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In Vivo Evaluation of a Novel Suture Design for Abdominal Wall Closure
Jason M. Souza, MD, Gregory A. Dumanian, MD.
Northwestern University, Chicago, IL, USA.
Plastic surgeons have become increasingly involved in the field of abdominal wall reconstruction. Here we present a novel suture design aimed at minimizing the early laparotomy dehiscence that drives ventral hernia formation. We hypothesized that modulation of the suture-tissue interface through use of a macroporous structure and increased aspect ratio (width-to-height ratio) would decrease the suture pull-through that leads to laparotomy dehiscence.
We produced incisional hernias in 30 animals according to an established rat hernia model. This model has been shown to produce predictable hernia recurrence when repaired with conventional suture. On postoperative day (POD) 28, the mature hernia rings were dissected and standardized photographs were taken. The animals were then randomized to repair with either two 5-0 polypropylene sutures (Group 1) or two mid-weight polypropylene mesh sutures (Group 2) placed in similar fashion. On POD 56, we completed necropsies, during which the recurrent hernia rings were again dissected and photographed. Waterproof 2mm grid graph paper was placed intra-abdominally to serve as a reference for all photographs. To minimize the investigator bias introduced in defining and measuring defect areas, edge-detection software was used to define the border of the hernia defect and calculate the area. All calculations were calibrated based on the 2mm grid present in each photograph. In addition to these measurements, histology was performed on all mesh suture specimens. In-growth was graded according to a 4-point scale adapted from the American Society for Testing and Materials (ASTM) guidelines, as previously described.
Seventeen hernias were repaired with mesh sutures, while 13 hernias were repaired with conventional 5-0 polypropylene sutures. Despite randomization, the defects repaired with mesh suture were significantly larger than those undergoing conventional suture repair (391.9 ± 33.4 mm2 vs. 255.4 ± 23.3 mm2; P<.0025). The mean area of the recurrent defects following repair with the mesh suture was 177.8 ± 27.1 mm2, compared to 267.3 ± 34.1 mm2 following conventional suture repair. This correlated to a 57.4% reduction in defect area after mesh suture repair, compared to a 10.1% increase in post-repair defect area following conventional suture repair (p<.0007). Notably, none (0/34) of the mesh sutures pulled-through the surrounding abdominal wall tissue, while 65% (17/26) of the conventional sutures used for repair demonstrated complete pull-through. With regard to histology, Excellent (ASTM 3) in-growth was observed in 13/17 mesh suture specimens, while the remaining 4 specimens demonstrated Good (ASTM2) in-growth.
The mesh sutures better resisted suture pull-through than conventional polypropylene sutures of comparable tensile strength. To our knowledge, this is the first laboratory investigation to highlight the importance of increased aspect ratio and macroporous structure with regard to suture design. By more evenly distributing distracting forces across the suture-tissue interface and permitting tissue integration into the substance of the suture, a suture incorporating these design elements would better prevent the early laparotomy dehiscence that leads to incisional hernia formation.
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