Alpha-defensin levels in native joint in patients with primary knee osteoarthritis without infection
Author(s):
Abdo R. (Brazil)
,
Abdo R. (Brazil)
Affiliations:
Filho M.
,
Filho M.
Affiliations:
Viana Vilma S. Trindade
,
Viana Vilma S. Trindade
Affiliations:
Gobbi R.
,
Gobbi R.
Affiliations:
Bonfa Eloisa Silva Dutra O.
,
Bonfa Eloisa Silva Dutra O.
Affiliations:
Demange M.
Demange M.
Affiliations:
ESSKA Academy. Abdo R. 05/09/18; 209534; P09-343 Topic: Joint Replacement
Dr. Rodrigo Calil Teles Abdo
Dr. Rodrigo Calil Teles Abdo
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Abstract
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Objectives: The number of total joint replacements has increased in the past decade and, consequently the number of complications of this procedure also increases. The most challenging complication is the periprosthetic joint infection (PJI). Diagnosis of PJI is very complex and there is no gold standard method. The most commonly used method for diagnosis is the one proposed by Musculoskeletal Infection Society.
Some synovial fluid biomarkers were described recently showing promising results in diagnosis of PJI. Alpha-defensin is one of these synovial biomarkers that have been studied widely with good results in PJI but there is a lack of studies to better understand its application on native knees in the presence and absence of infection to improve our knowledge about this peptide.
Our purpose of this study was to assess the levels of alpha-defensin in native knees with primary osteoarthritis without infection.

Methods: Patients with primary osteoarthritis evaluated or indicated for any invasive knee procedure were eligible for inclusion in this study. Patients were excluded because of a history of comorbid inflammatory conditions, including septic arthritis, rheumatoid arthritis, lupus erythematous, spondyloarthritis, use of immunosuppressive medication and/or chronic viral diseases. In this period, 23 patients who met the study criteria were prospectively evaluated up to one year, so that diagnosis of infection could be definitely ruled out.
Synovial fluid was obtained for alpha-defensin analysis via aseptically direct needle knee aspiration. Additionally, when a suspicious synovial fluid aspirate was attained, total and differential synovial cell count, culture, and susceptibility testing were requested to rule out infection.
The alfa-defensin was measured by standard ELISA and was the assay was optimized to operate at a cut-off value of 5.2 mg/L, according to previous studies.

Results: The total of 15 women and 8 men were included in our study, with the mean age of 54 ± 21 years. None of them had any infection complaint. The patients had an OA ranging from grade I to IV of Kellgren-Lawrence classification.
The mean value of alpha-defensin level was 1.65 ± 7.11 mg/L.
Twenty-two patients had normal alpha-defensin levels in synovial fluid. There was only one patient with abnormal levels of alpha-defensin (34.12 mg/L). However, the other tests for infection was normal. We considered her as a false-positive case. The specificity of alpha-defensin assay in our study was 95.6%.

Conclusions: The alpha-defensin immunoassay was able to provide an acceptable result for our group. However, it is not clear how much additional evidence this test provides beyond usually accessible tests.
Prospective studies endorsing its accuracy against current diagnostic criteria for septic arthritis should be done.

Keywords:
alpha-defensin, periprosthetic joint infection, osteoarthritis, knee infection
Objectives: The number of total joint replacements has increased in the past decade and, consequently the number of complications of this procedure also increases. The most challenging complication is the periprosthetic joint infection (PJI). Diagnosis of PJI is very complex and there is no gold standard method. The most commonly used method for diagnosis is the one proposed by Musculoskeletal Infection Society.
Some synovial fluid biomarkers were described recently showing promising results in diagnosis of PJI. Alpha-defensin is one of these synovial biomarkers that have been studied widely with good results in PJI but there is a lack of studies to better understand its application on native knees in the presence and absence of infection to improve our knowledge about this peptide.
Our purpose of this study was to assess the levels of alpha-defensin in native knees with primary osteoarthritis without infection.

Methods: Patients with primary osteoarthritis evaluated or indicated for any invasive knee procedure were eligible for inclusion in this study. Patients were excluded because of a history of comorbid inflammatory conditions, including septic arthritis, rheumatoid arthritis, lupus erythematous, spondyloarthritis, use of immunosuppressive medication and/or chronic viral diseases. In this period, 23 patients who met the study criteria were prospectively evaluated up to one year, so that diagnosis of infection could be definitely ruled out.
Synovial fluid was obtained for alpha-defensin analysis via aseptically direct needle knee aspiration. Additionally, when a suspicious synovial fluid aspirate was attained, total and differential synovial cell count, culture, and susceptibility testing were requested to rule out infection.
The alfa-defensin was measured by standard ELISA and was the assay was optimized to operate at a cut-off value of 5.2 mg/L, according to previous studies.

Results: The total of 15 women and 8 men were included in our study, with the mean age of 54 ± 21 years. None of them had any infection complaint. The patients had an OA ranging from grade I to IV of Kellgren-Lawrence classification.
The mean value of alpha-defensin level was 1.65 ± 7.11 mg/L.
Twenty-two patients had normal alpha-defensin levels in synovial fluid. There was only one patient with abnormal levels of alpha-defensin (34.12 mg/L). However, the other tests for infection was normal. We considered her as a false-positive case. The specificity of alpha-defensin assay in our study was 95.6%.

Conclusions: The alpha-defensin immunoassay was able to provide an acceptable result for our group. However, it is not clear how much additional evidence this test provides beyond usually accessible tests.
Prospective studies endorsing its accuracy against current diagnostic criteria for septic arthritis should be done.

Keywords:
alpha-defensin, periprosthetic joint infection, osteoarthritis, knee infection
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