Short term post-operative morphing of sacrocolpopexy mesh measured by magnetic resonance imaging

Can magnetisation transfer magnetic resonance imaging help for the follow-up of synthetic hernia composite meshes fate? A pilot study

PURPOSE

This study aims at evaluating the non-invasive Magnetic Resonance Imaging (MRI) technic to visualize a synthetic composite hernia mesh using a rodent model and to document the integration of this device over 4 months.

METHODS

Uncoated polyethylene terephthalate mesh and synthetic composite mesh-faced on the visceral side with a chemically engineered layer of copolymer of glycolide, caprolactone, trimethylene carbonate, and lactide to minimize tissue attachment-were placed intraperitoneally in rats, facing the caecum previously scraped to promote petechial bleeding and subsequent adhesions. Meshes fate follow-up was performed 4, 10, and 16-weeks post-implantation using a rodent dedicated high field MRI. Magnetization transfer (MT) images were acquired, associated with pneumoperitonealMRI performed after intraperitoneal injection of 8 mL gas to induce mechanical stress on the abdominal wall.

RESULTS

Uncoated meshes were clearly visible using both T2-weighted and MT imaging during the whole study while composite meshes conspicuity was not so evident on T2-weighted MRI and could be improved using MT imaging. Adhesions and collagen infiltration were massive for the uncoated meshes as expected. On the contrary, composite meshes showed very limited adhesion, and, if any, occurring at the edge of the mesh, starting at the fixation points.

CONCLUSIONS

Magnetization transfer imaging allows to detect mesh integration and, associated with pneumoperitoneum, was able to probe the effective minimizing effect of the synthetic polymeric barrier on visceral attachments. However, magnetization transfer imaging could not unambiguously allow the visualization of the mesh through the polymeric barrier.

The importance of developing relevant animal models to assess existing and new materials

PURPOSE OF REVIEW

We summarize the recent literature on the use of different animal models for testing existing and new materials for treatment of pelvic organ prolapse.

RECENT FINDINGS

A wide spectrum of animal models is being used in urogynecology, both for the study of physiologic and pathophysiologic processes, training in surgical procedures, yet mainly to study the host response to implant materials. The quality of studies is variable, and procedures, read-outs, and reporting are not standardized. This makes comparison very difficult. The research community is experimenting with different knitting patterns, novel polymers, bioactivation, as well as resorbable rather than durable implants. Outcomes of the experiments are dependent on the location of implantation. Lighter polypropylene constructs seem to induce a less vigorous host response than elder heavier products. Modification of the surface yields contradictory findings. Resorbable acellular collagen matrices may be reintroduced as prophylactically inserted support structures.

SUMMARY

Although animal experimentation with novel candidate implants is advocated, there is a lack of standardization in reporting. The concept of resorbable construct is being revived, as durable materials have caused clinical graft-related complications. Large animal experiments seem to provide interesting and more comprehensive information, yet their use may be contested.

Medium-term outcome of laparoscopic sacrocolpopexy using polivinylidene fluoride as compared to a hybrid polyglecaprone and polypropylene mesh: A matched control study

AIM

To compare 2-year outcomes of laparoscopic sacrocolpopexy (LSCP) either with polyvinylidene fluoride (PVDF) or hybrid polypropylene containing a resorbable polyglecaprone (PP+ PG) mesh.

MATERIALS AND METHODS

Retrospective audit on 105 consecutive patients undergoing LSCP a with PVDF-mesh (DynaMesh, FEG Textiltechniken), matched by prolapse stage and cervicopexy or vault suspension to 105 controls undergoing LSCP with a hybrid PP + PG-mesh (Ultrapro, Ethicon). Patients are part of an ongoing prospective study. The primary outcome measure was the Patient Global Impression of Change score (PGIC), the coprimary variable was failure rate at the vault (≤1 cm). Other outcomes were intraoperative and postoperative complications within 3 months categorized by the Clavien-Dindo classification, reinterventions, graft-related complications (GRCs) and functional outcomes. All assessments were performed by an independent assessor. Data are reported as median (interquartile range) number and percent as appropriate, the Mann-Whitney U, χ² , or Fisher exact were used for comparison.

RESULTS

Patient satisfaction in the PVDF group, as measured with the PGIC, was high (90.9% PGIC, ≥4) as well as was the anatomical success (97.3%) at a follow-up of 26 months. These outcomes were comparable to those of PP + PG-patients (84.8% PGIC, ≥4; 94.9% anatomical success). There were five patients (2.4%) with Dindo-III or higher complications and three patients had GRCs (1.5%), without differences between mesh type. Level-II posterior defects (Bp ≥ -1) were less likely in PVDF patients (34.1% vs 50% for PP + PG-patients; P = .003). Women in the PVDF group also were less bothered by prolapse (7.5% vs 26.4%; P = .001), yet they complained more of constipation (15.0% vs 9.0%; P = .01).

CONCLUSION

There were no differences in patient satisfaction and anatomical outcomes after LSCP either with PVDF or PP + PG mesh.

A prospective pilot study on MRI visibility of iron oxide-impregnated polyvinylidene fluoride mesh after ventral rectopexy

Background

Magnetic resonance imaging (MRI) provides excellent information about pelvic anatomy after ventral rectopexy, but the position of the conventional mesh is not seen constantly. Iron oxide-impregnated polyvinylidene fluoride (PVDF) meshes are proven to have MRI visibility in hernia or vaginal reconstructive surgery. This prospective pilot study was designed to assess the visualization, position, and shape of the magnetic resonance (MR)–visible synthetic pelvic mesh used in minimally invasive ventral rectopexy.

Methods

Eight patients with pelvic organ prolapse were recruited for laparoscopic (LVMR) or robotic-assisted ventral mesh rectopexy (RVMR) with a synthetic MR–visible PVDF mesh. A follow-up visit was scheduled at 3 months after surgery. MR imaging was performed to evaluate the position and dimensions of the mesh and anatomical result. The visibility of the mesh in each sequence was assessed subjectively.

Results

The visibility of the mesh was best on T1-weighted flash images. The mesh was also well visualized on T2-weighted sagittal images. T2-weighted images, in general, provided best visualization of the surrounding anatomical structures and enabled assessment of the mesh fixation.

Conclusions

T2 sagittal and T1-weighted flash images provide the best information about the position and integrity of the iron oxide-impregnated PVDF mesh after LVMR or RVMR with a short examination time.

Ultrasound visualization of sacrocolpopexy polyvinylidene fluoride meshes containing paramagnetic Fe particles compared with polypropylene mesh

INTRODUCTION AND HYPOTHESIS

Paramagnetic Fe particles can be added during synthetic mesh production to allow visibility on magnetic resonance imaging. Our aim was to evaluate whether transperineal ultrasound (TPUS) allows visualization, measurement, and characterization of polyvinylidene fluoride (PVDF mesh) containing Fe particles compared with regular polypropylene (PP) meshes used for sacrocolpopexy.

METHODS

Women up to 1.5 years after laparoscopic sacrocolpopexy who were implanted with a PP or PVDF mesh underwent clinical examination and 2D, 3D, and 4D TPUS. Acquired volumes were analyzed offline for mesh position at rest and maximal Valsalva and for mesh dimensions and characteristics, with the operator blinded to group assignment. The two groups were compared.

RESULTS

There were 17 women in the PP and 25 in the PVDF mesh group, without differences in baseline demographics. None had significant prolapse, recurrence, symptoms, or complications. On TPUS, mesh was visible in all patients both caudally (perineal) and cranially but was more echogenic in the PVDF mesh group. Mesh length from distal to proximal that was visible on TPUS was longer for PVDF mesh, for both anterior and posterior vaginal arms (all P < 0.05), and for mesh above the vaginal apex (P = 0.002). The inferior aspects of the mesh showed areas of double mesh layers, suggesting folding in 80% of women in both groups, without symptoms.

CONCLUSIONS

PVDF mesh permits clearer visualization and is seen over a longer stretch on TPUS, with longer visible mesh arms. The latter can be due to differences in operative technique, presence of microparticles, implant textile structure, or patient characteristics.