Evaluation of the effectiveness and safety of the ultralight, non-resorbable Optomesh® ULTRALIGHT surgical meshes for surgical treatment of hernias based on open and laparoscopic techniques – a retrospective analysis

Hernias are one of the most common diseases requiring surgical intervention. They occur in both women and men, regardless of their age. Inguinal hernia repair is one of the most commonly performed general surgery procedures, with over 20 million patients worldwide [1]. The estimated lifetime risk of undergoing inguinal hernia repair is 27–43% in men and 3–6% in women [2]. These hernias are almost always symptomatic, and the only cure is surgery. A minority of patients remain asymptomatic, but within 5 years, 70% of these patients still undergo surgery [3]. Ancient records show that hernia was known long before the birth of Christ and was described by the ancient Egyptians and Greeks - Hippocrates among them. Over the years, various materials have been tested to create hernia support prostheses, including tantalum sheets introduced in 1940 by Burke [4]. In 1857, Theodore Billroth stated: “If we could artificially produce tissue of the density and toughness of fascia and tendon, the secret of radical hernia cure would be discovered” [5]. This statement proved to be a foundation for further modifications of prosthetic materials for future pioneers.

The use of plastic polymers revolutionized hernia surgery and introduced new materials. The first material used was nylon [6], which unfortunately did not prove to be durable enough due to hydrolytic etching and required removal in case of infection. Koontz et al. [7] in 1959 proposed the use of other materials, taking into account such features as non-metallic, synthetic nature, non-absorbability and resistance to infections. Materials such as polypropylene (PP), polytetrafluoroethylene (PTFE), dacron, orlon, polyethylene, mylar and marlex were tested in this case [6]. An implant for hernia surgery should have adequate strength and biocompatibility, as well as an appropriate shape. So far, polypropylene materials in the form of monofilament yarns and macroporous knitted fabrics made of them are well-known and proven in clinical practice [8]. Monofilament or multifilament yarns of various surface masses are used for the production of surgical meshes [9]. Microporous and multifilament meshes are among the materials with a higher risk of infection, because macrophages and neutrophils are unable to penetrate through small pores (< 10 μm). This allows bacteria (< 1 μm) to survive inside the mesh pores. Therefore, there has been an evolution towards monofilament with holes larger than 75 μm [10], thus creating meshes with a low risk of infection [11].

The Optomesh^® ULTRALIGHT product described in the analysis below was manufactured using a knitting technique from transparent and blue, monofilament polypropylene yarn. Polypropylene is currently the most important and most commonly used polymer for the production of hernia meshes [12]. Its history of use in this application dates back to the 1960s [13]. It is a non-degradable polymer that is widely used in the production of implants intended for long-term use without the need for reoperation. As a material that is strong, flexible, easy to cut and biocompatible with natural tissues, it is the main polymer used for the worldwide production of hernia meshes [6, 14]. What is equally important, polypropylene is easy to process into a fibrous form and can be used to obtain a wide range of yarns, including monofilament yarns, which allow easy capillary growth and reduce the risk of infection [15]. Its beneficial properties make it suitable for use in many medical fields, including parastomal hernia surgeries and their prevention [16]. The formation of a hernia is a result of intra-abdominal pressure that is greater than the strength of the connective tissue [17]. A typical hernia consists of a hernial sac and its contents, e.g. an intestinal loop or a fragment of the omentum. The occurrence of hernias is facilitated by factors that weaken the transverse fascia or increase the pressure on it, as well as by defects of anatomical structures [18]. In addition, some diseases contribute to the development of hernias, including prostatic hypertrophy, malnutrition, constipation, diabetes, hypoproteinemia or previous surgical procedures that have weakened the strength of the connective tissue [19]. However, the main reason responsible for the formation of hernias and aneurysms is the disturbed collagen metabolism and each of its losses is manifested by the weakening of the abdominal walls [20]. Collagen is the most abundant protein of the extracellular matrix. Recent studies refer to the important role of connective tissue biology - the ratio and level between type I and type III collagen essentially determine the strength of both tissue and scar tissue [21]. The connective tissue abnormality has also been found to be inherited among some family members, which may indicate a multifactorial pattern of inheritance and an apparent genetic aspect [22].

The methods used in hernia surgeries are divided depending on the tension generated during reconstruction into: classical methods, i.e. tension methods, in which the reconstruction is performed using the patient’s own tissues (Bassini, Girard, McVay, etc.) and tension-free methods using a synthetic implant (Lichtenstein or TAPP/TEP, Rives-Stoppa, IPOM, for inguinal hernias and methods with the implant in the sub-lay position - in the preperitoneal space or in the retro-muscular space created between the rectus abdominis muscle and the posterior sheath of the rectus abdominis muscle or on-lay - between the subcutaneous tissues of the abdominal wall and the anterior sheath of the rectus abdominis muscle for abdominal hernias) [23]. Due to the risk of complications, frequency of hernia recurrence and longer recovery time, tension methods have now been almost completely replaced by tension-free methods, and fewer and fewer publications can be found on surgical operations performed using tension methods. There have been many reported cases of complications following surgeries performed using tension methods, such as: symptoms of deep vein thrombosis on the side operated on or vein compression. There is also a possibility of deep hematomas or abscesses resulting from suture placement, which causes tension which can also cause a prompt for clot formation [24]. These and other cases have led to the increasing popularity of tension-free methods. Complete elimination of tension reduces the risk of complications, i.e. pain in the early postoperative period. It speeds up the return to normal physical and professional activity and reduces the risk of hernia recurrence.

Depending on the type of hernia and the surgical method used, the appropriate surgical mesh can be selected based on the surgeon’s preferences, the location of the mesh, the nature of the reconstruction, and medical standards. Mesh surgery is recommended as the first choice for hernia repair for both open and laparoscopic methods. The most commonly used open method of treating inguinal hernia is the Lichtenstein method. Its popularity stems from its high effectiveness, but also from the low risk of complications and disease recurrence. The procedure involves the removal of hernia and the placement of a flat mesh on the posterior wall of the inguinal canal. The synthetic mesh allows for the reconstruction of the correct anatomical parameters of this area [24]. The laparoscopic method is a less invasive surgical technique, characterized by low morbidity and mortality, less postoperative pain and a quick return to normal activities. For this reason, it is increasingly recommended to patients who do not show contraindications to this method. Among the laparoscopic methods, during which Optomesh^® ULTRALIGHT meshes are implanted, the most commonly used are the TAPP and TEP techniques. In some high-resource countries, the utilization of laparoscopic surgery ranges from zero to a maximum of about 55% [1]. The European Standard recommends laparoscopic hernia repair as the technique of choice for the treatment of all primary inguinal hernias, unless there are contraindications to abdominal exploration or the patient’s overall condition does not allow for general anesthesia [25].

The aim of the conducted studies is to assess, based on open and laparoscopic techniques, the efficacy and safety of using ultralight, non-resorbable surgical meshes (Optomesh^® ULTRALIGHT, Tricomed S.A., Poland) made of monofilament polypropylene yarn for surgical treatment of abdominal hernias. The high rate of complications, including wound infections and recurrences, has led to the increasing use of minimally invasive techniques, which allow for the placement of large synthetic meshes using laparoscopic methods such as TAPP, TEP, IPOM, etc., without the need for extensive open tissue preparation [26]. The following analysis demonstrates the validity and efficacy of the increasing use of innovative laparoscopic techniques and the abandonment of open wound surgery where possible. The laparoscopic technique must be carefully compared with open procedures before its true place in hernia surgery can be determined.

Recovery time and hernia recurrence after inguinal hernia repair are significant socioeconomic problems, and chronic pain that interferes with daily life and work occurs in about 6% of patients [37]. 4.8% of primary repairs and 8.6% of recurrent hernias occur as an emergency case with complications. Some patients suffer from bilateral hernias, which can be repaired during the same surgery - such intervention is possible with the TAPP technique because it allows simultaneous viewing of both groins and, if necessary, repair of both inguinal canals. It has been reported that 30% of people with a primary unilateral hernia develop a hernia on the opposite side [27].

Worldwide, the results of inguinal hernia repair need to be improved. Recurrence rates—measured by reoperation incidence—still range from 10 to 15%; although it has to be stated that the increasing use of mesh has resulted in a decrease in recurrence rates. There is great concern about the complications of chronic pain, which still occurs in 10 to 12% of patients [1].

Postoperative ventral hernias occur after almost one in four laparotomies. Unfortunately, the still widely used simple suturing of the hernia ring edges leads to recurrence in as many as 25 to 54% of cases. Even the placement of synthetic mesh during reconstructive surgery does not guarantee a successful repair, and the recurrence rate in these cases still reaches 32% in anterior procedures [26].

Early recurrences are rare and usually result from an inadequate surgical technique. However, the main cause is inadequate mesh fixation and inappropriate size of the implant, which results in too small a margin of mesh extending beyond the hernia ring, usually about 3–5 cm, which leads to the lack of coverage of unidentified wall defects. The frequency of wound complications after anterior abdominal wall surgery in the case of postoperative abdominal hernias ranges from 20.9 to 67% [38]. Studies have shown that 70–75% of postoperative hernia recurrences develop within 2 years post-op, and 80–90% within 3 years [22].

Our study involved 171 patients. Most of them underwent open surgical mesh implantation (n = 155): tension-free Lichtenstein repair and Rives-Stoppa technique repair, while the second group consisted of patients who underwent laparoscopic surgery (n = 16): either TAPP or TEP. An untreated hernia can lead to intestinal entrapment and necrosis, in which case it is considered a direct life-threatening condition. For this reason, currently, elective procedures are being performed to reduce the risk of complications. All procedures included in the study were previously planned ones. The preoperative data obtained show that the most common type of disorder diagnosed in patients was an inguinal hernia. Umbilical, abdominal and linea alba hernias were also operated on - in these cases, an open procedure was always chosen. In the case of bilateral hernias (inguinal and femoral), only laparoscopic implantation was chosen.

In open methods, the mesh was placed in the on-lay position (131 patients and 2 patients), while in laparoscopic methods - in an under-lay position (14 patients and 21 patients). In 3 cases, the surgeons decided to use the sub-lay position in open procedures. The average duration of the procedure in open methods was significantly shorter (63 min) compared to laparoscopic methods (128 min), which require greater precision. This is probably one of the reasons why doctors more often prefer to use open techniques. Additionally, during surgery with open techniques, the presence of an anaesthesiologist is not required because the patient is not subjected to general anaesthesia, which then translates into significantly lower costs of the surgery. Due to this reason, these methods are more preferred in hospitals in Poland. In open methods, the use of ultralight meshes is much less noticeable to the patient than standard meshes, which should be a hint for their more frequent use in the future also for open methods.

No adverse events related to the implant were recorded during the surgeries and only one patient with open surgery suffered intraoperative complications (Rives-Stoppa repair). Only 2 open surgeries (Lichtenstein) required drainage. Significant differences were found in the need for fixation depending on the implant placement method.

Fixation was not necessary for most laparoscopic patients (14 TAPP/TEP). However, all patients with open surgery required mesh fixation. The analysis showed significant differences in the hospitalization and convalescence periods. The average hospitalization period for the open method was 3 days, and the convalescence period was 23 days. For the closed method, the average hospitalization period was 2 days, and the convalescence period was 30 days.

Ultralight meshes, in comparison to standard implants, have thinner fibers and larger pores which translates into a smaller amount of implanted material causing a significantly smaller reaction to a foreign body. The pores of the material which are larger than 75 μm ensure effective connective tissue overgrowth, which promotes smaller inflammatory reactions while maintaining its strength parameters [39]. Lightweight meshes are also more flexible in comparison to meshes with a heavier basis weight. This fact results in better tissue integration, less discomfort and pain for the operated patient. A randomized controlled trial showed that this fact is associated with an accelerated recovery time [40].

The reduced inflammatory response in lightweight meshes also translates into a reduced degree of shrinkage. Mesh materials must have adequate resistance to the stresses that are exerted on the abdominal wall in order to maintain the functional repair of the hernia and prevent potential recurrence and bulge formation. On the other hand, they should have elasticity that matches the elasticity of the abdominal wall so as not to restrict abdominal distension and so that their biomechanical properties reflect proper function [6].

Optomesh^® ULTRALIGHT is a non-resorbable, ultralight polypropylene surgical mesh which is characterized by a significantly reduced amount of implanted material (several times lower surface mass compared to standard meshes) and atraumatic edges, while providing appropriate mechanical properties supporting damaged connective tissue structures. Analyzing early postoperative information up to 3 days after surgery, we did not record any adverse event related to the implanted mesh during the patients’ hospitalization. The average assessment of pain sensation in the first days after surgery (on a VAS scale from 0 - no pain sensation, to 10 - intense pain) for patients with open surgery was higher (3 for the open method and 1 for the laparoscopic method). The average recovery time (return to normal activity) was about 3 weeks for the group of patients with open surgery and 4 weeks for the group of patients after laparoscopic intervention. While global trends suggest laparoscopic methods are more advantageous in terms of return to activity—often demonstrating recovery times equal to or shorter than open procedures—our specific findings present a slightly different picture. We believe this observation in our study is likely due to the smaller sample size in our laparoscopic group (16 patients). After a closer analysis of the 16 patients in the laparoscopic group, we identified three patients whose prolonged recovery times significantly inflated the average (two patients reported 84 days, and one reported 140 days). We suspect that these extended recovery periods may be attributable to co-morbidities. These patients presented with co-morbidities such as arterial hypertension, colonic diverticula, hyperglycemia, atherosclerosis, an unruptured right internal carotid artery aneurysm, and degenerative spinal disease with nerve compression in the thoracolumbar segment. Furthermore, one of these patients, treated for a recurrent left-sided hernia, had undergone two previous left inguinal hernia repairs in prior years, which may have contributed to his 84-day recovery. Had these three outlier patients been excluded, the average recovery time for the laparoscopic group would have been approximately 13 days, which is less than that of the open surgery group, aligning with global trends. However, we chose to include all patients in our analysis to avoid misrepresenting the overall findings. The recovery period for 99 patients lasted 1 day, and for 1 patient no information was provided.

Mild post-puncture syndrome in a patient operated with the open method was the only case of complications in the first days after surgery. Approximately 95% of the examined patients did not report any discomfort related to the mesh. Functional assessment was performed, during which almost 98% of patients did not report any problems – there were no dysfunctions. However 4 patients operated with the open method reported: cutaneous hypoesthesia of the right groin area, sensory disturbances in the right groin, cutaneous hypoesthesia of the left groin area and hypoesthesia of the medial side of the left thigh.

The clinical study plan assumed two follow-up visits. The first follow-up visit took place on average 18 days after the mesh implantation procedure. There was no hernia recurrence or adverse events related to the implant. Most patients reported no foreign body sensation (98%) and no dysfunction (97%). Only 3 patients who had undergone open surgery reported foreign body sensation (2 patients after Lichtenstein procedure - ONLAY mesh placement, 1 patient after Rives-Stoppa repair with SUBLAY mesh placement). During the first follow-up visit, statistically significant differences in complications were found between the surgical methods. No complications were diagnosed in 98% of patients who underwent open surgery and in nearly 82% of patients who underwent closed surgery. Among the study patients, only 3.5% of the patients experienced postoperative complications, such as seromas, groin pain requiring 1% Lignocaine blockades, or partial wound dehiscence. The efficacy and safety of the device used were assessed, and it was found that the device was effective and safe in all patients and that the hernia was properly treated. The comfort assessment associated with mesh implantation showed no discomfort in almost 95% of patients. Statistical analysis showed that there were significant differences in the feeling of pain recorded during the first follow-up visit depending on the method of implantation.

The second follow-up visit took place on average 347 days after the procedure. Conducting a follow-up visit after a longer period of time allowed for the observation of the impact of mesh implantation on the effectiveness of surgical treatment of hernias in the long term (even after 39 months). This allowed for a full assessment of the patients’ condition. During the interview, no adverse events related to the implant were noted. In 98% of patients the repair was found to be effective and safe. However, in 3 patients who underwent open surgery, the device was determined to be safe but ineffective due to hernia recurrence (3 patients after Lichtenstein surgery - mesh placement using the ONLAY method). Additionally, in 2 patients who underwent open surgery, significant implant folding was also observed in ultrasonographic examination (1 patient after Lichtenstein surgery - ONLAY mesh placement, 1 patient after Rives-Stoppa surgery with UNDERLAY mesh placement). Postoperative complications were noted in only 1% of patients (open surgery): seroma up to 6 weeks after surgery, not drained, 5 inguinal nerve blockades with 1% Lignocaine every week after surgery. Only 2% of patients reported a foreign body sensation - exclusively in the open surgery group. Comfort was also rated very high, as 91% of patients did not feel any discomfort or ailments related to mesh implantation, only 14 subjects from the open surgery group and 1 patient from the laparoscopic group mentioned various ailments. When assessing the pain associated with the procedure on the VAS scale, all patients rated it on average 0 (range 0–5, however with two patients: 1 TAPP, 1 Rives-Stoppa repair indicated a VAS 5 pain during exertion and 0 at rest). There were significant differences in pain sensation recorded during the second follow-up visit. Nearly 91% of patients in the open surgery group and 88% in the closed surgery group reported no pain. For the open surgery group, the value reached 0, and for the laparoscopic group 1. This translated into high functional assessment, as 95% of patients assessed the functions as lack of dysfunction.

In the study by M. Melkemichel et al. [41], it was shown that lightweight meshes offer benefits compared to heavyweight meshes in terms of accelerated postoperative recovery and reduced postoperative pain. Multivariate analysis revealed no significant difference in recurrence risk between heavyweight polypropylene (PP) meshes > 50 g/m² and regular lightweight PP meshes < 50 g/m² (HR 1.12, P = 0.13).

C. Nikkolo et al. [42] reported that significantly more patients in the heavyweight mesh (HW) group experienced pain at rest compared to the lightweight mesh (LW) group at 6-month follow-up (6.3% vs. 0%, P = 0.038). A feeling of foreign body sensation at the operative site was experienced by 32.8% of patients in the HW group and 20.9% of patients in the LW group at 6 months post-surgery (P = 0.123). No significant differences were found in any quality of life dimension on the SF36 scale between the two study groups at 6 months post-surgery. The authors concluded that, compared to HW mesh, LW mesh offers some advantages in reducing chronic inguinal pain at the operative site after inguinal hernia repair.

The 3-year results from the study by Bringman et al. [43] demonstrated that the use of lightweight (LW) mesh in Lichtenstein hernia repair did not affect the recurrence rate, but it did alleviate some aspects of pain and discomfort 3 years post-surgery compared to the use of standard polypropylene mesh. Patients who received LW mesh experienced less pain on examination, less pain when rising from a lying to a sitting position, fewer various groin problems, and less often felt the mesh than patients with standard mesh.

A limitation of this study might be the reliance on general interviews and the visual analog scale (VAS) for assessing patient comfort and mesh tolerance. In contemporary hernia research, the use of validated patient-reported outcome measures, such as the Carolina Comfort Scale or EuraHS-QoL, is increasingly encouraged. Considering the specific activities of the centers involved, they routinely employ this scale for patient assessment. Due to the retrospective nature of this study, we relied on data collected by the centers that were available to us, which might be considered a limitation. However, in addition to assessing pain using the VAS, our study’s Case Report Form (CRF) also included questions regarding, among other things, the sensation of a foreign body, feelings of discomfort, and return to activity. We analyzed the answers to these questions in this publication.

We continue to see fewer laparoscopic surgeries using ultralight meshes because many surgeons still favor the use of standard meshes due to their greater stiffness and speed of adaptation to the peritoneum, but it should be noted that the smaller thickness of ultralight meshes does not cause implant folding, and when precisely fitted, the adhesive forces between the mesh and the fascia hold it in place. During laparoscopic surgery, fitting ultralight meshes and placing them on the peritoneum is easier than standard meshes because, due to their lower mass, the adhesive forces are greater than the gravitational forces, which causes meshes to adhere well to the fitting site not falling down which is possible for meshes with a heavier grammage.

Summing up and analyzing the data collected at all follow-up visits, the effectiveness and safety of the Optomesh^® ULTRALIGHT implant can be assessed positively. Interviews at the second follow-up visit, which were conducted with all patients after an average of 347 days after the procedure, confirmed the long-term, satisfactory reception of the patients in terms of comfort and average pain sensation. The evaluation prepared after the procedure emphasizes that the Optomesh^® ULTRALIGHT implant is not only effective and safe, but also imperceptible to the patients, which translates into their high level of satisfaction and improved quality of life.

Implantation of the Optomesh^® ULTRALIGHT surgical mesh can be assessed as an effective and safe method in the treatment of hernias. The Optomesh^® ULTRALIGHT surgical mesh can be successfully implanted using open methods (Lichtenstein, Rives-Stoppa) as well as laparoscopic methods (TAPP, TEP). Based on the obtained results, it can be stated that the applied implantation methods are effective. Higher efficacy, no hernia recurrence, no foreign body sensation and no complications in long-term assessment present the advantages of laparoscopic methods over open repair.

Considering the fact that a significant part of the problems described in the literature related to the use of mesh implants for hernia repair occur within a period of several years after implantation, it is planned to conduct similar studies in the long-term period of 3–5 years after implantation.

PL 238,704 B1.