Introduction

Incisional hernias are one of the most common complications of laparotomies, and they enlarge over time [1]. There is an ongoing debate among surgeons regarding the reconstruction of large, midline incisional hernias. It has been reported that the recurrence rate following open suture repair can be up to 54% [2]. Even simple suture closure may not be possible for large incisional hernias since the fascial edges are retracted laterally due to the shortening of the external oblique muscle with time [3]. Nevertheless, the repair of such hernias can be performed through the component separation technique (CST), which was first introduced by Ramirez et al. [4]. The CST allows enlargement of the abdominal wall surface by increasing mobilization of the rectus muscles to the midline via separation and advancement of the flat muscular layers [4,5,6].

It is believed that the subcutaneous dissection needed for flap creation during CST dramatically increases the rate of wound complications. Therefore, since the original description of the CST, various modifications have been proposed to reduce surgical morbidity [7, 8]. Currently, prosthetic reinforcement materials with different locations are in use. Prior studies regarding the utility of mesh used in the CST showed fewer recurrence rates than the CST without mesh [9, 10]. However, the reluctance to use meshes can be attributed to the fear of mesh-related complications. Using mesh in such complex procedures may lead to an increased risk of surgical site complications, such as surgical site infection and seroma [11].

This study aimed to compare the outcomes of patients who underwent abdominal wall reconstruction by performing CST with and without mesh usage in large, midline incisional hernias. The primary outcome was recurrence complications, and the secondary outcome was seroma complications.

Material and Methods

This retrospective study evaluated consecutive patients who underwent anterior abdominal wall reconstruction (AWR) via CST for large, midline incisional hernias in a suburban hospital between January 2011 and May 2020. Based on mesh utilization, patients were grouped as “mesh” and “no mesh.” LIHs are defined as hernia sac > 10 cm [12]. All operations were performed by a single surgeon. The surgeon had 1 year of experience in this procedure. Patients who underwent AWR with another simultaneous procedure were excluded from the study. The Institutional Review Board approved the study (IRB No: VEAH2020/11), and signed consent was obtained.

Patient data assessed included patient demographics such as age, sex, body mass index (BMI), the American Society of Anesthesiologists (ASA) classification scores, comorbidities, and risk factors. Perioperative data included procedure setting, hernia location and size, the type and size of the mesh (if used), operating time, estimated blood loss (EBL), intraoperative complications, and the hospital length of stay (LOS). Postoperative variables were selected: hospital readmission within 30-day postoperatively and type of postoperative complications, if observed, during follow-up visits.

All postoperative complications were categorized according to the Clavien-Dindo (CD) classification system [13]. Then, using a web-based calculator (https://www.assessurgery.com/about_cci-calculator/), which utilizes the CD grades, the comprehensive complication index (CCI®, University of Zurich, Zurich, Switzerland) scores were measured to determine the morbidity of each patient’s complications [14]. Surgical site complications were also assessed, such as surgical site infection, seroma, hematoma, and wound dehiscence. While postoperative abdominal wall laxity without fascial defect on physical examination and/or imaging studies presented as protrusion of the abdominal contour was assumed as pseudorecurrence, any visceral tissue/organ protrusion through a fascial defect on the previous hernia side was defined as hernia recurrence. The patients were called for outpatient control at the 3rd, 6th, and 12th months. After 1 year, annual follow-up was done. Follow-up time is calculated as the time differences between the last visit date and the index operation’s date in months. Any patients lost to follow-up were not included in the statistical comparison of postoperative complications.

Surgical Technique

The procedures were performed following a similar technique initially described by Ramirez et al. [4]. The operation was performed under general endotracheal anesthesia with the patient in the supine position. The abdominal cavity was accessed via a midline incision, and the hernia defect was delineated. If present, the excess hernia sac was excised. After the hernia defect was identified, the skin and subcutaneous tissue were elevated to reveal the underlying anterior abdominal wall musculature. Depending on the size of the defect, the dissection was carried out laterally, superiorly, and inferiorly to the anterior or middle axillary line, to the costal margin, and to the suprapubic area, respectively. A vertical incision was made on the external oblique fascia, approximately 2 cm lateral to the linea semilunaris. The incision was extended superiorly and inferiorly. While dissecting the plane between the internal and external oblique muscles, special care was taken to avoid any injury that would damage the musculatures and innervations. Next, the rectus muscles were freed off the posterior sheathes at both sides by dissecting the plane posterior to rectus muscles achieved by an incision on the anterior rectus sheath, approximately 2 cm from the medial edge of the muscle. Similar separation steps were applied to the contralateral site. The midline closure (the linea alba reconstruction) was completed by suturing the freed edges of the rectus sheaths at the midline. The small bite suture technique was used in fascial edges. Kocher clamps were placed on the medial edge of the rectus muscle on both sides, the rectus muscles were mobilized toward the midline, and they were joined in the midline with long-lasting absorbable sutures (Fig. 1a). In some cases, at this stage of operation, the mesh size was determined by measuring with a ruler in the transverse plane from the edges of both external oblique fasciae. Tailored nonabsorbable synthetic mesh was placed in an onlay fashion and secured to the edges of the external oblique fascia on both sides with nonabsorbable sutures (Fig. 1b).

Fig. 1
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A completed component separation technique a without mesh, b with onlay mesh

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Two closed suction drains were placed on the operation field. The excision of excess or nonviable skin was removed if required. The subcutaneous tissue and the skin were closed with absorbable and nonabsorbable sutures, respectively. The drains were discontinued once the daily output was less than 30 mL.

Statistical Analysis

Statistical assessments were performed using the SPSS software pack (Statistical Package for Social Sciences for Windows version 28 software). A bootstrapping method with a thousand simple sampling was used in all analyses. Categorical variables were analyzed using Pearson’s chi-squared or Fisher’s exact test and were presented as the frequency with percentage (n (%)). Continuous variables using the independent-sample t-test (normal distributions) or Mann–Whitney U test (non-normal distributions) were presented as mean (± SD) or median (interquartile range (IQR)). Kaplan–Meier’s time-to-event analysis was run to calculate freedom from recurrence, and the result was given with a 95% confidence interval (CI). A p-value of < 0.05 was considered statistically significant.

Results

Sixty-five (56.5%) patients who underwent CST with mesh and 50 (43.5%) patients without mesh were included in this study. The comparison of patient demographics between the mesh and no-mesh groups is presented in Table 1. Accordingly, the distribution of patient demographics did not differ between groups, suggesting well balance between the two groups. All patients underwent AWR in an elective setting, except two patients in each group underwent AWR in an acute setting. Regarding the distribution of hernia locations, there was no difference between the two groups (Fig. 2). The median (IQR) defect size did not differ between groups. The median (IQR) operating time was significantly longer in the mesh group than in the no-mesh group (p < 0.001). None of the patients in either group experienced an intraoperative complication. The comparison of intraoperative variables between the two groups is given in Table 2. There was no difference between the two groups regarding hospital LOS (p = 0.112). The median (IQR) LOS was 2 (2, 4) and 4 (2, 4) in the mesh and no-mesh groups, respectively. Two (4%) patients in the no-mesh group vs. 3 (4.6%) patients in the mesh group were readmitted to the hospital within postoperative 30 days due to surgical site complications (p = 1.000).

Table 1 The comparison of study groups in terms of preoperative variables
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Fig. 2
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The comparison of the distribution of hernia locations across groups

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Table 2 The comparison of intraoperative variables between the CSTs with and without mesh
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The average follow-up period for the entire cohort was 30 (± 14.7) months; there was no difference between the two groups in terms of mean follow-up (p = 0.110; 28.1 (± 12.7) in the no-mesh group vs. 32.5 (± 16) in the mesh group). Two (4%) patients in the no-mesh group and 3 (4.6%) patients in the mesh group were noted as lost-to-follow-up (p = 1.000).

The detail of postoperative complications is given in Table 3. Of those who attended postoperative follow-up visits, 7 (14.6%) patients in the no-mesh group vs. 17 (27.4%) patients in the mesh group experienced a complication (p = 0.106). One patient in each group had to stay in the intensive care unit overnight due to respiratory distress secondary to hypoxia (CD-4a). Regarding surgical site complications, the proportion of patients who experienced postoperative seroma was higher in the mesh group (19.4%) than in the no-mesh group (4.2%). Of those, one (2.1%) patient in the no-mesh group and two (3.2%) patients in the mesh group required a procedural intervention (p = 1.000). Two patients in each group experienced hernia recurrence after seroma complication; those in the no-mesh group required partial mesh excision due to mesh infection secondary to an infected seroma. Regarding hernia recurrence, two patients in each group experienced recurrence within an average follow-up of 14.4 months. Kaplan–Meier’s analysis showed that the mean (95% CI) estimated recurrence-free time was 48.8 (46.5–51.1) for the no-mesh group and 57.3 (55.4–59.6) for the mesh group (Mantel-Cox Log Rank test p = 0.749). The survival plot is presented in Fig. 3. Additionally, two patients (4.2%) who underwent AWR without mesh experienced pseudorecurrence (p = 0.188); they presented with a bulging alongside the linea semilunaris where component separation technique had been performed, the abdominal fascial planes were reported as intact in the imaging studies, and they were managed conservatively.

Table 3 The comparison of postoperative complications between the CSTs with no mesh and mesh
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Fig. 3
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Kaplan–Meier’s plot for hernia recurrence

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Discussion

Acceptable results for incisional hernia repairs continue to be reported with various techniques. Since its introduction, CST has been increasingly applied and has become a preferred technique for repairing large hernia defects by releasing the contracted sides of the abdominal wall [15, 16]. So far, several modifications have been made to tackle the technique’s main issues regarding postoperative complications [7, 17,18,19]. Although the CST was initially described to avoid prosthetic materials, mesh reinforcement has been widely used in the current practice [16]. In the current study, although initial cases were completed with a CST using synthetic meshes, the surgeon switched his practice to the CST without mesh, hoping to minimize wound morbidity that occurred after some of the mesh-used cases. Thus, this study’s purpose was to compare the outcomes of both CSTs.

In this study, there were no differences between the two groups regarding perioperative variables except operating time, which was longer, almost 20 min in the mesh group (p < 0.001). This can be attributed to the time required for mesh fixation. This finding confirmed the first randomized controlled trial comparing the CST with prosthetic repair in the repair of giant midline abdominal wall hernias by Reilingh et al. [11] who stated that the operation time for prosthetic repair was significantly longer as compared with the CST. Besides, the increased operative time has been independently associated with increasing postoperative morbidity. Infectious complication risk increased for each additional half hour of operating time relative to cases lasting less than 1 h, almost doubling after 2 h of operation duration [20].

In a review comparing outcomes of mesh-only repair, laparoscopic CST, and open CST, the overall complication rate was reported to be 21% with mesh and 59% without mesh [10]. In another review by Deerenberg et al. [21], postoperative complication rates for anterior open CST without mesh and anterior open CST with mesh were reported as almost 50% and 55%, respectively. However, it should be kept in mind that included studies in the abovementioned reviews were heterogeneous in terms of mesh materials as well as their position on the abdominal wall. In the current study, the overall complication rate was 14.6% for the patient who underwent CST without mesh and 27.4% for the patient who underwent CST with polypropylene material and was placed in an onlay fashion.

It is well known that disturbed wound healing often complicates the repair of large abdominal wall hernias. Wound complications such as infection, seroma, and hematoma skin necrosis have been reported in 12–67% of patients after CST and 12–27% after mesh repair [11]. Among these, one of the most frequently reported complications following open mesh incisional hernia repair is seroma formation [22, 23]. The severity of the inflammatory response and the propensity to seroma formation have been attributed to the physical structure and quantity of prosthetic material and the extended subcutaneous dissection [23, 24]. Therefore, various seroma complications can also be observed after CST without mesh. In a study including 75 patients who underwent CST without mesh, 40% of those patients underwent a concomitant bowel surgery, and Slater et al. [9] have reported a 12% seroma complication. Reilingh et al. [11] have detailed seroma complications; 4 out of 19 patients in the CST group developed seroma complications and were not associated with other wound complications such as infection, hematoma, and skin necrosis. However, 7 out of 18 patients in the prosthetic repair group experienced seroma, two of which required intervention, resulting in infection, ultimately leading to the prosthesis’s extraction, and seven meshes required mesh removal. In the current study, seroma complications occurred in 19.4% of the mesh group and 4.2% of the no-mesh group. Of the patients with seroma, three patients in the mesh group complicated with infection alone, while two patients in each group complicated with infection followed by a recurrence; those with mesh required a partial mesh excision prior to recurrence.

In a review comparing the outcomes after mesh-only repair, laparoscopic CST, and open CST, when the authors further divided the open CST group into CST with mesh and CST alone, patients who had open CS alone had higher hernia recurrence than those who had open CS with mesh (27% vs. 16.7, respectively) [10]. In Slater et al.’s study [9], 25 (38.7%) out of 75 patients who underwent CST without mesh experienced a hernia recurrence at 11 months. Of these, 11 recurrences (14.7%) were small and/or asymptomatic, and patients did not undergo reoperation, whereas 18 (24%) patients with a recurrence were reoperated, and 15 out of these 18 patients ended up with mesh repair. In Reilingh et al.’s study [11], the recurrence rates in the CST without mesh and prosthetic repair groups were 52.6% and 55.5%, respectively. These rates can be attributed relatively to the small sample size. However, the authors have revealed that the repair of giant abdominal wall defects with the CST compares favorably with prosthetic repair because wound infection in patients with prosthetic repair had significant consequences, resulting in the removal of the prosthesis in 7 patients during the first 7 months. In contrast, wound infection in patients after CST had only minor consequences. In the current study, two patients in each group (4.2% in the no-mesh group vs. 3.2% in the mesh group) experienced hernia recurrence after an average follow-up of 14.4 months, and the estimated recurrence-free time was found to be over 4 years for both studied groups.

Regarding postoperative pseudorecurrence (laxity or bulge), some predisposing situations have been suggested to explain the splaying of the abdominal wall; for example, the denervation of the abdominal muscles during component separation and postoperative surgical site infection could result in the attenuation of the fascial structures [25,26,27]. Another possible cause of laxity in the CST may be the release of external oblique aponeurosis, resulting in thinner abdominal wall thickness compared to its previous state. In his recollection, Ramirez [8] has suggested reinforcing the lateral gaps derived from the external oblique muscle release with onlay mesh to avoid areas of muscle wall weakness or potential hernias. While a lateral laxity occurred in two patients who underwent CST without mesh, no patient in the mesh group had pseudorecurrence. Although the number of patients is minimal for a proper interpretation, it can be emphasized anecdotally that weight gain after the surgery might predispose to this situation.

This study has a few limitations. First, because of the retrospective nature, there might be a selection bias since several patient-related factors, such as age, BMI, and comorbid diseases, may have affected the surgeon’s decision regarding the surgical approach. However, the studied groups observed similar distribution in terms of patient demographics. Second, the study represents only a single center’s experience, though in the case of a multi-center experience would better reflect greater diversity. Additionally, the surgeon switched his practice during the study period; initially, most procedures were completed using a mesh technique. However, this was replaced later by a no-mesh technique. Therefore, this alteration in the surgeon’s practice might have impacted the outcomes of the patients who underwent AWR toward the end of the study period. However, studies involving such changes in practice have been previously reported in the literature [8, 28]. The sample size of this study might have been considered a limitation; however, a post hoc power analysis showed that the included sample size yielded an 80.5% power at the significance p-value level of 0.05. Furthermore, the bootstrapping method, which provides a way to account for the distortions caused by the specific sample that may not be fully representative of the population, increased the strength of the statistical tests. Other limitations include database-related limitations like the lack of critical variables such as patient-reported outcomes, the wound class, and the procedure’s cost, those of which could have given readers an insight to evaluate the study results better.

In conclusion, the repair of large incisional hernias can be performed utilizing the CST with or without using mesh. Both approaches may provide acceptable postoperative outcomes compared to their historical counterparts. However, it should be kept in mind that using mesh may lead to a higher rate of postoperative seroma. Further large-scale prospective studies are essential to better elucidate each approach’s long-term durability.