Non-fixation versus fixation of mesh in laparoscopic transabdominal preperitoneal repair of inguinal hernia: A systematic review and meta-analysis of randomized controlled trials.

Inguinal hernia is a common disease in general surgery, with over 20 million patients worldwide undergoing repair surgery annually [ 1 ]. For symptomatic inguinal hernias, mesh repair is recommended for treatment. Surgical procedures for inguinal hernia repair are primarily classified as open repair and laparoscopic mesh repair. Despite open mesh repair already having low recurrence rate [ 2 ], laparoscopic mesh repair has gained popularity in recent years due to its advantages such as well recognition of groin anatomy, convenience in dealing with bilateral hernias and good cosmetic effect. Laparoscopic totally extraperitoneal (TEP) and transabdominal preperitoneal (TAPP) repair are two most commonly used laparoscopic mesh repair techniques, both of which are based on the theory of myopectineal orifice. The primary distinction between TEP and TAPP is the approach to enter preperitoneal space. In TAPP, preperitoneal space is entered by dissecting parietal peritoneum through peritoneal cavity, while in TEP, the entering of peritoneal cavity and subsequent peritoneal closure are avoided. It is widely accepted that standard dissection of preperitoneal space [ 3 ], proper placement and fixation of the mesh are key points in both TEP and TAPP technique. However, there is still some controversy regarding mesh fixation in laparoscopic mesh repair. Advocates argue that mesh fixation can prevent mesh migration, which is believed to be an essential cause of hernia recurrence after laparoscopic repair [ 4 ]. While opponents contend that mesh fixation may increase the risk of nerve injury, potentially leading to postoperative pain including chronic groin pain (CGP) [ 5 ]. Several meta-analyses of randomized controlled trials (RCTs) have already compared the perioperative outcomes between non-fixation and fixation of the mesh in laparoscopic inguinal hernia repair [ 6 – 10 ]. They all demonstrated that non-fixation did not increase the risk of hernia recurrence. However, there were inconsistent results regarding postoperative pain. It is important to note that these systematic reviews were mainly focusing on TEP technique and there was only one review exploring the effects of non-fixation of mesh in TAPP separately [ 10 ]. Moreover, in that meta-analysis of Riemenschneider et al. [ 10 ], studies using self-gripping mesh which was considered as an atraumatic mesh fixation method were included. And only hernia recurrence and CGP between non-fixation and fixation of the mesh were investigated. Therefore, the influence of mesh non-fixation in TAPP remains not sufficiently concluded. The object of our present review was to comprehensively compare the clinic outcomes of non-fixation and fixation of the mesh in TAPP inguinal hernia repair to determine whether non-fixation could affect the outcomes.

Search and selection procedure are shown in Fig 1 . Each step of selection was conducted by two authors (CXZ and HJS) independently. Disagreements were resolved by discussion. Through systematically searching in PubMed, Embase and Cochrane database, 592 records were retrieved. Adding one additional article from bibliography, there were totally 593 records for further review. After removing duplicates, titles and abstracts of 463 records were screened. Then there were 19 articles remained after title and abstract screening. Full texts of the 19 articles were intent to retrieve for further review. Four conference abstracts and 2 articles of which the full texts were not possible to get were excluded. Two articles in Russian and 5 non-randomized trial articles were also excluded. Finally, six prospective, randomized controlled trials were included for meta-analysis. Details can be seen in S1 File . The characteristics of the six included studies are presented in Table 1 . There were a total of 1643 patients, of which 679 patients underwent TAPP surgery with non-fixation of mesh and 964 patients with fixation of mesh. Except for the additional article from reference, the other five studies were all conducted in the last decade. In the study of Kalidarei et al. [ 14 ] and the study of Smith et al. [ 15 ], there were 16 patients and 34 patients of bilateral inguinal hernia, respectively. Two studies [ 16 , 17 ] described the size of hernia defect and there was no significant difference of the size of hernia defect between non-fixation group and fixation group. The mean follow-up time ranged from 6 to 24 months. NM not mentioned, FG fixation group, NFG non-fixation group The details of procedure are shown in Table 2 . Except for two studies [ 17 , 18 ] in which all the surgeries were done by one experienced surgeon, the other four studies had a surgical team to perform the TAPP surgery. A kind of lightweight 3D mesh was used in the study of Li et al. [ 17 ] and normal polypropylene mesh was used in the remaining five studies. In all included studies the size of mesh was at least 15cm × 10cm. Suture, tacker, stapler and glue were mesh fixation methods used in the six included studies. Three studies [ 14 , 16 , 19 ] had used two methods for mesh fixation. Two studies [ 18 , 19 ] mentioned the use of prophylactic antibiotic. None of the studies mentioned the use of drainage. One study [ 19 ] reported that 15 cases were converted to open surgery, but there were no more details. NM not mentioned The risk of bias assessment of the included studies for recurrence is presented in Table 3 . Overall, two [ 14 , 19 ] out of the six trials were considered as ‘some concerns’ because they did not report their process of concealment. The overall risk of one trial [ 15 ] was high as the process of randomization was not reported and the rate of lost follow-up was high, in addition with some outcomes were assessed by patient themselves. The results of bias assessment of other outcomes are shown in S2 File . 0 = low risk, 1 = some concerns, 2 = high risk Recurrence . Recurrence rate was reported as an outcome in all included studies. The total recurrence rate in non-fixation group and fixation group were 0.6% and 0.7%, respectively. The pooled analysis did not demonstrate any significant difference in recurrence rate between the two groups (RR: 0.83; 95% CI, 0.29–2.39, P = 0.73). Heterogeneity among the included studies was low (I2: 8%, P = 0.35) ( Fig 2 ). Postoperative pain . Visual Analog Scale (VAS) pain scale, in which pain score is defined from 0 (no pain) to 10 (maximum pain), was used for postoperative pain evaluation in five included studies [ 14 , 16 – 19 ]. Among them, the study of Azevedo et al. [ 16 ] also used McGill pain questionnaire for pain evaluation. Four [ 14 , 16 – 18 ] of the five studies reported VAS pain score data of different time. Azevedo et al. [ 16 ] demonstrated that at six different time periods (first postoperative day, between Day 7 and Day 15, after 3 and before 6 months, after 1 year, after 1 year and 6 months and after 2 years) there were all no significant difference in pain score of VAS scale between non-fixation group and mesh fixation group. In the study of Li et al. [ 17 ], VAS pain scores of 2 days, 3 months, and 6 months postoperatively of non-fixation group were all significantly lower than those in fixation group. Data synthesis could only be done for postoperative pain at 6 months as three studies [ 16 – 18 ] reported VAS pain score of 6 months postoperatively. The analysis showed pain score at 6 months postoperatively of non-fixation group was significantly lower than that of fixation group (MD: -0.16; 95% CI, -0.23–-0.10, P < 0.0001). Between-study heterogeneity was moderate (I2: 44%, P = 0.17) ( Fig 3 ). Chronic groin pain . Chronic pain was reported as an outcome in four studies [ 14 , 16 , 18 , 19 ]. Three [ 14 , 16 , 18 ] of them showed there was no chronic pain in both non-fixation group and fixation group. The other study [ 19 ] showed the chronic pain rate were 1.9% and 13.5% in non-fixation group and fixation group respectively. However, only the study by Azevedo et al. [ 16 ] and the study by Habeeb et al. [ 19 ] gave a clear definition of chronic pain (chronic pain was defined as persistent pain lasting over 3 months). The available data did not allow us to conduct quantitative synthesis on chronic pain. Wound and mesh infection . Four studies [ 14 , 15 , 17 , 19 ] provided data of wound and mesh infection. There was no significant difference in infection rate between non-fixation group and fixation group (RR: 1.18; 95% CI, 0.39–3.62, P = 0.77). The between-study heterogeneity was low (I2: 24%, P = 0.25) ( Fig 4 ). Seroma . Data of seroma formation were available from five studies [ 14 – 17 , 19 ]. The total rate of seroma formation in non-fixation group and fixation group were 7.2% and 5.9%, respectively. The pooled analysis showed there was no significant difference of seroma formation rate between the two groups (RR: 0.94; 95% CI, 0.63–1.40, P = 0.75). There were moderate heterogeneity among the included studies (I2: 38%, P = 0.17) ( Fig 5 ). Time to normal activity . Time to normal activity was reported by three studies [ 14 , 15 , 18 ]. There was no significant difference in the time taken to normal activity between non-fixation group and fixation group (MD: -4.95; 95% CI, -11.36–1.45, P = 0.13). There was a high level of heterogeneity among the studies (I2: 98%, P<0.00001) ( Fig 6 ). Operation time . Three studies [ 14 , 15 , 17 ] reported data of operation time. In the study of Li et al. [ 17 ], they demonstrated the mean operation time of non-fixation (50.1 ± 10.3 min) group was significantly reduced compared to that of the fixation group (60.5 ± 12.2 min). While Kalidarei et al. [ 14 ] reported there was no significant difference of operation time between the two groups(non-fixation 70.2±0.44 min vs fixation 73.8±0.54 min, P = 0.585). The other study of Smith et al. [ 15 ] only reported mean value of operation time but without other information. The pooled analysis could not be conducted. Hospital stay . Data of hospital stay was reported by two studies [ 14 , 19 ]. Both of them reported the time of hospital stay of non-fixation group was significantly reduced compared to that of the fixation group. Cost of treatment . Data of cost of treatment was available in only one study. In that study by Li et al. [ 17 ], they reported hospitalization expense was significantly lower in non-fixation group (10,560 ± 160 yuan) than that in fixation group (14,280 ± 320 yuan). In the subgroup analysis of fixation method, there were no significant difference in recurrence rate, infection rate and seroma formation between non-fixation group and group of traumatic mesh fixation(tacker, stapler, or suture) (RR: 0.87; 95% CI, 0.28–2.68, I2: 16%; RR: 1.18; 95% CI, 0.39–3.62, I2: 24%; RR: 1.18; 95% CI, 0.78–1.79, I2: 0%, respectively). In the subgroup analysis for primary unilateral hernia, the results were consistent with the primary analysis. Mesh non-fixation did not differ significantly in recurrence rate and seroma formation compared to mesh fixation (RR: 0.90; 95% CI, 0.20–4.00, I2: 0%; RR: 0.56; 95% CI, 0.14–2.20, I2: 52%). Sensitivity analyses were carried out by excluding one study each time. Recurrence, infection and seroma formation were evaluated. The direction of pooled effect size all remained unchanged. Sensitivity analyses for other outcomes could not be conducted due to unavailable data.

Non-fixation may not affect the efficacy of TAPP based on the current evidence. It does not increase recurrence rate and may result in less postoperative pain compared to mesh fixation in inguinal hernia with small hernia defect (less than 3cm). Well-designed RCTs using TAPP technique with large sample size and adequate follow up are still required to confirm these findings and validate the influence of non-fixation on chronic groin pain.

PubMed, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for studies about TAPP repair of inguinal hernia and mesh fixation published up to June 2023. All searches were finished at June 22, 2023. The following medical subject headings (MeSH) terms: “Hernia, Inguinal”, “Hernia, Femoral” and relevant free words, such as “groin hernia”, “transabdominal preperitoneal”, “TAPP”, “fixation”, were used for search. The complete search strategies are shown in S1 Appendix . The references of relevant reviews were also reviewed to identify additional studies. Studies of randomized controlled trials which compared perioperative outcomes between mesh fixation and non-fixation of TAPP repair of inguinal hernia were included. TAPP repair was done according to the standard way [ 11 ]. Non-fixation of mesh was defined as leaving the mesh in preperitoneal space without fixing the mesh to around structures. Using self-gripping mesh was not considered as non-fixation. Fixation of mesh was defined as using traumatic methods (suturing, stapler, tacker) or atraumatic method (adhesive glue) to fix the mesh in the preperitoneal space. Non-English articles were excluded. Data extraction was conducted by two independent authors (CXZ and JL) with a pre-designed spreadsheet. The spreadsheet was created according to the Cochrane’s recommendations for intervention reviews. The following information was needed in the spreadsheet: 1. study-related data (first author, publication year, country of origin, publication journal, study period, follow-up time, method of randomization), 2. baseline of study population (study size, age, gender, weight, laterality of hernia, hernia defect size, history of recurrence), 3. procedure details (surgeon experience, type and size of mesh, method of fixation, use of antibiotic, drainage), 4. Primary outcomes (recurrence, evaluation of postoperative pain, chronic groin pain) and secondary outcomes (operation time, hospital stay, time to normal activity/work, infection, formation of seroma, Intraoperative complication, cost). Disagreements during data extraction were discussed until a consensus was made. The final data was checked by author CXZ. The quality of included studies was assessed by two authors (CXZ and HJS) using the revised Cochrane risk of bias tool for randomized trials [ 12 ]. The Cochrane’s tool assesses the risk of bias of RCTs in five domains: bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in measurement of the outcome, and bias in selection of the reported result. Each item is classified as low risk, some concerns or high risk. Discrepancies in risk of bias assessment were resolved by consulting to author (JPB). For dichotomous outcome variables (recurrence, chronic groin pain, seroma, infection and intraoperative complication), the risk ratio (RR) was calculated as summary measure. The RR is a ratio of the risk of an adverse event in the non-fixation group compared to that in fixation group. For continuous outcomes (operation time, postoperative pain, time to normal activity/work), the mean difference (MD) between the non-fixation group and fixation group was calculated as summary measure. If mean and (or) standard difference (SD) of interested outcome were not provided, they were tried to calculated through methods described by Hozo et al [ 13 ]. All data synthesis was performed using Review Manager 5.3 software (Cochrane Collaboration, Oxford, England). Fixed effect model or random effect model was used during data synthesis according to heterogeneity among the included studies. Heterogeneity was assessed by Q test and Higgins I2 statistic. Random effect model was used if p50%. Subgroup analyses were conducted according to mesh fixation method and hernia laterality to assess the robustness of results. Sensitivity analysis was also performed by repeating the analysis following excluding one study at a time. Publication bias could not be evaluated as there were totally fewer than 10 studies included.

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