Introduction

Abdominal wall hernia is a significant cause for reoperation following laparotomy [1], developing in 11–50% of patients [2]. In the USA, more than 105,000 ventral hernia repairs are performed annually [3]. Primary open suture repair of the fascia was the first method proposed to repair ventral hernias; however, this method was associated with more than a 50% long-term recurrence rate in multiple studies [4,5,6,7,8,9]. The inclusion of a mesh to maintain a tension-free environment decreased the long-term hernia recurrence rate to 32% [7, 8]. Complications of mesh herniorrhaphy include infection, separation of the bridging mesh, visceral erosion, and draining sinus tracts [10].

Component separation of the anterior abdominal wall was first introduced in 1977 by Mathes and Bostwick; however, Ramirez et al.’s landmark study was not published for another 13 years [11]. Ramirez et al. reported a 10-cm medial advancement of a compound flap of the rectus abdominis muscle, internal oblique muscle, and transversus abdominis after a lateral fasciotomy to separate the external oblique muscle from the internal oblique muscle in an avascular plane [12].

Traditional, open anterior component separation involves a lateral subcutaneous dissection to approximately 2 cm from the lateral border of the rectus sheath, extending from the inguinal ligament to the costal margin. A longitudinal incision is then made in the aponeurosis of the external oblique, and the external oblique is then separated from the internal oblique muscle. This technique can allow for advancement of 5 cm in the epigastrium, 10 cm at the umbilicus, and 3 cm in the suprapubic area in a unilateral release [12]. Component separation was shown to be associated with patient-reported improvement in the physical appearance and mental well-being in a retrospective study by Girotto et al. in which 108 successfully reconstructed patients reported improvement in the appearance of their abdomen, in their post-operative emotional state, and in their ability to lift objects, arise from chair or a bed, and exercise [13].

Component separation has become a workhorse technique in abdominal wall reconstruction, but despite the degree of advancement that can be achieved by component separation, we are often faced with defects wider than 20 cm at the umbilicus. Not only is the incidence of incisional hernia in the obese population greater than the general population, but obesity is considered one of the most significant risk factors associated with repair failure [14, 15]. Additionally, the degree of obesity as measured by BMI has been positively correlated with increasing hernia size, further complicating the challenge of successful surgical outcome in the obese population [16]. Ventral hernia repair in the obese patient is complicated not only by increased hernia size but also by an excess of adipose tissue and pannus at the surgical site [17]. In an era in which the prevalence of obesity is rapidly increasing, it becomes important to have a reliable method by which to repair such problematic defects, while at the same time minimizing complications in this high-risk surgical population [17].

Given that a standard open component separation can be inadequate for closing large abdominal wall defects, our study was designed to evaluate if the addition of transversalis fascia scoring in a standardized fashion, in addition to anterior component separation, increased midline advancement and could be a useful adjunct for reconstruction of large abdominal wall defects.

Materials and methods

We used a cadaver model in order to evaluate the midline advancement of the linea alba when component separation is performed with transversalis fascia scoring. All dissections were performed on fresh or methanol-prepared adult cadavers at room temperature. Prior to dissection, several landmarks were identified. Bilateral iliac crests were marked, and the two points were connected via a transverse line. Next, the xyphoid process and the pubic tubercle were marked, and these two points were connected via a vertical line. The intersection of the two lines represented the middle point for our dissections.

The skin and the subcutaneous tissue were opened via a midline incision along the marked vertical line. Open anterior component separation procedure as previously described was then performed [12]. The middle point was marked as described above on the anterior rectus sheath. Superior and inferior points were selected 7 cm superior and 7 cm inferior to the middle point, respectively, and marked along the rectus sheath (Fig. 1a). The ventral abdominal wall was dissected from the overlying skin and subcutaneous tissue laterally to expose the aponeurosis of the external oblique muscle. The aponeurosis was then incised over its length, from the costal margin superiorly to the inguinal ligament inferiorly. The external oblique muscle was then bluntly dissected from the internal oblique muscle. Laparotomy was performed. Study points were marked with traction loops of 3-0 prolene suture along the leading edge of bilateral anterior rectus sheath in the following locations: middle, 7 cm proximal to middle point (superior) and 7 cm inferior to middle point (inferior). Traction loops were placed through the anterior rectus sheath leaving only the underlying rectus abdominis muscle free.

Fig. 1
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a Superior and inferior points marked 7 cm superior and 7 cm inferior to the middle point. b Measurement of medial advancement of myofascial flap with 5 lb load. c Transversalis fascia scoring at three lines placed 1 cm apart from lateral to medial, extending from the costal margin (superiorly) to the inguinal ligament (inferiorly)

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While applying a constant load of 5 lb, measured by a Protege handheld scale (Wal-Mart Inc., Bentonville, AR) at the previously mentioned study points, medial advancement of the rectus abdominis-internal oblique-transversus abdominis myofascial flap was measured (Fig. 1b). All measurements were obtained independently by two investigators, and the mean values were recorded. The transversalis fascia was then scored in a similar manner in all cadavers. After traditional anterior component separation was performed, the entire thickness of the abdominal wall was retracted on each side, exposing the transversalis fascia. Scoring was performed with a #10 blade at three lines placed 1 cm apart from most lateral to medial, spanning the abdominal wall. Scoring was performed from the costal margin superiorly to the iliac crest inferiorly (Fig. 1c). Again, midline advancement was recorded as previously described. Mean total advancement and percentage advancement both before and after scoring were calculated, and p values calculated using the standard equation utilizing Microsoft Excel (Microsoft Corp., Redmond, WA).

In addition to the presented cadaver study, this technique was recently used for the repair of large ventral hernias on two patients. The patients were a 76-year-old female and a 49-year-old male both with recurrent, complex ventral hernias, which could not be primarily repaired with anterior component separation alone.

Results

Dissections were performed on eight cadavers from April 2012 to July 2014. Two cadavers were fresh, and six were methanol infused. Three cadavers were female, and five cadavers were male. Mean age of the cadavers at death was 80.25. All dissections were performed at room temperature. Mean medial advancement of anterior rectus sheath after component separation alone was 2.77 cm at superior point, 3.72 cm at middle point, and 3.34 cm at inferior point. Transversalis fascia scoring increased midline advancement in every case. The mean medial advancement of anterior rectus sheath increased to the following: 3.58 cm at the superior point (p < 0.01), 4.65 cm at the middle point (p < 0.01), and 4.16 cm at the inferior point (p < 0.01).

Overall, mean superior point advancement increase of 34% (p < 0.01), middle point advancement increase of 27% (p < 0.01), and inferior point advancement increase of 25% (p < 0.01) are greater when scoring of the transversalis fascia is performed than with component separation alone (Table 1).

Table 1 Percentage and net medial advancement (centimeters) of anterior rectus sheath after transversalis fascia scoring per cadaver
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Patient A is a 73-year-old morbidly obese woman with a BMI of 46 kg/m2 and bilateral complex lower quadrant hernias. She had a history of necrotizing soft tissue infection of the abdominal wall. She initially underwent ventral hernia repair with bioprosthetic mesh and subsequently was referred to plastic surgery due to recurrence. The bilateral hernias were lateral to the rectus abdominis muscle on both sides, and there was concern for the integrity of the surrounding tissue for use in local tissue rearrangement for primary closure. Anterior component separation was performed, but it was not sufficient to close the defects primarily. Transversalis scoring was then performed as an adjunct, allowing the right anterior rectus sheath to be advanced 12 cm to midline and the left anterior rectus sheath 10 cm to midline. This increased medial advancement on both sides of the abdominal wall allowed for primary closure of the abdominal wall coupled with placement of biologic mesh underlay. At 3-year follow-up, the patient has suffered no complications or hernia recurrence.

Patient B is a 49-year-old male with a history of morbid obesity, with BMI of 30 kg/m2 following massive weight loss (prior BMI of 48 kg/m2), with a history of multiple recurrent ventral hernias. Prior to plastic surgery evaluation, he had undergone laparotomy for bowel obstruction with removal of infected prosthetic mesh, following which his abdominal wall was bridged with biologic mesh. One year later, he was referred to plastic surgery with recurrent ventral hernia with a fascial defect measuring 26 cm at its widest (Fig. 2). Intra-operatively, after a laparotomy was performed, it was confirmed that the patient’s large midline fascial defect could not be repaired with anterior component separation alone. In order to generate the advancement necessary for primary closure, transversalis fascia scoring was performed as an adjunct to anterior component separation which enabled primary midline fascial closure with reinforcing biologic mesh placement and abdominal skin closure. Post-operative CT scan at 1 month showed complete restoration of abdominal wall integrity (Fig. 3). At 2-month follow-up, the patient has suffered no complications or hernia recurrence.

Fig. 2
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Pre-operative CT scan showing large ventral hernia defect measuring 26 cm at the widest

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Fig. 3
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Post-operative CT scan at 1 month with completely repaired fascial defect with restoration of abdominal wall integrity

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In both patient cases, primary fascial closure was achieved with defects in excess of 20-cm width at the midline through anterior component separation in addition to transversalis fascia scoring. Both patients have been followed since their initial surgeries without wound healing complication or hernia recurrence, the female patient being followed for over 3 years and the male for 6 months.

Discussion

With this study, we have been able to quantify an increase in the size of abdominal wall defect that can be repaired using component separation with transversalis fascia scoring. Initial clinical application has allowed primary closure of complex ventral hernias in excess of 20 cm at the midline, when anterior component separation alone did not provide the advancement necessary to close these large, recurrent defects. Further clinical studies are needed to confirm long-term outcomes.

Van Geffen stated that “the ideal method of reconstruction of large incisional hernias should regain the abdominal visceral domain by means of a dynamic and tension reducing technique which is incorporated in the abdominal wall” [18]. We believe that component separation with the described modification fulfills this requirement in the case that anterior component separation alone does not achieve primary closure. Our modification is easy and quick to perform, and can be used in patients who are not candidates for posterior component separation. Based on both cadaver studies and clinical cases, we are optimistic that adding transversalis fascia scoring to anterior component separation provides a new technique in the surgeon’s armamentarium with which we can solve this very common problem.

Multiple modifications to component separation have been described since Ramirez’s original study, chiefly minimally invasive component separation, minimally invasive component separation with inlay bioprosthetic mesh (MICSIB), posterior component separation with transversus abdominis release, or component separation with preservation of periumbilical rectus abdominis perforators (PUPSs) [19,20,21]. All modifications to the traditional anterior component separation have been developed with the ultimate goal to decrease morbidity associated with the original technique. Although these modifications decrease the incidence of some of the common complications of anterior component separation including wound complications and hernia recurrence rate, some studies have demonstrated a trade-off of decreased morbidity for the maximal size of the defect that can be repaired. Furthermore, there are no studies quantifying the medial advancement of the anterior rectus sheath when using these modifications.

In our study, anterior open component separation technique with transversalis fascia scoring results in a 25–34% increase in medial advancement of linea alba when compared with traditional, open anterior component separation alone. This significant increase in advancement allows for the potential to close larger defects, minimizing the need for techniques typically used for large midline defects such as placement of bridging mesh and local or regional flap transposition, which have significant complication rates. The use of these techniques could be minimized in favor of the modified component separation procedure outlined in this study, which can serve as an adjunct to anterior component separation when additional release through posterior component separation is not a viable option.

Our proposed technique allows for repair of the defect while adhering to the goals of abdominal wall reconstruction including the preservation of local anatomy and muscle strength, as well as the function and appearance of the abdominal wall [22, 23]. It also allows for recreation of the dynamic nature of the abdominal wall by maintaining muscle strength through the preservation of the neurovascular bundles located deep to the inferior oblique muscle. These neurovascular bundles remain unharmed during the dissection and subsequent scoring of the transversalis fascia (Fig. 4). Our results demonstrate the ability of this technique to repair defects up to 30% larger transversely than the current component separation method can accommodate. Unlike posterior component separation, transversalis fascia scoring can also be safely used in patients with previous ostomy and other violations of the posterior sheath [20]. Additionally, once the fascia has been scored, it can still be reinforced with placement of biologic underlay mesh, which has been shown to be biomechanically superior to an overlay mesh with lower hernia recurrence rates [24]. Limitations of this study include the relatively small number of cadaver dissections performed (8), though our results with this limited number demonstrated consistent advancement with the addition of transversalis fascia scoring as compared to traditional anterior component separation alone.

Fig. 4
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Schematic showing the location of the transversalis fascia scoring, leaving neurovascular bundles intact

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Our technique is easy to perform, relatively quick, and does not require any additional laparoscopic or endoscopic equipment. A disadvantage of our modification is the need for extensive lysis of adhesions prior to scoring of the transversalis fascia, thus limiting the subset of patients in whom this procedure can be performed.

Interestingly, during the course of this study, our anatomic laboratory (Anatomic Gift Program, Albany Medical Center, Albany, NY) adopted the technique of cadaver embalming with methanol-based embalming solution. Our first two dissections were performed on fresh cadavers, and later, we transitioned our dissections to methanol-embalmed cadavers. Previous studies by Messmer et al. reported the natural feel to the tissues of methanol infused cadavers which approximates surgical environment [25]. As recorded in that study, we found that the methanol-embalmed cadaver tissues (skin, muscle, fascia) preserved their natural softness, elasticity, and consistency much like a fresh cadaver tissue. We are therefore confident that the additional medial advancement of the anterior rectus sheath which transversalis fascia scoring achieved in the methanol-embalmed cadavers is valid.

Finally, initial clinical application has shown primary closure of defects in excess of 20 cm in select patients requiring the additional advancement from transversalis fascia scoring. Primary fascial closure was achieved allowing for placement of reinforcing rather than bridging mesh, thus decreasing the rate of hernia recurrence. Short-term outcomes have been favorable in both of these patients. In the senior author’s experience with initial clinical application of this technique, the number of incisions can vary by patient and is based upon the ability to access the transversalis fascia and width of the posterior rectus sheath. Our assumption is that a greater number of incisions will result in a greater potential for advancement and closure of large defects. Further studies are required to quantify and obtain objective information regarding the optimal number of transversalis fascia incisions. We plan to complete more extensive studies to evaluate long-term outcomes and specific complications associated with using transversalis fascia scoring as an adjunct to anterior component separation.