Repair of complex abdominal wall hernias entails a significant challenge for surgeons. The abdominal wall dysfunction is not only due to the hernia itself but also to the intrinsic muscle impairment [1]. Chronic muscle retraction typically reduces abdominal cavity volume. The reconstruction of the linea alba resembles to reverse the lateral retraction and fibrosis of the musculature [2, 3]. Restore the anatomy and function of the abdominal wall through a tension-free, mesh-reinforced, midline fascial closure is the main goal of surgery.

Rives-Stoppa retrorectus repair allows reconstruction of the abdominal wall by placing the mesh in a vascularized space, which promotes incorporation on the tissue and avoids subcutaneous dissection [4]. In some cases, achieving primary and tension-free myofascial closure is impossible with this technique, and component separation techniques (CST), such as transversus abdominis release (TAR), are required [5]. CST are more challenging to perform and can lead to irreversible disruption of the abdominal wall anatomy, as well as an increased risk of perioperative complications [6]. Alternatively, adjuvant therapies, such as injection of botulinum toxin type A (BTA), progressive pneumoperitoneum (PPP) or intraoperative dynamic fascial traction (IFT) can be used to increase abdominal wall compliance, avoiding CST [7–9].

BTA induces temporary paralysis of the lateral abdominal muscles, leading to their elongation and thinning. Simultaneously, the abdominal shape becomes more ovoid [10]. On the other hand, PPP increases the volume of the abdominal cavity by stretching the abdominal wall muscles and facilitates the reduction of herniated contents through the pneumatic dissection of adhesions [11–13]. The combined effects of both techniques can facilitate effective hernia downsizing. While BTA induces relaxation of the anterolateral abdominal muscles, PPP gradually expands the abdominal cavity, creating a more conducive environment for tension-free closure of the abdominal wall. Additionally, the use of BTA reduces the duration required for PPP insufflation [14, 15]. However, certain patients with hernias with significant myofascial retraction may benefit more from the administration of BTA followed by IFT - a controlled and time-limited mechanism designed to stretch the anterior aponeurosis during surgery [9, 16].

Preoperative planning is the cornerstone to achieve successful surgical outcomes. Based on the preoperative computed tomography (CT) some criteria can predict if the closure of the fascia will require CST, such as defect width greater than 8 cm, a rectus/defect ratio (RDR) below 1.34 [17], or a component separation index (CSI) exceeding 0.146 [18]. Guidelines recommend that only surgeons skilled in advanced techniques should perform surgery on hernias that meet or surpass these criteria [19].

Although some studies have already addressed the effects of adjuvants on the abdominal wall [10, 20], it remains unclear whether their application, particularly when used simultaneously, impacts the surgical technique used for the repair of complex midline hernias.

Our aim is to evaluate the rate of CST in abdominal wall reconstruction for complex midline hernias following adjuvant therapies, either alone or in combination, and to propose a structured algorithm for their use.

A total of 58 patients underwent abdominal wall reconstruction after adjuvant therapy. Twelve (22.4%) were excluded due to hernia location (lateral, parastomal, synchronous ventral and lateral, inguinal), and two (3.4%) due to less than 3 months of follow-up.

Preoperative patient demographic and hernia characterization are presented in Table 1. The mean hernia defect width was 9.97 ± 2.97 cm, with an equal proportion of W2 and W3 hernias. Twelve (27.3%) had loss of domain. The CSI was >0.146 in 52.3% of the hernias. The RDR was inferior to 1.34 in the same percentage of patients.

Eleven patients (25%) were enrolled in a surgical and/or non-surgical weight loss program before surgery. In this subgroup of patients, the mean initial and preoperative BMI were 39.8 ± 5.2 kg/m² and 30.0 ± 5.6 kg/m², respectively. Bariatric surgery was performed on eight patients, most of them before the abdominal wall reconstruction.

In 61.4% of the surgeries, the abdominal wall reconstruction was performed without CST. When it was needed, TAR was most frequently used (Table 2). The rate of posterior and anterior fascial closure was 100%. Ninety-six percent of the cases underwent adjuvant BTA. The median time from BTA to surgery was 38 days (31–55). PPP was performed in 25% of patients and IFT in 20.5%. There was no morbidity associated with BTA. However, two complications occurred during the PPP, one patient developed atrial fibrillation with rapid ventricular response and there was an inadvertent placement of catheter into subcutaneous tissue.

In the postoperative period, early complication rate was 20.5% (Table 3). Most of the complications were surgical site occurrences and classified with a Clavien Dindo I-IIIA [21]. The rate of superficial surgical site infection, seroma, and haemorrhagic complications was 6.8% for each complication among the patients. Additionally, 4.5% of patients experienced skin and subcutaneous dehiscence. One patient required surgical reintervention 20 months after the initial surgery due to an interparietal hernia, and a TAR was performed. Another case of hernia recurrence was reported 13 months after a Rives-Stoppa. These patients were submited to BTA and BTA + IFT, respectively. During a median follow-up of 13 months (8–25), late complications occurred in four patients. Two patients with mesh infection underwent surgical removal of the infected mesh, 11 and 24 months after the initial surgery. Both patients had significant comorbidities, including obesity and diabetes, and underwent BTA plus PPP followed by TAR.

Comparing the abdominal wall reconstruction surgeries with and without CST, no significant statistical differences were observed in hernia characteristics, adjuvant treatments, or postoperative outcomes. However, a trend was observed towards a higher proportion of M1 hernias (23.5% vs. 14.8%) and hernias with loss of domain (41.2% vs. 18.5%) in the CST group. The opposite was true for early complications rate (11.8% vs. 25.9%). Operative time and mesh width were higher in the CST group. The width of the hernia defect and the retrorectus space did not differ between the two groups. In patients with defects larger than 8 cm in width, 60% underwent repair without CST (Table 4).

A subset analysis was performed in hernias with CSI >0.146 and RDR <1.34. In patients with CSI >0.146, 65.2% underwent abdominal wall reconstruction without CST. Of those patients, 60% were W3 hernias and three patients had loss of domain. In the RDR <1.34 group, 60.9% did not require CST for abdominal wall closure. 58.8% were W3 hernias and two patients had loss of domain.

In our study, 61.4% of patients underwent surgery without CST after the use of adjuvant therapies, a percentage higher than previously reported by others [10, 20, 26]. The impact of adjuvant therapy on abdominal wall musculature before complex hernia surgery has been demonstrated in previous studies [10] however, information regarding their effect on final surgical technique remains limited. The available evidence primarily originates from systematic reviews and retrospective studies [8, 27–29].

The overall complication rate was 20.5% and 9.1% in the early and late postoperative period, respectively. These rates are lower than those reported in other studies [7, 26, 30]. Factors that may have contributed to these outcomes include a strong emphasis on the preoperative rehabilitation of patients, particularly concerning weight loss. The average BMI in our study was lower than that reported in other investigations [30, 31]. In contrast to previous studies, the complication rate in patients undergoing CST was not found to be higher than that in patients who did not undergo this procedure [24, 31].

Concerning the recurrence rate, two cases were observed during follow-up: one following a Rives-Stoppa repair, complicated by postoperative retrorectus bleeding, and another after a TAR, presenting with an intraparietal hernia. Nonetheless, our recurrence rate is lower than that reported in the existing literature [20, 28]. However, the median follow-up of 13 months may influence the findings, limiting the extrapolation of medium- and long-term conclusions.

There is established evidence of the reshaping of the abdominal cavity after adjuvant therapy with BTA. When applied at the lateral abdominal wall musculature, results in their elongation [32]. The increased length and reduced thickness of the lateral muscles, as well as the decrease in the width of the hernia defect, increase abdominal wall compliance [10, 29]. Due to the demonstrated benefits within our group, over recent years, the cutoff for utilization has progressively decreased and is now applied to hernias larger than 8 cm. Nonetheless, adjuvant therapies may prove beneficial in selected cases of smaller hernias. Careful, individualized assessment remains essential, as certain patients may require therapeutic strategies beyond those defined in the current algorithm. Tailoring treatment to specific patient or hernia-related factors may ultimately enhance clinical outcomes in appropriately selected cases.

Midline closure seems to be more related to compliance due to the elasticity of the muscle fibres elicited by the BTA blockade, rather than solely due to the value found for lateral fibre advancement [26]. Whether this effect is responsible for the downsizing of the hernia and prevention of the need for CST in some cases remains to be determined. Although the maximum effects of muscle paralysis is achieved after 3–4 weeks, its effect lasts for 6–9 months, allowing the abdominal wall to heal in a low-tension environment [33]. It is not yet known whether, regardless of the technique used, achieving midline closure with less tension is associated with a lower recurrence rate [29].

PPP induces a mechanical stretching of muscle fibres, that combined with the relaxation induced by BTA, increases the compliance of the abdominal wall and the volume that can be accommodated within the abdominal cavity. This combined approach of techniques was successfully used in a quarter of our patients. The gradual and steady increase in intra-abdominal pressure improves respiratory function adaptation and decreases the likelihood of developing a quaternary compartment syndrome in the postoperative period [13]. Because of that, in our group, those hernias presenting with a tight defect characterized by a “mushroom” pattern are assigned for adjuvant treatment with PPP, an indication never reported before to our knowledge.

In hernias with a greater separation between the rectus muscles and significant myofascial retraction of the lateral abdominal muscles, particularly in the middle and lower abdomen, better outcomes can be achieved with BTA muscle blockade combined with IFT. In these cases, PPP may result in insufflation of the hernia sac, causing stretching of the skin and subcutaneous tissue rather than increasing the abdominal cavity volume through lateral muscle elongation. This time-limited traction, applied during surgery, can facilitate a tension-free closure of the abdominal wall by stretching the temporarily paralyzed muscles [9].

In our study, 45.5% of patients received a combination of two adjuvant techniques due to their presumed synergy in hernia downsizing. Rather than applying all adjuvant methods simultaneously, we utilize a tailored approach based on specific clinical criteria. Our strategy does not prioritize one adjuvant over another; instead, we acknowledge that each technique has distinct roles and is best suited for each clinical scenario. The comprehensive availability and expertise in utilizing these adjuvant methods contribute to enhanced patient care and allow for the individualized tailoring of treatment strategies.

The benefits of using adjuvants do not come without limitations. Although economic costs were not addressed in this study, the expenses associated with BTA and IFT are considerable, and PPP entails prolonged hospital stays with inherent costs. Outpatient protocols are already being described [34]. Regarding morbidity, we observed two cases of complications during the PPP, while other studies stated that complications can be as high as 25% [8].

The width of the hernia defect is considered a criterion that can define the need for CST. Traditionally, the Rives-Stoppa technique is an option for hernias up to 10 cm and thus possibly not applicable to W3 hernias [35]. In our study, 59.1% of patients with W3 hernias achieved abdominal wall closure without CST. Additionally, the width of the hernia defect did not differ between the two groups, showing the importance of factors other than diameter in determining hernia complexity.

Regarding hernia location, despite a higher proportion of patients with M1 hernias in the CST group, our study found no significant differences in the rate of component separation based on the hernia site, in contrast to the findings of some other authors [31]. There is still no evidence whether CST after adjuvant therapy can be reduced in certain hernia groups.

Another point of discussion is the size of the mesh used and its impact on the recurrence rate. The width, and consequently the overlap of the mesh, was smaller in the group of patients where CST was avoided. Whether downstaging the hernia with reduced mesh overlap will adversely affect long-term outcomes remains to be determined, and we aim to address this question through prospective follow-up of these patients.

No factors related to the patient or hernia characteristics were identified as predictors of the surgical technique used. Even in the subgroup of patients for whom CSI and RDR predicted the need for CST, it was avoided in 65.2% and 60.9% of the cases, respectively. This demonstrates the limitation of applying these tools to patients undergoing adjuvant treatments for hernia downstage.

Our study has several limitations that must be acknowledged. First, its retrospective design inherently restricts the depth of data that could be collected. Additionally, the absence of a control group, as we did not include all other hernia cases that were not treated with adjuvants, precludes the comparative analysis. Furthermore, we did not perform follow-up CT scans after adjuvant therapy, leaving unanswered whether certain subgroups of patients may experience a more pronounced benefit from these therapies. It did not alter our surgical approach, given that we initiated with a Rives-Stoppa technique and performed TAR on demand. It is also important to consider that, assessment of tension during closure is subjective, and some variability between surgeons may had occurred. The strict application of our inclusion criteria to the patient cohort may have resulted in the exclusion of certain patients with smaller hernias who were not included in our study but who may nonetheless require component separation. We included two cases in which bariatric surgery was performed simultaneously with abdominal wall reconstruction, as preoperative bariatric surgery was not feasible. We acknowledge that this may introduce bias.

However, several strengths can be mentioned. To the best of our knowledge, this study is the first to demonstrate the simultaneous effects of different adjuvant therapies employed both before and during surgery, an effect that we believe is amplified by their combined application. Despite the small number of patients in our cohort, we are not aware of any previous studies reporting a comparable sample size. Furthermore, our focus on preoperative rehabilitation—particularly in managing patients with obesity—and the establishment of criteria for the use of BTA, PPP, and IFT contribute to reducing treatment heterogeneity.

Despite the encouraging results, individual responses to adjuvant therapies may vary among patients. The selection of patients or hernias that would benefit the most from each approach is still unknown, and further research is needed. Maintaining a holistic and individualized approach for each patient is critical in hernia repair.

The use of adjuvant therapies in patients with complex ventral hernias is safe and may influence the surgical strategy for abdominal wall reconstruction, potentially influencing the use of a less disruptive surgical technique. A structured approach to their application, guided by specific clinical criteria, may enhance their effectiveness and provide additional benefits.