Ventral hernia repair using allogenic acellular dermal matrix in a swine model.
ABSTRACT This study was designed to assess the long-term efficacy of allogenic acellular dermal matrix (ADM) used as an interpositional graft for ventral hernia repair in a swine model.
We created 12x4-cm full-thickness abdominal wall defects in 22 Yucatan miniature pigs. The defect was repaired with either two 6x4-cm pieces of AlloDerm (acellular dermal matrix processed from pig skin in order to avoid a xenogenic response, LifeCell Corporation, Branchburg, NJ USA) (n = 12), or expanded polytetrafluoroethylene mesh (ePTFE) (Gore-Tex, W.L. Gore & Associates, Inc., Newark, DE USA) (n = 10). In six pigs, a separate 3-cm fascial incision was made, which was then suture repaired as a control for tensiometry testing. The surgical sites were evaluated at either 3 months or 9 months for the presence of a hernia, stretching of the implant, adhesions, vascularity, and biomechanical strength.
Two hernias occurred in both the ADM and the ePTFE groups. There was minimal stretching of the implants and minimal adhesions in both groups. Fluorescein testing and histology indicated vascular ingrowth into the ADM. There was no statistical difference between the mean breaking strengths of the ADM-fascial interface (106.5 N +/- SD 40.1), the interface between two pieces of ADM (149.1 N +/- SD 76.7), and the primary fascial repair (108.1 N +/- SD 20.9) at 9 months. The ADM-fascial interface had a significantly higher breaking strength than that of the ePTFE-fascia interface (66.1 N +/- SD 30.1) (P = 0.017, t-test, P = 0.043 Wilcoxon rank sum test).
In this study, we were unable to demonstrate a difference between ADM and ePTFE in their ability to repair ventral hernias at 9 months in a swine model. The ADM additionally supports vascular ingrowth and exhibits increased breaking strength at the fascia-implant interface.
Article: The effect of AlloDerm envelopes on periprosthetic capsule formation with and without radiation.[show abstract] [hide abstract]
ABSTRACT: The pathobiology of radiation-induced periprosthetic capsular formation and factors that may ameliorate its development have not been fully elucidated. The authors hypothesized that AlloDerm would diminish radiation-induced capsular formation. Two 5-ml implants were placed submuscularly in the backs of 41 rats. The right implant was wrapped with AlloDerm and the left remained bare. After 48 hours, 20 animals underwent irradiation to each implant, and 21 animals underwent no further treatment and served as controls. After 3 and 12 weeks, the capsules were harvested and submitted for tensile strength and histologic examination. Intraprosthetic pressures were measured in each implant at the time of surgery and when the animals were killed. The intraprosthetic pressure decrease was uniform among all groups at 3 and 12 weeks. Between 3 and 12 weeks, capsular tensile strength increased in nonirradiated bare implants. There was considerable invasion of nonirradiated AlloDerm by inflammatory infiltrates at 3 weeks, and AlloDerm thickness decreased over time. Cellular invasion of AlloDerm was decreased with irradiation at both time points. Capsular tensile strength and thickness of the irradiated bare and AlloDerm capsules did not change between 3 and 12 weeks. Radiation increased inflammation of bare capsules at 12 weeks, but it was significantly reduced in irradiated AlloDerm capsules. The majority of irradiated bare capsules developed pseudoepithelium, whereas AlloDerm protected capsules from this transformation. AlloDerm decreases radiation-related inflammation and delays or diminishes pseudoepithelium formation and thus may slow progression of capsular formation, fibrosis, and contraction.Plastic and reconstructive surgery 04/2009; 123(3):807-16. · 2.74 Impact Factor
Article: Soft polypropylene mesh, but not cadaveric dermis, significantly improves outcomes in midline hernia repairs using the components separation technique.[show abstract] [hide abstract]
ABSTRACT: The search continues for the "ideal" repair of the midline ventral hernia, and the components separation technique has a low, but still concerning, hernia recurrence rate. The authors hypothesize that adding prosthetic or bioprosthetic meshes to the midline closure during components separation would reduce recurrence rates with minimal added morbidity. Over a 3-year period, patients had a components separation procedure where either acellular cadaveric dermis (n = 26) or soft polypropylene mesh (n = 28) was used as an intraperitoneal underlay for reinforcement of the midline repair, but not as a "bridging material." In 36 operations, the mesh or cadaveric dermis was placed at the time of the components separation, and in the remaining cases (n = 18), the underlay was used to treat a recurrence after components separation. Cadaveric dermis was associated with a 46 percent "true" recurrence rate that required reoperation (mean follow-up, 17.3 months), whereas soft polypropylene mesh had a significantly lower recurrence rate of 11 percent (p = 0.0057) during a follow-up period of 16 months. Because of a higher incidence of concomitant bowel surgery and contamination in the cadaveric dermis group, additional subset analysis of uncontaminated cases was performed, demonstrating a 61 percent recurrence rate for cadaveric dermis compared with 12 percent for soft polypropylene (p = 0.0017). No significant differences in major and minor complications were seen between groups. Soft polypropylene mesh, but not acellular dermis, demonstrates acceptably low complication and hernia recurrence rates when used as a reinforcement of the midline ventral hernia closure in conjunction with components separation.Plastic and reconstructive surgery 10/2009; 124(3):836-47. · 2.74 Impact Factor
Article: The component separation index: a standardized biometric identity in abdominal wall reconstruction.[show abstract] [hide abstract]
ABSTRACT: Objective: Reconstruction of traumatic ventral hernias often requires additional techniques to the abdominal wall component separation, such as the use of interpositional reconstruction with an acellular dermal matrix or other mesh to bridge the defect. Methods: We have developed a new value termed the "Component Separation Index" to evaluate ventral hernia defects. Choosing a fixed point on a preoperative axial computed tomographic scan (aorta) and the medial leading edges of the rectus abdominus muscles, we determined the angle of diastasis of the hernia. This angle is divided by 360° giving a relative value of the transverse defect size as compared to the estimated circular body habitus for that specific patient. A retrospective review of 36 cases of ventral hernia repairs was performed. The Component Separation Index was calculated from the preoperative computed tomographic scans obtained before repair. Group 1 (n = 18) required component separation for closure. Group 2 (n = 18) required component separation and placement of interpositional mesh to span the hernia defect. Results: The Component Separation Index values were then compared using the student t test for each group. The mean Component Separation Index for group 1 was 0.11 with standard deviation of 0.06. The mean Component Separation Index for group 2 was 0.21 with standard deviation of 0.04 (P < .0001). As this value approaches 0.21, the likelihood of an interpositional repair in addition to component separation becomes much greater. Conclusions: While there is no substitute for clinical acumen when evaluating these defects, objective measurements can provide a valuable additional tool for the surgeon facing these challenging cases.Eplasty 01/2012; 12:e17.