Karbysheva S, et al. - In this study, the performance of synovial fluid d-lactate was analyzed applying 2 definition criteria and ascertained its optimal cutoff value for diagnosing periprosthetic joint infection (PJI). Researchers prospectively enrolled consecutive patients who underwent joint aspiration before prosthesis revision. They obtained synovial fluid for culture, leukocyte count, and d-lactate concentration (by spectrophotometry). They applied Youden's J statistic for ascertaining optimal d-lactate cutoff value on the receiver operating characteristic curve by maximizing sensitivity and specificity. There were a total of 224 patients who included in this study. Applying both definition criteria and correlated with the pathogen virulence, the synovial fluid d-lactate revealed high sensitivity (>90%) for diagnosis of PJI. The findings suggested that the high sensitivity makes this biomarker beneficial as a point-of-care screening test for PJI.