Authors: Tommaso Bonanzinga Akos Zahar Michael Dütsch Christian Lausmann Daniel Kendoff Thorsten Gehrke
Publish Date: 2016/06/24
Volume: 475, Issue: 2, Pages: 408-415
Abstract
A key issue in the treatment of periprosthetic joint infection PJI is the correct diagnosis The main problem is lack of diagnostic tools able to diagnose a PJI with high accuracy Alphadefensin has been proposed as a possible solution but in the current literature there is a lack of independent validationWe performed a prospective study to determine 1 what is the sensitivity specificity and positive and the negative predictive values of the alphadefensin immunoassay test in diagnosing PJI and 2 which clinical features may be responsible for falsepositive and falsenegative resultsPreoperative aspiration was performed in all patients presenting with a painful hip/knee arthroplasty including both primary and revision implants Metallosis other inflammatory comorbidities and previous/concomitant antibiotic therapy were not considered as exclusion criteria An inadequate amount of synovial fluid for culture was an exclusion criterion A total of 156 patients 65 knees 91 hips were included in this prospective study At the time of revision synovial fluid samples were taken to perform the alphadefensin assay During surgical débridement of tissue samples for cultures and histologic evaluation were taken and samples were cultured until positive or until negative at 14 days A diagnosis of PJI was confirmed in 29 patients according to the International Consensus Group on PJIThe sensitivity of the alphadefensin immunoassay was 97 95 confidence interval CI 92–99 the specificity was 97 95 CI 92–99 the positive predictive value was 88 95 CI 81–92 and the negative predictive value was 99 95 CI 96–99 Among four falsepositive patients two had metallosis and one had polyethylene wear The falsenegative case presented with a draining sinus and intraoperative cultures were also negativeAlphadefensin assay appears to be a reliable test but followup evaluation is needed to estimate longer term performance of the test The authors believe that alphadefensin has demonstrated itself to be sufficiently robust that PJI diagnostic criteria now should include this test Future studies are needed to compare the differences among the diagnostic capability of the available tests in particular when metallosis is present because metallosis may predispose the test to a falsepositive result
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