Uvodich ME, Dugdale EM, Osmon DR, et al. - As difficulty remains in early diagnosis of postoperative periprosthetic joint infection (PJI) following total knee arthroplasty (TKA), researchers aimed at validating the optimal cutoff values of ESR, CRP, and synovial fluid analysis that may aid in early detection of postoperative PJI in a large series of primary TKAs. A total of 27,066 primary TKAs were retrospectively identified. Of these, 169 patients (170 TKAs) had an aspiration within 12 weeks. The patients were grouped into two: those evaluated ≤ 6 weeks, or between 6 and 12 weeks postoperatively. Based on findings, researchers herein emphasize suspecting early PJI after TKA within 6 weeks if the CRP is ≥ 82 mg/l, synovial WBCs are ≥ 8,676 cells/μl, the percentage of synovial neutrophils is ≥ 88%, and/or the ANC is ≥ 8,346 cells/μl. Between 6 and 12 weeks, thresholds include a CRP of ≥ 34 mg/l, synovial WBC of ≥ 1,983 cells/μl, a percentage of synovial neutrophils of ≥ 76%, and/or an ANC of ≥ 1,684 cells/μl.