Prospective Evaluation of a Standardized Outcome Reporting System for Fracture-Related Infection (Fri-End): A Cohort Study

Aim Until recently, no standardized outcome reporting system for fracture-related infection (FRI) was available. An international expert consortium (FRI-end initiative) therefore proposed a comprehensive outcome reporting framework distinguishing infection control and bone healing. The aims of this study were (1) to determine whether two-year follow-up provides additional value compared to one-year follow-up, and (2) to evaluate the applicability of this outcome reporting system in a cohort of patients undergoing treatment for FRI. Methods Adult patients undergoing curative surgery for FRI between 2020 and 2023 with a minimum follow-up of one year were included in this prospective cohort study. The outcome reporting system was assessed at one- and two-year follow-up. The system categorizes outcomes separately for infection control, bone union, and a combined outcome. Four stages were defined for each category: C1 (successful outcome with optimal course), C2 (successful outcome with deviations from optimal course, e.g., revision surgery), S (suppressive antibiotic treatment or bone union not expected, e.g., complex reconstruction), and F (failure, defined as persistent infection or non-union). Results A total of 106 patients with 112 confirmed FRIs were included. At one-year follow-up, infection control was successful in 73.2%(C1) and 17.9%(C2), while seven cases (6.3%) were under suppressive antibiotics (S) and in three cases (2.7%) an infection persisted (F). Bone union was achieved in 67.0%(C1) and 0.9%(C2), whereas in ten cases (8.9%) bone union was not expected (S) and in 23.2% a non-union was diagnosed (F). The combined outcome showed 58.0% C1, 8.0% C2, 10.7% S, and 23.2% F. At two-years follow-up, data were available for 99 FRIs (94 patients), with seven FRIs lost to follow-up and six deaths. In the category “infection control”, success rate improved to 79.8% (C1) and 18.2% (C2), with one case each of categories S and F. Bone union rates increased to 76.8% (C1) and 18.2% (C2), with no cases in S and five persistent non-unions (F). The combined outcome showed 65.7% C1, 28.3% C2, 1.0% S, and 5.1% F. Conclusions The proposed outcome reporting system for FRI is feasible and provides a differentiated assessment of treatment success by separately capturing infection control and bone union. While infection control rates were high at one year, bone healing remained the limiting factor for overall success. Continued improvement between one- and two-year follow-up highlights the importance of longer-term assessment. This standardized framework enables more precise outcome reporting and may improve comparability across future studies.