Elastic TPU Mesh as Abdominal Wall Inlay Significantly Reduces Defect Size in a Minipig Model

No difference in outcomes between large- and small-pore meshes in a prospective, randomized, multicenter trial investigating open retromuscular meshplasty for incisional hernia repair

STUDY DESIGN

A randomized, controlled, prospective multicenter clinical trial with a parallel group design was initiated in eight surgical centers to compare a large-pore polypropylene mesh (Ultrapro®) to a small-pore polypropylene mesh (Premilene®) within a standardized retromuscular meshplasty for incisional hernia repair.

METHODS

Between 2004 and 2006, patients with a fascial defect with a minimum diameter of 4 cm after vertical midline laparotomy were recruited for the trial. Patients underwent retromuscular meshplasty with either a large-pore or a small-pore mesh to identify the superiority of the large-pore mesh. Follow-up visits were scheduled at 5 and 21 days and 4, 12, and 24 months after surgery. A clinical examination, a modified short form 36 (SF-36®), a daily activity questionnaire, and an ultrasound investigation of the abdominal wall were completed at every follow-up visit. The primary outcome criterion was foreign body sensation at the 12-month visit, and the secondary endpoint criteria were the occurrence of hematoma, seroma, and chronic pain within 24 months postoperatively.

RESULTS

In 8 centers, 181 patients were included in the study. Neither foreign body sensation within the first year after surgery (27.5% Ultrapro®, 32.2% Premilene®) nor the time until the first occurrence of foreign body sensation within the first year was significantly different between the groups. Regarding the secondary endpoints, no significant differences could be observed. At the 2-year follow-up, recurrences occurred in 5 Ultrapro® patients (5.5%) and 4 Premilene® patients (4.4%).

CONCLUSION

Despite considerable differences in theoretical and experimental works, we have not been able to identify differences in surgical or patient-reported outcomes between the use of large- and small-pore meshes for retromuscular incisional hernia repair.

TRIAL REGISTRATION

Clinical Trials NCT04961346 (16.06.2021) retrospectively registered.

Novel Elastic Threads for Intestinal Anastomoses: Feasibility and Mechanical Evaluation in a Porcine and Rabbit Model

Gastrointestinal anastomoses are an important source of postoperative complications. In particular, the ideal suturing material is still the subject of investigation. Therefore, this study aimed to evaluate a newly developed suturing material with elastic properties made from thermoplastic polyurethane (TPU); Polyvinylidene fluoride (PVDF) and TPU were tested in two different textures (round and a modified, “snowflake” structure) in 32 minipigs, with two anastomoses of the small intestine sutured 2 m apart. After 90 days, the anastomoses were evaluated for inflammation, the healing process, and foreign body reactions. A computer-assisted immunohistological analysis of staining for Ki67, CD68, smooth muscle actin (SMA), and Sirius red was performed using TissueFAXS. Additionally, the in vivo elastic properties of the material were assessed by measuring the suture tension in a rabbit model. Each suture was tested twice in three rabbits; No major surgical complications were observed and all anastomoses showed adequate wound healing. The Ki67+ count and SMA area differed between the groups (F (3, 66) = 5.884, p = 0.0013 and F (3, 56) = 6.880, p = 0.0005, respectively). In the TPU-snowflake material, the Ki67+ count was the lowest, while the SMA area provided the highest values. The CD68+ count and collagen I/III ratio did not differ between the groups (F (3, 69) = 2.646, p = 0.0558 and F (3, 54) = 0.496, p = 0.686, respectively). The suture tension measurements showed a significant reduction in suture tension loss for both the TPU threads; Suturing material made from TPU with elastic properties proved applicable for intestinal anastomoses in a porcine model. In addition, our results suggest a successful reduction in tissue incision and an overall suture tension homogenization.

Improved tissue integration of a new elastic intraperitoneal stoma mesh prosthesis

Parastomal herniation is a frequent complication in colorectal surgery, occurring with a prevalence of 30-80%. The aim of the study was to create a new intraperitoneal colostoma mesh prosthesis (IPST) with enhanced elastic properties made with thermoplastic polyurethane (TPU) monofilaments. We performed open terminal sigmoid colostomies reinforced with either a 10 cm by 10 cm polyvinylidene fluoride (PVDF) or a new TPU/PVDF composite mesh in a total of 10 minipigs. Colostoma was placed paramedian in the left lower abdomen and IPST meshes were fixed intraperitoneal. After 8 weeks, the animals were euthanized after laparoscopic exploration and specimen were explanted for histological investigations. Implantation of a new IPST-mesh with enhanced elastic properties was feasible in a minipig model within an observation period of 8 weeks. Immunohistochemically, Collagen I/III ratio as a marker of tissue integration was significantly higher in TPU-group versus PVDF group (9.4 ± 0.5 vs. 8.1 ± 0.5, p = 0.002) with a significantly lower inflammatory reaction measured by a smaller inner granuloma at mesh-colon interface (17.6 ± 3.3 μm vs. 23 ± 5 μm, p < 0.001). A new TPU/PVDF composite mesh with enhanced elastic properties as IPST was created. Stoma surgery and especially the evaluation of the new stoma mesh prosthesis are feasible with reproducible results in an animal model. Tissue integration expressed by Collagen I/III ratio seems to be improved in comparison to standard-elastic PVDF-IPST meshes.