Chinese expert consensus on adult ventral abdominal wall defect repair and reconstruction

Recent Advances in Functional Hydrogel for Repair of Abdominal Wall Defects: A Review

The abdominal wall plays a crucial role in safeguarding the internal organs of the body, serving as an essential protective barrier. Defects in the abdominal wall are common due to surgery, infection, or trauma. Complex defects have limited self-healing capacity and require external intervention. Traditional treatments have drawbacks, and biomaterials have not fully achieved the desired outcomes. Hydrogel has emerged as a promising strategy that is extensively studied and applied in promoting tissue regeneration by filling or repairing damaged tissue due to its unique properties. This review summarizes the five prominent properties and advances in using hydrogels to enhance the healing and repair of abdominal wall defects: (a) good biocompatibility with host tissues that reduces adverse reactions and immune responses while supporting cell adhesion migration proliferation; (b) tunable mechanical properties matching those of the abdominal wall that adapt to normal movement deformations while reducing tissue stress, thereby influencing regulating cell behavior tissue regeneration; (c) drug carriers continuously delivering drugs and bioactive molecules to sites optimizing healing processes enhancing tissue regeneration; (d) promotion of cell interactions by simulating hydrated extracellular matrix environments, providing physical support, space, and cues for cell migration, adhesion, and proliferation; (e) easy manipulation and application in surgical procedures, allowing precise placement and close adhesion to the defective abdominal wall, providing mechanical support. Additionally, the advances of hydrogels for repairing defects in the abdominal wall are also mentioned. Finally, an overview is provided on the current obstacles and constraints faced by hydrogels, along with potential prospects in the repair of abdominal wall defects.

Designing a bi-layer multifunctional hydrogel patch based on polyvinyl alcohol, quaternized chitosan and gallic acid for abdominal wall defect repair

In abdominal wall defect repair, surgical site infection (SSI) remains the primary cause of failure, while complications like visceral adhesions present significant challenges following patch implantation. We designed a Janus multifunctional hydrogel patch (JMP) with antibacterial, anti-inflammatory, and anti-adhesive properties. The patch comprises two distinct layers: a pro-healing layer and an anti-adhesion layer. The pro-healing layer was created by a simple mixture of polyvinyl alcohol (PVA), quaternized chitosan (QCS), and gallic acid (GA), crosslinked to form PVA/QCS/GA (PQG) hydrogels through GA's self-assembly effect and hydrogen bonding. Additionally, the PVA anti-adhesive layer was constructed using a drying-assisted salting method, providing a smooth and dense physical barrier to prevent visceral adhesion while offering essential mechanical support to the abdominal wall. The hydrogel patch demonstrates widely adjustable mechanical properties, exceptional biocompatibility, and potent antimicrobial properties, along with a sustained and stable release of antioxidants. In rat models of skin and abdominal wall defects, the JMP effectively promoted tissue healing by controlling infection, inhibiting inflammation, stimulating neovascularization, and successfully preventing the formation of visceral adhesions. These compelling results highlight the JMP's potential to improve the success rate of abdominal wall defect repair and reduce surgical complications.

Suturing Versus Adhesion for Mesh Fixation in Ventral Hernia Repair and Abdominal Wall Reconstruction: A Systematic Review and Network Meta-Analysis

Abdominal wall reconstruction (AWR) is a surgical procedure performed to address various conditions such as hernias, incisional hernias, and complex abdominal wall defects. Mesh fixation plays a crucial role in providing mechanical reinforcement to the weakened abdominal wall during AWR. Traditionally, suturing has been the preferred method for mesh fixation; however, adhesion techniques using tissue adhesives or glues have gained attention as an alternative approach. This systematic review aims to compare suturing and adhesion techniques for mesh fixation in AWR and assess their effectiveness in preventing hernia recurrence. A comprehensive literature search was conducted across relevant databases, including PubMed, MEDLINE, Embase, and the Cochrane Library. Studies that fulfilled the predetermined eligibility criteria were included. The primary outcome measure of interest was hernia recurrence rates. Secondary outcomes included mesh-related complications, surgical site infections, patient-reported outcomes, and functional outcomes. A risk of bias assessment was performed for the included studies, and data were synthesized qualitatively. Overall, the results of the included studies suggest that atraumatic mesh fixation with glue may have the potential to reduce chronic groin pain (CGP). However, there were significant variations in patient selection criteria, glue administration techniques, and hernia repair methods among the trials, which limited the ability to draw definitive conclusions. Additionally, the definitions of CGP and measurement scales for postoperative pain varied across studies, making it challenging to compare outcomes. The limitations of the review include the small sample sizes in some trials, relatively short follow-up durations, and the lack of standardized criteria for assessing variables such as foreign body sensation and groin compliance. Furthermore, the economic implications of using glue fixation compared to traditional suture fixation need to be considered.

Killing two birds with one stone: A therapeutic copper-loaded bio-patch promoted abdominal wall repair via VEGF pathway

Hernia and life-threatening intestinal obstruction often result from abdominal wall injuries, and the regeneration of abdominal wall defects is limited due to the lack of biocompatible, antibacterial and angiogenic scaffolding materials for treating injured tissues. Taking inspiration from the facile preparation of dopamine polymerization and its surface modification technology, in this study, multi-therapeutic copper element was introduced into porcine small intestinal submucosa (SIS) bio-patches through polydopamine (PDA) deposition, in order to regenerate abdominal wall injury. In both in vitro antibacterial assays, cytocompatibility assays and in vivo abdominal wall repair experiments, the SIS/PDA/Cu bio-patches exhibited robust antibacterial efficiency (＞99%), excellent biocompatibility to cells (＞90%), and enhanced neovascularization and improved collagen maturity compared to other commercially available patches (3.0-fold higher than the PP mesh), due to their activation of VEGF pathway. These findings indicated the bio-patch was a promising application for preventing visceral adhesion, bacterial infection, and promoting soft tissue regeneration.

Polypropylene composite hernia mesh with anti-adhesion layer composed of PVA hydrogel and liposomes drug delivery system

Polypropylene (PP) mesh has been widely used in hernia repair as prosthesis material owing to its excellent balanced biocompatibility and mechanical properties. However, abdominal adhesion between the visceral and PP mesh is still a major problem. Therefore, anti-adhesive PP mesh was designed with poly(vinyl alcohol) (PVA) hydrogel and liposomes drug delivery system. First, PVA hydrogel coating was formed on the surface of PP mesh with freezing-thawing processing cycles (FTP). Subsequently, the lyophilized PVA₁₀-c-PP was immersed in rapamycin (RPM)-loaded liposome solution until swelling equilibrated to obtain the anti-adhesion mesh RPM@LPS/PVA₁₀-c-PP. It was demonstrated that the hydrogel coating can stably fix on the surface of PP mesh even after immersed in PBS solution at 37 °C or 40 °C for up to 30 days. In vitro cell tests revealed the excellent cytocompatibility and the potential to inhibit cell adhesion of the modified PP mesh. Moreover, the anti-adhesive effects of the RPM@LPS/PVA₁₀-c-PP mesh was evaluated through in vivo experiments. The RPM@LPS/PVA₁₀-c-PP mesh exhibited less adhesion than original PP mesh throughout the duration of implantation. At 30 days, the adhesion score of RPM@LPS/PVA₁₀-c-PP mesh was 1.37 ± 0.75, however the original PP was 3 ± 0.71. Furthermore, the results of H&E and Masson trichrome staining proved that the RPM@LPS/PVA₁₀-c-PP mesh showed slighter inflammation response and significant looser fibrous tissue surrounded the PP filaments as compared to the native PP. The current findings manifested that this type of RPM@LPS/PVA₁₀-c-PP might be a potential candidate for anti-adhesion treatment. DATA AVAILABILITY: Data will be made available on request.

The external oblique muscle flap technique for the reconstruction of abdominal wall defects

PURPOSE

Several modifications to the anterior component separation technique (ACST) have been reported to facilitate the closure of abdominal wall defects. In this study, the external oblique (EO) muscle flap for modified ACST during major abdominal wall defect reconstructions has been described.

METHODS

A retrospective review of consecutive patients undergoing modified ACST was conducted. The clinical data were collected and retrospectively analyzed.

RESULTS

Among the 36 patients admitted to our hospital from December 2014 to December 2020, 9 cases had rectus abdominis tumors, 1 case had rectus abdominis trauma, and 26 cases had incisional hernias. The average age was 61.17 ± 13.76 years, and the mean BMI was 24.25 ± 3.18 kg/m². The average width of the defect was 14.33 ± 2.90 cm. Unilateral EO muscle flap technique was used to reconstruct the abdominal wall. 3 cases of surgical site infection (8.3%), 4 cases of grade III or IV seroma (11.1%) and 2 cases of intestinal obstruction (5.5%)were reported postoperatively. Ischemic necrosis of the abdominal EO muscle flap, incision dehiscence, intestinal fistula, or other complications were not observed. 1 case of incisional hernia recurrence (2.8%) was reported. Recurrence of tumors or abdominal wall bulging were not noted during the follow-up period of 32.53 ± 14.21 months.

CONCLUTIONS

The EO muscle flap technique is associated with low postoperative morbidity and recurrence rate, which approves it a reliable technique for selected groups of patients. Further research are needed to confirm the effectiveness of this technique.

Body mass index and the risk of abdominal hernia: a Mendelian randomization study

PURPOSE

Abdominal hernia (AH) is one of the most common clinical diseases. A large number of observational studies have found that obesity is an important risk factor for AH. However, the causal relationship between obesity and AH cannot be determined because of the clinical studies on AH induced by obesity are relatively few and only have some small- or medium-scale observational studies. Observational studies have so many confounding factors and reverse causality due to their shortcomings. From an evidence-based medicine perspective, they are not sufficiently convincing. Therefore, there is still a lack of high-quality, evidence-based medical evidence supporting a causal relationship between obesity and AH. A causal relationship between obesity and AH is also almost impossible to confirm by randomized controlled trials (RCTs). Our study based on Mendelian randomization (MR) may provide a higher level of evidence-based medical support for the relationship between obesity and AH. Body mass index (BMI) is the most common measure used for defining obesity. Finally, we employed two-sample Mendelian randomization (TSMR) to explore the causal relationship between BMI and AH.

METHODS

AH-related single nucleotide polymorphisms (SNPs) data were obtained from the FinnGen Biobank (FB), and BMI-related single nucleotide polymorphisms (SNPs) data were obtained from the UK Biobank (UKB). Genetic loci are used as instrumental variables (IVs), methods such as inverse variance weighted (IVW) were used for two-sample Mendelian randomization analysis, and the odds ratio (OR) value was used to evaluate the causal relationship between BMI and AH.

RESULTS

The results of the horizontal pleiotropy test were calculated by Egger-intercept method: p = 0.34 > 0.05. The Cochran Q test of MR-Egger method and IVW method showed heterogeneity P = 0.03 < 0.05, so the IVW random effect model was used as the gold standard. We found a genetically determined 1-standard deviation (SD) increment of BMI causally increased a 66.0% risk of AH (N = 371 SNPs, OR = 1.66, 95% CI 1.46-1.89, p = 1.55E-14) based on the IVW random effect model which was almost consistent with the results of other seven methods.

CONCLUSIONS

Our MR found genetic evidence for BMI and AH. The risk of developing AH increases with the number of BMI. This finding provides further evidence that maintaining a healthy BMI can prevent the development of AH. In addition, clinicians may need to focus on the potential risk of AH on some high-BMI patients.

Tension-reduced closure of large abdominal wall defect caused by shotgun wound: A case report

BACKGROUND

Large abdominal wall defect (LAWD) caused by shotgun wound is rarely reported.

CASE SUMMARY

Herein, we describe a case of LAWD caused by a gunshot wound in which the abdominal wall was reconstructed in stages, including debridement, tension-reduced closure (TRC), and reconstruction with mesh and a free musculocutaneous flap. During a 3-year follow-up, the patient recovered well without hernia or other problems.

CONCLUSION

TRC is a practical approach for the temporary closure of LAWD, particularly in cases when one-stage abdominal wall restoration is unfeasible due to significant comorbidities.

A myogenic niche with a proper mechanical stress environment improves abdominal wall muscle repair by modulating immunity and preventing fibrosis

Volumetric muscle loss (VML) healing is often complicated by fibrosis, which impairs muscle regeneration and function. Adjusting mechanical stress in the repair environment may modulate immunity and reduce fibrosis. In this study, we aimed to create a biomaterial with suitable tension conditions and bidirectional tissue-inducing abilities to prevent fibrosis thus promote muscle regeneration and induce aponeurosis-like structures to restore muscle force transmission. A protocol was developed to manufacture decellularized muscle aponeurosis (D-MA) patches with an intact extracellular matrix (ECM) and low cytotoxicity. D-MA optimized the mechanical stress distribution in muscle injury sites and decreased the number of proinflammatory macrophages and myofibroblasts, thereby attenuating muscle fibrosis. Muscle and aponeurosis ECM environments had different microstructures and mechanical properties, which specifically enhanced stem cell differentiation into muscle-like cells on muscle ECM and tenocyte-like cells on aponeurosis ECM in vitro. Four weeks after orthotopic implantation, the biphasic muscle-aponeurosis-like tissue was successfully regenerated by the D-MA scaffold. The regenerated muscle fibers in D-MA were more abundant than those in the fibrotic decellularized muscle (D-M) scaffold. D-MA can be used to repair abdominal defects, which significantly improves the repair outcomes. Our results suggest D-MA as a promising material for VML repair.

Peritoneum-Inspired Janus Porous Hydrogel with Anti-Deformation, Anti-Adhesion, and Pro-Healing Characteristics for Abdominal Wall Defect Treatment

Implantable meshes used in tension-free repair operations facilitate treatment of internal soft-tissue defects. However, clinical meshes fail to achieve anti-deformation, anti-adhesion, and pro-healing properties simultaneously, leading to undesirable surgery outcomes. Herein, inspired by the peritoneum, a novel biocompatible Janus porous poly(vinyl alcohol) hydrogel (JPVA hydrogel) is developed to achieve efficient repair of internal soft-tissue defects by a facile yet efficient strategy based on top-down solvent exchange. The densely porous and smooth bottom-surface of JPVA hydrogel minimizes adhesion of fibroblasts and does not trigger any visceral adhesion, and its loose extracellular-matrix-like porous and rough top-surface can significantly improve fibroblast adhesion and tissue growth, leading to superior abdominal wall defect treatment to commercially available PP and PCO meshes. With unique anti-swelling property (maximum swelling ratio: 6.4%), JPVA hydrogel has long-lasting anti-deformation performance and maintains high mechanical strength after immersion in phosphate-buffered saline (PBS) for 14 days, enabling tolerance to the maximum abdominal pressure in an internal wet environment. By integrating visceral anti-adhesion and defect pro-healing with anti-deformation, the JPVA hydrogel patch shows great prospects for efficient internal soft-tissue defect repair.

Application of 3D Visualization Technology in Complex Abdominal Wall Defects

Purpose

To explore the value of medical three-dimensional visualization technology in precise preoperative assessment of complex abdominal wall defects.

Methods

The clinical data of 30 patients were analyzed retrospectively from November 2017 to December 2020 in our department. Ten patients had abdominal wall hernias and 20 patients suffered from abdominal wall tumors. CT examination was performed, and data were stored in the form of DICOM. Three-dimensional reconstruction and related data analysis were performed by Medraw software, which can accurately show the calculation of the abdominal wall defect area, abdominal wall defect classification and zoning.

Results

The ratio of the volume of the hernia sac to the whole abdominal volume in 10 patients with abdominal wall hernia was 4.75%. The average ratio of defect area to the whole abdominal wall in 16 patients suffered from abdominal wall tumors was 17.68%. Preoperative three-dimensional reconstruction can accurately obtain an average abdominal wall defect area of 227.83 ± 157.33 cm² and accurate abdominal wall classification and zoning. Combined with clinical information, we can develop personalized surgical plans for patients. The average operating time was 5.39 ± 2.71 h, respectively, and the average hospital stay was 22.77 ± 11.59 days. The mean follow-up time was 21.09 ± 9.72 months. The incidence of postoperative complications was 23.33% (7/30). The recurrence rates of incisional hernias and abdominal wall tumors were 20.00% (2/10) and 15.00% (3/20), respectively. The patient survival rate was 86.67% (26/30).

Conclusion

Three-dimensional visualization technology can be used for the accurate evaluation of patients with complex abdominal defects before surgery and can help surgeons design personalized surgical plans for patients.

Surgical treatment strategy for locally advanced colorectal cancer with abdominal wall invasion

Background

The incidence of abdominal wall metastasis from colorectal cancer (CRC) is very low, but it has a poor prognosis. Despite the advances in radiotherapy, chemotherapy, and targeted therapy, patient prognosis has not improved significantly. Through surgical treatment, some patients with locally advanced CRC with abdominal wall invasion can achieve tumor-free survival or an improved quality of life.

Methods

The clinical data of 15 patients in our department from January 2015 to January 2020 were retrospectively analyzed. All patients underwent preoperative three-dimensional reconstruction of the tumor and abdominal wall after discussion with a multidisciplinary team (MDT). Patient information, including tumor size, defect size, operation time, intraoperative bleeding, hospital stay, and other factors, was collected.

Results

All 15 patients underwent resection followed by reconstruction for locally advanced CRC with abdominal wall invasion. The average tumor area and abdominal wall defects were 98.13±71.70 and 270.07±101.95 cm², respectively; and accurate abdominal wall classification and zoning were obtained for all patients. The average operation time was 431.7±189.2 min, and the average blood loss was 513.3±244.6 mL. The recurrence rates in the incisional hernia and abdominal wall were 6.0% and 13.3%, respectively. The patient survival rate was 87.7%.

Conclusions

Surgical treatment of locally advanced CRC with abdominal wall invasion is feasible, but requires accurate and comprehensive preoperative evaluation.