Sonication versus peri-implant tissue culture in fracture-related infection: diagnostic performance and therapeutic consequences in a single-center cohort.

Introduction: Fracture-related infections (FRIs) represent a severe complication and pose diagnostic challenges due to biofilm-associated microorganisms. While peri-implant tissue culture (PTC) remains the standard, its sensitivity is limited. Sonication of explanted osteosynthesis material has been proposed as a complementary diagnostic tool; however, its contribution remains controversial. The aim of this study was to compare sonication and peri-implant tissue culture and their impact on antimicrobial management. Methods: In this retrospective single-center study, all patients undergoing implant removal for FRI between 2016 and 2023 were screened. Cases with peri-implant tissue cultures and sonication fluid cultures (SFCs) were included. The diagnostic yield and pathogen spectrum of PTC and SFC were compared, including analyses in patients receiving antibiotic therapy. The impact of microbiological findings on antibiotic management was evaluated. Results: Of 287 screened cases, 157 patients met the inclusion criteria. Pathogen detection was achieved in 60.5 % using PTC and 57.3 % using SFC. Incorporating both methods increased the diagnostic yield to 70.1 %. Sonication identified additional pathogens in 17.8 % of cases and PTC in 22.9 %. Under antibiotic therapy, PTC demonstrated a slightly higher diagnostic yield than SFC. Antibiotic therapy was modified after revision surgery in 47.8 % of cases, while sonication alone influenced treatment decisions in 4.5 % of patients. Conclusions: Neither PTC nor SFC alone achieved the diagnostic performance of their combined use. Combined testing improved diagnostic yield, supported targeted antimicrobial management, and reinforced the value of a multimodal microbiological approach to FRI.