Table 2 Summary of synovial fluid biomarkers
From: Joint aspiration for diagnosis of chronic periprosthetic joint infection: when, how, and what tests?
Biomarker | Efficacy | Amount of Fluid Required (mL)a | Wait Timea | Advantages | Disadvantages | Ref. |
|---|---|---|---|---|---|---|
Leukocyte esterase | Sensitivity: 49%–95% Specificity: 82%–100% PPV: 72%–100% | ~ 20 µL | 10 min | Readily available, easy to use, inexpensive Can be used in the setting of recent antibiotics | Can be influenced by presence of blood or metallic debris | |
Alpha-defensin | Sensitivity: 65%–95% Specificity: 87%–99.6% PPV: 75%–98% NPV: 84%–98% | 0.5 mL | Lateral flow test: 10 min ELISA: 2–5 days | Not influenced by recent antibiotic use | Can be influenced by metallic debris and crystalline arthropathies | |
Synovial CRP | Sensitivity: 70%–96% Specificity: 85%–100% PPV: 68% NPV: 95% | 0.5 mL | Approx 1–3 h | Can be used in the setting of recent antibiotic use and inflammatory arthropathies | No information regarding organism | |
Multiplex PCR | Sensitivity: 85% Specificity: 98% PPV: 97.6% NPV: 87.5% | 180 µL | Approx. 5 h | Provides causative organism and potential antibiotic resistance Can be used in the setting of recent antibiotic use | Not readily available Causitive organism must be present on the cassette in order to be detected | |
Next generation sequencing | Sensitivity: 89% | 2 mL | In house: 9–48 h Send out: 2–7 days | Provides causative organism and potential antibiotic resistance Can be used in setting of recent antibiotic use and inflammatory arthropathies Most useful in culture-negative cases | Not readily available, costly Requires specialized equipment or lab send-out High rate of contamination and false positives | |
Interleukins | Sensitivity: 100% Specificity: 100% | 110 µL | Lateral flow: < 20 min Immuno-assay: approx. 1–5 h | Can be used in the setting of recent antibiotic use | Accuracy is dependent on immunoassay technique | |
Calprotectin | Sensitivity: 71%–94% Specificity: 81%–88% PPV: 0.71–0.77 NPV: 0.76–0.98 | 20 µL | 15 min | Fast turn-around Requires smartphone application only for analysis | No definitive thresholds for PJI at this time Not yet widely available | |
Neutrophil gelatinase-associated lipocalin | Sensitivity: 86%–100% Specificity: 77%–100% | 0.5 mL | 15 min to 4.5 h | Can be used in the setting of recent antibiotic use and inflammatory arthropathies | No definitive thresholds for PJI at this time May be correlated with number of neutrophils present in sample | |
Lactoferrin | Sensitivity: 97%–100% Specificity: 90%–100% | 0.5 mL | In house: 4–24 h Send out: 4–8 days | Can be used in the setting of inflammatory arthropathies | No definitive thresholds for PJI at this time May be correlated with number of neutrophils present in sample Minimal clinical studies available |