Possibilities of latent PJI detection in revision knee arthroplasty

Introduction The paper presents a comparative analysis of routine screening methods and the EBJIS 2021 algorithm in detection of latent periprosthetic joint infection in patients admitted for revision knee arthroplasty due to aseptic loosening and after spacer implantation. Materials and methods Group 1 included 49 patients who underwent revision knee arthroplasty due to aseptic loosening, group 2 were 47 patients with PJI after spacer implantation. Results and discussion There were no significant differences between patient groups in terms of age, gender, and preoperative ESR and CRP levels. In 62.2 % of all cases, the aspirate was inappropriate for cytological examination; this fact limited its diagnostic value. The most frequently intraoperatively isolated pathogen in both groups was coagulase-negative staphylococci. However, in 70 % of cases these results were not diagnostically significant, and infection was diagnosed only in 8.2 % of cases in group 1 and 12.8 % in group 2. Moreover, the chances of isolating the pathogen from tissue biopsies were 5.6 times higher than from intraoperative aspirate (OR = 5.6, 95 % CI = 1.2-26.4). In case of negative preoperative aspirate, in almost 25 % of cases, pathogens were isolated from intraoperative tissues, 40.9 % of them were diagnostically significant. The chances of its detection increased 4.7 times in combined increase in ESR and CRP blood level (OR = 4.686, 95 % CI = 0.765-28.700). Using EBJIS 2021 criteria, infection was confirmed in more than 10 % of cases in each group, and the diagnostic significance of the criteria exceeded the significance of using routine screening methods. At a follow-up period of more than 2 years, the effectiveness of treatment was 95.3 %, while signs of infection were detected in 4.7 % of cases, regardless of the group. Conclusion EBJIS 2021 criteria are characterized by high diagnostic sensitivity and specificity and enable to identify periprosthetic joint infection in knee revision cases even in its latent form and to correct treatment tactics in patients without a history of PJI.