Sensitivity of synovial fluid analysis in hematogenous native joint septic arthritis – overall accuracy and pathogen-specific differences
Abstract
This study aimed to evaluate the sensitivity of synovial fluid (SF) white blood cell count (SF-WBC), SF polymorphonuclear neutrophil percentage (PMN%), and the SF/serum glucose ratio in a study population with a definitive diagnosis of hematogenous native joint septic arthritis (SA) and explore factors influencing their performance, including the causative pathogen. We conducted a retrospective register and medical record study of 57 patients with culture-verified hematogenous native joint SA identified through ICD-codes between 2016 and 2019 in western Sweden. All patients included had documented SF-WBC analysis. Clinical data and SF analyses were compared between patients above and below cutoffs for SF-WBC (50,000 cells/mm ³ ) and SF/serum glucose ratio of 0.5. SF findings were also compared between S. aureus and other pathogens. The sensitivity of SF-WBC ≥ 50,000 cells/mm ³ was 51%, SF/serum glucose ratio < 0.5 was 57% and PMN% ≥ 70 was 95%. Patients with SF-WBC ≥ 50,000 cells/mm ³ were significantly older. SA caused by S. aureus were associated with lower PMN% and higher SF/serum glucose ratio compared to other organisms. While PMN ≥ 70% had a high sensitivity for native joint SA, the conventional cutoffs for SF-WBC and SF/serum glucose ratio showed poor sensitivity. SA caused by S. aureus may be associated with a less pronounced inflammatory response compared with other pathogens, a finding that warrants further investigation.
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BibTeX
@article{alexandersson2026sensitivity,
title = {{Sensitivity of synovial fluid analysis in hematogenous native joint septic arthritis – overall accuracy and pathogen-specific differences}},
author = {Hanna Alexandersson and Jonatan Tillander and Mats Dehlin and Tao Jin},
journal = {Scientific Reports},
year = {2026},
month = oct,
doi = {10.1038/s41598-026-75208-6},
url = {https://www.nature.com/articles/s41598-026-75208-6},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Sensitivity of synovial fluid analysis in hematogenous native joint septic arthritis – overall accuracy and pathogen-specific differences
AU - Hanna Alexandersson
AU - Jonatan Tillander
AU - Mats Dehlin
AU - Tao Jin
PY - 2026
DA - 2026/10/16
JO - Scientific Reports
DO - 10.1038/s41598-026-75208-6
UR - https://www.nature.com/articles/s41598-026-75208-6
AB - This study aimed to evaluate the sensitivity of synovial fluid (SF) white blood cell count (SF-WBC), SF polymorphonuclear neutrophil percentage (PMN%), and the SF/serum glucose ratio in a study population with a definitive diagnosis of hematogenous native joint septic arthritis (SA) and explore factors influencing their performance, including the causative pathogen. We conducted a retrospective register and medical record study of 57 patients with culture-verified hematogenous native joint SA identified through ICD-codes between 2016 and 2019 in western Sweden. All patients included had documented SF-WBC analysis. Clinical data and SF analyses were compared between patients above and below cutoffs for SF-WBC (50,000 cells/mm ³ ) and SF/serum glucose ratio of 0.5. SF findings were also compared between S. aureus and other pathogens. The sensitivity of SF-WBC ≥ 50,000 cells/mm ³ was 51%, SF/serum glucose ratio < 0.5 was 57% and PMN% ≥ 70 was 95%. Patients with SF-WBC ≥ 50,000 cells/mm ³ were significantly older. SA caused by S. aureus were associated with lower PMN% and higher SF/serum glucose ratio compared to other organisms. While PMN ≥ 70% had a high sensitivity for native joint SA, the conventional cutoffs for SF-WBC and SF/serum glucose ratio showed poor sensitivity. SA caused by S. aureus may be associated with a less pronounced inflammatory response compared with other pathogens, a finding that warrants further investigation.
SN - 2045-2322
ER -