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Synovial fluid alpha-defensin, CRP diagnosed aseptic, infected periprosthetic joint infections
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Despite the inclusion of patients with systemic inflammatory disease and those receiving antibiotic treatment, the combined measurement of synovial fluid alpha-defensin and C-reactive protein levels correctly diagnosed 99% of periprosthetic joint infection cases as aseptic or infected, according to study results.
Researchers tested 149 synovial fluid aspirates for alpha-defensin and C-reactive protein (CRP) levels with use of enzyme-linked immunosorbent assay, including 112 from patients with an aseptic diagnosis and 37 from patients with periprosthetic joint infection. Utilizing the Musculoskeletal Infection Society definition of the periprosthetic joint infection, the researchers classified the cases as aseptic or infected. Comorbidities such as inflammatory conditions, which could confound a test for periprosthetic joint infection, were documented, but those patients were still included in the study.
Results showed a 97% sensitivity and 100% specificity for the diagnosis of periprosthetic joint infections when synovial fluid alpha-defensin and CRP tests were combined, according to the researchers.
When used separately, synovial fluid alpha-defensin tests demonstrated a sensitivity of 97% and a specificity of 96% for the diagnosis of periprosthetic joint infection, whereas synovial fluid CRP tests with a low threshold of 3 mg/L reversed all false-positive alpha-defensin results without affecting the sensitivity of the test, the researchers found.
The researchers achieved diagnostic characteristics of these assays among patients demonstrating 23% rate of systemic inflammatory disease and, among the infection group, a 27% rate of concurrent antibiotic treatment.
During concurrent antibiotic treatment, synovial fluid levels of alpha-defensin were unchanged among patients with periprosthetic joint infection, according to the researchers.
Disclosure: See the full study for all authors’ relevant financial disclosures.
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