Magnetic resonance-visible meshes for laparoscopic ventral hernia repair

Prospective cohort study on mesh shrinkage measured with MRI after robot-assisted minimal invasive retrorectus ventral hernia repair using an iron-oxide-loaded polyvinylidene fluoride mesh

BACKGROUND

Mesh-reinforced ventral hernia repair is considered the gold standard treatment for all but the smallest of hernias. Human data on mesh shrinkage in the retrorectus mesh position is lacking. A prospective observational cohort study was performed to measure mesh shrinkage in robot-assisted minimal invasive retrorectus repair of ventral hernias.

METHODS

A cohort of 20 patients underwent a robot-assisted minimal invasive retrorectus repair of their ventral hernia. Magnetic resonance imaging (MRI) imaging was performed one month and thirteen months after implantation of an iron-oxide-impregnated polyvinylidene fluoride (PVDF) mesh to assess the decrease in mesh surface area. Inter-rater reliability among three radiologists regarding measurement of the mesh dimensions was analyzed. Quality of Life scoring was evaluated.

RESULTS

The inter-rater reliability between the radiologists reported as the intra-class correlations proved to be excellent for mesh width (ICC 0.95), length (ICC 0.98) and surface area (ICC 0.99). Between MRI measurements at one month and thirteen months postoperatively, there was a significant increase in mesh surface area (+ 12.0 cm², p = 0.0013) and mesh width (+ 0.8 cm, p < 0.001), while the length of the mesh remained unchanged (-0.1 cm, p = 0.754). Quality of Life Scoring showed a significant improvement in Quality of Life after one month and a further improvement at thirteen months (p < 0.001).

CONCLUSION

There was an excellent inter-rater reliability between three radiologists when measuring width, length, and surface area of an iron-oxide-impregnated PVDF mesh using MRI visualization. Mesh shrinkage was not observed, instead the effective mesh surface area and width of the mesh increased.

Combined numerical and experimental approach to determine numerical model of abdominal scaffold

A proper junction of the prosthesis and the abdominal wall is important in successful hernia repair. The number of tacks should be balanced to assure appropriate mesh fixation and not to induce post-operative pain. Numerical simulations help to find this balance. The study is aimed at creating a proper numerical model of a knitted surgical mesh subjected to boundary conditions and load occurring in the abdominal cavity. Continuous, anisotropic constitutive relation is considered to reflect the mesh behaviour. Different sets of material law parameters are determined on the basis of different bi-axial tests setups. Force- and displacement-controlled tests with different ratios are considered. Consequently, some numerical model variants are obtained featuring various reaction distributions in the scaffold fixation points. The proper variant is selected based on comparison of the position of maximal reaction force in the numerical model and in the reference physical model of operated hernia. Force-driven tests have shown anisotropic mesh behaviour, while equibiaxial displacement-driven test has demonstrated reduced anisotropic response. Within seven scenarios of constitutive parameters identification (based on single or combined experimental data), the equibiaxial force-controlled test appeared to produce the most relevant model to follow the prosthesis behaviour under pressure. The position of maximal reaction force in such model is similar to obtained in the physical hernia model. The equibiaxial force-driven test provides most suitable data for Gasser-Ogden-Holzapfel constitutive model identification of a considered surgical mesh to be used to model the mesh under pressure.

Functionalized Strategies and Mechanisms of the Emerging Mesh for Abdominal Wall Repair and Regeneration

Meshes have been the overwhelmingly popular choice for the repair of abdominal wall defects to retrieve the bodily integrity of musculofascial layer. Broadly, they are classified into synthetic, biological and composite mesh based on their mechanical and biocompatible features. With the development of anatomical repair techniques and the increasing requirements of constructive remodeling, however, none of these options satisfactorily manages the conditional repair. In both preclinical and clinical studies, materials/agents equipped with distinct functions have been characterized and applied to improve mesh-aided repair, with the importance of mesh functionalization being highlighted. However, limited information exists on systemic comparisons of the underlying mechanisms with respect to functionalized strategies, which are fundamental throughout repair and regeneration. Herein, we address this topic and summarize the current literature by subdividing common functions of the mesh into biomechanics-matched, macrophage-mediated, integration-enhanced, anti-infective and antiadhesive characteristics for a comprehensive overview. In particular, we elaborate their effects separately with respect to host response and integration and discuss their respective advances, challenges and future directions toward a clinical alternative. From the vastly different approaches, we provide insight into the mechanisms involved and offer suggestions for personalized modifications of these emerging meshes.

Prospective randomized controlled trial on comparison of standard CO2 pressure pneumoperitoneum insufflator versus AirSeal®

Background

AirSeal® is a valve-free insufflation system that enables a stable pneumoperitoneum with continuous smoke evacuation and CO₂ recirculation during laparoscopic surgery. Comparative evidence on the use of AirSeal® and standard CO₂ insufflator in laparoscopic general surgery procedures is scarce. The aim of this study was to compare surgical outcomes between AirSeal® and standard CO₂ insufflators in patients undergoing the most frequently performed laparoscopic procedures.

Methods

One hundred and ninety-eight patients undergoing elective laparoscopic cholecystectomy, colorectal surgery and hernia repair were randomized to either AirSeal® (group A) or standard pressure CO₂ insufflator (group S). The primary endpoints were operative time and level of postoperative shoulder tip pain (Visual Analog Scale). Secondary outcomes included Clavien–Dindo grade complications, surgical side effect and length of hospital stay.

Results

Patients were randomized to either group A (n = 101) or group S (n = 97) and were analyzed by intention-to-treat. There was no significant difference in mean operative time between the groups (median [IQR]; 71 min [56–94] in group A vs. 69 min [52–93] in group S; p = 0.434). Shoulder tip pain levels were significantly lower in group S (VAS 0 [0–3] in group S vs. 2 [0–4] in group A; p = 0.001). There was no significant difference in complications, surgical side effects (subcutaneous emphysema was not observed in any group) and length of hospital stay.

Conclusion

This randomized controlled trial showed that using the AirSeal® system did not reduce operative time and was associated with a higher postoperative shoulder tip pain compared to standard CO₂ insufflator for short elective surgeries.

ClinicalTrials.gov (NCT01740011).

Magnetic resonance visualization of iron-loaded meshes in patients with pain after inguinal hernia repair

PURPOSE

Chronic post-operative inguinal pain (CPIP) is defined as pain lasting more than 3 months and the incidence is less than 4% after laparoscopic hernia repair. CPIP can have several causes. In this study, we aimed to show that 3D-iron loaded mesh preparations are useful in radiological evaluation of post-operative complications, especially patients with chronic pain and the mesh status of operated inguinal hernia cases.

METHODS

A total of 450 cases who had been operated for inguinal hernia with 3D-iron loaded mesh and who had ongoing pain at the post-operative period were included in this study. MRI (Magnetic Resonance Imaging) was performed at the post-operative 90th day of the seven symptomatic (groin pain, limitation of movement) cases which were operated using a 3D-iron loaded mesh, 10 × 15 cm in size, (DynaMeshEndolap visible with 25% MRI-visible filaments, FEG TextiltechnikmbH, Aachen, Germany) for inguinal hernia repair to evaluate mesh status, localization, and local complications. Gradient echo sequences in the sagittal, axial, and coronal sections on MRI were discussed by two radiologists. Mesh localizations, their relationship with surrounding structures and their complications related with mesh were evaluated by two radiologists (D.Y, D.E.T.Ş).

RESULTS

No significant radiological findings related to defined anatomical structures were found in the MRI images of the study group. The dimensions measured on the sagittal, axial and coronal images were correlated with original mesh sizes and no significant shrinkage was detected.

CONCLUSION

Mesh position and deformation as shrinkage can be the mesh-related cause of pain. The incidence of CPIP in our patients is less than 2%. 3D-iron loaded meshes were monitored with MRI in CPIP patients and there was no mesh-related changes found in our study. The use of MRI-visible meshes will most likely help us to monitor mesh preparations and show potential time-dependent changes in mesh characteristics and consequent complications. In case of doubtful clinical postoperative hernia recurrence or chronic groin pain, mesh position can be identified by MRI and unnecessary surgical intervention can be avoided.

[Titanium mesh implants in herniology]

Literature review is devoted to the main implants used in hernia surgery and their disadvantages. Advisability of titanium mesh implants in surgery of anterior abdominal wall hernias is shown.

Surgical and radiological behavior of MRI-depictable mesh implants after TAPP repair: the IRONMAN study

PURPOSE

Knowledge of postoperative behavior of mesh implants used for hernia repair is generally limited to cases of recurrence, local complications or return to the previous operative field in other pathological conditions. Previous studies with MRI-visible mesh implants in different parts of the abdominal wall have led to variable findings with regard to mesh properties and mostly described a reduction in size over time with subsequently limited mesh overlap over hernia defects which could contribute to recurrence. We aimed to evaluate implant properties in a mechanically stable anatomical region after TAPP repair of primary unilateral inguinal hernias in men with clinical and MRI examinations 4 weeks and 1 year after surgery.

METHODS

From 11/2015 to 01/2019, 23 men with primary, unilateral, inguinal hernias underwent TAPP repair with iron particle-loaded, MRI-visible mesh implants in a prospective cohort study. In 16 patients the operative outcome could be evaluated 4 weeks and 12 months after surgery by clinical examination and MRI evaluation with regard to postoperative course, possible adverse outcomes and radiological findings related to implant behavior-namely MRI-identifiability, mesh dislocation or reduction in surface area.

RESULTS

All included patients had an uneventful postoperative clinical course. MRI after 4 weeks revealed one postoperative seroma, which resolved spontaneously. No recurrence was detected. Mesh implants could be accurately delineated in DIXON-IN studies and showed neither clinically nor statistically significant changes in size or position.

CONCLUSION

4 weeks and 1 year after a standardized TAPP procedure the mesh implant used in this study showed no tendency towards dislocation or reduction in size in this anatomical position. Its MRI visibility allows accurate delineation during the postoperative course by experienced radiologists in appropriate MRI protocols. Larger patient series are desirable to further support these findings. Shrinkage of implants in the groin as a reason for early recurrence may be overestimated.

3D printing of surgical hernia meshes impregnated with contrast agents: in vitro proof of concept with imaging characteristics on computed tomography

BACKGROUND

Selected medical implants and other 3D printed constructs could potentially benefit from the ability to incorporate contrast agents into their structure. The purpose of the present study is to create 3D printed surgical meshes impregnated with iodinated, gadolinium, and barium contrast agents and characterize their computed tomography (CT) imaging characteristics. Commercial fused deposition layering 3D printing was used to construct surgical meshes impregnated with imaging contrast agents in an in vitro model. Polycaprolactone (PCL) meshes were printed containing iodinated, gadolinium, or barium contrast; control PCL meshes without contrast were also fabricated. The three different contrast agents were mixed with PCL powder and directly loaded into the 3D printer. CT images of the three contrast-containing meshes and the control meshes were acquired and analyzed using small elliptical regions of interest to record the Hounsfield units (HU) of each mesh. Subsequently, to test their solubility and sustainability, the contrast-containing meshes were placed in a 37 °C agar solution for 7 days and imaged by CT at days 1, 3 and 7.

RESULTS

All 3D printed meshes were visible on CT. Iodinated contrast meshes had the highest attenuation (2528 mean HU), significantly higher than both and gadolinium (1178 mean HU) and barium (592 mean HU) containing meshes. Only barium meshes sustained their visibility in the agar solution; the iodine and gadolinium meshes were poorly perceptible and had significantly lower mean HU compared to their pre-agar solution imaging, with iodine and gadolinium present in the adjacent agar at day 7 CT.

CONCLUSION

3D prints embedded with contrast materials through this method displayed excellent visibility on CT; however, only barium mesh maintained visibility after 7 days incubation on agar at human body temperature. This method of 3D printing with barium may have potential applications in a variety of highly personalized and CT visible medical devices.

Mesh implants for hernia repair: an update

INTRODUCTION

Today the use of textile meshes has become a standard for the treatment of abdominal wall hernias and for the reinforcement of any tissue repair as the strength of the implant decreases the recurrence rates. With increasing use, side effects of the textile implants became apparent, as well.

AREAS COVERED

Based on publications in Medline over the past decade, general and specific benefits, as well as risks, are discussed with the challenge to define individual risk-benefit ratios. For meshes, certain high-risk or low-risk conditions can be defined. In an attempt to eliminate mesh-related risks, quality control for medical devices has meanwhile been revised. In both the USA and the EU post-market surveillance studies are required to keep medical devices approved.

EXPERT COMMENTARY

The impact of material on the complication rate will vary depending on the patient's co-morbidity or the risks of the procedure. Even the best material can end up with disappointing results in case of poor healing or poor surgery. On the other hand, when using high-risk devices, most of the complications after excellent surgery with excellent indication can be supposed to be mesh-related. Thus, the use of low-risk devices is recommended even though its advantage may not be demonstrable in clinical studies.

Prospective cohort study on mesh shrinkage measured with MRI after laparoscopic ventral hernia repair with an intraperitoneal iron oxide-loaded PVDF mesh

BACKGROUND

Current data on shrinkage of intraperitoneal meshes come mainly from animal studies. High-quality human data in prospective studies are scarce.

METHODS

We used the ability to visualize intraperitoneal PVDF meshes enhanced with iron particles (DynaMesh IPOM visible) with magnetic resonance imaging (MRI) to determine the amount of shrinkage between 1 and 13 months postoperatively. All measurements of the width, length, and surface area of the mesh were performed with a standardized methodology independently by four radiologists blinded for the timing of the MRI.

RESULTS

Of the 15 patients undergoing laparoscopic ventral hernia repair, 13 patients received an MRI both at 1 and at 13 months. Evaluation of inter-rater reliability between the radiologists showed intra-class correlations of 0.95 (95% CI 0.92-0.98) for the width, 0.96 (95% CI 0.93-0.98) for the length, and 0.99 (90% CI 0.99-1.00) for the surface area of the mesh. The change between measurement at implantation and 1-month MRI was - 0.7 cm (P = 0.023; - 3.6%) for the width and - 1.9 cm (P = 0.001; - 7.2%) for the length. The change between 1 and 13 months was - 0.06 cm (P = 0.74; shrinkage = 0.3%) for the width, - 0.12 cm (P = 0.56; shrinkage = 0.5%) for the length, and - 4.0 cm² (P = 0.20; shrinkage = 1.0%) for the surface area of the mesh.

CONCLUSION

There is excellent inter-rater reliability between radiologists when measuring width, length, and surface area of visible intraperitoneal PVDF mesh with MRI. There is no significant shrinkage between 1 and 13 months of intraperitoneal PVDF mesh after laparoscopic ventral hernia repair.

Long-term retromuscular and intraperitoneal mesh size changes within a randomized controlled trial on incisional hernia repair, including a review of the literature

Abstract

Purpose Ingrowth of fibroblasts in a polypropylene mesh may cause contraction and a later recurrence. We assessed mesh contraction in intraabdominal and retromuscular implantation after incisional hernia repair.

Methods

A cohort of patients within an RCT on laparoscopic (LHR) versus open hernia repair (OHR) had their mesh borders marked with metal clips. X-ray was performed on postoperative day 1 and after 1 year. Total length, width, and dislocation were measured. A tacker fixated large-pore polypropylene mesh was used in LHR, and a retromuscular small-pore heavy-weight mesh was sutured to the midline in OHR. Patient’s pain was assessed before surgery and after 1 year.

Results

For analysis 37/47 patients remained: 20 LHR and 17 OHR. Hernia defect area was median 41 cm² in LHR and 25 cm² in OHR (p < 0.140). Implanted mesh size was 300 cm² for LHR and 240 cm² for OHR (p < 0.341). After 1 year the mesh area decreased by 4.4% and 0.5% in LHR and OHR, respectively (p < 0.063). Longitudinal distance decreased by 2.8% in LHR and by 2.6% in OHR (p < 0.269). Transverse distance decreased by 1.6% in LHR but increased by 3.1% in OHR (p < 0.005). Dislocation was seen in four LHR and one OHR. Two recurrent and one port-site hernia were diagnosed after LHR. Measurements between observers were identical in 58% and consensus was made in the remainder. Pain was not correlated to mesh area change.

Conclusions

Mesh contraction after 1 year is not a clinical issue for an intraperitoneal large-pore mesh or a retromuscular small-pore mesh. It is not correlated to postoperative pain.

MRI Evaluation of an Elastic TPU Mesh under Pneumoperitoneum in IPOM Position in a Porcine Model

BACKGROUND

The frequency of laparoscopic approaches increased in hernia surgery over the past years. After mesh placement in IPOM position, the real extent of the meshes configurational changes after termination of pneumoperitoneum is still largely unknown. To prevent a later mesh folding it might be useful to place the mesh while it is kept under tension. Conventionally used meshes may lose their Effective Porosity under these conditions due to poor elastic properties. The aim of this study was to evaluate a newly developed elastic thermoplastic polyurethane (TPU) containing mesh that retains its Effective Porosity under mechanical strain in IPOM position in a porcine model. It was visualized under pneumoperitoneum using MRI in comparison to polyvinylidenefluoride (PVDF) meshes with similar structure.

METHODS

In each of ten minipigs, a mesh (TPU containing or native PVDF, 10 × 20 cm) was randomly placed in IPOM position at the center of the abdominal wall. After 8 weeks, six pigs underwent MRI evaluation with and without pneumoperitoneum to assess the visibility and elasticity of the mesh. Finally, pigs were euthanized and abdominal walls were explanted for histological and immunohistochemical assessment. The degree of adhesion formation was documented.

RESULTS

Laparoscopic implantation of elastic TPU meshes in IPOM position was feasible and safe in a minipig model. Mesh position could be precisely visualized and assessed with and without pneumoperitoneum using MRI after 8 weeks. Elastic TPU meshes showed a significantly higher surface increase under pneumoperitoneum in comparison to PVDF. Immunohistochemically, the amount of CD45-positive cells was significantly lower and the Collagen I/III ratio was significantly higher in TPU meshes after 8 weeks. There were no differences regarding adhesion formation between study groups.

CONCLUSIONS

The TPU mesh preserves its elastic properties in IPOM position in a porcine model after 8 weeks. Immunohistochemistry indicates superior biocompatibility regarding CD45-positive cells and Collagen I/III ratio in comparison to PVDF meshes with a similar structure.

MRI visible Fe3O4 polypropylene mesh: 3D reconstruction of spatial relation to bony pelvis and neurovascular structures

INTRODUCTION AND HYPOTHESIS

To demonstrate mesh magnetic resonance imaging (MRI) visibility in living women, the feasibility of reconstructing the full mesh course in 3D, and to document its spatial relationship to pelvic anatomical structures.

METHODS

This is a proof of concept study of three patients from a prospective multi-center trial evaluating women with anterior vaginal mesh repair using a MRI-visible Fe₃O₄ polypropylene implant for pelvic floor reconstruction. High-resolution sagittal T2-weighted (T2w) sequences, transverse T1-weighted (T1w) FLASH 2D, and transverse T1w FLASH 3D sequences were performed to evaluate Fe₃O₄ polypropylene mesh MRI visibility and overall post-surgical pelvic anatomy 3 months after reconstructive surgery. Full mesh course in addition to important pelvic structures were reconstructed using the 3D Slicer® software program based on T1w and T2w MRI.

RESULTS

Three women with POP-Q grade III cystoceles were successfully treated with a partially absorbable MRI-visible anterior vaginal mesh with six fixation arms and showed no recurrent cystocele at the 3-month follow-up examination. The course of mesh in the pelvis was visible on MRI in all three women. The mesh body and arms could be reconstructed allowing visualization of the full course of the mesh in relationship to important pelvic structures such as the obturator or pudendal vessel nerve bundles in 3D.

CONCLUSIONS

The use of MRI-visible Fe₃O₄ polypropylene meshes in combination with post-surgical 3D reconstruction of the mesh and adjacent structures is feasible suggesting that it might be a useful tool for evaluating mesh complications more precisely and a valuable interactive feedback tool for surgeons and mesh design engineers.

Practical Approaches to Definitive Reconstruction of Complex Abdominal Wall Defects

With advances in abdominal surgery and the management of major trauma, complex abdominal wall defects have become the new surgical disease, and the need for abdominal wall reconstruction has increased dramatically. Subsequently, how to reconstruct these large defects has become a new surgical question. While most surgeons use native abdominal wall whenever possible, evidence suggests that synthetic or biologic mesh needs to be added to large ventral hernia repairs. One particular group of patients who exemplify "complex" are those with contaminated wounds, enterocutaneous fistulas, enteroatmospheric fistulas, and/or stoma(s), where synthetic mesh is to be avoided if at all possible. Most recently, biologic mesh has become the new standard in high-risk patients with contaminated and dirty-infected wounds. While biologic mesh is the most common tissue engineered used in this field of surgery, level I evidence is needed on its indication and long-term outcomes. Various techniques for reconstructing the abdominal wall have been described, however the long-term outcomes for most of these studies, are rarely reported. In this article, I outline current practical approaches to perioperative management and definitive abdominal reconstruction in patients with complex abdominal wall defects, with or without fistulas, as well as those who have lost abdominal domain.