Echelon of Care at Time of External Fixation and Infection Risk in Military Combat Casualties

Role 2 (R2) U.S. military treatment facilities provide lifesaving far forward damage control resuscitation and surgery. Given the austere conditions at R2s, infection risk is a major concern. We aimed to evaluate the infection rate after external fixation (EF) in military casualties based on where in the evacuation pathway the EF was performed, hypothesizing that lower-echelon EF would be associated with increased infections.

The Department of Defense Trauma Registry (DoDTR) was retrospectively reviewed from 2003 to 2024. Non-U.S. military patients, deaths, and burns were excluded. Lower-echelon EF was defined as the first EF performed at R2, or Role 3 (R3) in cases of R2 bypass. Infection was defined as any one of seventeen infectious complications recorded in the DoDTR. We evaluated the independent association of lower-echelon EF on both wound infection (WI) and overall infection using multiple regression.

In 6,115 patients, 2,529 met inclusion criteria, of whom 646 (25.5%) developed postoperative infection. 19.0% of all EFs were placed at R2, 67.7% at R3, 5.4% at Role 4 (R4), and 7.8% at R4-Continental United States (R4c). Overall infection rate after EF was 19.2% for R2, 24.9% for R3, 19.8% for R4, and 38.8% for R4c (25.5% overall). Wound infection was the most common infectious complication at (8.6% after EF at R2, 14.5% for R3, 15.3% for R4, and 24.5% for R4C, 15.2% overall). On adjusted analysis, higher-echelon EF was independently associated with WI and overall infection: adjusted odds ratio of 1.718 (97.5% CI, 1.311-2.250), and 1.514 (97.5% CI, 1.208-1.899), respectively.

For U.S. military casualties, lower-echelon external fixation is associated with decreased infection despite the austere setting. Although this study is unable to elucidate the specific factor(s) responsible for this association, it highlights the need to maintain orthopedic expertise close to point-of-injury and for future work to identify the specific characteristics of either the patients who receive lower-echelon EF, their injuries, or the EFs at the Role 2 and Role 3 facilities themselves that are responsible for this association.