Year: 2025
Type: article
Study design: Observational Study
Abstract: Background Synovial fluid analysis is a critical step in the diagnosis of periprosthetic knee joint infection. We hypothesized that clinically meaningful differences between white blood cell (WBC) count, polymorphonuclear leukocyte (PMN) cell percentage, and culture results would exist between 2 independent laboratories when the same synovial fluid aspirate is analyzed. Methods A retrospective chart review was completed on total knee arthroplasty patients who underwent knee arthrocentesis between 2017 and 2025. The synovial fluid aspirate from a single knee arthrocentesis was divided into identical samples and analyzed by 2 independent laboratories. WBC count, PMN percentage, and culture results were recorded. Results In total, 202 consecutive prosthetic knee aspirates were analyzed. Agreement was found in 14 of 20 samples (70%) that tested ≥3000 WBC/μl ( k = 0.81; 95% confidence inverval [CI], 0.66-0.96), 9 of 13 samples (69%) that tested ≥80% PMNs ( k = 0.81; 95% CI, 0.62-0.99), 7 of 12 cases (58%) reported both ≥80% PMNs and ≥3000 WBC/μl, 8 of 9 cases (89%) that tested ≥90% PMNs ( k = 0.94; 95% CI, 0.82-1.00), 3 of 23 cases (13%) with positive culture results ( k = 0.18; 95% CI, −0.05-0.40). Conclusions Two independent laboratories displayed clinically meaningful variability in WBC count, PMN percentage, and culture results. The difficulty in diagnosing periprosthetic joint infection may at least in part be due to poor interlaboratory reliability concerning synovial fluid analysis. Refinement of interlaboratory agreement, further research into advanced diagnostic methods, and measures to improve the accuracy of synovial fluid analysis are all critical steps toward refining the diagnosis of periprosthetic joint infection. Level III Retrospective Cohort study, Diagnostic.
Source: Arthroplasty Today
Institution: University of Tennessee at Chattanooga
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,500
OpenAlex ID: W7116432276