Prospective Study
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Aug 18, 2022; 13(8): 760-767
Published online Aug 18, 2022. doi: 10.5312/wjo.v13.i8.760
Quantitative alpha-defensin testing: Is synovial fluid dilution important?
Rodrigo Calil Teles Abdo, Riccardo Gomes Gobbi, Chilan Bou Ghosson Leite, Sandra Gofinet Pasoto, Elaine Pires Leon, Ana Lucia Lei Munhoz Lima, Eloisa Bonfa, José Ricardo Pécora, Marco Kawamura Demange
Rodrigo Calil Teles Abdo, Riccardo Gomes Gobbi, Chilan Bou Ghosson Leite, Ana Lucia Lei Munhoz Lima, José Ricardo Pécora, Marco Kawamura Demange, Instituto de Ortopedia e Traumatologia, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Sao Paulo 05403-010, Brazil
Rodrigo Calil Teles Abdo, Riccardo Gomes Gobbi, Orthopaedic Department, HCor - Hospital do Coração, Sao Paulo 04004-030, Brazil
Sandra Gofinet Pasoto, Elaine Pires Leon, Eloisa Bonfa, Division of Rheumatology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Sao Paulo 05403-010, Brazil
Author contributions: Abdo RCT collected the samples; Leite CBG wrote the article; Abdo RCT, Leite CBG, Lima ALLM and Bonfa E contributed to the data analysis; Abdo RCT, Gobbi RG, Lima ALLM, Bonfa E, Pécora JR and Demange MK contributed to the intellectual concept and design of the study; Pasoto SG performed the laboratory tests and contributed to the strategy for alpha-defensin analysis according to its dilution; Leon EP conducted the laboratory tests; Gobbi RG reviewed the article.
Supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), No. 2017/25540-9.
Institutional review board statement: The study was approved by the local Institutional Review Board, No. 71039317.3.0000.0068.
Informed consent statement: All study participants, or their legal guardian, provided written consent prior to study enrollment.
Conflict-of-interest statement: All authors report no relevant conflict of interest for this article.
Data sharing statement: There is no additional data available.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Rodrigo Calil Teles Abdo, MD, Surgeon, Instituto de Ortopedia e Traumatologia, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, R. Dr. Ovídio Pires de Campos, 333 - Cerqueira César., Sao Paulo 05403-010, Brazil. rctabdo@gmail.com
Received: October 15, 2021
Peer-review started: October 15, 2021
First decision: January 11, 2022
Revised: February 4, 2022
Accepted: August 5, 2022
Article in press: August 5, 2022
Published online: August 18, 2022
Processing time: 304 Days and 21.2 Hours
ARTICLE HIGHLIGHTS
Research background

Periprosthetic joint infection (PJI) is a serious complication post-surgery that is associated with substantial morbidity and financial burden to the healthcare system. The alpha-defensin quantitative enzyme-linked immunosorbent assay (ELISA) is one of the most useful methods to investigate PJI.

Research motivation

Although the alpha-defensin ELISA is currently the most reliable test to diagnose PJI, there is a lack of detailed information regarding its proper laboratory technique, including the best sample dilution.

Research objectives

This study aimed to assess the influence of dilution in the synovial fluid during ELISA for the diagnosis of knee PJI and determine which dilution presents a better performance.

Research methods

In this prospective study, 40 cases of total knee arthroplasty were evaluated: 17 classified as PJI and 23 classified as aseptic knees. Initially, 5 synovial fluid samples from each group were assessed by ELISA using different dilution ratios (1:10, 1:100, 1:500, 1:1000 and 1:5000). The dilutions had better performance were used to compare the results of all samples.

Research results

For infected cases, a gradual increase in the synovial fluid dilution led to an equivalent increase in alpha-defensin level, which was not seem in the aseptic cases. Both 1:1000 and 1:5000 dilutions presented satisfactory results to differentiate infected and aseptic cases. Further analyses were performed using 1:1000 and 1:5000 for all 40 samples. The 1:1000 dilution resulted in a sensitivity of 88.2% (95%CI, 66%-98%) and specificity of 95.7% (95%CI, 79%-99%), whereas the 1:5000 dilution presented a sensitivity of 94.1% (95%CI, 73%-99%) and a specificity of 100% (95%CI, 86%-100%).

Research conclusions

Synovial fluid dilution appears to influence the alpha-defensin ELISA results. Dilutions of 1:5000 showed the best performance for the diagnosis of knee PJI.

Research perspectives

The results of this current study may set the basis for more reliable and reproducible alpha-defensin ELISA during PJI investigation, contributing to the expansion of this technique in different treatment centers worldwide.