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Successful Salvage of Infected PTFE Mesh after Ventral Hernia Repair
Use of prosthetic biomaterials for the repair of abdominal wall hernias has decreased hernia recurrence rates when compared with primary fascial closure.1
By allowing for "tension-free" closure of incisional hernia defects, prosthetic mesh provides a permanent replacement for native fascia that frequently has been weakened or removed by previous surgery. Polypropylene and polytetrafluoroethylene (PTFE) are the most commonly used prosthetic biomaterials in the repair of ventral hernias. Both are biologically inert and allow for ingrowth of normal adjacent tissues. In the large majority of cases, the use of mesh results in a durable and lasting hernia repair.
However, implantation of permanent foreign material may increase the risk of postoperative infectious complications.2-5 The morbidly obese patient is at greatest risk for developing postoperative wound complications following ventral hernia repair, with or without the use of prosthetic biomaterials.6 Standard surgical practice supports removal of prosthetic material when a wound infection involves prosthetic mesh.7 Unfortunately, the removal of mesh in this situation is often technically difficult and may result in substantial additional complications. Local tissue incorporation can make removal of mesh dangerous, as adjacent vascular structures or the bowel can be injured, which may result in acute bleeding or subsequent development of an enterocutaneous fistula. Because achieving closure of the fascial defect after mesh removal usually is not possible, this surgery may result in an incisional hernia that is larger than the original hernia. The objective of this report is to describe a novel approach to the complex problem of exposed prosthetic mesh following incisional hernia repair.
Case Report
A 37-year-old morbidly obese female (body mass index 63 kg/m2, weight 450 lb) with multiple co-morbid problems including hypertension, gastroesophageal reflux disease, obstructive sleep apnea, and depression, underwent Roux-en-Y gastric bypass for weight loss.
Ten months after gastric bypass, the patient had lost 123 lb and developed a large lower abdominal pannus as well as a large ventral hernia. The patient underwent panniculectomy and simultaneous incisional hernia repair. A fascial defect, measuring 30 cm x 7.5 cm, was repaired with a 36 cm x 15 cm sheet of PTFE mesh (Dual Mesh™ , W. L Gore and Associates, Inc., Flagstaff, Ariz.). One dose of intravenous antibiotic (cefazolin, 2 g) was administered preoperatively and continued every 8 hours for three postoperative doses. The patient was discharged home on oral cephalexin. Oral antibiotics were continued until two subcutaneous closed-suction drains were removed 10 days postoperatively.
Four months after initial ventral hernia repair, the patient returned with an infected midline wound. She had no signs or symptoms of systemic infection. The skin and subcutaneous tissues were open, revealing exposed PTFE mesh. Cultures grew methicillin-resistant S. aureus (MRSA). Based upon cultures and antibiotic sensitivities, she was treated with intravenous levofloxacin (500 mg daily) and vancomycin (1 g daily). A vacuum-assisted closure system (V.A.C.® system, Kinetics Concepts Inc., San Antonio Tex.) was applied to the open portion of the wound. The polyurethane vacuum foam was cut to size and intermittent vacuum suction applied at 125 mm Hg for 1 week. The foam was removed and replaced at 48-hour intervals for visual inspection and evaluation of the wound. These interventions resulted in progressive debridement and granulation of the open wound but, despite contraction of the wound edges, the mesh remained exposed in the central portion of the wound (see Figure 1).
Following 7 days of local wound care, the patient underwent surgical debridement and partial excision of the mesh with irrigation and surgical closure. During the procedure, a small area of granulation tissue and skin were debrided from the wound edges (see Figure 2). A redundant portion of mesh, measuring approximately 4 cm x 8 cm, protruded from the wound and was excised. The mesh was re-approximated with nonabsorbable (0-polypropylene) sutures and two subcutaneous drains were placed. Overlying skin and soft tissues were closed with interrupted sutures (see Figure 3). The patient recovered without complications and was discharged home on the second postoperative day. Oral levofloxacin was continued for 1 month. Drains were removed 18 days postoperatively. Eighteen months following her last procedure, no infection or hernia recurrence were evident (see Figure 4).
Discussion
Infection following incisional hernia repair may result in substantial morbidity. Although traditional surgical teaching advocates the removal of prosthetic materials when infections occur, isolated cases of mesh salvage have been reported in the literature. In his personal series of more than 360 ventral hernia repairs using mersilene mesh, Stoppa4 reported an infection rate of 12%. No prosthesis required removal. Similarly, in a prospective study by Luijendijk et al1 comparing suture repair with mesh repair of incisional hernias, three out of 84 patients developed a wound infection following placement of polypropylene mesh. All were successfully managed without mesh removal. While animal studies have provided support for the use of PTFE mesh in contaminated abdominal wounds, no clinical reports of salvaging infected PTFE mesh in humans are available.8
Surgical site infections account for almost 40% of all postoperative infectious complications and are the most frequent source of nosocomial infection in surgical patients. Risk factors for wound infection are frequently related to underlying patient factors including diabetes, steroid use, and malnutrition.9 Morbid obesity (as it relates to the relatively poor vascular supply to the skin and subcutaneous tissues in patients with this condition) is an independent risk factor for wound complications. Large abdominal incisions in patients with excess subcutaneous fatty tissue create "dead space" beneath the skin and provides a favorable environment for bacterial proliferation and infection. The current case involves a morbidly obese patient who underwent ventral hernia repair with a large PTFE mesh, complicated by a postoperative MRSA wound infection. Her infection was treated with intravenous and oral antibiotics, dressing changes, and local wound debridement using a vacuum-assisted-closure device. Ultimately, primary skin and soft tissue coverage of the exposed mesh was achieved without mesh removal.
Previous publications describe the use of suction-based debridement systems in achieving closure of a variety of acute and chronic wounds, but use of this device for the management of an open wound complicated by exposed prosthetic mesh has not been previously reported.10,11 Vacuum suction results in the removal of excess wound fluid, increases local tissue perfusion,12 and produces mechanical distraction of soft tissues which results in stimulation of cellular mitosis. These factors appear to promote fibroblast, macrophage, and epithelial cell migration and proliferation within the wound.10
Previous investigators have argued that PTFE mesh is unsuitable for use in a contaminated site and recommend early removal of the prosthetic.13 In the only reported series of patients managed with contaminated PTFE mesh, Bleichrodt et al14 described the removal of mesh in two of three patients due to complications of wound infection. Subsequent animal studies by this same group revealed that wound complications occurred in 76% of animals managed with contaminated PTFE mesh, compared with 67% of those with polypropylene mesh. In contrast, Brown8 reported that bacterial adherence to expanded PTFE mesh is significantly less than for polypropylene mesh. These results suggest that PTFE may be preferable to polypropylene in a contaminated setting. In summary, based upon animal studies, conflicting evidence exists regarding the ability of PTFE mesh to withstand bacterial contamination.
Data on PTFE in humans are similarly sparse. Several authors have described successful management of infected vascular grafts, but no data currently is available for abdominal wall defects.15-17 Based on the above-mentioned data and the limited experience described here, one could argue that care of these patients should be individualized. For patients with signs or symptoms of systemic sepsis, removal of the involved prosthetic is usually necessary. Unfortunately, this involves not only the risks and morbidity of re-operation, but also results in hernia recurrence. For patients with limited prosthetic contamination and/or mesh exposure, an attempt at local management without mesh removal may be considered.
Conclusions
Prosthetic mesh infection represents an important source of morbidity following incisional hernia repair. For patients with exposed mesh in the absence of systemic sepsis, a conservative approach that includes local wound care, antimicrobial therapy, and soft tissue coverage may allow for salvage of the infected prosthetic material. Further evaluation of this technique is warranted to define the most appropriate management strategy for these patients.
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