The Significance of Sonication in the Detection of Peri-Implant Infections.

Objective: The current gold standard for detection of implant-related infections is the intraoperative collection of tissue samples. However, false-negative results frequently occur, particularly in infections caused by biofilm-forming bacteria. As a complementary method, sonication has therefore been established for detecting implant-associated infections, especially in periprosthetic joint infections. In trauma surgery, this technique is still rarely used. The aim of this study is to evaluate the diagnostic significance of sonication after osteosynthesis. Methods: A retrospective single-center analysis was conducted on all patients who underwent plate osteosynthesis removal between 1 January 2019, and 1 May 2021, with both sonication and intraoperative tissue sampling performed. Patients with inlying arthroplasties or nail-less osteosynthesis systems were excluded. Pre- and postoperative infection parameters (leukocytes, CRP) were recorded, and preoperative clinical findings were used to classify suspected infection. Results: A total of 57 patients (30 men, 27 women; mean age 57.6 years, range 12-91) were included. The mean treatment duration was 20.1 days (range 1-152). Sonication was positive in 33 patients, tissue samples in 28, with 31 cases (54%) showing concordant results. In cases with preoperative suspicion of infection, sonication was positive in 21 of 26 cases (80.7%) and tissue samples in 18 of 26 (69.2%), whereas without suspicion, positivity rates were 38% and 31%, respectively. Sonication and tissue results matched in 14 of 26 cases; in the remainder, results were different or incomplete. Preoperative CRP elevation and the presence of an infection membrane influenced sensitivity: sonication generally detected more bacteria (59-81%) than tissue samples (49-73%), though discrepancies remained. Conclusions: Sonication represents a valuable complementary method for detecting implant-related infections. Due to its high sensitivity but limited specificity, it should not be used as a standalone diagnostic method.