Does inflammatory joint diseases affect the accuracy of infection biomarkers in patients with periprosthetic joint infections? A prospective comparative reliability study.

BACKGROUND: The diagnosis of periprosthetic joint infections (PJI) in patients with inflammatory joint diseases (IJD) could be challenging. Several tests used for diagnosing PJI may be inaccurate due to baseline inflammatory characteristics of such diseases. We aimed to evaluate the accuracy of several infection biomarkers, in a specific subgroup of patients with PJI and IJD.

METHODS: From January 2014 to August 2017, patients with resisting pain at the relevant site, following total knee arthroplasty were evaluated prospectively. A total of 38 patients were undergone revision arthroplasty. Patients were categorized in terms of MSIS criteria: Patients with PJI (Group 1, n = 17) and patients without PJI (Group 2, n = 21). Serum ESR, CRP, Procalcitonin, synovial cell count, percentage of neutrophils in synovial fluid, synovial CRP, Lactoferrin, ELA-2, Thiol - Disulphide levels, BPI and the Alpha defensin test results were obtained. The results of two groups were compared and the diagnostic accuracy of each variable was evaluated.

RESULTS: There were 22 women, 16 men with a mean age of 67.8 ± 6.9 years. The differences were significant in all evaluated biomarkers in terms of PJI (p values of all biomarker were <0.001). Alpha defensin, Lactoferrin, ELA-2, BPI, Procalcitonin and synovial CRP were the most accurate tests with area under curve >0.90.

CONCLUSIONS: Our results demonstrated that IJD may not affect the accuracy of infection biomarkers in patients with PJI. Alpha defensin test, Lactoferrin, ELA-2, BPI, Procalcitonin and synovial CRP can be used in the diagnosis of PJI in patients with IJD.