Medical College of Wisconsin
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The Alpha-Defensin Prosthetic Joint Infection Test Has Poor Validity for Native Knee Joint Infection. J Arthroplasty 2021 Aug;36(8):2957-2961

Date

04/27/2021

Pubmed ID

33896668

DOI

10.1016/j.arth.2021.03.020

Scopus ID

2-s2.0-85106207086 (requires institutional sign-in at Scopus site)   8 Citations

Abstract

BACKGROUND: The alpha-defensin test known as Synovaure has been very effective in diagnosis of prosthetic joint infections (PJIs). Being able to easily and accurately differentiate septic and inflammatory arthropathies in native joints would improve diagnostic workup and management. We tested the ability of an alpha-defensin test to distinguish septic from inflammatory or crystalline arthropathy in the native knee.

METHODS: 40 native knee joint fluid specimens were tested with cell count, fluid analysis, and culture and alpha-defensin testing. We determined the sensitivity and specificity of the alpha-defensin test using culture-positive fluid as the gold standard for septic arthropathy and positive crystals as the gold standard for crystalline arthropathy.

RESULTS: The Synovasure PJI test had 100% specificity for septic arthritis coupled with a 28% false-positive rate when applied to native knee aspirations. False-positive rate was 5.3 times higher in patients with crystals found in the joint fluid.

CONCLUSION: Alpha-defensin testing, in the form of the Synovasure PJI test, has a high-false-positive rate when used to distinguish septic and inflammatory arthritis in the native knee joint. Future work will need to determine the sensitivity and specificity of the newer native joint panel. Clinicians should be cognizant of the specific alpha-defensin test used when sampling native knee synovial fluid.

Author List

Cooper KB, Siegel ER, Stambough JB, Bumpass DB, Mears SC

Author

Kasa Blaine Pugh MD Assistant Professor in the Orthopaedic Surgery department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Arthritis, Infectious
Arthroplasty, Replacement, Knee
Biomarkers
Humans
Knee Joint
Prosthesis-Related Infections
Sensitivity and Specificity
Synovial Fluid
alpha-Defensins