Evaluating the Duration of Prophylactic Post-Operative Antibiotic Agents after Open Reduction Internal Fixation for Closed Fractures.

Background: The importance of timely pre-operative antibiotic agents for effective surgical prophylaxis has been established but the optimal duration of antimicrobial coverage post-operatively has not yet been defined clearly. The purpose of this study was to determine if prophylactic post-operative cefazolin for 23 hours decreases the risk of surgical site infection (SSI) after open reduction internal fixation (ORIF) of closed extremity fractures. Patients and Methods: After Institutional Reviews Board approval, patients undergoing ORIF of closed extremity fractures who had a planned post-operative stay of at least 23 hours were randomly assigned to either receive 23 hours of cefazolin or a placebo. Both groups received weight-based pre-operative cefazolin and intra-operative re-dosing at three-hour intervals until surgery completion. The primary end point was infection. Patients were followed clinically until bony union. Published risk factors were accumulated as a risk score to help determine risk of SSI. Results: A total of 227 patients were randomized to either receive post-operative cefazolin or placebo and 160 patients completed clinical follow-up to bony union. There were 83 patients in the cefazolin group and 77 in the placebo group. Surgical site infections occurred in a total of 15 patients (9.4%) in this trial without any differences between the cefazolin and placebo groups. Patients with diabetes mellitus were 4.33 times more likely to develop an SSI (95% confidence interval [CI], 1.30-14.38; p = 0.02). Patients with a risk score of two or more were 3.14 times more likely to develop an infection (95% CI, 1.02-9.68; p < 0.05). Conclusions: Although not statistically significant, in a randomized double-blinded placebo-controlled trial, patients who were treated with a 23-hour post-operative regimen of antibiotics after ORIF were less likely to develop SSIs. Patients with diabetes mellitus and those with a risk score of two or greater were more likely to develop an SSI.