Synovial hyperperfusion indicates low-grade periprosthetic joint infection after knee arthroplasty : contrast-enhanced ultrasound as a complementary diagnostic tool.

Aims: Accurate and timely diagnosis of periprosthetic joint infection (PJI) is crucial, yet often challenging due to the disease's ability to evade even advanced imaging techniques and laboratory tests. This clinical prospective study evaluates the diagnostic quality of a contrast-enhanced ultrasound (CEUS)-based tissue microperfusion assessment in patients where a PJI is suspected. Methods: This current work was conducted as a cross-sectional monocentric study. In total, 61 patients with a mean age of 66.36 years (SD 8.70) were included between October 2021 and February 2024. Established laboratory markers, the microbiological results of joint fluid aspiration, and intraoperative tissue biopsy results were correlated with synovial perfusion patterns assessed with CEUS. Results: The CEUS-assessed perfusion differences between aseptic and infected knees after total knee arthroplasty (TKA) were highly significant (p < 0.001). For the detection of a PJI, a sensitivity of 77.8% and specificity of 88.5% with a cutoff peak enhancement of 568 (a.u.) was demonstrated. Conclusion: If confirmed in larger studies, CEUS may contribute to the growing diagnostic toolbox applicable in cases where a low-grade PJI is suspected, aiming to improve and accelerate therapy planning in difficult PJI cases.