A Pilot Study Comparing Incisional Negative Pressure Wound Therapy (Prevena) to Conventional Sterile Dressing in Patients Undergoing Thoracolumbar Posterior Spine Surgery

Patients with surgical site infection (SSI) of the spine have higher morbidity and mortality and higher costs of care. Hospital length of stay has been shown to be significantly longer, and readmission rate significantly higher, for infected patients than that for uninfected patients. Repeated surgery, typically irrigation and debridement (I&D), due to deep SSI is required in the majority of these patients. The risk of post-operative spinal wound infection is reported to be 1-20% depending on patient factors, surgical factors and spine pathology factors. The risk of SSI can be as high as 10-25% in major risk groups, such as posterior surgical approach in revision lumbar surgery, thoracolumbar trauma with neurological deficit, and in surgery for metastatic disease. Wound complications such as seroma or dehiscence can be as high as 40% in spine oncology patients, especially if they have received radiation and/or chemotherapy. Definitive management is based on etiology, clinical course, and patient risk factors. A patient who develops a post-operative wound infection often requires prolonged hospitalization, revision surgical procedures, and long-term intravenous antibiotics, which significantly increase health care resource utilization, and thus the overall cost. Awareness of risk factors and development of preventive measures can lead to improved outcomes.

There are many supplemental treatment strategies for post-operative spine infection and wound complications in addition to I&D. Vacuum assisted closure (VAC) of infected spine wounds has proven to be an acceptable adjunct to aid in the closure or staging of complex spinal wounds. The VAC system has proven to be safe and effective in the treatment of complex spinal wounds, spinal SSI and wounds that are at high risk for failed primary closure. Indications for VAC treatment as a means of preventing wound complications are evolving. Preemptive use of VAC treatment on closed primary wounds has been employed in high risk (morbidly obese) patients with acetabular fractures, and successful outcomes have been achieved. Use of VAC treatment on closed wounds as a preventive measure in properly selected patients appears safe and has effectively decreased wound complication rates. This mode of prophylactic treatment is called "incisional VAC therapy".

KCI (the manufacturer of a Vacuum Assisted Closure System) has gained FDA and Health Canada approval for a specific device called "Prevena™", which is designed for incisional vacuum therapy. The Prevena™ System is indicated for use over clean, closed incisions that continue to drain following sutured or stapled closure. It acts by removing exudate, helping hold the edges of the incision together and protecting the surgical site from external contamination in a clean, protected postoperative wound environment.

To date, no studies have been done to establish the efficacy of the Prevena™ System for use on patients requiring spine surgery to reduce wound complications such as SSI, wound dehiscence, or seroma formation. A recent systematic review of published studies examining the use of dressings and drains in posterior spinal surgery found no evidence to support the use of any particular system. A number of recent studies have also examined the incidence of surgical site infection in different high-risk populations (10-25%) and a predictive model for the development of a complex post surgical wound infection. The factors identified lead to considerable disability, cost and additional utilization of health care resources. If a prophylactic wound treatment can decrease wound complications in high risk patients, this may lead to a decreased need for post-operative services, reduced complication rate, less antibiotic usage and fewer returns to the operating room. If patients can avoid complications, they can resume normal activities faster and ultimately should have higher satisfaction.

In an era where health expenditure is literally exploding and becoming non-sustainable in many countries, cost effectiveness analysis is required to responsibly manage scarce health care resources. Specifically in the context of SSI, is the added cost of the Prevena™ System justified by the potential decrease in wound complication rate?