Diagnosing periprosthetic joint infection: current and novel technologies

IntroductionPeriprosthetic joint infection (PJI) remains a devastating complication of arthroplasty, afecting 1% to 2% of cases, and increasing with procedural volume. 1 Activity based analysis estimates a two-year cost of $64,585 (£31,322) per case. 2 Accurate diagnosis is essential to minimize morbidity and guide treatment, yet current tests are imperfect and no defnition is universally accepted.New technologies must therefore improve speed and certainty without sacrifcing rigour. Current diagnosticsSeveral diagnostic criteria for PJI coexist, but no single standard is universally accepted.The Infectious Diseases Society of America (IDSA), 3 International Consensus Meeting (ICM) 2018, 4 and European Bone and Joint Infection Society (EBJIS) 2021 criteria 1 perform diferently by infection timing and joint involved.5 The EBJIS ofers a pragmatic three level framework, with infection unlikely, likely, or confrmed, by integrating clinical signs, biochemical markers, microbiological cultures, histology and, in selected cases, nuclear imaging. 1 All negative fndings make infection unlikely.Raised CRP or suggestive clinical fndings together with another positive test make infection likely.A sinus tract communicating with the joint, synovial white cell count (WCC) > 3,000 cells/µl, polymorphonuclear neutrophil (PMN) > 80%, two or more concordant cultures, or histology showing at least fve neutrophils in at least fve high-power felds confrm infection.Caution is required in infammatory disease and the early postoperative period. 1 Within this framework, serum CRP, synovial WCC, and ESR are useful screening tests.Interleukin-6 (IL-6) peaks at 48 hours postoperatively and then rapidly falls to normal values and may be a more sensitive marker, though limited availability restricts its routine use.6 Serum marker trends support clinical suspicion, although normal or Diagnosing periprosthetic joint infection: current and novel technologies 1395 D. S.