Evaluation of absorbable and permanent mesh fixation devices: adhesion formation and mechanical strength

The effect of N-acetyl-l-cysteine on inflammation after intraperitoneal mesh placement in a potentially contaminated environment: Experimental study in the rat

BACKGROUND

The use of prosthetic meshes in abdominal wall reconstruction is a well-established approach; however, in certain cases where a bowel resection coexists its application is disputed. Any underlying inflammatory process may augment adhesion formation which is a major postoperative complication. In this animal study, our aim was to investigate the effect of N-acetyl-l-cysteine (NAC) on adhesion formation and the expression of inflammatory markers when a mesh was used in a clean or a potentially contaminated environment.

METHODS

Sixty male Wistar rats were randomly and equally allocated in 3 groups: A, B and C. Animals in all groups underwent laparotomy, a prosthetic mesh was placed and chemoprophylaxis with ciprofloxacin was administered. In groups B and C an enterectomy was also performed. NAC was injected intraperitoneally in group C. Adhesion formation, IL-1a, IL-6, TNF-a and histological data including fibrosis, neutrophils' infiltration and neovascularization were assessed. Mesh samples were sent for cultivation.

RESULTS

Adhesion formation was significantly less and inflammation markers were also lower in group C compared to group B (p<0.05). Histological findings were significant for greater fibrosis, neutrophils' infiltration and neovascularization in group B compared to both group A and C. Regarding mesh cultures, more specimens were tested positive in group B (p <0.05). Outcomes between group A and C did not differ.

CONCLUSION

NAC effectively ameliorated adhesion formation and inflammation in a potentially septic environment where a prosthetic mesh was placed.

Absorbable Mg surgical tack: Proof of concept &in situ fixation strength

A prototype magnesium (Mg) surgical tack is tested comparatively against commercially available tacks made of titanium (ProTack^tm, Medtronic) and PLGA (AbsorbaTack^tm, Medtronic). The pull-out force is measured in situ in a lap-shear pull-out test, using porcine abdominal muscle tissue as a model. The Mg tack had a pull-out force comparable to those of the commercially available tacks. The majority of the Mg tacks also had a more ductile failure mode (i.e. the tacks deformed prior to failure), compared to the commercial tacks which pulled directly from the tissue with no deformation. The Mg tacks deformed as they were removed from the tissue, causing less damage to the tissue in the process. This is the first reported use of a Mg alloy in this application, and the proof of concept indicates that this is an area that deserves further interest and study.

Postoperative Pain After Laparoscopic Repair of Primary Umbilical Hernia: Titanium Tacks Versus Absorbable Tacks: A Prospective Comparative Cohort Analysis of 80 Patients With a Long-term Follow-up

We investigated if a novel fixation device with absorbable tacks (Securestrap) causes less early and chronic postoperative pain after laparoscopic repair with a double-crown mesh fixation of ventral abdominal wall hernia when compared with the standard fixation device with nonabsorbable titanium tacks (Protack). The primary outcome measure was early postoperative pain at 2, 6, and 12 weeks postoperatively. The secondary outcome measure was chronic postoperative pain measured ≥18 months after surgery. Pain levels were assessed using a visual analog scale ranging from 0 (no pain) to 100 mm (excruciating pain). Early postoperative pain was significantly lower in group 2 (absorbable tacks) at 6 (2 vs. 5; P=0.008) and 12 weeks (1 vs. 2; P=0.008) but not at follow-up (6 vs. 11; P=0.21). Given the very low visual analog scale scores in both groups, the clinical significance of these finding remains open to discussion.

Repair of primary and incisional hernias using composite mesh fixed with absorbable tackers: preliminary experience of a laparoscopic approach with a newly designed mesh in 29 cases

Outcome of primary and incisional hernia repair is still affected by clinical complications in terms of recurrences, pain and discomfort. Factors like surgical approach, prosthesis characteristics and method of fixation might influence the outcome. We evaluated in a prospective observational study a cohort population which underwent primary and incisional laparoscopic hernia repair, with the use of a composite mesh in polypropylene fixed with absorbable devices. We focused on assessing the feasibility and safety of these procedures; they were always performed by an experienced laparoscopic surgeon, analyzing data from our patients through the EuraHS registry. Seventy nine procedures of primary and incisional hernia repair were performed from July 2013 to November 2015 at Santa Maria Regina degli Angeli Hospital in Adria (RO). All cases have been registered at the EuraHS registry ( http://www.eurahs.eu ); among them, we analyzed 29 procedures performed using a new composite polypropylene mesh (CMC, Clear Composite Mesh, DIPROMED srl San Mauro Torinese, Turin, Italy), fixed with absorbable tackers (ETHICON, Ethicon LLC Guaynabo, Puerto Rico 00969). We performed 23 incisional hernia repairs, 4 primary hernia repairs (1 umbilical, 2 epigastric and 1 lumbar hernia) and 2 parastomal hernia repairs. The median operation time was 65.1 min for elective and 81.4 min for urgent procedures (three cases). We had two post-operative complications (6.89%), one case of bleeding and another case of prolonged ileus successfully treated with conservative management. We had no recurrences at follow-up. According to QoL, at 12 months patients do not complain about any pain or discomfort for esthetic result. Laparoscopic treatment of primary and incisional hernia with the use of composite mesh in polypropylene fixed with absorbable devices is feasible and safe.

Evaluation of a novel permanent capped helical coil fastener in a porcine model of laparoscopic ventral hernia repair

Background

Existing permanent helical coil fasteners, although commonly employed for mesh fixation during laparoscopic hernia repair, are associated with peritoneal tissue attachment formation and resultant visceral complications. We evaluated attachment formation, fastener engagement, and mesh/tissue integration associated with laparoscopic fixation using a novel permanent capped helical coil fastener (HC-Capped) compared to permanent non-capped helical coil fasteners (HC-Non-Capped) in a porcine model.

Methods

Twelve female pigs underwent bilateral laparoscopic intraperitoneal fixation of Composix™ L/P Mesh (10 × 15 cm oval) with HC-Capped or HC-Non-Capped fasteners. Thirty-two fasteners were used to secure each mesh utilizing a “double-crown” technique. Laparoscopy at 30 days was used to evaluate the presence and area coverage of attachments (Diamond Score) and percentage of engaged fasteners. At 90 days, following necropsy, each mesh was evaluated for the presence, percentage, and tenacity (Butler Score) of attachments and fastener engagement. Samples were biomechanically evaluated to assess tissue integration via T-peel testing.

Results

HC-Capped fasteners demonstrated a significantly lower attachment area score compared to the HC-Non-Capped group at 30 days (0.92 ± 0.26 vs. 2.50 ± 0.29/3.00, p = 0.002) and 90 days (0.60 ± 0.22 vs. 2.08 ± 0.29/3.00, p = 0.004). At 90 days, the HC-Capped group evidenced significantly lower attachment tenacity score (1.00 ± 0.37 vs. 2.75 ± 0.33/4.00, p = 0.013). Furthermore, at 30 and 90 days, a significantly greater percentage of HC-Capped fasteners remained properly engaged (30 days: 99.7 % vs. 86.5 %, p < 0.001 and 90 days: 99.4 % vs. 74.5 %, p = 0.001). T-peel biomechanical testing demonstrated significantly greater mesh/tissue integration for HC-Capped group (2.16 ± 0.24 vs. 1.16 ± 0.29 N/cm, p = 0.038).

Conclusions

In a porcine model, HC-Capped fasteners demonstrated significantly less attachment coverage and tenacity in the early postoperative period. Furthermore, the HC-Capped cohort evidenced significantly greater percentage of properly engaged fasteners and greater mesh/tissue integration. Data suggest that shielding exposed fastener points on the visceral mesh surface with polymer caps may reduce attachment formation and aid in mesh fixation and integration.

Laparoscopic ventral/incisional hernia repair: updated Consensus Development Conference based guidelines [corrected]

BACKGROUND

The Executive board of the Italian Society for Endoscopic Surgery (SICE) promoted an update of the first evidence-based Italian Consensus Conference Guidelines 2010 because a large amount of literature has been published in the last 4 years about the topics examined and new relevant issues.

METHODS

The scientific committee selected the topics to be addressed: indications to surgical treatment including special conditions (obesity, cirrhosis, diastasis recti abdominis, acute presentation); safety and outcome of intraperitoneal meshes (synthetic and biologic); fixing devices (absorbable/non-absorbable); abdominal border and parastomal hernia; intraoperative and perioperative complications; and recurrent ventral/incisional hernia. All the recommendations are the result of a careful and complete literature review examined with autonomous judgment by the entire panel. The process was supervised by experts in methodology and epidemiology from the most qualified Italian institution. Two external reviewers were designed by the EAES and EHS to guarantee the most objective, transparent, and reliable work. The Oxford hierarchy (OCEBM Levels of Evidence Working Group*. "The Oxford 2011 Levels of Evidence") was used by the panel to grade clinical outcomes according to levels of evidence. The recommendations were based on the grading system suggested by the GRADE working group.

RESULTS AND CONCLUSIONS

The availability of recent level 1 evidence (a meta-analysis of 10 RCTs) allowed to recommend that not only laparoscopic repair is an acceptable alternative to the open repair, but also it is advantageous in terms of shorter hospital stay and wound infection rate. This conclusion appears to be extremely relevant in a clinical setting. Indications about specific conditions could also be issued: laparoscopy is recommended for the treatment of recurrent ventral hernias and obese patients, while it is a potential option for compensated cirrhotic and childbearing-age female patients. Many relevant and controversial topics were thoroughly examined by this consensus conference for the first time. Among them are the issue of safety of the intraperitoneal mesh placement, traditionally considered a major drawback of the laparoscopic technique, the role for the biologic meshes, and various aspects of the laparoscopic approach for particular locations of the defect such as the abdominal border or parastomal hernias.

Recurrence rate after absorbable tack fixation of mesh in laparoscopic incisional hernia repair

Background

The mesh fixation technique in laparoscopic incisional hernia repair may influence the rates of hernia recurrence and chronic pain. This study investigated the long-term risk of recurrence and chronic pain in patients undergoing laparoscopic incisional hernia repair with either absorbable or non-absorbable tacks for mesh fixation.

Methods

This was a nationwide consecutive cohort study based on data collected prospectively concerning perioperative information and clinical follow-up. Patients undergoing primary, elective, laparoscopic incisional hernia repair with absorbable or non-absorbable tack fixation during a 4-year interval were included. Follow-up was by a structured questionnaire regarding recurrence and chronic pain, supplemented by clinical examination, and CT when indicated. Recurrence was defined as either reoperation for recurrence or clinical/radiological recurrence.

Results

Of 1037 eligible patients, 84·9 per cent responded to the questionnaire, and 816 were included for analysis. The median observation time for the cohort was 40 (range 0–72) months. The cumulative recurrence-free survival rate was 71·5 and 82·0 per cent after absorbable and non-absorbable tack fixation respectively (P = 0·007). In multivariable analysis, the use of absorbable tacks was an independent risk factor for recurrence (hazard ratio 1·53, 95 per cent c.i. 1·11 to 2·09; P = 0·008). The rate of moderate or severe chronic pain was 15·3 and 16·1 per cent after absorbable and non-absorbable tack fixation respectively (P = 0·765).

Conclusion

Absorbable tack fixation of the mesh was associated with a higher risk of recurrence than non-absorbable tacks for laparoscopic mesh repair of incisional hernia, but did not influence chronic pain.

Biomechanical evaluation of three fixation modalities for preperitoneal inguinal hernia repair: a 24-hour postoperative study in pigs

PURPOSE

Tacks and sutures ensure a strong fixation of meshes, but they can be associated with pain and discomfort. Less invasive methods are now available. Three fixation modalities were compared: the ProGrip™ laparoscopic self-fixating mesh; the fibrin glue Tisseel™ with Bard™ Soft Mesh; and the SorbaFix™ absorbable fixation system with Bard™ Soft Mesh.

MATERIALS AND METHODS

Meshes (6 cm ×6 cm) were implanted in the preperitoneal space of swine. Samples were explanted 24 hours after surgery. Centered defects were created, and samples (either ten or eleven per fixation type) were loaded in a pressure chamber. For each sample, the pressure, the mesh displacement through the defect, and the measurements of the contact area were recorded.

RESULTS

At all pressures tested, the ProGrip™ laparoscopic self-fixating mesh both exhibited a significantly lower displacement through the defect and retained a significantly higher percentage of its initial contact area than either the Bard™ Soft Mesh with Tisseel™ system or the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system. Dislocations occurred with the Bard™ Soft Mesh with Tisseel™ system and with the Bard™ Soft Mesh with SorbaFix™ absorbable fixation system at physiological pressure (,225 mmHg). No dislocation was recorded for the ProGrip™ laparoscopic self-fixating mesh.

CONCLUSION

At 24 hours after implantation, the mechanical fixation of the ProGrip™ laparoscopic self-fixating mesh was found to be significantly better than the fixation of the Tisseel™ system or the SorbaFix™ absorbable fixation system.

Evaluation of absorbable mesh fixation devices at various deployment angles

BACKGROUND

Hernia repair failure may occur due to suboptimal mesh fixation by mechanical constructs before mesh integration. Construct design and acute penetration angle may alter mesh-tissue fixation strength. We compared acute fixation strengths of absorbable fixation devices at various deployment angles, directions of loading, and construct orientations.

METHODS

Porcine abdominal walls were sectioned. Constructs were deployed at 30°, 45°, 60°, and 90° angles to fix mesh to the tissue specimens. Lap-shear testing was performed in upward, downward, and lateral directions in relation to the abdominal wall cranial-caudal axis to evaluate fixation. Absorbatack™ (AT), SorbaFix™ (SF), and SecureStrap™ in vertical (SSV) and horizontal (SSH) orientations in relation to the abdominal wall cranial-caudal axis were tested. Ten tests were performed for each combination of device, angle, and loading direction. Failure types and strength data were recorded. ANOVA with Tukey-Kramer adjustments for multiple comparisons and χ (2) tests were performed as appropriate (p < 0.05 considered significant).

RESULTS

At 30°, SSH and SSV had greater fixation strengths (12.95, 12.98 N, respectively) than SF (5.70 N; p = 0.0057, p = 0.0053, respectively). At 45°, mean fixation strength of SSH was significantly greater than SF (18.14, 11.40 N; p = 0.0002). No differences in strength were identified at 60° or 90°. No differences in strength were noted between SSV and SSH with different directions of loading. No differences were noted between SS and AT at any angle. Immediate failure was associated with SF (p < 0.0001) and the 30° tacking angle (p < 0.01).

CONCLUSIONS

Mesh-tissue fixation was stronger at acute deployment angles with SS compared to SF constructs. The 30° angle and the SF device were associated with increased immediate failures. Varying construct and loading direction did not generate statistically significant differences in the fixation strength of absorbable fixation devices in this study.

Development of a dynamic model for ventral hernia mesh repair

Introduction

The adequate way of mesh fixation in laparoscopic ventral hernia repair is still subject to debate. So far, simulation has only been carried out in a static way, thereby omitting dynamic effects of coughing or vomiting. We developed a dynamic model of the anterior abdominal wall.

Materials and methods

An aluminium cylinder was equipped with a pressure controlled, fluid-filled plastic bag, simulating the abdominal viscera. A computer-controlled system allowed the control of influx and efflux, thus creating pressure peaks of up to 200 mmHg to simulate coughing and 290 mmHg to simulate vomiting. We tested fixation with tacks (Absorbatack, Covidien Deutschland, Neustadt a. D., Germany). The model was controlled for the friction coefficient of the tissue against the mesh and the physiologic elasticity of the abdominal wall surrogate.

Results

The model was able to create pressure peaks equivalent to physiologic coughs or vomiting. Physiologic elasticity was thereby maintained. We could show that the friction coefficient is crucial to achieve a physiologic situation.

The meshes showed a tendency to dislocate with an increasing number of coughs (Fig. 4). Nevertheless, when applied in a plain manner, the meshes withstood more cough cycles than when applied with a bulge as in laparoscopic surgery.

Conclusions

The dynamic movement of the abdominal wall, the friction between tissue and mesh and the way of mesh application are crucial factors that have to be controlled for in simulation of ventral abdominal hernia closure. We could demonstrate that patient specific factors such as the frequency of coughing as well as the application technique influence the long term stability of the mesh.

What would surgeons like from materials scientists?

Surgery involves the repair, resection, replacement, or improvement of body parts and functions and in numerous ways, surgery should be considered human engineering. There are many areas in which surgical materials could be improved, but surgeons are generally unaware of materials available for use, while materials scientists do not know what surgeons require. This article will review some of the areas where surgeons and materials scientists have interacted in the past and will discuss some of the most pressing problems which remain to be solved. These include better implant materials for hernia repair, breast reconstruction, the treatment of diabetes, vascular stenting and reconstruction, and electrical pacing devices. The combination of tissue engineering and nanomaterials has great potential for application to nearly every aspect of surgery. Tissue engineering will allow cells or artificial organs to be grown for specific uses while nanotechnology will help to ensure maximal biocompatibility. Biosensors will be combined with improved electrodes and pacing devices to control impaired neurological functions.

Laparoscopic mechanical fixation devices: does firing angle matter?

BACKGROUND

A variety of permanent and absorbable tacks are available for mesh fixation during laparoscopic hernia repairs. Although manufacturers recommend deploying tacks perpendicular to the tissue, achieving this can sometimes be challenging. This study aimed to analyze comparatively the effects of angled deployment among commonly used tacks.

METHODS

A piece of composite mesh was fixed to the peritoneal surface of a pig with a single tack fired at either a perpendicular (90°) or acute (30°) angle. A lap-shear test was performed to determine fixation strength. Two permanent tacks (a titanium spiral tack: Protack [PT]; and a hollow screw fastener: PermaFix [PF]) and three absorbable tackers (a solid screw: Absorbatack [AT]; a hollow screw fastener: SorbaFix [SF]; and a strap: SecurStrap [SS]) were challenged. A total of 16 samples were performed for each device at each angle. A nonabsorbable transfascial suture was used as a control condition.

RESULTS

Transabdominal sutures had the maximum acute tensile strength (ATS) (29.9 ± 5.5 N). Protack at both 90° and 30° performed significantly better than absorbable tacks (p < 0.01). No significant difference was found among absorbable tacks at 90°. When the same construct was compared at different angles, SS and SF performance was not affected (p = 0.07 and 0.2, respectively). In contrast, PT and AT had significantly reduced fixation strength (p = 0.003 and 0.004, respectively). However, PT fired at an acute angle had fixation equal to that of absorbable tacks fired perpendicularly.

CONCLUSION

Transabdominal sutures performed better than tacks in the acute setting. No absorbable fixation device demonstrated superior efficacy within its class. Spiral titanium tacks provided better fixation than absorbable tacks at both perpendicular and acute angles. Moreover, titanium spiral tacks deployed at 30° performed equal to or better than absorbable tacks fired perpendicularly to the tissue. It appears that spiral titanium tacks should be strongly considered for cases in which perpendicular tack deployment cannot be achieved.

May titanium spiral tacks contribute to intra-abdominal adhesion formation?

PURPOSE

To verify if titanium spiral tacks may contribute to intra-abdominal adhesion formation in rabbits.

METHODS

Ten New Zealand white rabbits were used. Through videolaparoscopic surgery two titanium spiral tacks (ProTack(®), Covidien(®)) were applied in the right flank. After 30 days the animals were submitted to evaluate peritoneal cavity by videolaparoscopy.

RESULTS

No adhesion was found where the titanium spiral tacks were placed.

CONCLUSION

Titanium spiral tacks for fixation do not cause adhesions in rabbits.