Biological implants in abdominal wall repair

A retrospective, Italian multicenter study of complex abdominal wall defect repair with a Permacol biological mesh

Complex abdominal wall defects (CAWDs) can be difficult to repair and using a conventional synthetic mesh is often unsuitable. A biological mesh might offer a solution for CAWD repair, but the clinical outcomes are unclear. Here, we evaluated the efficacy of a cross-linked, acellular porcine dermal collagen matrix implant (Permacol) for CAWD repair in a cohort of 60 patients. Here, 58.3% patients presented with a grade 3 hernia (according to the Ventral Hernia Working Group grading system) and a contaminated surgical field. Permacol was implanted as a bridge in 46.7%, as an underlay (intraperitoneal position) in 38.3% and as a sublay (retromuscolar position) in 15% of patients. Fascia closure was achieved in 53.3% of patients. The surgical site occurrence rate was 35% and the defect size significantly influenced the probability of post-operative complications. The long-term (2 year) hernia recurrence rate was 36.2%. This study represents the first large multi-centre Italian case series on Permacol implants in patients with a CAWD. Our data suggest that Permacol is a feasible strategy to repair a CAWD, with acceptable early complications and long-term (2 year) recurrence rates.

The open abdomen in trauma and non-trauma patients: WSES guidelines

Damage control resuscitation may lead to postoperative intra-abdominal hypertension or abdominal compartment syndrome. These conditions may result in a vicious, self-perpetuating cycle leading to severe physiologic derangements and multiorgan failure unless interrupted by abdominal (surgical or other) decompression. Further, in some clinical situations, the abdomen cannot be closed due to the visceral edema, the inability to control the compelling source of infection or the necessity to re-explore (as a "planned second-look" laparotomy) or complete previously initiated damage control procedures or in cases of abdominal wall disruption. The open abdomen in trauma and non-trauma patients has been proposed to be effective in preventing or treating deranged physiology in patients with severe injuries or critical illness when no other perceived options exist. Its use, however, remains controversial as it is resource consuming and represents a non-anatomic situation with the potential for severe adverse effects. Its use, therefore, should only be considered in patients who would most benefit from it. Abdominal fascia-to-fascia closure should be done as soon as the patient can physiologically tolerate it. All precautions to minimize complications should be implemented.

The role of open abdomen in non-trauma patient: WSES Consensus Paper

The open abdomen (OA) is defined as intentional decision to leave the fascial edges of the abdomen un-approximated after laparotomy (laparostomy). The abdominal contents are potentially exposed and therefore must be protected with a temporary coverage, which is referred to as temporal abdominal closure (TAC). OA use remains widely debated with many specific details deserving detailed assessment and clarification. To date, in patients with intra-abdominal emergencies, the OA has not been formally endorsed for routine utilization; although, utilization is seemingly increasing. Therefore, the World Society of Emergency Surgery (WSES), Abdominal Compartment Society (WSACS) and the Donegal Research Academy united a worldwide group of experts in an international consensus conference to review and thereafter propose the basis for evidence-directed utilization of OA management in non-trauma emergency surgery and critically ill patients. In addition to utilization recommendations, questions with insufficient evidence urgently requiring future study were identified.

Risk-adjusted procedure tailoring leads to uniformly low complication rates in ventral and incisional hernia repair: a propensity score analysis and internal validation of classification criteria

BACKGROUND

The usual approach in hernia surgery is to select the ideal repair method independent of the patient's characteristics. In the present study, we change the approach to ask which technique is best for the individual patient`s risk profile. For this, two criteria are important: does the patient need reconstruction of the abdominal wall? or does he or she need treatment of symptoms without being exposed to unnecessarily high perioperative risks?

METHODS

In a heuristic selection procedure, 486 consecutive patients were classified according to their characteristics as low-risk or high-risk for postoperative complications. Low-risk patients preferentially underwent open abdominal wall reconstruction with mesh (MFR + mesh), high-risk patients mainly a bridging-mesh procedure, either by laparoscopic (Lap.-IPOM) or open approach (Open-IPOM). Primary outcome was the incidence of postoperative complications. Secondary outcome was the recurrence-free interval. The propensity score was used for covariate adjustment analyzing recurrence rate as well as postoperative complications using Cox regression and logistic regression, respectively.

RESULTS

Comparison of all surgical procedures showed risk factors had no independent influence on occurrence of complications (p = 0.110). Hernial gap width was an independent factor for occurrence of complications (p = 0.002). Propensity score adjustment revealed Lap.-IPOM to have a significantly higher recurrence rate than MFR + mesh (HR 2.367, 95% CI 1.123-4.957, p = 0.024). Three or more risk factors were protective against recurrence (HR 0.454, 95% CI 0.221-0.924, p = 0.030). In the univariate Cox regression analysis for recurrence, age >50 years was a protective prognostic factor (HR 0.412, 95% CI 0.245-0.702, p = 0.002).

CONCLUSIONS

The classification criteria applied were internally validated. The heuristic algorithm ensured that patients at high-risk of complications did not have a higher perioperative complication rate than patients at low-risk.

Onlay parastomal hernia repair with cross-linked porcine dermal collagen biologic mesh: long-term results

PURPOSE

The optimal technique and mesh type for parastomal hernia repair have yet to be ascertained. Biologic meshes have been advocated in parastomal hernia repair due to purported resistance to infection in contaminated fields. The aim of this study was to evaluate the effectiveness of additionally cross-linked acellular porcine dermal collagen mesh (Permacol) for onlay parastomal hernia repair.

METHODS

A retrospective review of case notes, and abdominal CT scans when available, was performed for consecutive patients who had a parastomal hernia repaired between January 2007 and May 2010. All hernias were repaired with onlay placement of the biologic mesh. Hernias were classified according to the Moreno-Matias classification where CT scans were available.

RESULTS

Over a 34-month period, 30 consecutive patients, median age 74 years, 17 female, underwent parastomal hernia repair using onlay biologic mesh. There were 23 paracolostomy and seven paraileostomy hernias. The hernia was primary in 26 patients. Pre-operative CT scans were available in 18 patients (Moreno-Matias Type 1 = 1, Type 2 = 4, Type 3 = 13). There was one perioperative death, and 29 patients were available for follow-up, and median duration of follow-up (either CT or clinical) was 36 months (range 3-79). Twenty-six patients developed recurrence of the parastomal hernia (89.6%), and median time to recurrence was 10 months (range 3-72),with Moreno-Matias Type 1 = 0, Type 2 = 4, Type 3 = 14, unknown = 8. Fifteen out of 26 patients have had repairs of the recurrence using a variety of techniques. Of these, 10 patients have had further recurrence.

CONCLUSION

Onlay repair of parastomal hernia with cross-linked porcine dermal collagen biologic mesh reinforcement has poor long-term outcomes with unacceptably high recurrence rates and should not be performed.

The use of an acellular porcine dermal collagen implant in the repair of complex abdominal wall defects: a European multicentre retrospective study

BACKGROUND

The use of biological materials for the repair of complex abdominal wall defects has increased over the years; however, the role of these materials in routine practice remains unclear. The aim of the study was to evaluate clinical outcomes following the use of Permacol™ porcine collagen surgical implant in complex abdominal wall repair.

METHODS

This subset analysis of seven European sites from a multicentre retrospective study included patients undergoing open or laparoscopic surgery and treated with Permacol™ surgical implant. Inguinal, parastomal, diaphragmatic, perineal, and hiatal repairs were excluded. Only patients with at least 12 months of follow-up after surgery were included.

RESULTS

A total of 109 patients (56 males and 53 females) were included. Patients had a median of two comorbidities (range 0-6). Thirty-three per cent of patients were treated for recurrent hernia. All but one case used an open approach. Sixty-six per cent were Center for Disease Control wound class II-IV at the time of surgery. Fascial closure was achieved in 69%. Median follow-up length was 720 days (range 368-2857). Recurrence rates at 1 and 2 years were 9.2 and 18.3 %, respectively, and were higher in cases without fascial closure. One-year recurrence was higher following use of an onlay technique (P = 0.025). In a multivariate analysis, among 16 comorbidities examined only fascial closure significantly impacted 1-year recurrence (P = 0.049).

CONCLUSIONS

Data from this large retrospective multicentre European study strongly suggest the use of Permacol™ porcine collagen surgical implant to be safe and effective for complex abdominal wall repair. The recurrence rate was impacted by fascial closure.

[Indications for laparoscopic treatment of large incisional hernias]

Hernia surgeons and patients have learned to appreciate the advantages of minimally invasive laparoscopic procedures. After overcoming the early learning curve phase, smaller wound surface areas, shorter operation times and briefer hospital stays have become routine. Severe surgery-related complications are rare. Patients with poor risk profiles (e.g. age >70 years, BMI >30 and nicotine consumption) profit especially from these advantages. This positive picture is clouded, however, by the need for an intraperitoneal mesh and specifically by the unchanged recurrence rate. The latter is not significantly lowered even by laparoscopic intraperitoneal on-lay mesh (laparoscopic IPOM) procedures. The current literature shows that irrespective of surgical technique, e.g. retromuscular mesh or laparoscopic IPOM, the risk profile and size of the hernia defect are independent factors that determine the prognosis for recurrence. While a cure of incisional hernia is no longer the only goal, the new indication scenario has two main goals: (a) for young patients at low risk or in patients for whom functional and morphological reconstruction of the abdominal wall are of primary importance, an open retromuscular mesh procedure is indicated (despite the higher morbidity) and (b) for older patients and chiefly for patients with a complex risk profile for whom treatment of the ventral hernia symptoms is paramount, laparoscopic procedures are indicated (due to the lower morbidity). This algorithm assumes that the treating surgeons have the requisite expertise and is discussed using the examples of four complex case reports.

Porcine dermis implants in soft-tissue reconstruction: current status

Soft-tissue reconstruction for a variety of surgical conditions, such as abdominal wall hernia or pelvic organ prolapse, remains a challenge. There are numerous meshes available that may be simply categorized as either synthetic or biologic. Within biologic meshes, porcine dermal meshes have come to dominate the market. This review examines the current evidence for their use and the limitations of knowledge. Although there is increasing evidence to support their safety, long-term follow-up studies that support their efficacy are lacking. Numerous clinical trials that remain ongoing may help elucidate their precise role in soft-tissue reconstruction.

Ultrasound biomicroscopy (UBM) and scanning acoustic microscopy (SAM) for the assessment of hernia mesh integration: a comparison to standard histology in an experimental model

BACKGROUND

Mesh integration is a key parameter for reliable and safe hernia repair. So far, its assessment is based on histology obtained from rare second-look operations or experimental research. Therefore, non-invasive high-resolution imaging techniques would be of great value. Ultrasound biomicroscopy (UBM) and scanning acoustic microscopy (SAM) have shown potential in the imaging of hard and soft tissues. This experimental study compared the detection of mesh integration, foreign body reaction and scar formation in UBM/SAM with standard histology.

MATERIALS AND METHODS

Ten titanized polypropylene meshes were implanted in rats in a model of onlay repair. 17 days postoperative animals were killed and samples were paraffin embedded for histology (H&E, Cresyl violet) or processed for postmortem UBM/SAM. The observation period was uneventful and meshes appeared well integrated.

RESULTS

Relocation of neighboring cross-sectional levels could easily be achieved with the 40-MHz UBM and granulation tissue could be distinguished from adjacent muscle tissue layers. The spatial resolution of approximately 8 μm of the 200-MHz UBM system images was comparable to standard histology (2.5-5× magnification) and allowed a clear identification of mesh fibers and different tissue types, e.g., scar, fat, granulation, and muscle tissues, as well as vessels, abscedations, and foreign body giant cell clusters.

CONCLUSION

This pilot study demonstrates the potential of high-frequency ultrasound to assess hernia mesh integration non-invasively. Although the methods lack cell-specific information, tissue integration could reliably be assessed. The possibility of conducting UBM in vivo advocates this method as a guidance tool for the indication of second-look operations and subsequent elaborate histological analyses.

The in vivo evaluation of tissue-based biomaterials in a rat full-thickness abdominal wall defect model

Hernias are defects in which an anatomical fascia is breached resulting in ectopic positioning of an organ into an orifice which routinely does not contain it. Intervention often involves repositioning translocated organs and repair of damaged fascia using exogenous grafts. Despite hernia prevalence, repairs can still fail due to postoperative complications, such as chronic pain and decreased mobility. This study compared repair capacities and characterized the foreign body response elicited by a number of hernia repair grafts to deduce their bulk inflammatory properties while also concluding the point in their fabrication when these are inferred. Materials derived from human dermis (Alloderm(®) ), porcine dermis (Permacol™, patch A, patch D and Strattice(®) ), porcine small-intestinal submucosa (Surgisis™) and a synthetic (multifilament Surgipro™) were implanted into a rat full-thickness abdominal wall excision model, incubated for up to 2 years and characterized histopathologically. Surgisis™ resorbed the fastest of the materials tested (1-3 months) resulting in a mechanically stable parietal peritoneum. Decellularization using sodium dodecyl sulfate (patch A) stimulated a large early inflammatory response which ultimately may have contributed to increased resorption of porcine dermal matrix however the remaining materials typically persisted throughout the 2-year incubation. Cross-linking porcine dermis using 1,6-hexamethylene disocyanate (vs. an identical noncross-linked counterpart) showed no difference in cell recruitment or material integration over 2 years. Typically Strattice(®) and Alloderm(®) recruited larger early populations of cells than Permacol™; however, over extended periods of time in vivo this response normalized.