What Is the Risk of Irrigation and Debridement Following Foot and Ankle Surgery? Development of a Risk Severity Scoring System
Authors: Bonsignore-Opp Lisa , Malka Matan S. , Gorroochurn Prakash , Bender Joshua , Kunes Jennifer A. , Fogel Hart , Schweppe Eric , Vosseller J. Turner , Greisberg Justin K. 
Published: July 2024

Background
Surgical site infection (SSI) after foot and ankle surgery has serious negative effects on patient health and quality of life. While previous studies have looked at predisposing factors for SSI, to our knowledge, no study has proposed a risk severity score.

Questions/purposes
Can a risk severity score, based on patient demographic characteristics and surgical variables, be developed for preoperative use in patients undergoing foot and ankle surgery that will calculate the risk of an irrigation and debridement (I&D) procedure within 90 days of surgery utilizing data from previous surgeries?

Methods
A retrospective chart study was performed on patients undergoing foot and ankle surgery. Data on demographic characteristics including age, sex, and BMI were recorded. Data on patient factors including diabetes and smoking history were also recorded. Surgical details including length of surgery, procedure type, surgeon, antibiotic delivery time, antibiotic type, and antibiotic dose were analyzed. Of 2979 procedures, 1% (36) of I&Ds were performed within 90 days. The mean age at surgery was 49 ± 17 years, and 57% (1702) of patients were female. The mean BMI was 28 ± 6 kg/m2. The primary outcome was I&D within 90 days postoperatively. Descriptive statistics of differences in patient characteristics between those who underwent I&D and those who did not were examined using chi-square tests and t-tests (p < 0.05 was taken as significant). Significant variables from a simple regression analysis were included in a multiple logistic regression model with a forward stepwise procedure for variable selection. We required all data in the model to be categorical; thus, continuous variables such as time were dichotomized. We factored odds ratios determined by multiple regression for significant variables into the final risk severity score, and an easy-to-use tool based on this risk severity score was created in Excel (Microsoft).

Results
Current tobacco use, diabetes, and longer operative times were the only factors associated with I&D within 90 days postoperatively. A risk severity score was developed using current tobacco use, diabetes, and length of surgery greater than 60 minutes as factors. A patient with a severity score of 0 (no risk factors) had a 0.6% chance of I&D within 90 days, while a severity score of 1 indicated a 1.1% chance, a score of 2 indicated a 2.1% chance, a score of 3 indicated a 4.0% chance, and a score of 4 (all risk factors) indicated a 7.5% chance of I&D within 90 days. A spreadsheet that can be used at the point of care was created based on these findings.

Conclusion
Our risk severity score may help inform preoperative patient guidance and operative planning. Calculating the score in the office setting during preoperative visits can also improve communication between physician and patient. Future research should focus on validation of this risk severity score at multiple institutions.

Level of Evidence
Level III, prognostic study.