Exploring Novel Diagnostic Tools for Periprosthetic Joint Infection

Study Overview
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Brief Summary
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Joint replacement is a valuable surgical intervention that improves quality of life, provides pain relief, and restores function of patients. However, some patients need revision surgery due to failure of the implant, with periprosthetic joint infection (PJI) remaining a rare but serious complication following total hip (THA) and knee (TKA) arthroplasty. Diagnosing PJI is a major challenge as no diagnostic test with absolute accuracy exists. The diagnosis is based on a combination of clinical findings, laboratory results from peripheral blood and synovial fluid, microbiological culture, histological evaluation of periprosthetic tissue, and intraoperative findings. However, the preoperative diagnosis can be inconclusive and operative criteria are required for the definitive diagnosis. Therefore, novel diagnosing tools for identification of PJI are necessary. A recent study using a gene reporter assay, identified biomarkers in synovial fluid that define joint states in patients with osteoarthritis.However, no previous studies have investigated cellular signaling in synovial fluid of patients with PJI. With this study we want to explore the potential of a reporter gene assay of synovial fluid in patients with PJI and without PJI of their TKA and THA. Also, flow cytometry analysis of biological fluids has recently received increased attention as a potentially valuable method in diagnosing infections. For example, the method is already used to analyze urine samples for urinary tract infections. Recently, researchers have now also used this method to screen for the presence of bacteria. The most important limitation of flow cytometry analysis of synovial fluids for bacteria to date is that it is unclear as to which bacteria count value - the cutoff value - represent patients with PJI and which represent patients without PJI. With this study we want to explore the potential of flow cytometry analysis of synovial fluid in categorizing patients with PJI and without PJI. Our primary objective is to explore the value of synovial fluid analysis using a reporter gene assay and flow cytometry in the detection of a periprosthetic joint infection.

Official Title
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Exploring the Value of the Reporter Gene Assay and Flow Cytometry of Synovial Fluid in Total Hip and Knee Arthroplasty as a Diagnostic Tool for Periprosthetic Joint Infection

Conditions
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Prosthesis-Related Infections, Arthroplasty, Replacement, Hip, Arthroplasty, Replacement, Knee

Intervention / Treatment
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* Diagnostic Test: Reporter Gene Assay
* Diagnostic Test: Flow Cytometry


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients planned for elective THA or TKA revision surgery with revision of one or more fixed components will be eligible to participate in this study. Exclusion Criteria: are planned for a revision of single mobile parts only; have received intravenous and/or oral antibiotics within 2 weeks before the diagnostic workup and/or surgery; are unable to provide their consent for use of their human tissues for medical research.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| PJI<br>Patients diagnosed with a PJI based on the EBJIS criteria ('Infection confirmed') | Diagnostic Test: Reporter Gene Assay<br>* Transcription factor reporter gene assay using luciferase<br>Diagnostic Test: Flow Cytometry<br>* Flow Cytometry Analysis using the Sysmex UF-4000, analyzing for bacteria, mononuclear and polymorphonuclear cells, and red blood cell and white blood cell count.<br>|
| No PJI<br>Patients not diagnosed with a PJI based on EBJIS criteria | Diagnostic Test: Reporter Gene Assay<br>* Transcription factor reporter gene assay using luciferase<br>Diagnostic Test: Flow Cytometry<br>* Flow Cytometry Analysis using the Sysmex UF-4000, analyzing for bacteria, mononuclear and polymorphonuclear cells, and red blood cell and white blood cell count.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fold change of luciferase assay | Diagnostic performance of the reporter gene assay of synovial fluid by calculating fold change data from the reporter gene measurements. A luciferase assay will be performed using the collected synovial fluid and the amount of luciferase activity will be measured by luminometer and expressed in relative light units (RLU). A background control (e.g., medium or buffer alone) will be used to evaluate raw RLU values that will be subtracted from all the sample values for better accuracy. The data for the reporter assay will be expressed using an equation to determine normalized fold change in activity between the two groups. | Within 30 days of surgery | 
| Diagnostic performance of flow cytometric analysis | Diagnostic performance of the flow cytometry analysis of synovial fluid by determining difference in results between two groups using ROC curve analysis. If a cut-off point has been determined, sensitivity (SN), specificity (SP), negative (NPV) and positive predictive value (PPV) can be calculated. | Within 4 hours of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Sensitivity of the flow cytometric analysis |  | Within 4 hours of surgery | 
| Specificity of the flow cytometric analysis |  | Within 4 hours of surgery | 
| Positive predictive value of the flow cytometric analysis |  | Within 4 hours of surgery | 
| Negative predictive value of the flow cytometric analysis |  | Within 4 hours of surgery |