Abstract
BackgroundThe leukocyte esterase (LE) strip is considered as a helpful method to detect infection, which might be influenced by other inflammatory diseases. This study aims to explore whether the centrifugation of synovial fluid could influence the positive result of LE strip caused by inflammatory arthritis during the diagnosis of periprosthetic joint infection (PJI).MethodsFrom March 2016 to December 2018, 64 patients who were diagnosed as PJI or aseptic arthritis and another 20 patients with inflammatory arthritis were enrolled in our study. After synovial fluid samples were obtained, the LE strip test was performed with and without centrifugation. Then clinicians read the color changes 3 min after the samples were dropped and classify the results based on the instruction of strip. The differences between septic and aseptic arthritis patients and septic and inflammatory arthritis patients were analyzed.ResultsAmong the included 21 PJI samples, 19 of them showed positive results (++) of LE strip before centrifugation. After centrifugation, two samples changed from two-positive (++) to one-positive (+), which is also considered as positive. Before centrifugation, 29 of the LE strip tests in the aseptic arthritis group (43 samples included) were ++ or +. After centrifugation, 16 of the samples yielded negative results. Among 20 samples with inflammatory arthritis, LE strip of 18 samples were positive (++ or +) before centrifugation, among which only 3 samples remained as positive after centrifugation.ConclusionLE strip test results could be influenced by inflammatory arthritis during the diagnosis of PJI. Centrifugation should be performed for LE strip tests to determine whether the result is a true positive or a false positive influenced by inflammatory arthritis.
Highlights
Periprosthetic joint infection (PJI) is one of the most severe complications of total joint arthroplasty (TJA)
From March 2016 to December 2018, patients who were suspected of periprosthetic joint infection (PJI) from the Department of Orthopedics or patients who were diagnosed with inflammatory arthritis from the Department of Rheumatology and Immunology were included in our study
Patients meeting one of the three following criteria were classified in the PJI group: (1) sinus tract communication with a prosthesis; (2) the same pathogen isolated by culture from two separate fluid samples or tissues; and (3) four of the following six criteria were positive: (1) increased erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) (ESR > 30 mm/h, CRP > 10 mg/L); (2) increased synovial fluid white blood cells (> 3000/μL); (3) increased synovial fluid percentage of polymorphonuclear neutrophils (> 65%); (4) presence of purulence in synovial fluid; (5) positive culture in synovial fluid or tissue; and (6) histopathological analysis of perisprosthetis showed more than five neutrophils per high-power field on frozen section in more than five high-power fields (× 400)
Summary
Periprosthetic joint infection (PJI) is one of the most severe complications of total joint arthroplasty (TJA). PJI biomarkers including elevated erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and leukocyte esterase (LE) strip test have been reported in recent years. Among these PJI patients, some are accompanied with inflammatory arthritis, such as rheumatoid arthritis (RA), psoriatic arthritis (PsA), reactive arthritis, and ankylosing spondylitis (AS) [1]. White blood cell (WBC) count, and polymorphonuclear percentage (PMN%) can be a key component in the diagnosis of septic arthritis. These biomarkers are frequently influenced by the use of antibiotics [2]. This study aims to explore whether the centrifugation of synovial fluid could influence the positive result of LE strip caused by inflammatory arthritis during the diagnosis of periprosthetic joint infection (PJI)
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