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It can be unnecessary to combine common synovial fluid analysis and alpha-defensin tests for periprosthetic joint

Hao Li1,2,3, Rui Li2,3, Niu Erlong4

  • 1Medical School of Chinese PLA, Beijing, People's Republic of China.

BMC Musculoskeletal Disorders
|June 29, 2023
PubMed
Abstract

Insights

The alpha-defensin test does not improve periprosthetic joint infection (PJI) diagnosis when standard synovial fluid analysis is already performed. Adding this test offers no additional diagnostic value for PJI.

Area of Science:

  • Orthopedic Surgery
  • Infectious Diseases
  • Diagnostic Medicine

Background:

  • Periprosthetic joint infection (PJI) is a significant complication following total joint arthroplasty.
  • The diagnostic role of synovial fluid alpha-defensin in PJI, despite its inclusion in the 2018 International Consensus Meeting (ICM) criteria, remains debated.
  • This study evaluated the necessity of alpha-defensin testing when standard synovial fluid analyses are conducted.

Purpose of the Study:

  • To determine if synovial fluid alpha-defensin testing provides additional diagnostic value for periprosthetic joint infection (PJI) when routine synovial fluid analysis is performed.
  • To assess the impact of adding alpha-defensin testing on diagnostic concordance and cost-effectiveness in suspected PJI cases.

Main Methods:

  • A retrospective pilot study included 90 patients with suspected PJI undergoing revision arthroplasty.
  • Interobserver agreements and reliability were calculated based on the 2018 ICM criteria, with and without alpha-defensin testing.
  • Receiver operating characteristic (ROC) analysis and cost-effectiveness evaluation were performed.

Main Results:

  • Adding alpha-defensin testing did not alter preoperative or postoperative PJI diagnostic results or the concordance between them.
  • The risk-benefit ratio exceeded 90 per changed decision, indicating limited added benefit.
  • The direct cost-effectiveness of alpha-defensin was calculated to be over $8370 per case.

Conclusions:

  • Alpha-defensin assays are sensitive and specific for PJI detection as a standalone test under the 2018 ICM criteria.
  • However, additional alpha-defensin testing offers no supplementary evidence for PJI diagnosis when standard synovial fluid analyses (WBC count, PMN%, LE strip tests) are already completed.
Keywords:
Alpha-defensinPeriprosthetic joint infectionThe 2018 ICM criteriaTotal joint arthroplasty

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