Microbiological diagnostic criteria of infectious inflammatory complications after total knee replacement in the aspect of periprosthetic joint infection (PJI) pathogenesis

Background. The system of accurate microbiological diagnostics of PJI for timely identification of infectious inflammatory complications after total joint replacement and distinguishing between PJI and aseptic infection has not been yet defined which is associated with the pathogenesis of PJI. The Aim of the study is to define valuable microbiological diagnostic criteria for PJI and estimate diagnostic value of various clinical specimens with the account to pathogenetic features of infectious complications after primary total knee replacement. Material and Methods. We analyzed 412 specimens of various clinical origin obtained from 182 patients with deep PJI after primary total knee replacement treated at the Research Institute of Traumatology, Orthopedics and Neurosurgery of Razumovsky Saratov State Medical University in 2014-2018, both retro- and prospectively. Results and Discussion. Fistula, aspirate and superficial wound specimens taken from the joint cavity have not been proven to have any diagnostic value for PJI. Optimized microbiological algorithm included prolonged culture time, the complex of 3-5 tissue bioptate cultures and implant sonication which allowed obtaining more valuable results for PJI diagnostics. Tissue bioptates and lavage fluid specimens tests were the most sensitive methods for PJI diagnostics with sensitivity of 81% and 95% and specificity of 96% and 97% respectively, especially in case of coagulase-negative Staphylococcus and Gram-negative bacteria frequently appearing in the biofilm form at PJI. Conclusions. Complex assessment of obtained results and optimization of microbiological methods allow obtaining sufficient diagnostic accuracy of PJI.