Deep infections after low-velocity ballistic tibia fractures are frequently polymicrobial and recalcitrant.

Abstract

Objectives: To identify risk factors for developing a fracture-related infection in operatively treated ballistic tibia fractures and to report the microbiologic results of intraoperative cultures.

Design: Retrospective review.

Setting: Level 1 trauma center.

Patients/participants: One hundred thirty-three adults with operatively treated low-velocity ballistic tibia fractures, from 2011 to 2021.

Intervention: One dose of prophylactic cefazolin or equivalent as well as perioperative prophylaxis.

Main outcome measurements: Deep infection rate.

Results: The deep infection rate was 12% (16/134) with no significant difference in injury characteristics, index surgical characteristics, or time to antibiotics between the groups (P > 0.05). Patients who were slightly older (35.5 vs. 27 median years, P = 0.005) and with higher median body mass indexes (BMIs) (30.09 vs. 24.51, P = 0.021) developed a deep infection. 56.3% of patients presented with signs of infection within the first 100 days after injury. Nine patients had polymicrobial infections. There were 29 isolated organisms, 69% were uncovered by first-generation cephalosporin prophylaxis (anaerobes, gram-negative rods, Enterococcus, methicillin resistant Staphylococcus Aureus [MRSA]), and 50% of patients developed recalcitrant infection and required a second reoperation where 6 organisms were isolated, half of which were not covered by first-generation prophylaxis (Enterococcus, Staphylococcus Aureus MRSA).

Conclusions: We found a deep infection rate of 12% among ballistic tibia fractures receiving standard-of-care antibiotic prophylaxis. Increased age and body mass index were associated with deep infections. Half became recalcitrant requiring a second reoperation. 66.7% of isolated organisms were not covered by first-generation cephalosporin prophylaxis. Consideration should be given to treatment options such as broader prophylaxis or local antibiotic treatment.

Level of evidence: IV.