Are Obese Patients at Greater Risk for SSI after Revision TJA?

    Orthopaedic surgeons are concerned about the risk for deep surgical site infection (SSI) in their obese patients who need total joint arthroplasty.

    A study from the University of California, San Francisco shows that these concerns are valid, at least for patients undergoing revision procedures.

    As reported at ICJR’s Pan Pacific Orthopaedic Congress, the study had 3 main purposes:

    • Describe the prevalence of obesity in revision total joint arthroplasty
    • Determine a BMI threshold most predictive of deep SSI
    • Evaluate obesity as an independent risk factor for deep SSI following revision total joint arthroplasty

    The researchers identified 12,579 patients in the National Surgical Quality Improvement Program (NSQIP) database who underwent either revision total hip arthrtoplasty (n=6,214) or revision total knee arthroplasty (n=6,361) between 2005 and 2013.

    They calculated BMI for these patients and found that 6,530 (52%) of all patients who underwent a revision procedure were obese (BMI ≥30); 1,364 (12%) were morbidly obese (BMI ≥40). 

    Statistical analysis showed that a BMI of 40 was the optimal cutoff for predicting deep SSI (ROC area under curve: 0.55), and a BMI of 40 or more was an independent predictor for deep SSI in multivariate analysis (OR 2.03, 95% CI: 1.34-3.07; P<0.001).

    Other significant covariates predicting deep SSI included:

    • American Society of Anesthesiologist score (ASA ≥3 vs. 1-2, OR 1.58, CI: 1.04-2.39; P=0.032)
    • Functional status (dependent vs. independent, OR 1.96, CI: 1.22-3.13; P=0.005)
    • Preoperative hematocrit (≤35 vs. >35, OR 1.83, CI: 1.24-2.68; P=0.002)

    We asked one of the study authors, Alfred C. Kuo, MD, PhD, to comment on the findings and their implication for practice. Click the image above to hear what he had to say. Then click the link below to watch his presentation from the Pan Pacific Orthopaedic Congress.

    Producer: Michael Szuch; Director: Michael Bugera; Post Production: Charles J. Maynard


    Sing D, Ward D, Kuo A. Morbid obesity is a risk factor for early surgical site infection following revision total joint arthroplasty. Presented at the 2nd Annual Pan Pacific Orthopaedic Congress, July 12-15, 2015, Kona, Hawaii.