We found the highest PLR, as indicator for the presence of a PJI, for the combined microbiological and histological evaluation of arthroscopic biopsy specimens (21.7; 95% CI 1.4–333.4) followed by synovial aspirate with sole microbiologic workup (6.0; 95% CI 0.8–44.4) and concurrent assessment of ESR, CRP, cell count as well as differential and microbiological analysis from synovial aspirate (10.5; 95% CI 1.6–69.8) (Table 2; Fig. 1). This evidence concerns the gene ESR1 and juvenile polyposis syndrome.