Absolute synovial polymorphonuclear neutrophil cell count as a biomarker of periprosthetic joint infection

Abstract

AimsThe aim of this study was to evaluate the diagnostic accuracy of the absolute synovial polymorphonuclear neutrophil cell (PMN) count for the diagnosis or exclusion of periprosthetic joint infection (PJI) after total hip (THA) or knee arthroplasty (TKA).MethodsIn this retrospective cohort study, 147 consecutive patients with acute or chronic complaints following THA and TKA were included. Diagnosis of PJI was established based on the 2018 International Consensus Meeting criteria. A total of 39 patients diagnosed with PJI (32 chronic and seven acute) and 108 patients with aseptic complications were surgically revised.ResultsUsing receiver operating characteristic curves and calculating the area under the curve (AUC), an optimal synovial cut-off value of 2,000 PMN/µl was determined (AUC 0.978 (95% confidence interval (CI) 0.946 to 1)). Using this cut-off, sensitivity and specificity of absolute synovial PMN count for PJI were 97.4% (95% CI 91.2 to 100) and 93.5% (95% CI 88.9 to 98.1), respectively. Positive and negative predictive value were 84.4% (95% CI 72.7 to 93.9) and 99.0% (95% CI 96.7 to 100), respectively. Exclusion of 20 patients with acute complications improved specificity to 97.9% (95% CI 94.6 to 100). Different cut-off values for THA (< 3,600 PMN/µl) and TKA (< 2,000 PMN/µl) were identified. Absolute synovial PMN count correlated strongly with synovial alpha-defensin (AD) (r = 0.759; p < 0.001). With a positive AD result, no additional PJI could be identified in any case.ConclusionAbsolute synovial PMN count is a widely available, rapid, cost-effective, and accurate marker in PJI diagnostics, whereas synovial AD appears to be a surrogate parameter of absolute synovial PMN count. Despite limitations in the early postoperative phase, wear, and rheumatic diseases in confirming PJI, an absolute synovial PMN count below 2,000/µl is highly suitable for ruling out PJI, with specific cut-off values for THA and TKA.Cite this article: Bone Joint J 2023;105-B(4):373–381.

Do Clinical Parameters Reflect Local Bone Metabolism in Heterotopic Ossification After Septic or Aseptic THA?

“…As noted above, PJI was diagnosed based on the International Consensus Meeting 2018 criteria [33] through preoperative assessment of serum (C-reactive protein, erythrocyte sedimentation rate, and D-dimer) and synovial parameters (white blood cell count, polymorphonuclear neutrophil count, alpha-defensin, and microbiological analysis) [16]. Furthermore, tissue samples for histologic and microbiologic analysis were obtained during revision surgery in all patients from the bone-prosthesis interface.…”

Treatment of femoral bone loss in revision total hip arthroplasty: a clinical practice review

“…Synovial fluid obtained with a hip aspirate should be sent for differential cell analysis and both aerobic and anaerobic cultures. A white cell count of 2,000–3,600 and a differential of >80% polymorphnuclear (PMN) leukocytes is suspicious for infection ( 11 , 12 ). Jandl et al ( 12 ) demonstrated an absolute PMN cell count of less than 2,000/µL as adequate for ruling out periprosthetic joint infection.…”

“…A white cell count of 2,000–3,600 and a differential of >80% polymorphnuclear (PMN) leukocytes is suspicious for infection ( 11 , 12 ). Jandl et al ( 12 ) demonstrated an absolute PMN cell count of less than 2,000/µL as adequate for ruling out periprosthetic joint infection. In the presence of metal-on-metal components, or an adverse reaction to metal debris in metal on polyethylene implants, metal ions including cobalt and chrome should also be tested.…”