A deep surgical site infection risk score for patients with open tibial shaft fractures treated with intramedullary nail

Objectives: To identify deep infection risk factors in patients with open tibial shaft fractures and to develop a scoring algorithm to predict the baseline deep infection risk in this patient population.

Methods: A retrospective cohort study conducted at a single academic trauma center identified patients with open tibial shaft fractures treated with intramedullary nail fixation from December 2006 to October 2020. The primary outcome was a deep surgical site infection requiring surgical debridement. The outcome was identified by Current Procedural Terminology codes and confirmed with a medical chart review documenting evidence of a tibial draining wound or sinus tract.

Results: Deep surgical site infection occurred in 13% of patients (97/769). Factors that predicted deep surgical site infection were identified. Gustilo-Anderson type IIIB or IIIC was the strongest predictor with a 12-fold increase in the odds of deep infection (OR 11.8, p < 0.001). Additional factors included age >40 years (OR 1.7, p = 0.03), American Society of Anesthesiologists score ≥3 (OR 1.9, p < 0.01), Gustilo-Anderson type IIIA vs. type I or II (OR 2.8, p = 0.004), and gunshot wounds (OR 2.9, p = 0.02). The risk scoring model predicted patients who would develop an infection with an acceptable level of accuracy (AUC 0.79). The risk score categorized patients from a low probability of deep infection 2%-6% with <10 points to high risk (58%-69%) with >40 points.

Conclusions: This risk score model predicts deep postoperative infection in patients with open tibial shaft fractures treated with intramedullary nails. The ability to accurately estimate deep infection risk at the time of presentation might aid patient expectation management and allow clinicians to focus infection prevention strategies on the high-risk subset of this population.