An estimated 300,000 to 500,000 patients who undergo surgery annually in the United States will contract a surgical site infection (SSI). Patient risk factors such as diabetes, obesity, and patient age have long been associated with SSIs. But an article in the February issue of the Journal of the AAOS contends that intraoperative factors may have a bigger impact on SSI rates than patient-related factors.


Published 2/1/2012
Jennie McKee

Intraoperative Factors Closely Linked to SSI Rates

Perioperative protocols may have greater impact on infection rates than patient-related factors

James S. Harrop, MD

“Current literature has demonstrated that measures such as contact-precaution gowns, adhesive incision drapes, and preoperative hair shaving seem to have a limited effect on lowering SSI rates,” wrote lead author James S. Harrop, MD, and his colleagues. “However, factors that have been shown to contribute to reducing the occurrence of SSIs include shorter surgical time, covering equipment whenever possible, preventing intraoperative hypothermia, and limiting repetitive minor breaches in sterile technique.”

The authors noted that “to provide the highest level of patient care in an efficient manner, orthopaedic surgeons must understand the current evidence regarding the factors that affect the rates of SSIs and implement techniques to reduce or eliminate them.”

To learn more about this issue, AAOS Now spoke with Dr. Harrop, of Jefferson Medical College at Thomas Jefferson University in Philadelphia.

AAOS Now: Why did you conduct this review?
Dr. Harrop: The economic costs—both societal and patient-related—resulting from SSIs are significant. These infections result in more than $1.5 billion in additional costs in this country every year, and are responsible for 77 percent of deaths in patients with nosocomial infections. The best-case scenario with a wound infection is that the patient returns to the operating room, the wound is cleaned out, and the patient requires 6 weeks of intravenous antibiotics. But with delayed wound healing, the potential for morbidity from the effects of the infection exists. Conditions such as osteomyelitis can develop, requiring longer hospital stays.

At our hospital, we wanted to identify the best evidence available on factors that contribute to SSI to help us standardize a spine infection protocol.We wanted to create an algorithm they could follow. So, we needed to review all of the evidence-based data available on factors that contribute to SSIs. Chengyuan Wu, MD, one of my co-authors, has been a driving force behind our efforts to study the data and create an algorithm.

AAOS Now: What is the impact of intraoperative factors on infection rates?
Dr. Harrop: We found that factors such as proper skin preparation, adherence to sterile technique, surgical duration, and traffic in the operating room seem to have more of an impact than factors such as a patient’s prior history of SSI, for example.

The bottom line is that, in many ways, we can’t choose our patients, particularly at tertiary care hospitals. Many patients—such as obese, diabetic patients who have undergone radiation therapy for cancer—are referred to my hospital because they have a high risk of infection.

Because we can’t change our patients, we need to look at things that we, as surgeons, can change to reduce infections. We can do better at following hand-washing guidelines and using effective preoperative antibiotics.

Surgical duration is another factor. The literature shows that surgical duration longer than 2 hours is an independent risk factor for infection in both orthopaedic and general surgical procedures. One study found that the risk of infection increased 2.5 percent and the odds ratio increased by 0.32 for every 30 minutes of surgery (Figure 1).

We know that we can lower infection rates by adjusting our practices. At my hospital, SSI rates dropped significantly after we changed our surgical protocols based on this review.

AAOS Now: How aware are orthopaedic surgeons about the impact of intraoperative factors have on SSI rates?
Dr. Harrop: Surgeons generally understand the risks. But staying up-to-date on the most current literature and adjusting protocols when necessary are important steps for orthopaedists.

For example, orthopaedic surgeons should consider whether the effectiveness of some traditional practices—such as preoperative hair shaving or using contact-precaution gowns and adhesive incision drapes—are supported by data or are simply things that have always been done. For example, solid data to support the use of occlusive drapes are lacking, but we tend to use them, even though they increase costs.

AAOS Now: What is your advice to orthopaedic surgeons for reducing SSIs?
Dr. Harrop: Operating room practices need to be standardized so that specific factors can be analyzed, patterns identified, and changes made.

Orthopaedic surgeons, patients, hospitals, and government agencies need to place more of an emphasis on furthering our understanding of factors that contribute to SSI risk.

Jennie McKee is a staff writer for AAOS Now. She can be reached at

Coauthors of “Contributing Factors to Surgical Site Infections” are John C. Styliaras, MD, MS (no conflicts); Yinn Cher Ooi, MD (no conflicts); Kristen E. Radcliff, MD (no conflicts); Alexander R. Vaccaro, MD, PhD (Aesculap/B.Braun Melsungen AG, DePuy, Globus Medical, Medtronic Sofamor Danek, K2M, Stout Medical, Progressive Spinal Technologies, Applied Spinal Intellectual Properties, Benvenue Medical, Disc Motion Technology, Computational Biodynamics, Paradigm Spine, Replication Medica, Spinology, Spine Medica, Orthovita, VertiFlex, Small Bone Technologies, NeuCore, CrossCurrent, Syndicom, InVivo Therapeutics, Flagship Surgical, PearlDriver Technologies, Location Based Intelligence, Gamma Spine, AO North America, Cerapeutics, Stryker); and Chengyuan Wu, MD (Johnson & Johnson). Dr. Harrop reports ties to DePuy, Stryker, Neurostem, Geron, and AxioMed.