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Open anterior component separation techniques

Open anterior component separation techniques
Author:
Clayton C Petro, MD
Section Editor:
Michael Rosen, MD
Deputy Editor:
Wenliang Chen, MD, PhD
Literature review current through: Jan 2024.
This topic last updated: Jun 15, 2023.

INTRODUCTION — Component separation is an abdominal wall reconstructive technique that strategically divides the rectus and lateral abdominal wall musculofascial layers in order to achieve tension-free midline fascial approximation.

Depending on the myofascial layer(s) divided, techniques of component separation can be broadly categorized into anterior and posterior. Anterior component separations divide the external oblique muscle lateral to the linea semilunaris and separate the external oblique from the underlying internal oblique muscle.

The original open anterior component separation operation creates wide skin flaps to access the external oblique aponeuroses for division. Undermining subcutaneous tissue from the rectus muscle and its associated anterior epigastric perforating vessels can devascularize this tissue, creating potential for wound necrosis, infection, or seroma formation [1]. Other techniques that can divide the external oblique muscle without raising large skin flaps have since been described, which are associated with fewer wound complications. (See "Overview of component separation", section on 'Wound morbidity'.)

This topic will discuss technical details of four anterior component separation operations. The relevant anatomy and patient selection criteria, as well as efficacy and complications of component separation, are discussed in another topic. (See "Overview of component separation".)

Posterior component separation techniques can be found in a separate topic. (See "Open posterior component separation techniques" and "Robotic component separation techniques".)

OPEN ANTERIOR COMPONENT SEPARATION — The original Ramirez component separation involved two myofascial divisions on each side of the abdominal wall: a medial division of the posterior rectus sheath and a lateral division of the external oblique (EO) muscle [2].

Incision and lysis of adhesion

The operation is begun with a generous midline laparotomy incorporating the patient's previous scar and any redundant, attenuated, or ulcerated skin. We prefer to enter the abdominal cavity sharply cephalad to any previous incisions in a virgin area of the abdomen.

Intra-abdominal adhesions are completely lysed, and the viscera are freed from the abdominal wall in order to place a large towel over the bowel during the myofascial dissection. After placement of the towel, the edges of the fascial defect are identified and the length/width measured.

Division of posterior rectus sheath

The posterior rectus sheath is incised 1 to 2 cm lateral to the medial border of the rectus muscle, starting at the costal margin and continuing below the arcuate line where the posterior sheath becomes continuous with the peritoneum and transversalis fascia (figure 1). If this is done bilaterally but midline fascial approximation is not possible, additional myofascial releases are then performed.

Division of external oblique muscle

Next, the EO muscles should be divided one at a time. This is done 1 to 2 cm lateral to the linea semilunaris, which is palpable at the lateral edge of the rectus muscle belly (figure 2 and figure 3). When in doubt, divide the EO further lateral to the rectus to prevent unintentional division of the internal oblique (IO) muscle or the linea semilunaris.

Since the EO muscle originates from ribs 5 to 12, its division can be extended superiorly to 5 cm over the costal margin and inferiorly to the inguinal ligament. However, the entire length of the EO is not always divided; rather, the length of division can be adjusted based on the location of the midline fascial defect.

Bluntly liberating the underlying IO/transversus abdominis (TA) muscle apparatus from the divided EO reveals a relatively avascular plane, and visualization of any large neurovascular components should cause concern that the wrong layers are being divided. Maturation of this plane affords additional medialization of the rectus. That is because neurovascular bundles travel between IO and TA and therefore should not be visible after division of the EO (see "Overview of component separation", section on 'Retrorectus space'). Recognizing that IO muscle fibers travel superomedial to inferolateral will also reassure the surgeon that the appropriate layer has been divided.

Midline fascial approximation should be attempted after each individual myofascial release, rather than after division of both posterior rectus sheaths and both EO muscles. Further myofascial release should be avoided once tension-free midline approximation is achieved.

Mesh placement and closure

Midline fascial approximation is performed with either running or interrupted #1 slowly absorbable monofilament suture (figure 4). While some authors use permanent sutures for fascial closure, in our opinion, use of permanent and/or braided sutures for these operations increases the risk of chronic suture track sinuses, particularly in a context of raising skin flaps where wound necrosis is possible.

When the wound tension is high, we close the fascia with interrupted figure-of-eight sutures, waiting to tie them down after all have been placed. By distributing the tension onto each stitch, this technique will often allow for closure of large defects that initially seem improbable to close.

Mesh should be an integral part of any modern large or complex ventral hernia repair. There are several options for mesh placement after open anterior component separations:

Since skin flaps have been raised for EO division, our preference is to place an uncoated, medium-weight, macroporous polypropylene mesh in the onlay position with at least 8 cm of circumferential overlap. The mesh can be secured to the edge of the divided EO with a running absorbable suture. To promote tissue approximation and subsequent ingrowth, we utilize a skin stapler and apply fibrin glue to adhere the mesh to the underlying fascia [3]. Typically, 10 to 30 cc of fibrin glue is required depending on the size of the defect (figure 5).

Mesh can alternatively be placed in the retrorectus plane, provided that the posterior rectus sheaths can be approximated to exclude the viscera without an additional posterior component separation. Anterior and posterior component separation should not be done concomitantly, as this can significantly destabilize the abdominal wall.

A third option is to place a coated mesh in the peritoneum as an underlay.

Two to four large-bore closed-suction drains (eg, 19 French Jackson-Pratt) should be placed on top of the mesh and kept in place until their output is consistently <20 cc/day. This typically takes several weeks.

For most patients, the skin is closed with a deep dermal layer of 3-0 rapidly absorbable monofilament suture and a skin layer of 4-0 absorbable monofilament suture. For patients who have significant tension at skin closure after scar excision, we close the skin with 2-0 nylon at approximately 1 cm intervals as interrupted vertical mattress sutures and keep them in for approximately four weeks.

Postoperative care — An abdominal binder should be applied immediately postoperatively, and patients should be encouraged to wear it as much as possible for the first eight weeks. The classic open anterior component separation operation has been associated with a high wound morbidity rate. Thus, careful assessment of the viability of soft tissue in the operating room, appropriate management of drains, and patient compliance with binder usage are important to mitigate potential wound complications. (See "Overview of component separation", section on 'Wound morbidity'.)

PERIUMBILICAL PERFORATOR-SPARING ANTERIOR COMPONENT SEPARATION — The periumbilical perforator-sparing technique avoids dividing the periumbilical perforators and raising large skin flaps by using subcutaneous tunnels or lateral counterincisions to access the linea semilunaris and divide the external oblique (EO) muscle [4]. It has been shown to reduce wound morbidities compared with the original Ramirez open anterior component separation [4-6].

Incision and lysis of adhesion

These initial steps are similar to those of the original Ramirez technique described above. (See 'Incision and lysis of adhesion' above.)

The anterior rectus fascia is cleared of subcutaneous tissue for 4 cm on either side, preserving any anterior perforating vessels lateral to this. If the rectus fascia cannot be brought to the midline, an additional release can be performed.

Anterior component separation techniques other than the original Ramirez operation do not mandate division of the posterior rectus sheath. If the posterior rectus sheath is divided, the mesh should be inserted in the retrorectus space; if not, the mesh can be placed intraperitoneally as an intraperitoneal onlay mesh (IPOM). (See 'Mesh placement and closure' below.)

Division of external oblique muscle — The linea semilunaris can be accessed from the midline by either subcutaneous tunnels above and below the umbilicus or lateral counterincisions, depending on the width of the rectus muscle.

Subcutaneous tunnels above and below the umbilicus — For patients with a narrow rectus muscle, the linea semilunaris can be accessed from the midline by two subcutaneous tunnels, one above and one below the area of the umbilicus on each side of the abdomen.

Once the linea semilunaris is identified by palpating the lateral edge of the rectus, the EO aponeurosis is divided 1 to 2 cm lateral to it for 2 to 3 cm through each of the four subcutaneous tunnels.

Through these openings, the EO and internal oblique (IO) can be bluntly separated superiorly to above the costal margin, inferiorly to the pubis and medially to the rectus complex.

The subcutaneous tissue can then be liberated from the medial EO aponeurosis using blunt digital dissection, which isolates the EO along its entire cephalad to caudad extent and connects the subcutaneous tunnels above and below the umbilicus.

The EO aponeurosis is then completely divided 1 to 2 cm lateral to its insertion on the anterior rectus sheath and carefully inspected for hemostasis.

Once the EO is divided, additional blunt dissection can be done to liberate the IO from the EO.

Lateral counterincisions — For patients with a wide rectus muscle such that the linea semilunaris is further away from the midline, the linea semilunaris can be accessed via lateral counterincisions rather than long subcutaneous tunnels from the midline.

For these patients, an initial 6 to 8 cm transverse incision is made at the inferior aspect of the costal margin over the anticipated linea semilunaris.

Using Deaver retractors, expose the linea semilunaris from above the costal margin to the anterior superior iliac spine (ASIS).

The EO fascia is elevated with forceps and divided, exposing underlying fat. The plane between the EO and IO can be bluntly developed with a finger.

The EO aponeurosis is divided from above the costal margin to the level of the ASIS.

To complete the inferior aspect of the EO release, suprapubic subcutaneous tunnels are made from the inferior part of the incision toward the ASIS. Through the tunnel, the plane between the EO and IO initiated through the lateral counterincision can be hooked with the surgeon's index finger and brought into the midline. Here, the remaining inferior EO can be divided under direct visualization without injuring the anterior rectus fascia.

Patients with obesity sometimes require a second counterincision near the ASIS when EO division is limited by a large subcutaneous component.

Once the EO is completely divided, the EO and IO can be separated bluntly to aid fascial medialization.

Mesh placement and closure — With periumbilical perforator-sparing anterior component separation, mesh is typically placed either in the retrorectus space (for hernia width <12 cm) or in the peritoneum (for hernia width ≥12 cm). If the posterior rectus sheath is divided, the mesh should be inserted in the retrorectus space; if not, the mesh can be placed intraperitoneally as an IPOM.

Retrorectus mesh placement — Mesh placement in the retrorectus space is the preferred technique for periumbilical perforator-sparing anterior component separation.

The posterior rectus sheaths are divided just lateral to the medial edge of the rectus to expose the underlying belly of the rectus muscle.

The retrorectus spaces are developed laterally for at least 4 cm on either side, taking care to preserve the deep inferior epigastric vessels and laterally perforating neurovascular bundles at the lateral aspect of the retrorectus space.

Once the retrorectus space is adequately developed bilaterally, the posterior rectus sheaths and contiguous preperitoneal fat or peritoneum are closed with a running 2-0 monofilament suture to isolate the underlying viscera.

With an 8 cm wide retrorectus space and 8 cm of anterior rectus exposed, a 7.5 cm wide macroporous uncoated medium-weight polypropylene mesh is cut to fit the retrorectus space.

0-polypropylene sutures are passed through the anterior rectus sheath 4 cm from the medial edge and secured to the edge of the mesh every 2 to 3 cm. At the end, the mesh is tight and flat in the retrorectus space.

Interrupted sutures are used to approximate the anterior rectus fascia over the mesh; this may require up to 45 sutures for the entire length of the incision.

Redundant skin as well as the patient's hernia sac should be resected before skin closure.

Subcutaneous drains should be left.

Intraperitoneal mesh placement — For hernias ≥12 cm wide, retrorectus mesh placement is typically not feasible, because the posterior rectus sheaths cannot be reapproximated at the midline without undue tension despite the anterior component separation, but a posterior component separation such as a transversus abdominis release cannot be performed. In these scenarios, barrier-coated mesh suited for intraperitoneal placement can be utilized and placed as an underlay with circumferential suture fixation.

MINIMALLY INVASIVE COMPONENT SEPARATION — The minimally invasive component separation technique only creates one subcutaneous tunnel on each side of the abdomen for division of the external oblique (EO) aponeurosis [7]. This technique also has demonstrated improved wound morbidity with perforator preservation compared with the traditional Ramirez technique.

Incision and lysis of adhesion — These initial steps are similar to those of the open Ramirez technique described above. (See 'Incision and lysis of adhesion' above.)

Division of external oblique muscle — This technique only requires one subcutaneous tunnel on each side of the abdomen to divide the EO aponeurosis.

A 3 cm subcutaneous access tunnel is created anterior to the rectus sheath toward the linea semilunaris 2 cm below the costal margin (figure 6).

Through the access tunnel, the EO aponeurosis is divided 1 to 2 cm lateral to the linea semilunaris.

Through the opening of the divided EO, a metal Yankauer suction tip is used to bluntly develop the avascular plane between the internal oblique (IO) and EO. This can be done from over the costal margin down to the pubis and helps identify the linea semilunaris at the medial extent of this pocket.

Using narrow lighted retractors, subcutaneous tunnels approximately 2.5 cm wide are developed over the anticipated area of EO division using a combination of cautery and blunt dissection. At this point, the EO is completely isolated anteriorly and posteriorly.

Next, the Yankauer suction tip is placed back in the plane between the EO and IO to help identify the medial border of the pocket and prevent inadvertent injury to the anterior rectus sheath. The EO aponeurosis is then divided over the suction tip approximately 1.5 cm lateral to the semilunar line from 12 cm above the costal margin to the pubis inferiorly.

Once the EO is divided, additional blunt dissection with the suction tip can be done to liberate the EO from the IO laterally to the midaxillary line.

Mesh placement and closure — Although the authors of this technique reported acceptable rates of long-term recurrence utilizing biologic mesh [8], the use of biologic mesh in a bridging scenario has been shown to lead to nearly inevitable recurrence and should still be avoided [9]. Thus, we suggest placing a synthetic mesh in either the retrorectus or intraperitoneal position as described above. (See 'Mesh placement and closure' above.)

ENDOSCOPIC COMPONENT SEPARATION — Much like the other anterior component separation techniques, this technique also divides the external oblique (EO) muscle with minimal subcutaneous tissue disruptions or associated ischemia [10]. However, the use of laparoscopic instruments and blind placement of a balloon trocar could lead to unique complications that the surgeon should be mindful of during the dissection.

Endoscopic division of external oblique muscle — The endoscopic portion of the procedure is typically done first before the midline hernia repair. If there is a transverse incision or ostomy present, the contralateral side is done first.

Near the tip of the 11th rib, a 2 to 4 cm subcostal transverse incision is made, erring lateral to avoid inadvertent injury to the linea semilunaris.

S-retractors are used to dissect down to the EO muscle fibers. EO fibers are bluntly spread to expose the underlying internal oblique (IO) fascia that is white.

An S-retractor is placed into the avascular plane between the EO and IO, allowing for placement of a round balloon dissector, which is placed blindly toward the ipsilateral groin or 2 to 3 cm medial to the anterior superior iliac spine (ASIS). Take care to angle the tip of the balloon anteriorly so as not to inadvertently traverse the IO.

Fill the balloon three to four times, just enough to create space between the EO and IO muscles for dissection. Overdistention can tear muscle fibers and cause bleeding.

Next, the balloon is removed and redirected superiorly to dissect the EO from the IO as it travels over the costal margin.

Once the IO/EO are separated along their entire course, a 12 mm AirSeal port is placed through the incision to insufflate the intramuscular space to 12 mmHg with carbon dioxide.

A laparoscope is inserted, and the appropriate direction of the overlying (EO) and underlying (IO) muscle fibers will confirm that the appropriate plane has been dissected.

Two additional 5 mm ports are placed along the anterior axillary line under direct visualization. The inferior port should be just medial and inferior to the ASIS.

Keeping the laparoscope in the 12 mm port and using laparoscopic scissors through the middle port, the overlying EO aponeurosis is divided just lateral to the junction of the overlying EO and underlying IO. This should reveal subcutaneous fat, and if not, the surgeon should pause and reassess the anatomy.

Once the subcutaneous fat is seen to confirm the appropriate location, the scissors can be used to transect the EO inferiorly from the midabdomen to just above the inguinal ligament. Care should be taken to keep this dissection parallel and lateral to the rectus complex.

Next, the laparoscope can be placed in the inferior port, and the EO fascia can be divided superiorly from the midabdomen to 5 to 7 cm above the costal margin.

Once the entire EO aponeurosis is divided, the subcutaneous fascia can then also be divided with an energy device, as this will allow for additional relaxation.

Ports should be removed under direct visualization.

Ventral hernia repair — The endoscopic component separation technique does not mandate any method of midline hernia repair. As examples, an open retrorectus repair can be done if posterior sheath approximation is possible to allow for retrorectus mesh placement. Alternatively, a laparoscopic repair can be done as the myofascial release can aid midline fascial approximation before an intraperitoneal underlay mesh is placed.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Ventral hernia".)

SUMMARY AND RECOMMENDATIONS

Definitions – Component separation is a reconstructive technique that strategically divides myofascial layers of the abdominal wall in order to achieve tension-free midline fascial approximation. Anterior component separations divide the external oblique (EO) muscle lateral to the linea semilunaris and separate the EO from the underlying internal oblique (IO) muscle. (See 'Introduction' above.)

Open anterior component separation – The original component separation characterized by Ramirez involved two myofascial divisions on each side of the abdominal wall: a medial division of the posterior rectus sheath and a lateral division of the EO muscle. Because of the extensive skin flaps raised, open anterior component separation is associated with a high wound morbidity rate. (See 'Open anterior component separation' above.)

Periumbilical perforator-sparing anterior component separation – The periumbilical perforator-sparing technique avoids dividing the periumbilical perforators and raising large skin flaps by using subcutaneous tunnels (for narrow rectus muscle) or lateral counterincisions (for wide rectus muscle) to access the linea semilunaris and divide the EO muscle. (See 'Periumbilical perforator-sparing anterior component separation' above.)

Minimally invasive anterior component separation – The minimally invasive component separation technique only creates one subcutaneous tunnel on each side of the abdomen for division of the EO aponeurosis. (See 'Minimally invasive component separation' above.)

Endoscopic anterior component separation – The endoscopic component separation technique utilizes laparoscopic balloon dissectors and instruments to divide the EO muscle with minimal subcutaneous tissue disruptions or associated ischemia. (See 'Endoscopic component separation' above.)

Mesh placement – After anterior component separations, meshes can be placed as an onlay (open technique), sublay/retrorectus (for hernia width <12 cm) without transversus abdominis release (TAR), or underlay (coated intraperitoneal mesh for wider hernias). (See 'Mesh placement and closure' above and 'Mesh placement and closure' above and 'Mesh placement and closure' above.)

Pitfalls – Anterior component separations should not be performed concomitantly with a posterior component separation (eg, TAR), as this can significantly destabilize the abdominal wall and lead to permanent disability. (See "Open posterior component separation techniques".)

  1. Krpata DM, Blatnik JA, Novitsky YW, Rosen MJ. Posterior and open anterior components separations: a comparative analysis. Am J Surg 2012; 203:318.
  2. Ramirez OM, Ruas E, Dellon AL. "Components separation" method for closure of abdominal-wall defects: an anatomic and clinical study. Plast Reconstr Surg 1990; 86:519.
  3. Stoikes N, Webb D, Powell B, Voeller G. Preliminary report of a sutureless onlay technique for incisional hernia repair using fibrin glue alone for mesh fixation. Am Surg 2013; 79:1177.
  4. Saulis AS, Dumanian GA. Periumbilical rectus abdominis perforator preservation significantly reduces superficial wound complications in "separation of parts" hernia repairs. Plast Reconstr Surg 2002; 109:2275.
  5. Dumanian GA. Periumbilical perforator sparing component separation. In: Atlas of Abdominal Wall Reconstruction, 2nd ed, Rosen MJ (Ed), Elsevier, 2017. p.166.
  6. Dumanian GA. Open anterior component separation with perforator preservation. In: Hernia Surgery: Current Principles, Novitsky YW (Ed), Springer, 2016. p.159.
  7. Ghali S, Turza KC, Baumann DP, Butler CE. Minimally invasive component separation results in fewer wound-healing complications than open component separation for large ventral hernia repairs. J Am Coll Surg 2012; 214:981.
  8. Asaad M, Kapur SK, Baumann DP, et al. Acellular Dermal Matrix Provides Durable Long-Term Outcomes in Abdominal Wall Reconstruction: A Study of Patients with Over 60 Months of Follow-up. Ann Surg 2022; 276:e563.
  9. Blatnik J, Jin J, Rosen M. Abdominal hernia repair with bridging acellular dermal matrix--an expensive hernia sac. Am J Surg 2008; 196:47.
  10. Earle D. Endoscopic anterior component separation. In: Hernia Surgery: Current Principles, Novitsky YW (Ed), Springer, 2016. p.149.
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