Introduction

Minimally invasive inguinal hernia repair has a well-established reputation for decreased postoperative pain and disability, earlier return to work and activities of daily living, and equivalent recurrence rates compared to open approaches [1]. The two main approaches to minimally invasive inguinal hernia repair are transabdominal preperitoneal (TAPP) and totally extraperitoneal (TEP). Similar outcomes may be expected between the two approaches assuming similar hernia disease [2]. Still, due to the significant worldwide frequency of inguinal hernia repair (estimated at 20 million repairs per year) [1] and the associated economic burden and loss of productivity related to postoperative convalescence, there is an increasing need to quantify surgical outcomes beyond inguinal hernia recurrence [3]. Because recurrence rates are generally expected to be similar in experienced hands between the operative approaches and mesh reinforcement is universally accepted, a more contemporary consideration would be short term outcomes of various mesh fixation methods with respect to pain and quality of life.

The ideal method of mesh fixation (or, alternatively, avoidance of fixation) remains heavily debated. Specifically, some believe that lack of adequate fixation can lead to hernia recurrence [4], however there is also concern that fixation itself contributes to nerve damage and subsequent pain after surgery [5, 6]. Further complicating the scenario is the emergence of adhesives and self-fixating meshes as an alternative to traumatic mechanical fixation. The advent of robotic inguinal hernia repair has also introduced the possibility of suture fixation, where previous mechanical fixation modalities consisted of staples and non-absorbable and absorbable tacks. Of the few studies that have compared no fixation to some form of mechanical fixation, results have been contradictory and incomplete due to either small sample size or inconsistent methods to define and measure pain [7,8,9,10,11]. Given the wide variety of mesh fixation methods and the lack of consensus, we utilized the Americas Hernia Society Quality Collaborative (AHSQC) database to compare 30-day pain and disease-specific quality of life outcomes between the different mesh fixation methods in minimally invasive inguinal hernia repair.

Methods

After Institutional Review Board (IRB) approval was obtained, The Americas Hernia Society Quality Collaborative AHSQC was queried for all patients undergoing minimally invasive inguinal hernia repair including both robotic and laparoscopic approaches between 2017 and 2019. The AHSQC is a continuous quality improvement effort in hernia care utilizing point of care data entry. This registry is prospectively maintained by 325 participating surgeons practicing in various clinical settings around the United States including community, academic, and academic affiliated [12].

All patients who underwent elective minimally invasive inguinal hernia repairs with 30-day follow-up completed were included. We excluded patients with chronic groin pain which is defined as pain that is present for more than 3 months. Symptoms include pain and a burning sensation in the inguinal area. We also excluded patients with contaminated wounds (CDC 2–4), patients with bilateral inguinal hernia, patients who had ventral and inguinal hernia repaired at the same operation. Patient characteristics including age, gender, body mass index (BMI), American Society of Anesthesiologists class (ASA), comorbidities and smoking status were collected. In addition, hernia characteristics and operative approach were recorded.

The primary outcomes measured were groin pain at 30-days (Yes/No) and 30-day quality of life as captured through the European Registry for Abdominal Wall Hernias (EuraHS) assessment. Secondary outcomes of interest were 30-day complications and wound morbidities including recurrence within 30 days, surgical site infection (SSI), surgical site occurrence (SSO), and SSI or SSO requiring procedural interventions. EuraHS is a multi-dimensional numerical quality of life score which includes a pain domain (range 0–30), a restrictions domain (range 0–40), a cosmetic domain (range 0–20), and an overall score (range 0–90). Higher EuraHS scores indicate worse outcomes. The quality of life evaluation is performed preoperatively as a baseline score and then postoperatively within the 30-day follow-up time period after hospitalization [3]. EuraHS has been validated for use with inguinal hernia repair [13].

As described in one of our previous studies using AHSQC data base, “SSIs were reported and classified according to the Centers for Disease Control and Prevention (CDC) classification, as superficial, deep incisional and organ space. SSO includes any SSI as well as wound cellulitis, non-healing incisional wound, fascial disruption, skin or soft tissue ischemia, skin or soft tissue necrosis, wound serous or purulent drainage, stitch abscess, seroma, hematoma, infected or exposed mesh, or development of an enterocutaneous fistula. SSI or SSO requiring procedural intervention is defined as any SSI or SSO that requires wound opening, wound debridement, suture excision, percutaneous drainage, or partial or complete mesh removal” [14].

Fixation method was categorized into three groups: (1) atraumatic fixation (AF) which included no fixation, self-fixating mesh, and adhesives, (2) traumatic non-suture fixation (TNS) which included permanent and absorbable tacks and staples and (3) traumatic suture fixation (TS). Outcomes were compared across fixation methods using univariate analysis. Comparison of median was performed using the Wilcoxon test and proportions were evaluated using Pearson chi-square test and Fisher’s exact test. A 2-tailed p value < 0.05 was considered significant. Logistic and linear regressions were performed on patients with reported pain at site at 30-days (Yes/No) and EuraHS quality of life assessment scores to adjust for the following confounders: age, gender, BMI, diabetes, ASA class, nicotine, hernia size, hernia repair indications, recurrent hernia and operative approach.

Results

After applying all inclusion and exclusion criteria, 2119 patients were identified in the AHSQC registry. 864 patients had surgical site pain scores, 30-day EuraHS scores and quality of life outcomes reported; among them 253 had atraumatic fixation (AF), 451 had traumatic non-suture fixation (TNS) and 160 patients had traumatic suture fixation (TS). In the AF group, 37 (14%) had no fixation, 113 (45%) had self-fixating mesh and 103 (41%) had fixation with adhesives. In the TNS group, 424 (94%) had tack fixation and 27 (6%) had staple fixation.

Patients’ demographics, hernia characteristics and operative approaches are reported in Tables 1 and 2, respectively.

Table 1 Demographics
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Table 2 Operative approach and hernia characteristics
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When evaluating pain as a binary variable, in total, 262 (30%) out of 864 patients reported”Yes” to having pain at 30 days after the inguinal hernia repair. Univariate analysis showed that TNS was associated with a higher number of patients with pain at 30-day follow-up (Yes/No), 34% compared to AF 29% and TS 21% (p = 0.005). After applying a logistic regression model to adjust for age, gender, BMI, diabetes, ASA class, nicotine use, hernia size, recurrent hernia and operative approach, this difference disappeared and odds ratio showed no statistically significant difference in groin pain presence as answered “Yes” at 30 days between the three groups. Age was the only variable that was significantly associated with pain as younger patients were more likely to have pain (Table 3).

Table 3 Odds ratio for 30-day pain (Yes/No)
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When looking at the EuraHS evaluation for pain and quality of life outcomes, TS had higher scores (indicating worse outcomes) in all EuraHS domains including pain (P < 0.001), restrictions (p = 0.001), cosmetic (p < 0.001) and overall score (p < 0.001) when compared to both AF and TNS (Table 4). Linear regression models were performed for EuraHS quality of life outcomes to adjust for the previously defined confounders. The adjusted analysis for 30-day EuraHS scores is displayed in Fig. 1. AF was associated with better overall EuraHS scores than both TNS and TS fixation methods. Within each domain, AF had a better quality of life than both TNS and TS as it relates to the restriction domain and cosmetic domain and was only better than TS fixation in the pain domain. Although patients who had TS fixation reported worse scores, when comparing TS to TNS, there was no statistically significant difference between the two groups (Fig. 1).

Table 4 Descriptive statistics of EuraHS scores at 30 day follow-up by mesh fixation
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Fig. 1
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a Effect size for EuraHS pain score [95% CI], b effect size for EuraHS restrictions score [95% CI], c Effect size for EuraHS cosmetic score [95% CI], d Effect size for EuraHS overall score [95% CI]. Variables: Age—(48–70), BMI—(23.8–28.6), Hernia size (average)—(2.0–2.5), Mesh Fixation—TNS:AF, Mesh Fixation—TS: AF, Mesh Fixation—TS: TNS, Gender—Female:Male (F:M), Diabetes mellitus (DM)—Yes:No, ASA class—1, 2:3, 4, 5, Smoker (Currently uses nicotine within one month)—Yes:No, Recurrent (Recurrent hernia)—Yes:No, Operative approach—Robotic:Laparoscopic. Asterisk statistically significant

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Other factors associated with worse quality of life outcomes (EuraHS) were female gender [pain (p = 0.029) and cosmetic (p = 0.001) domains] and recurrent hernia [pain (p = 0.030), cosmetic (p = 0.012), and overall domains (p = 0.019)]. Age had a statistically significant negative effect size in pain (p < 0.001), restrictions (< 0.001), and overall domains (p < 0.001) showing that higher age is associated with better quality of life outcomes. (Fig. 1). There was no statistically significant difference between different fixation methods in quality of life outcomes based on the operative approach (robotic vs. laparoscopic) (Fig. 1), (Table 3).

Our data also did not show any statistically significant difference between the three groups in 30-day complications including early recurrence, SSI, SSO including seroma and hematoma, SSI or SSO requiring procedural intervention (Table 5).

Table 5 Outcomes by mesh fixation for patients with 30-day patient-reported outcomes reported
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Discussion

To our knowledge, our study is the first to describe pain and disease-specific quality of life outcomes encompassing all currently available fixation and non-fixation techniques in minimally invasive inguinal hernia repair. We found that patients undergoing minimally invasive hernia repair without traumatic mesh fixation have better EuraHS quality of life scores at 30 days after surgery compared to patients having any other method of mesh fixation. While quality of life was higher with atraumatic fixation, there was no significant difference between the various methods of mesh fixation in the presence of pain (Yes/No) at the surgical site 30 days after surgery and in postoperative complications and wound morbidities.

The available literature comparing postoperative pain between mesh fixation techniques in minimally invasive inguinal hernia repair focuses primarily on comparing two single methods such as glue fixation versus staples [9, 11, 15, 16] or mesh fixation versus non-fixation [17, 18].Notably, there is a 2016 meta-analysis by Antoniou, et al. which identified nine randomized controlled trials of non-penetrating versus penetrating fixation of inguinal mesh during laparoscopic inguinal hernia repair. Within the nine trials, six methods of either glue fixation of penetrating fixation were studied. None of the studies compared more than two specific methods [19]. While these studies provided contemporaneous literature at some point to help guide surgeons in terms of operative technique, they are hindered by variability in the tools used to quantify postoperative pain. Furthermore, they are arguably ill-positioned to address the wide variety of fixation options available to surgeons today and are therefore somewhat outdated. Our study is unique in that it examines multiple methods of mesh fixation including AF which includes no fixation, self-fixating mesh and adhesives, TNS which includes permanent or absorbable tacks and staples and TS which includes suturing the mesh.

Traditionally, evaluation of inguinal hernia repair techniques has focused on hernia recurrence as the primary outcome. In a systematic review by Lederhuber et al. they included randomized controlled trials from PubMed, EMBASE and the Cochrane Library that looked into minimally invasive inguinal hernia repair. Eight trials compared recurrence rate between different mechanical mesh fixation methods or fixation to no fixation of mesh. Among them, none showed significant difference in recurrence. Of note, all evaluated recurrence with a minimum of 12 month follow-up [20]. Acknowledging that overall recurrence rates have decreased over time for all approaches [21], and also that hernia recurrence is not the sole meaningful outcome after inguinal hernia repair, there has been a recent transition towards collecting and reporting on patient-based outcomes to better inform surgeons of whether or not their treatment has made their patients feel better [22]. This suggests the need to take into account the overall wellbeing and morbidity in addition to pain when evaluating hernia patients postoperatively. A randomized trial by Lovisetto et al. was the first study to evaluate the postoperative functional status, general health and limitations in addition to pain. VAS scores were significantly lower at 30-days in the fibrin glue group compared to the staples group. The 30-day evaluation showed lower morbidity and faster return to work and social life with the fibrin glue [10]. Still, there remains considerable debate as to whether the VAS, a generic pain scale, is adequate for evaluation of post-herniorrhaphy pain [23]. Additionally, return to work and activities of daily living are known to be affected by a variety of human factors, including the patient’s outlook on life and therefore are also likely inadequate to fully elucidate the patient’s true recovery process [24]. In the EuraHS assessment, the pain domain (0–30) includes pain in rest while laying down (0–10), pain during activities like walking, biking, and sports (0–10), and worst pain felt during the last 7 days (0–10). The restrictions domain (0–40) includes daily activities inside the house (0–10), outside the house (0–10), during sports (0–10), and during heavy activities (0–10). The cosmetic domain (0–20) includes the shape of abdomen (0–10) and site of the hernia and the scars (0–10). This allows for a very broad and comprehensive assessment of the patient-reported outcomes and satisfaction following surgery [3].

One of the strengths of our study is the ability to give a fairly comprehensive overview of disease-specific postoperative quality of life in a substantial number of patients undergoing minimally invasive inguinal hernia repair with respect to the method of fixation utilized. Indeed, we found that atraumatic fixation of mesh is associated with better EuraHS quality of life outcomes in all domains including pain when compared to traumatic fixation techniques especially suture fixation. To our knowledge, there are three meta-analyses supporting the idea that inguinal hernia recurrence rate is not increased without fixation [18, 25, 26]. Considering the data available in the literature and the results of this study, one might argue whether traumatic mesh fixation (or fixation at all) is warranted in minimally invasive hernia repair. Further comprehensive prospective study comparing all methods of AF with subsequent recurrence rates and hernia-specific quality of life measures may help to clarify remaining uncertainty.

The fact that we did not find a difference between the group in 30-day postoperative pain (Y/N) is not entirely surprising. While early postoperative pain is known to be a major contributor to overall health-related quality of life [27], it is also noted to be multi-dimensional. Additionally, there are various contributors to postoperative pain including preoperative pain, anxiety, age and type of surgery [28]. As such, simple pain scores are known to be inadequate in truly evaluating a patient’s pain experience [29] and we would therefore surmise that a binary question related to pain is equally of limited utility. Indeed, this begs the question of the overall utility of this variable in our registry, which will be further considered for amendment/removal.

There are some limitations to our study. Although female gender was associated with worse quality of life outcomes, the small number of females compared to males decreases the statistical power of this comparison. Also due to the low number of patients with baseline EuraHS assessment completed in the AHSQC database, the baseline assessment could not be included in the adjusted analysis. However, we feel that the effect of this was minimized when we excluded patients with chronic groin pain. We also believe that baseline quality of life scores should be included in the routine preoperative evaluation to guide future studies. Although hernia size was slightly lower in the AF group (Table 2), a 0.5–1 cm difference in hernia size is likely clinically insignificant. Additionally, we only reported outcomes at 30 days postoperatively, thus we cannot comment on the superiority of one approach over another with regard to recurrence and other long-term complications.

Conclusion

Our study is the first to evaluate all currently available fixation methods for minimally invasive inguinal hernia repair. We found that atraumatic fixation of mesh, including no fixation, self-fixating meshes, and adhesives, had a significantly improved hernia-specific quality of life in all domains at 30 days postoperatively. Also, we did not find any statistically significant difference between different mesh fixation techniques in early postoperative complications and wound morbidity. Further, we identified an opportunity for improvement of our registry in the binary pain variable, which likely is inadequate for its stated purpose.