Evaluation of fenestrated and non-fenestrated biologic grafts in a porcine model of mature ventral incisional hernia repair.

INTRODUCTION: The purpose of this study is to compare the tissue incorporation of a novel fenestrated and non-fenestrated crosslinked porcine dermal matrix (CPDM) (CollaMend™, Davol Inc., Warwick, RI) in a porcine model of ventral hernia repair.
METHODS: Bilateral abdominal wall defects were created in 12 Yucatan minipigs and repaired with a preperitoneal or intraperitoneal technique 21 days after hernia creation. Animals were randomized to fenestrated or non-fenestrated CPDM for n = 6 pieces of each graft in the preperitoneal or intraperitoneal location. All animals were sacrificed at 1 month. Adhesion characteristics and graft contraction/growth were measured by the Garrard adhesion grading scale and transparent grid overlay. Histological analysis of hematoxylin and eosin (H&E)-stained slides was performed to assess graft incorporation. Tissue incorporation strength was measured by a T-peel tensile test. The strength of explanted CPDM alone and de novo CPDM was measured by a uniaxial tensile test using a tensiometer (Instron, Norwood, MA) at a displacement rate of 0.42 mm/s. Statistical significance (P < 0.05) was determined for histological analysis using a Kruskal-Wallis non-parametric test with a Bonferroni correction, and for all other analyses using a two-way analysis of variance (ANOVA) with a Bonferroni post-test or a Kruskal-Wallis non-parametric test with a Dunn's post-test.
RESULTS: Intraperitoneal placement of fenestrated CPDM resulted in a significantly higher area of adhesions and adhesion score compared to the preperitoneal placement of fenestrated CPDM (P < 0.05). For both preperitoneal and intraperitoneal placement, histological findings demonstrated greater incorporation of the graft due to the fenestrations. No significant differences were detected in the uniaxial tensile strengths of the graft materials alone, either due to the graft type (non-fenestrated vs. fenestrated) or due to the placement location (preperitoneal vs. intraperitoneal). The incorporation strength (T-peel force) was significantly greater for fenestrated compared to non-fenestrated CPDM when placed in the preperitoneal location (P < 0.01). The incorporation strength was also significantly greater for fenestrated CPDM placed in the preperitoneal location compared to fenestrated CPDM placed in the intraperitoneal location (P < 0.05).
CONCLUSIONS: Fenestrations in CPDM result in greater tissue incorporation strength and lower adhesion area and score when placed in the preperitoneal location. Fenestrations in CPDM allow for greater tissue incorporation without accelerating graft degradation. Fenestrations may be placed in CPDM while still allowing adequate graft strength for intraperitoneal and preperitoneal hernia repairs at 1 month in a porcine model.