Background: Sonication fluid culture is routinely conducted in patients with suspected orthopedic devicerelated infection (ORI). However, its value in the assessment of orthopedic devices that have explanted because of presumed aseptic loosening is still debatable. A meta-analysis was conducted to estimate the yield of sonication fluid culture in detecting the presence of microorganisms in orthopedic devices with presumed aseptic loosening, and to summarize the clinical characteristics and outcomes of these patients.
Methods: A meta-analysis was performed of peer-reviewed publications detailing the characteristics of patients whose orthopedic devices were explanted for presumed aseptic loosening and who underwent subsequent sonication fluid culture. Diagnostic data were extracted and pooled to estimate the yield of sonication fluid culture for detecting the presence of microorganisms with 95% confidence intervals (CI).
Results: Eight studies involving 421 patients were included in the meta-analysis analysis. The pooled results showed that sonication fluid culture had a yield of approximately 30% (95% CI: 20-41%) for identifying the presence of microorganisms in presumed aseptic loosening of orthopedic devices; this yield was higher than that of intraoperative tissue culture (22%, 95% CI: 8-41%) and aspirated fluid culture (13%, 95% CI: 7-21%). Sonication and vortexing for ≤5 min had a detection rate of 49% (95% CI: 43-55%), which exceeded that of >5 min. Coagulase-negative Streptococcus accounted for 74% (95% CI: 51-92%) of the isolated microorganisms. However, patients with positive microbiological results of sonication fluid culture and those with negative results showed similar outcomes after revision surgery.
Conclusions: Colonization of low-virulent microorganisms may exist in a considerable number of patients with clinically presumed aseptic loosening of orthopedic devices. When this occurs, sonication (1-5 min at 40 kHz) of fluid culture could act as a sensitive diagnostic tool. However, the question of whether sonication fluid culture should be integrated into the routine treatment of loosened orthopedic devices requires further investigation.
Keywords: Sonication fluid culture; aseptic loosening; meta-analysis; microorganism colonization; orthopedic devices.