAs applied with ADM as an appropriate strategy to treat the extended burn injuries. The current evidence regarding the cultured epithelial cell or keratinocyte autograft and dermal grafts applied in the treatment of burn injuries was investigated with an extensive electronic and manual search (MEDLINE and EMBASE). The included literature (N=136 publications) was critically evaluated focusing on the efficacy and safety of this technique in improving the healing of the deep dermal and full-thickness burn injuries. This review concluded that the use of ADM with CEAs is becoming increasingly routine, particularly as a life-saving tool after acute thermal trauma.

Comparative study of the effectiveness and safety of porcine and bovine atelocollagen in Asian nasolabial fold correction

Bovine-derived collagen has been used for soft-tissue augmentation since 1977. However, there are issues regarding the possibility of bovine spongiform encephalopathy (BSE). Researchers discovered that the histologic structure of porcine-derived collagen is similar to that of human dermal collagen and that it is free from the risk of BSE. This study was conducted to establish the effectiveness and safety of porcine-derived collagen compared to bovine-derived collagen. The 73 patients included in this study were healthy volunteers who responded to an advertisement approved by the Institutional Review Board (IRB). They had visited the authors' hospital complaining of wrinkles on their nasolabial fold. Either porcine (TheraFill®) or bovine atelocollagen was randomly injected into each side of their nasolabial folds, and the five-grade Wrinkle Severity Rating Scale (WSRS) was used to evaluate the wrinkles before and after the injection. The average age of the 73 study patients was 46.18 years. The WSRS scores of the porcine and bovine atelocollagen-injected patients were 2.90 ± 0.71 and 2.85 ± 0.72 at the baseline and 2.15 ± 0.70 and 2.21 ± 0.67 after 6 months. There were no statistically significant differences between the two groups. Adverse effects of the porcine atelocollagen injection were seen in 12 patients, with the most common symptom being redness. This study showed that porcine atelocollagen can be used easily and without the need for the skin testing which is necessary before bovine atelocollagen injection. The efficacy of porcine atelocollagen is also similar to that of bovine atelocollagen.

Bioprosthetic tissue matrices in complex abdominal wall reconstruction

Background:

Complex abdominal defects are difficult problems encountered by surgeons in multiple specialties. Although current evidence supports the primary repair of these defects with mesh reinforcement, it is unclear which mesh is superior for any given clinical scenario. The purpose of this review was to explore the characteristics of and clinical relevance behind bioprosthetic tissue matrices in an effort to better clarify their role in abdominal wall reconstruction.

Methods:

We reviewed the peer-reviewed literature on the use of bioprosthetic mesh in human subjects. Basic science articles and large retrospective and prospective reviews were included in author’s analysis. The clinical performance and characteristics of 13 bioprosthetic tissue matrices were evaluated.

Results:

The majority of the products evaluated perform well in contaminated fields, where the risk of wound-healing difficulties is high. Clinical outcomes, which included infection, reherniation, and bulge formation, were variable, and the majority of the studies had a mean follow-up of less than 24 months.

Conclusions:

Although bioprosthetic matrix has a multitude of indications within the growing field of abdominal wall reconstruction, the functionality, regenerative capacity, and long-term fate of these products have yet to be fully established. Furthermore, the clinical performance, indications, and contraindications for each type of matrix need to be fully evaluated in long-term outcome studies.

Repair of traumatic muscle herniation with acellular porcine collagen matrix

BACKGROUND

Muscle hernias are uncommon clinical conditions with no uniform solution of repair. Biocompatible mesh allows for repair of hernias without the donor site morbidity and complications from direct repair under tension.

METHODS

Over a 6-month period at a Level 1 Trauma centre, four consecutive symptomatic muscle hernias were identified, two in the forearm and two in the lower limb. Three resulted from high-speed motorbike accidents, one from a mining accident. All patients had hernia repair at a minimum of 4 months post accident. A 10 × 15 cm × 1.0 mm sheet of acellular collagen matrix was fashioned to fit as an underlay of the fascia defect. Patients were clinically followed at the 2-, 6-, 12- and 26-week mark. Final phone contact was made 18 months post-operatively.

RESULTS

All patients were pleased with their cosmetic and functional outcomes. All patients returned to work and sport 3 months after reconstruction.

CONCLUSION

Symptomatic hernias as a result of trauma can be safely reconstructed with a biological mesh implant. This approach can prevent complications from previously described methods and return to active lifestyles with good results.

Permacol in eyelid reconstruction -- a novel use

BACKGROUND

Reconstruction of a full-thickness lower eyelid defect is not an uncommon procedure and requires repair of both the anterior and posterior lamella. The modified Hughes procedure is commonly used for large defects, however this requires a second procedure and since the flap must be left in place for at least 3 weeks prior to the second-stage separation, it is not suitable for patients with only eyes or of amblyogenic age. In such situations, a free tarsoconjunctival graft from the opposite upper eyelid or a mucoperiosteal graft from the hard palate is more appropriate. These have the advantage of being autologous tissue with excellent recipient tolerance, however, they are not without drawbacks, including donor site scarring, limited availability and prolonged operating time. In order to avoid donor-site morbidity, several substitutes on the market can be used to replace autologous grafts. Permacol is a relatively new biomaterial made from acellular cross-linked porcine dermal collagen with a structural architecture very similar to that of human dermis.

METHODS

The authors present the first report of the use of Permacol to replace tarsus in the reconstruction of a full-thickness lower eyelid defect.

RESULTS

Permacol seems to be far superior to other commercially available tissue substitutes because of its increased tensile strength, rigidity, durability, predictability of structure and robust behaviour. It is well incorporated by the body, and it serves as an excellent matrix for tissue ingrowth.

CONCLUSION

We feel it is a very good autologous graft substitute in eyelid reconstructive surgery and achieved satisfactory functional and aesthetic results.

A decade of ventral incisional hernia repairs with biologic acellular dermal matrix: what have we learned?

BACKGROUND

Innovative types of biologic mesh have provided new alternatives to ventral incisional hernia repair, especially in the face of contamination. The authors studied the experience and outcomes of patients who underwent repair of a ventral incisional hernia with biologic mesh.

METHODS

Online database and detailed reference searches were conducted. Studies chosen for review had a sample size of at least 40 patients, level IV evidence at most, and a Methodological Index for Nonrandomized Studies index of at least 10. Indications for use of biologic mesh, type of mesh, patient comorbidities, and surgical techniques were also noted.

RESULTS

Eight studies fulfilled the search criteria and included 635 patients using AlloDerm, Surgisis, and Strattice biologic tissue matrices. In one study, indications and surgical techniques were standardized, and follow-up was prospective. In the other seven studies, indications, surgical techniques, and follow-up were assessed retrospectively. The mean patient age, when reported, was 55.7 years. Body mass index ranged from 30 to 35 kg/m2 in 44 percent of the reported patients. In seven of the eight studies [565 patients (89 percent)], the mean follow-up was 25.8 months and the mean hernia recurrence rate was 21 percent. Complication rate exceeded 20 percent in most studies.

CONCLUSIONS

Biologic tissue matrices are mostly used in contaminated fields, which has allowed for a one-stage repair with no or little subsequent mesh removal. Ventral incisional hernia repair with these matrices continues to be plagued by a high recurrence rate and complications. Prospective randomized trials are needed to properly direct practice in the use of these meshes and evaluate their ultimate value.

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.

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.

Outcomes of complex abdominal herniorrhaphy: experience with 106 cases

PURPOSE

Reconstruction of abdominal wall defects is a challenging problem. Often, the surgeon is presented with a patient having multiple comorbidities, who has already endured numerous unsuccessful operations, leaving skin and fascia that are attenuated and unreliable. Our study investigated preoperative, intraoperative, and postoperative factors and techniques during abdominal wall reconstruction to determine which variables were associated with poor outcomes.

METHODS

Data were collected on all patients who underwent ventral abdominal hernia repair by 3 senior-level surgeons at our institution during an 8-year period. In all cases, placement of either a synthetic or a biologic mesh was used to provide additional reinforcement of the repair.

RESULTS

A total of 106 patients were included. Seventy-nine patients (75%) had preoperative comorbid conditions. Sixty-seven patients developed a postoperative complication (63%). Skin necrosis was the most common complication (n = 21, 19.8%). Other complications included seroma (n = 19, 17.9%), cellulitis (n = 19, 17.9%), abscess (n = 14 13.2%), pulmonary embolus/deep vein thrombosis (n = 3, 2.8%), small bowel obstruction (n = 2, 1.9%), and fistula (n = 8, 7.5%). Factors that significantly contributed to postoperative complications (P < 0.05) included obesity, diabetes, hypertension, fistula at the time of the operation, a history of >2 prior hernia repairs, a history of >3 prior abdominal operations, hospital stay for >14 days, defect size > 300 square cm, and the use of human-derived mesh allograft. Factors that significantly increased the likelihood of a hernia recurrence (P < 0.05) included a history of >2 prior hernia repairs, the use of human-derived allograft, using an overlay-only mesh placement, and the presence of a postoperative complication, particularly infection. Hernia recurrences were significantly reduced (P < 0.05) by using a "sandwich" repair with both a mesh overlay and underlay and by using component separation.

CONCLUSIONS

A history of multiple abdominal operations is a major predictor of complications and recurrences. If needed, component separation should be used to achieve primary tension-free closure, which helps to reduce the likelihood of hernia recurrences. Our data suggest that mesh reinforcement used concomitantly in a "sandwich" repair with component separation release may lead to reduced recurrence rates and may provide the optimal repair in complex hernia defects.

Evaluation of human acellular dermis versus porcine acellular dermis in an in vivo model for incisional hernia repair

Incisional hernias commonly occur following abdominal wall surgery. Human acellular dermal matrices (HADM) are widely used in abdominal wall defect repair. Xenograft acellular dermal matrices, particularly those made from porcine tissues (PADM), have recently experienced increased usage. The purpose of this study was to compare the effectiveness of HADM and PADM in the repair of incisional abdominal wall hernias in a rabbit model. A review from earlier work of differences between human allograft acellular dermal matrices (HADM) and porcine xenograft acellular dermal matrices (PADM) demonstrated significant differences (P < 0.05) in mechanical properties: Tensile strength 15.7 MPa vs. 7.7 MPa for HADM and PADM, respectively. Cellular (fibroblast) infiltration was significantly greater for HADM vs. PADM (Armour). The HADM exhibited a more natural, less degraded collagen by electrophoresis as compared to PADM. The rabbit model surgically established an incisional hernia, which was repaired with one of the two acellular dermal matrices 3 weeks after the creation of the abdominal hernia. The animals were euthanized at 4 and 20 weeks and the wounds evaluated. Tissue ingrowth into the implant was significantly faster for the HADM as compared to PADM, 54 vs. 16% at 4 weeks, and 58 vs. 20% for HADM and PADM, respectively at 20 weeks. The original, induced hernia defect (6 cm²) was healed to a greater extent for HADM vs. PADM: 2.7 cm² unremodeled area for PADM vs. 1.0 cm² for HADM at 20 weeks. The inherent uniformity of tissue ingrowth and remodeling over time was very different for the HADM relative to the PADM. No differences were observed at the 4-week end point. However, the 20-week data exhibited a statistically different level of variability in the remodeling rate with the mean standard deviation of 0.96 for HADM as contrasted to a mean standard deviation of 2.69 for PADM. This was significant with P < 0.05 using a one tail F test for the inherent variability of the standard deviation. No significant differences between the PADM and HADM for adhesion, inflammation, fibrous tissue or neovascularization were noted.

Porcine dermal collagen (Permacol) for chest and abdominal wall reconstruction in thoraco-omphalopagus conjoined twin separation

Each set of conjoined twins presents a unique challenge, which centers on the ability to separate and if necessary reconstruct shared organs and to achieve subsequent skin cover of the often very large residual defect after completion of the separation. This report describes the use of a bioprosthetic Permacol derived from porcine dermal collagen to reconstruct the chest and abdominal wall.

Major Complications Associated With Xenograft Biologic Mesh Implantation in Abdominal Wall Reconstruction

Background. There is limited research for xenograft biologic mesh performance in the setting of infection despite widespread use and significant associated costs. Design. The authors retrospectively reviewed an FDA database for reported xenograft adverse events (AEs). All meshes were used in the setting of abdominal wall reconstruction from 1997 to 2008. Results. The authors identified 150 AEs. Permacol and Collamend comprised 75% (n = 112) of reported cases. Main AEs included acute mechanical failure (42%; n = 63), mesh disintegration (32%; n = 48), and poor mesh integration (13%; n = 20); 80% of cases were described as infected, and nearly 90% of AEs required reoperation. Conclusions . Major complications are reported to the FDA for xenograft biologic meshes. Cross-linked meshes had the most AE reports to the FDA. The intrinsic properties of meshes and how they relate to infection-related outcomes are poorly understood. The findings from this FDA database review point toward a need to carefully evaluate these products.

[PAUL procedure. A new biocompatible concept for the therapy of congenital abdominal wall defects]

Treatment of small congenital abdominal wall defects (e.g. omphalocele and gastroschisis) can be performed by direct closure. In large defects non-resorbable artificial materials (e.g. Gore-Tex) are necessary to close the fascia. The aim of this study was to find out whether a new procedure, the PAUL pocedure, might be suitable for the treatment of large abdominal wall defects. A full thickness abdominal wall defect was created in young Wistar Rats. These defects were then closed by implantation of a 1x2 cm sized piece of PTFE (Dual-Mesh), a polypropylene mesh (Prolene(R)) or by using the PAUL procedure. Over a period of 6 weeks no wound infections or hernias were monitored. In contrast to PTFE the PAUL procedure showed only minimal adhesion to the intestine and a high stability of the implanted material. A xenogenic extracellular matrix, such as that used in the PAUL procedure, may induce an immune response, which is comparable with a remodeling reaction rather than rejection. Based on these good results a large animal model study (Goettinger mini-piglets) was performed. No wound infections or hernias could be observed throughout the experiment. Control laparoscopy after 3, 6, 9, and 12 months showed only minimal adhesion to the intestine. Our results indicate that the PAUL procedure can be used easily and successfully for the therapy of congenital abdominal wall defects.

Use of Homologous Acellular Dermal Matrix for Abdominal Wall Reconstruction in Rats

Homologous acellular dermal matrix graft (HADMG) has been used for the reconstructions of bowel, bladder, or urethra, but its suitability in the reconstruction of abdominal wall has not been tested. Therefore an experimental study was performed to evaluate the use of HADMG for the reconstruction of abdominal wall defects in weanling rats. Thirty weanling Wistar rats were used. A patch of abdominal wall 20 x 20 mm in dimension was removed. The defects were reconstructed with HADMGs that were derived from rat skin and prepared through a detergent enzymatic method. The reconstructed abdominal walls were evaluated as hernia rate and graft take ratio, excised and prepared for histological examination at 21 (n = 10), 40 (n = 10), and 90 (n = 10) days postoperation. The healing of repaired abdominal walls was uneventful. Histological evaluation demonstrated the migration of fibroblasts and neovascularization within the HADMG. Hernia in four rats were developed at 90 days. Neither significant wound contraction nor inflammation was seen at 21, 40, and 90 days after surgery in wounds receiving HADMGs. Thus, the use of a HADMG for reconstructing the abdominal wall in weanling rats has not given rise to any complications. HADMG has progressively remodeled into fibrous tissue. It appears to represent an important alternative substitute for the reconstruction of abdominal wall.

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.

Absorbable mesh and topical negative pressure therapy for closure of abdominal dehiscence with exposed bowel

Permacol mesh is a porcine dermis-derived biomaterial used for the repair of abdominal incisional and inguinal hernia. It has been found to be a safe and effective alternative to non-absorbable mesh for application over exposed bowel. This mesh has also been successfully applied over contaminated abdominal wound beds and around stomas. Topical negative pressure therapy has been used for the management of wound complications after surgical implantation of Permacol mesh. We describe our experience with the combined use of Permacol mesh and simultaneous application of topical negative pressure therapy to aid wound contraction and granulation in a patient with abdominal dehiscence and exposed bowel.

Use of the anterior rectus sheath for abdominal wall reconstruction: a study in cadavers

Our aim was to evaluate the amount of tension present after incision and undermining of the anterior rectus sheaths and the external oblique muscles in 20 fresh adult cadavers. Resistance to traction of the anterior and posterior rectus sheaths towards the midline was measured at three stages of dissection: before any aponeurotic undermining; after incision and undermining of the anterior rectus sheaths; and after incision and undermining of the external oblique muscles associated with the previous dissection. Significance of differences was assessed using non-parametric tests. There was a significant reduction in tension in the anterior and posterior sheaths on both levels after each stage of dissection. The incision and undermining of the anterior rectus sheaths and the external oblique muscles promoted a progressive reduction in tension at the aponeurotic edges of the abdominal wall.

Parastomal hernia prevention using a novel collagen implant: a randomised controlled phase 1 study

BACKGROUND

Parastomal hernias can be prevented or repaired using synthetic mesh; however, reported complications include infection, fibrosis and potential bowel erosion. The study aim was to assess the safety, feasibility and potential efficacy of using a prophylactic collagen implant.

METHODS

Twenty patients undergoing defunctioning stomas were randomised to a conventional procedure or reinforcement with the implant. Follow-up included regular symptom questionnaires, clinical examination, stoma site ultrasound, and serum inflammatory markers.

RESULTS

Ten patients (four males; mean BMI 26.3) had a conventional stoma, and ten (three males; mean BMI 26.3) received the implant. At a median of 6.5 months follow-up, a parastomal hernia was clinically evident in three of ten patients without the implant, and in none of ten patients with the implant. There were no clinical complications, ultrasound evidence of chronic seromas or serological evidence of a systemic inflammatory response.

CONCLUSIONS

Xenogeneic collagen has been demonstrated to aid soft tissue reinforcement. In this study, in contrast to published data relating to the use of conventional synthetic mesh, there were no complications related to infection or the implant's proximity to the bowel. This trial demonstrates that the implant is safe, feasible to use and has the potential to prevent parastomal herniation.

Human in vivo cellular response to a cross-linked acellular collagen implant

BACKGROUND

Hernia surgery, in particular parastomal hernia mesh repair and new techniques for hernia prevention, require novel biomaterials that avoid fibrosis and potential bowel erosion, while retaining adequate strength for their intended purpose. The aim was to evaluate the human host response to an acellular porcine-derived cross-linked collagen implant.

METHODS

In a prospective pilot study on prevention of parastomal herniation, 15 patients undergoing loop stoma formation had an implant placed within the anterior abdominal wall. Histopathology and immunohistochemistry were performed to analyse the implant qualitatively and, where appropriate, quantitatively for biocompatibility, degradation, cellular infiltration, neo-extracellular matrix (ECM) formation and neovascularization.

RESULTS

At a median of 7 (range 1-8) months, 12 of 15 patients had stoma reversal and 11 implant biopsies were obtained. In biopsies from ten of the 11 patients all responses were limited to the periphery of the implant and native pores. There was a minimal inflammatory response and minimal degradation of the implant. Fibroblastic and neovascular infiltration were noted, as was matrix metalloproteinase 1 activity with organized deposition of host collagen, fibronectin and laminin.

CONCLUSION

The collagen implant demonstrated excellent biocompatibility and resistance to degradation in most patients. However, fibrovascular in-growth and ECM deposition were limited. This implant has excellent potential for soft tissue reinforcement.

The use of porcine dermal collagen implants in assisting abdominal wall closure of pediatric renal transplant recipients with donor size discrepancy

Children may have kidneys transplanted from donors larger than themselves. Abdominal wall closure may be difficult, with risks of abdominal compartment syndrome and graft compromise. Meshes used to facilitate closure may cause dense intra-abdominal adhesions, making further surgery or peritoneal dialysis difficult. We present five cases in which abdominal wall closure was facilitated by porcine dermal collagen implant. Five children (2-15 yr) received transplanted kidneys from adult donors of significantly greater weight. In four recipients, the kidney was transplanted onto the aorta and vena cava intra-abdominally using a midline incision. In the fifth, the kidney was anastomosed onto the iliac vessels. The skin overlying the implant was closed normally. Maximum follow-up was three yr. In all cases, primary closure was achieved. One child received a second intra-abdominal transplant as an emergency, which later failed. The other kidneys are functioning well. One recipient developed a small incisional hernia three yr post-transplant. Another developed a skin dehiscence over the implant 23 days post-operatively. The implant was removed and skin closed. The other two recipients recovered well. Porcine dermal collagen implant is a helpful adjunct to abdominal wall closure following organ transplantation in children with donor size discrepancy.

An assessment of porcine dermal xenograft as an augmentation graft in the treatment of extensive rotator cuff tears

Porcine dermal collagen (Zimmer Patch, formerly known as Permacol; Tissue Science Laboratories plc, Aldershot, Hampshire, UK) has been used for reinforcement of several human body tissues with success and has been shown to act as a durable, permanent tissue scaffold that assists healing. The purpose of this study was to determine the effectiveness of porcine dermal collagen as a tendon augmentation graft in the repair of extensive rotator cuff tears. This prospective study evaluated the clinical, ultrasound, and magnetic resonance imaging outcome 4.5 years (range, 3-5 years) after the treatment of extensive rotator cuff tears with porcine dermal collagen tendon augmentation grafting. The study group consisted of 10 patients (5 men, 5 women) with a mean age of 66 years (range, 46-80 years). Patients were evaluated clinically using the Constant score preoperatively, at 1 year, and at final follow-up when ultrasound and magnetic resonance imaging scans were performed to assess for graft and rotator cuff integrity. Average Constant scores improved from 41 preoperatively to 62 at final follow-up (P = .0003). Pain, abduction power, and range of motion significantly improved after surgery (P < .05), and patient satisfaction levels were high. Imaging studies identified intact grafts in 8 patients and graft detachment in 2. No adverse side effects were reported during the study period. The use of porcine dermal collagen as an augmentation graft in the treatment of massive rotator cuff tears is safe and, in most patients, is associated with improved clinical outcome. Randomized trials are required to assess any benefit over standard current surgical treatment regimens.

Use of porcine dermal collagen graft and topical negative pressure on infected open abdominal wounds

This article reports on two cases in which porcine dermal collagen grafts were used successfully alongside topical negative pressure therapy in order to close open abdominal wounds in which severe infection was present.

Abdominal wall reconstruction using biological tissue grafts: present status and future opportunities

Surgeons often encounter the challenge of treating acquired abdominal wall defects following abdominal surgery. The current standard of practice is to repair most defects using permanent synthetic mesh material. Mesh augments the strength of the weakened abdominal wall fascia and enables the hernia repair to be performed in a tension-free manner. However, there is a risk of acute and/or chronic infection, fistula formation and chronic abdominal wall pain with the use of permanent mesh materials, which can lead to more complex operations. As a means to avoid such problems, surgeons are turning increasingly to the use of xenogenic and allogenic materials for the repair of abdominal wall defects. Their rapid evolution and introduction into the clinical operating room is leading to a new era in abdominal wall reconstruction. There are promising, albeit limited, clinical data with short-term follow-up for only a few of the many biological tissue grafts that are being promoted currently for the repair of abdominal hernias. Additional clinical studies are required to better understand the long-term efficacy and limitations of these materials.

Porcine dermal collagen (Permacol) for abdominal wall reconstruction

OBJECTIVE

A review of Eisenhower Army Medical Center's experience using Permacol (Tissue Science Laboratories, Covington, Georgia) for the repair of abdominal wall defects.

METHODS

Retrospective review of medical records of patients undergoing abdominal wall reconstruction with Permacol.

RESULTS

From July 30, 2003 to February 12, 2005, 9 patients underwent repair of complicated fascial defects with Permacol. Indications for surgery included reoperative incisional hernia repair after removal of a infected mesh (3 patients), reconstruction of a fascial defect after resection of an abdominal wall tumor (2 patients), incisional hernia repair in a patient with a previous abdominal wall infection after a primary incisional hernia repair (1 patient), incisional hernia repair in a patient with an ostomy and an open midline wound (1 patient), emergent repair of incisional hernia with strangulated bowel and multiple intra-abdominal abscesses (1 patient), and excision of infected mesh and drainage of intra-abdominal abscess with synchronous repair of the abdominal wall defect (1 patient). At a median follow-up of 18.2 months, 1 recurrent hernia existed after intentional removal of the Permacol. This patient developed an abdominal wall abscess 7 months after hernia repair secondary to erosion from a suture. Overall, 1 patient developed exposure of the Permacol after a skin dehiscence. The wound was treated with local wound care, and the Permacol was salvaged. Despite the presence of contamination (wound classification II, III, or IV) in 5 of 9 patients (56%), no infectious complications occurred.

CONCLUSION

Complex reconstruction of the abdominal wall can be associated with a high complication rate. Placement of a permanent prosthetic mesh in a contaminated field is associated with a high rate of wound infections and subsequent mesh removal. Permacol becomes incorporated by tissue ingrowth and neovascularization. Permacol is a safe and acceptable alternative to prosthetic mesh in the repair of complicated abdominal wall defects.

Use of porcine dermal collagen graft (Permacol) for hernia repair in contaminated fields

BACKGROUND

Complicated hernias often involve contaminating surgical procedures in which the use of polypropylene meshes can be hazardous. Prostheses made of porcine dermal collagen (PDC) have recently been proposed as a means to offset the disadvantages of polypropylene meshes and have since been used in humans for hernia repairs. The aim of our study was to evaluate the safety and efficacy of incisional hernia repair using PDC as a mesh in complicated cases involving contamination.

METHODS

A prospective study of hernia repair of complicated incisional hernias with contamination using PDC grafts was carried out at the Department of General, Emergency and Transplant Surgery of St Orsola-Malpighi University Hospital.

RESULTS

From January 2004 up to the writing of this article, seven patients were treated for complicated incisional hernias with a PDC prosthesis. In six out of seven patients a bowel resection was carried out. There were not surgical complications. Morbidity was 14.2%. No recurrences and wound infections were observed.

CONCLUSIONS

Incisional hernioplasty using PDC grafts is a potentially safe and efficient approach in complicated cases with contamination.

Anterior abdominal wall reconstruction with a Permacol implant

Laparostomy wound management is a difficult problem especially with a stoma and the potential risk of infection. A case describing the use of a permanent porcine dermal collagen implant in the repair of a massive ventral hernia, in a patient with a large post-laparostomy defect and colostomy is outlined. The implant was not rejected, and after 12 months, there was no evidence of residual or recurrent hernia. The search for the ultimate biomaterial for reconstructing abdominal wall defects is ongoing. Collagen based implants appear to have many of the requirements that an ideal material should possess.

Delayed closure of ventral abdominal hernias after severe trauma

BACKGROUND

Primary closure after trauma celiotomies is not always accomplished. We reviewed our experience with delayed closure in trauma patients.

METHODS

Prospective data were collected on patients who had damage-control celiotomy and were discharged with open abdomens. The time to closure, repair methods, and complication data also were compiled.

RESULTS

In the 6-year period, 84 patients underwent damage-control celiotomy. Thirty-one patients died and 33 patients had early closure. Twenty patients had closure during a subsequent hospitalization (mean time to delayed closure, 193 days): 8 patients (40%) had component separation, 3 (15%) had component separation with mesh, 4 (20%) had mesh alone, and primary closure occurred in 5 (25%). Nine patients (45%) had complications such as wound and mesh infections, hernias, and fistulas. Repair before or after 6 months showed no statistically significant difference for the presence of complications or enterotomies (P = .64 and .5743, respectively).

CONCLUSIONS

Open-abdomen reconstruction presents significant challenges. Closure within 6 months is possible; the presence of complications is not affected by early repair.

The Role of Bioprosthetics in Abdominal Wall Reconstruction

In several common situations, bioprosthetic materials may have distinct advantages over synthetic mesh and autologous flap or graft techniques for abdominal wall reconstruction. These off-the-shelf materials entail no donor site morbidity and are used successfully in contaminated wounds owing to their ability to resist infection, become revascularized and incorporated into host tissue, and reduce visceral adhesions. Fibrovascular incorporation into surrounding tissues and implant remodeling reduce the risks associated with a persistent foreign body, such as chronic infection, enterocutaneous fistulae, and cutaneous exposure. Disadvantages of bioprosthetic materials include higher implant cost relative to synthetic mesh, limited size of individual sheets in some cases, and risk of seroma formation. Bioprosthetic mesh has been used for abdominal wall reconstruction for approximately 5 years, so long-term studies are not available. Current laboratory and clinical evidence suggests that these materials provide a strong, durable musculofascial repair when used for abdominal wall repair. Further studies and ongoing clinical experience will be important in determining the indications for which bioprosthetic mesh will have the greatest impact. Currently available commercial products have distinct differences that result in varied clinical biologic and physiologic activity. New products and modifications to existing products may further enhance the benefits of bioprosthetic mesh, particularly in challenging cases. The use of bioprosthetic mesh has attracted interest in a relatively short period of time, with rapidly increasing indications and volume of cases successfully performed. Bioprosthetic mesh likely will play a progressively greater role in trunk reconstruction in the future.

A new biocompatible material (Lyoplant) for the therapy of congenital abdominal wall defects: first experimental results in rats

Congenital abdominal wall defects are impressive and dramatic malformations. Common surgical therapy for omphalocele and gastroschisis is to place the herniated viscera back into the abdomen and to close the fascia. Small defects can be closed directly by surgical treatment. In large defects, resorbable and non-resorbable artificial materials are necessary to close the fascia. The aim of this study is to find out whether new biocompatible materials might be suitable for the treatment of such abdominal wall defects. A median laparotomy was performed in young Wistar rats with a body weight of 75-100 g. Then a full thickness defect was created by excising a 1.5 x 2.5 cm segment including fascia, muscles and peritoneum. These defects were then closed by implantation of a PTFE mesh (Dual-Mesh, n = 6), a PPP mesh (Prolene, n = 6) or a new biocompatible mesh (NBM; Lyoplant, n = 6). Each rat was examined daily after treatment. Bodyweight was determined and the possible development of a hernia was monitored. After 6 weeks, the abdomen was opened again. Adhesions to the intestine were measured and the abdominal wall was removed for histological and tensiometric examination. (1) Compared to the untreated controls, all animals showed physiologic growth and normal bodyweight curve. (2) Only in one rat (Prolene) did an abdominal hernia develop. (3) In contrast to PTFE and PPP mesh, NBM showed only minimal adhesion to the intestine. (4) Tensiometry revealed high stability for non-resorbable materials. However, the characteristics of NBM were very similar to untreated abdominal wall. Our initial results indicate that biocompatible materials can also be used for the therapy of congenital abdominal wall defects.

Porcine dermal collagen graft in pediatric renal transplantation

Successful closure of the anterior abdominal wall in infants following renal transplantation of adult organs may present a challenging dilemma to the transplant surgeon. Restricted volume of the recipient abdominal cavity and size discrepancy of donor adult kidney may lead to graft compromise. Pressure on the graft may be exacerbated further in the postoperative period by oedema that may lead to abdominal compartment syndrome. Donor/recipient size disparity remains the major obstacle in infant renal transplantation. We describe the use of a porcine collagen graft to facilitate closure of the abdominal wall following intra-peritoneal transplantation of an adult cadaveric kidney.

Host response after reconstruction of abdominal wall defects with porcine dermal collagen in a rat model

OBJECTIVE

The purpose of this study was to compare the inflammatory response after implantation of Pelvicol with Prolene in a rat model.

STUDY DESIGN

Full-thickness abdominal wall defects were created in 64 Wistar rats, and reconstructed with either Pelvicol or Prolene. Animals were sacrificed on days 7, 14, 30, and 90 to evaluate the presence of herniation, infection, adhesions, and changes in thickness and tensile strength of the implants. Histopathology and immunohistochemistry were performed to evaluate the collagen deposition and the inflammatory response. Statistics were done with unpaired t test and Mann-Whitney rank test.

RESULTS

Pelvicol implantation induced infiltration of granulocytes, macrophages, and NK cells, which showed up-regulated expression of surface activation markers ICAM-1 and CD11b. This inflammatory response was significantly milder, and declined faster than in Prolene-implanted rats, and was also associated with fewer adhesions. Moreover, Pelvicol induced a slower, but more orderly collagen deposition, paralleling the surface of the implant. Pelvicol implants showed a slower increase in thickness and tensile strength early on, but this difference disappeared by day 90.

CONCLUSION

Pelvicol induces a milder inflammatory response, less adhesion formation, more orderly collagen deposition than Prolene, and reaches a comparable tensile strength only after 90 days.

Intra-abdominal hypertension and the abdominal compartment syndrome

BACKGROUND

Abdominal compartment syndrome (ACS) occurs when intra-abdominal pressure is abnormally high in association with organ dysfunction. It tends to have a poor outcome, even when treated promptly by abdominal decompression.

METHODS

A search of the Medline database was performed to identify articles related to intra-abdominal hypertension and ACS.

RESULTS

Currently there is no agreed definition or management of ACS. However, it is suggested that intra-abdominal pressure should be measured in patients at risk, with values above 20 mmHg being considered abnormal in most. Abdominal decompression should be considered in patients with rising pressure and organ dysfunction, indicated by increased airway pressure, reduced cardiac output and oliguria. Organ dysfunction often occurs at an intra-abdominal pressure greater than 35 mmHg and may start to develop between 26 and 35 mmHg. The mean survival rate of patients affected by compartment syndrome is 53 per cent.

CONCLUSION

The optimal time for intervention is not known, but outcome is often poor, even after decompression. Most of the available information relates to victims of trauma rather than general surgical patients.

Closure of Abdominal Wall Defects Using Acellular Dermal Matrix

BACKGROUND

After some abdominal surgical procedures, the abdominal wall defect may be too large for closure by tension-free approximation of the wound margins because of tissue loss or swelling of the abdominal viscera. A variety of absorbable and nonabsorbable prosthetic materials have been used for emergency abdominal wall reconstruction. Of these materials, polytetrafluoroethylene (PTFE) sheets have proved to be the most efficacious.

METHODS

This study compared the efficacy of allogenic acellular dermal matrix (ADM) and PTFE as prosthetic materials for wound closure in rats with surgical, full-thickness, 2 x 3-cm abdominal wounds. Healing was studied among animals with and those without experimentally induced peritonitis for 21 days after surgery.

RESULTS

Acellular dermal matrix became vascularized and incorporated into the wound bed and was partially or fully epithelialized without the need for skin grafting. As a result, little superficial bleeding was seen, and ADM effectively closed the wounds even in the presence of peritonitis. Wounds treated with ADM also showed a significant reduction in wound area (sterile:p < 0.001; contaminated:p < 0.05). In contrast, PTFE temporarily closed the wounds, but was not incorporated into them. It consequently evoked the formation of extensive underlying granulation tissue that showed significant superficial bleeding when the PTFE was removed. Very limited wound contraction occurred in PTFE-treated wounds, and some instances of evisceration and fistula formation were observed. Wounds treated with both types of material showed significant amounts of adhesion to visceral organs underlying the wound site.

CONCLUSIONS

Acellular dermal matrix exhibits a number of favorable features relative to PTFE for closing sterile or contaminated full-thickness abdominal wall defects.