Risk Factors and Microbiological Profile of Knee Periprosthetic Joint Infections with Sinus Tract.

BACKGROUND:A sinus tract is an abnormal channel that communicates between the skin and the joint and meets one of the major criteria that is diagnostic of periprosthetic joint infection (PJI). The purpose of this study was to compare the risk factors and the microorganism profile of PJI of the knee with an overlying sinus tract to PJI without a sinus tract. METHODS:This was a retrospective case-control study of PJI following TKA with and without the presence of an overlying sinus tract from 1996 to 2020. There were 2,685 unique cases of chronic PJI following TKA, of which 405 cases (15.1%) had a sinus tract and 2,280 cases (84.9%) did not. Univariate and multivariate analyses were performed to evaluate risk factors and the microorganism profiles of the two groups. Odds ratios (OR) with 95% confidence intervals (CI) were reported. RESULTS:After adjusting for potential confounders in the multivariate analysis, the presence of a sinus tract was associated with a history of severe liver disease (P = 0.039, OR 1.99, 95% CI 1.04 to 3.84). Polymicrobial infections comprised 41.7% of PJI in the sinus tract group, compared to 29.1% in patients who did not have a sinus tract (P < 0.001). Of the monomicrobial PJI, Staphylococcus aureus (P < 0.001), Enterococcus faecalis (P < 0.001), Enterobacter cloacae (P = 0.002), Corynebacterium species (P = 0.037), Proteus mirabilis (P = 0.028), coagulase-negative Staphylococci (P = 0.019), and Candida albicans (P = 0.029) were more common in patients who had a sinus tract. CONCLUSION:The microbiology profile is significantly different in patients who have PJI of the knee with a sinus tract. These findings can guide the surgeon with surgical planning and selecting the appropriate antibiotic-loaded bone cement and empiric antibiotic treatment.