From OncoLog, June 2012, Vol. 57, No. 6

Minimally Invasive Component Separation Reduces Wound-Healing Complications from Abdominal Surgery

By Sarah Bronson

Component separation, a major advance in abdominal wall reconstruction, can prevent hernia recurrence in many patients.

Recently, a surgeon at The University of Texas MD Anderson Cancer Center developed a minimally invasive approach to component separation that reduces complications and potentially improves functional outcomes.

Component separation was introduced in 1990 for abdominal wall reconstructions in ventral hernia repair or other surgeries requiring resection along the midline of the rectus abdominis complex. Traditional, open component separation enables the surgeon to close musculofascial defects without excessive tension and without a distant transposition flap. However, the amount of dead space created and the need to transect the blood vessels that supply the overlying fat and skin during the open procedure can lead to seromas, infections, and wound-healing complications.

In response to these complications, Charles E. Butler, M.D., a professor in the Department of Plastic Surgery, developed minimally invasive component separation with inlay bioprosthetic mesh (MICSIB), a new technique that preserves the rectus abdominis perforator vessels and maintains the connection between the subcutaneous fat and the anterior rectus sheath.

“The minimally invasive operation was de signed to be more predictable and more reliable and to achieve better outcomes with lower complication rates than open component separation. This may help cancer patients to be able to start postoperative chemotherapy or radiation therapy sooner,” Dr. Butler said.

Abdominal wall defects in cancer patients

Concurrent cancer and abdominal wall defects such as hernias can be difficult to manage because treatments for one condition can exacerbate the other. For example, complications such as an unhealed wound that persists or an infection that develops after hernia repair can delay chemotherapy or radiation therapy. Conversely, surgeons are less likely to immediately repair a hernia if treatments like chemotherapy and radiation therapy, which deplete the body’s ability to withstand and recover from hernia repair surgery, need to be given first.

Chemotherapy, radiation therapy, and cancer itself are risk factors for hernias, and cancer treatments increase the risk of wound-healing complications and hernia occurrence after abdominal surgery. By decreasing wound-healing complications, MICSIB can reduce the interference of one intervention with another.

Cancer patients have both a high rate of ventral hernias and an increased risk of hernia recurrence and wound complications after repair. Many of Dr. Butler’s patients have ventral hernias that other surgeons did not consider for elective repair because of the hernias’ severity, the high risk of complications associated with repairing the hernias, the patients’ comorbidities, or the need for extremely complex reconstructions, which sometimes require the use of a tissue flap to close the wound. MICSIB can improve these patients’ outcomes, enabling optimal cancer care. MICSIB is also used for immediate reconstruction of the abdominal wall following tumor resection.

Open component separation

Component separation reduces the muscular tension that can accompany the closure of the rectus abdominis muscle by separating the rectus abdominis muscle from the topmost of the three layers of oblique muscles to the left and right of the rectus abdominis.

The surgeon creates skin flaps on each side of the semilunar line, which is just lateral to the rectus abdominis muscle. The external oblique aponeurosis is then released from the costal margin to near the pubis. This release and subsequent separation of the internal and external oblique muscles enables the surgeon to advance the rectus complex toward the midline, thus reducing the size of the defect. If the defect is narrow enough, the surgeon can perform a primary musculofascial closure reinforced with an inlay of synthetic or bioprosthetic mesh; in large defects mesh is used as a bridge between the musculofascial edges.

In traditional, open component separation, the surgeon accesses the oblique muscles and external oblique aponeurosis by elevating the skin flaps over the entire rectus abdominis muscle, thus separating the subcutaneous fat from the anterior rectus sheath and dissecting the rectus abdominis myocutaneous perforator vessels that are the main blood supply to the skin and subcutaneous fat. However, elevating the skin flaps results in subcutaneous dead space, which can lead to seromas and infections, and the reduced blood flow caused by cutting the perforator vessels inhibits wound healing. Thus, open component separation carries a risk of postoperative complications that can prolong recovery time and interfere with the management of other conditions.

The minimally invasive procedure

Whereas open component separation fully separates the rectus abdominis muscle from the overlying skin, MICSIB uses narrow tunnels to access the external oblique aponeurosis and thus damages few, if any, rectus abdominis perforator vessels. With more vessels preserved, wounds can heal faster and more completely. The use of tunnels also limits the undermining of skin flaps that occurs with the separation of the anterior rectus sheath and the subcutaneous fat, which would otherwise devascularize the overlying skin fat and result in dead space.

To access the sites where the aponeurosis will be incised, the surgeon creates a tunnel 3–4 cm wide between the subcutis and the anterior rectus fascial sheath to connect the midline and semilunar line. By retracting the skin around this small tunnel, the surgeon can access and visualize a large area without the use of a laparoscope. The surgeon then makes a 1.5-cm incision in the external oblique aponeurosis just lateral to the semilunar line, inserts a suction handle (without suction) through the incision and into the avascular plane between the internal and external oblique aponeuroses (lateral to the rectus complex), and sweeps the handle inferiorly and superiorly to bluntly separate those aponeuroses and muscles. Then, the surgeon uses electrocautery and blunt dissection to create narrow vertical subcutaneous tunnels over the anticipated line along which the external oblique aponeurosis will be released.

At this point, the external oblique aponeurosis is not connected to either the inferior oblique aponeurosis or the subcutis and can be cut without injuring the overlying or underlying tissues. Scissors are used to incise the external oblique aponeurosis inferiorly toward the pubis, and scissors and electrocautery are used to incise the aponeurosis superiorly over the costal margin, where the amount of interdigitation between the aponeurosis and underlying muscle is greatest. As the surgeon incises the external oblique aponeurosis along the semilunar line, the suction handle is placed against the rectus complex between the internal and external oblique aponeuroses to guide dissection and prevent inadvertent incision of the rectus complex. The procedure is then repeated on the other side of the midline. All of this work is performed through the lateral access tunnels with use of a headlight and good retraction. No additional incisions are required, and no endoscopic equipment is involved, which makes MICSIB an efficient, fast, safe, and cost-effective procedure.

Outcomes of open component separation and MICSIB

Preserving vascularity and reducing dead space have been shown to improve wound healing. In a recent retrospective study, Dr. Butler and his colleagues compared the outcomes of complex ventral hernia repairs with open component separation in 50 patients and MICSIB in 57 patients. Significantly more patients who had undergone open component separation had wound-healing complications and skin dehiscences compared with those who had undergone MICSIB. Dr. Butler noted that, compared with the group of patients who had undergone open component separation, the group of patients who had undergone MICSIB had significantly larger defects and required significantly larger amounts of mesh for repair, indicating a possible selection bias toward patients with more severe hernias. Nevertheless, in the outcomes measured, the group that had undergone MICSIB had similar or better results compared with the group that had undergone open component separation.

“Seeing cancer patients whose sickness was made more complex by hernias stimulated me to develop a technology to address the complicated and severe cases that we see here at MD Anderson,” Dr. Butler said. “This technique is now used for challenging ventral hernia repairs regardless of whether patients have cancer.”

For more information, contact Dr. Charles E. Butler at 713-794-1247.

FURTHER READING

Butler CE, Campbell K. Minimally invasive component separation with inlay bioprosthetic mesh (MICSIB) for complex abdominal wall reconstruction. Plast Reconstr Surg 2011;128: 698-709.

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