Risk Factors for Surgical Site Infections in Orthopedic Surgery: A Case-Control Study Lama Almutairi, Michael Klompas, James Maguire, Madeleine Bartzak, Brandon Dionne, Jeffrey C. Pearson
Background/objective: Surgical site infections (SSIs) complicate orthopedic surgery, highlighting the need to clarify associated risk factors. By the end of the presentation, participants should be able to identify risk factors for SSIs in hip or knee surgery.
Methods:This was a single-center retrospective case-control study conducted at a tertiary academic medical center. Patients who underwent orthopedic knee or hip surgery between August 2020 and May 2025 were included. Cases were patients who developed an SSI within 90 days, according to the National Healthcare Safety Network criteria. Controls were patients who did not develop an SSI within the same follow-up period. Cases were matched 1:4 to controls by surgery type (hip vs. knee) and procedure date (month and year). The association between risk factors and SSIs was assessed using univariable and multivariable logistic regression. Prespecified risk factors included body mass index (BMI) ≥25 kg/m², diabetes mellitus with most recent A1C ≥7%, surgical duration ≥120 minutes, age ≥60 years,
S. aureus nares screening, and perioperative antibiotic choice (cefazolin alone vs. other).
Results: Among 250 patients (50 cases, 200 controls), the mean BMI was 30.2 kg/m² for cases and 27.9 kg/m² for controls. Hypertension was present in 62% of cases versus 55% of controls, and diabetes was present in 24% of cases versus 14.5% of controls. Perioperative antibiotic regimens were similar between groups: cefazolin alone was used in 48% of cases vs 49% of controls, while cefazolin plus vancomycin was used in 40.0% vs 43.5%.
S. aureus was the most common pathogen. Of the prespecified risk factors, BMI ≥25 kg/m² [adjusted odds ratio (aOR) 3.59, 95% confidence interval (CI) 1.21-10.66] and surgical duration ≥120 minutes [aOR 2.30, 95% (CI) 1.18-4.48] were each associated with an increased risk of SSIs in the multivariable regression analysis.
Conclusion: These findings provide insight into risk factors associated with SSIs, which can be considered to optimize peri-operative practices to reduce SSIs risk in patients undergoing orthopedic surgery.
Assessment QuestionWhich of the following perioperative risk factors has been associated with an increased risk of surgical site infection following orthopedic surgery?
- Age younger than 50 years
- Surgical duration ≤60 minutes
- Body mass index ≥25 kg/m²
- Cefazolin alone for surgical prophylaxis
Correct answer: C
