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Alpha Defensin Biomarker for PJI Diagnosis

Periprosthetic Joint Infection (PJI) is one of the most common complications following total joint arthroplasty, accounting for 25% of total knee arthroplasty failures and 16% of total hip arthroplasty failures.1 As a result, a timely and accurate diagnosis is necessary. Biomarkers such as alpha defensin are used to aid in the diagnosis of PJI.

What is Alpha Defensin?

Alpha Defensin is an antimicrobial peptide released into the body through activated neutrophils in response to an infection. In cases of PJI, a patient will have elevated levels of alpha defensin in their synovial fluid.

Reference Table

Clinical findings show that alpha defensin test results are not influenced by:

  • Prior antibiotic administration2,3
  • Comorbidities related to inflammation2,4
  • Type and/or virulence of the organism2,5

Since discovery, alpha defensin has aided in the diagnosis of PJI following total joint replacement. In 2018, the alpha defensin biomarker was included as a minor criteria for diagnosing PJI by the International Consensus Meeting (ICM) on Joint Infection.6

Two Testing Options

Alpha Defensin testing is only available from Zimmer Biomet. The test is available in two formats: Synovasure Alpha Defensin Lateral Flow Test and Synovasure Alpha Defensin ELISA Laboratory Test, part of the Synovasure Comprehensive Infection Laboratory Test Panel.*

*Available in the US and selected EMEA markets.  

Synovasure® Alpha Defensin Lateral Flow Test

Synovasure Alpha Defensin Lateral Flow Sensitivity Specificity

The Synovasure Alpha Defensin Lateral Flow Test is a standalone, rapid device for detecting alpha defensin in synovial fluid. The test offers results in 10 minutes on the presence of elevated alpha defensin levels. In a multicenter clinic study, the Synovasure Alpha Defensin Lateral Flow showed high sensitivity and specificity:

Study

N

Sensitivity

Specificity

FDA Multi-Center7

305

94.3%

94.5%

Includes patients with a draining sinus

The Synovasure Alpha Defensin Lateral Flow also shows  no statistically significant difference in performance when compared to the laboratory-developed test.7

Synovasure® Alpha Defensin ELISA Laboratory Test*

A laboratory-developed test that identifies alpha defensin levels in 24 hours and is available as part of the Synovasure Comprehensive Infection Panels. As part of the panel, physicians can obtain alpha defensin results in addition to other tests, such as Synovasure Microbial Identification, Synovasure Neutrophil Elastase, Culture, and White Blood Cell (WBC) count.

In clinical studies, the Synovasure Alpha Defensin ELISA Test demonstrates high sensitivity and specificity2,7-12:

Study

N

Sensitivity

Specificity

Rothman Institute2

149

97% (36/37)

96% (107/112)

Mayo Clinic8

61

100% (19/19)

95% (40/42)

Cleveland Clinic9

78

100% (24/24)

98% (53/54)

Endo Klinik10

156

97% (28/29)

97% (123/127)

Cleveland Florida11

70

97% (34/35)

97% (34/35)

Charité – Universitätsmedizin Berlin12

71

85% (11/13)*

98% (57/58)

FDA Multi-center7

369

93% (113/122)

98% (241/247)

Combined

954

95% (265/279)

97% (655/675)

Includes patients with a draining sinus


*Available in the US and selected EMEA markets.  

Legal Manufacturer:

CD Diagnostics
650 Naamans Road
Suite 100
Claymont, DE 19703 USA

 

  1. Deirmengian C, et al. Diagnosing Periprosthetic Joint Infection: Has the Era of the Biomarker Arrived? Clinical Orthopaedics and Related Research. 472(11):3254-62, 2014.
  2. Deirmengian C, et al. Combined Measurement of Synovial Fluid a-Defensin and C-reactive Protein Levels: Highly Accurate for Diagnosing Periprosthetic Joint Infection. Journal of Bone and Joint Surgery. 96(17):1439-45, 2014.
  3. Shahi A, et al. The alpha-defensin Test for Periprosthetic Joint Infections is Not Affected by Prior Antibiotic Administration. Clinical Orthopaedics and Related Research. 474(7):1610-5, 2016.
  4. Miyamae Y, et al. Diagnostic Accuracy of the Alpha-Defensin Test for Periprosthetic Joint Infection in Patients with Inflammatory Diseases. Journal of Arthroplasty. 34(8):1767-1771, 2019.
  5. Deirmengian C, et al. The C-reactive Protein May Not Detect Infections Caused by Less-Virulent Organisms. Journal of Arthroplasty. 31:152-155, 2016.
  6. Amanatullah D, et al. Hip and Knee Section, Diagnosis, Definitions: Proceedings of International Consensus on Orthopedic Infections. Journal of Arthroplasty. 34(2S):S329-S337, 2019.
  7. CDD-CLI-001: Clinical Validation of CD Diagnostics Synovasure PJI ELISA Test and Synovasure PJI Lateral Flow Test for Detection of Periprosthetic Joint Infection (PJI) in Synovial Fluid, 2019
  8. Bingham J, et al. The Alpha Defensin-1 Biomarker Assay can be Used to Evaluate the Potentially Infected Total Joint Arthroplasty. Clinical Orthopaedics and Related Research. 72(12):4006-9, 2014.
  9. Frangiamore S, et al. a-Defensin Accuracy to Diagnose Periprosthetic Joint Infection – Best Available Test? Journal of Arthroplasty. 312:456-60, 2016.
  10. Bonanzinga,T, et al. How Reliable Is the Alpha-defensin Immunoassay Test for Diagnosing Periprosthetic Joint Infection? A Prospective Study. Clinical Orthopaedics and Related Research. 475(2):408-415, 2017.
  11. Kanwar S, et al. What is the Optimal Criteria to Use for Detecting Periprosthetic Joint Infections Before Total Joint Arthroplasty? Journal of Arthroplasty. 33:S201e4, 2018.
  12. Sigmund I, et al. Is the Enzyme-linked Immunosorbent Assay More Accurate Than the Lateral Flow Alpha Defensin Test for Diagnosing Periprosthetic Joint Infection?. Clinical Orthopaedics and Related Research. 476:1645-1654, 2018.

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