The Diagnosis Of Persistent Infection In Patients Without Synovial Fluid Before Reimplantation

Section A Changes in serum markers failed to predict persistent infection after two-stage exchange arthroplastyObjective: The proper timing of reimplantation is importation to treatment success in two-stage exchange revision.The 2018 International Consensus Meeting suggested that a variation trend toward normalization in serum markers was useful for determining the proper timing of reimplantation.However,the opposite results were found that by previous studies,and the normalization of serum markers was reported to fail to predict infection control.We investigated whether value changes and percent changes in four common serum markers(erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),interleukin-6(IL-6)and fibrinogen)can predict persistent infection?Methods: A retrospective review of 141 patients treated with two-stage revision from 2014 to 2018 was conducted.The variation trend in serum indicators was evaluated by the percent changes(using values of serum markers prereimplantation divided by values preresection)and value changes(using values of serum markers preresection minus values prereimplantation).Treatment success was defined according to the Delphi-based consensus criteria with a minimum follow-up of 1 year,and the receiver operator characteristic(ROC)was used to examine the usefulness of changes in serum markers.Results: 22 patients(15.60%)were persistently infected.No significant difference was found in either the value change or percent change in serum markers between reinfection and non-reinfection patients.When predicting persistent infection,the area under the curves(AUC)demonstrated that both percent changes and value changes in serum markers were poor indicators.The AUC of value changes was0.533 for the CRP,0.504 for the IL-6,0.508 for the ESR and 0.586 for fibrinogen when predicted persistent PJI.In addition,the AUC indicated that percent changes in the CRP(0.464),the IL-6(0.534),the ESR(0.527)and fibrinogen(0.586)were all poor markers.Conclusions: We have shown that both value changes and percent changes in serum markers were not sufficiently rigorous to aid in persistent infection diagnosis.The proper timing of reimplantation must therefore take into account various clinical tests rather than the downward trend of serum markers only.Section B: The 2018 New Definition of Periprosthetic Joint Infection is Valuable for Diagnosis of Persistent Infection at Reimplantation in Patients without Synovial FluidObjective: The aim of our study was to(1)evaluate the performance of the 2018 new definition in determining the persistent infection at reimplantation in the absence of synovial fluid;(2)evaluate the performance of the modified MSIS criteria in determining the persistent infection at reimplantation in the absence of synovial fluid;and(3)compare the diagnostic accuracy in determining the persistent infection between the new definition and modified MSIS.Materials and Methods: We retrospectively reviewed 150 patients who underwent 2-stage exchange revision from January 2014 to December 2018.All medical records were manually reviewed in detail,which included patients’ demographics,comorbidities,serum markers,histopathology findings,microbial culture results,and intraoperative findings at the time of resection and reimplantation.In the absence of joint fluid,the diagnosis model of persistent infection with the 2018 new definition and the 2013 MSIS was established by referring to the previous literature and expert consensus.Two criteria were used to define persistent infection:model 1:identical major criteria of the MSIS criteria and new definition and model 2: identical major criteria of 2 criteria and/or subsequent infection after reimplantation.Patients in the infection and non-infection groups were all graded according to the 2018 new definition,and the control of infection was determined by total scores.The predictive accuracy of persistent infection in 2 models was calculated by using receiver operating characteristic(ROC)curves.The optimal cut-off in scoring system of the 2018 new definition was determined by Youden’s J-statistic.The sensitivity,specificity,positive predictive value(PPV),and negative predictive value(NPV)of the 2018 new definition and the MSIS criteria in 2 models were calculated.Results: According to the Youden’s J-statistic,the optimal threshold for aggregate scores in new definition was 4 in both model 1 and model 2.In model 1,the sensitivity and specificity of the 2018 new definition were 86.96%(95% confidence interval [CI] 67.83-95.51),84.25%(95% CI 77.83-90.67),and the AUC was 0.871;the sensitivity and specificity of the 2013 MSIS criteria were 47.83%(95% CI 25.74-69.91),93.70%(95% CI 88.06-96.77),and the AUC was 0.708.In model 2,the sensitivity and specificity of the 2018 new definition were 78.57%(95% CI 58.54-90.97),85.25%(95% CI 77.42-90.79),and the AUC was 0.835;the sensitivity and specificity of the 2013 MSIS criteria were 39.29%(95% CI 22.12-59.27),93.44%(95% CI 87.08-96.92),and the AUC was 0.664.The 2018 new definition had significant higher diagnostic value than MSIS criteria in both model 1(P= 0.004)and model 2(P=0.0002).Conclusions: the 2018 new definition of PJI is valuable in the diagnosis of persistent infection at reimplantation,which had both high sensitivity and specificity.It can obviously improve diagnostic accuracy compared with the MSIS criteria in patients without synovial fluid.In the absence of synovial fluid,the 2018 new scoring system may guide the timing of reimplantation and prevent the occurrence of postoperative infection.