Abstract
The aim of this review was to evaluate the available literature and to calculate the pooled sensitivity and specificity for the different alpha-defensin test systems that may be used to diagnose prosthetic joint infection (PJI). Studies using alpha-defensin or Synovasure (Zimmer Biomet, Warsaw, Indiana) to diagnose PJI were identified from systematic searches of electronic databases. The quality of the studies was evaluated using the Quality Assessment of Studies of Diagnostic Accuracy (QUADAS) tool. Meta-analysis was completed using a bivariate model. A total of 11 eligible studies were included. The median QUADAS score was 13 (interquartile range 13 to 13) out of 14. Significant conflicts of interest were identified in five studies. The pooled sensitivity for the laboratory alpha-defensin test was 0.95 (95% confidence interval (CI) 0.91 to 0.98) and the pooled specificity was 0.97 (95% CI 0.95 to 0.98) for four studies with a threshold level of 5.2 mgl-1 The pooled sensitivity for the lateral flow cassette test was 0.85 (95% CI 0.74 to 0.92) and the pooled specificity was 0.90 (95% CI 0.91 to 0.98). There was a statistically significant difference in sensitivity (p = 0.019), but not specificity (p = 0.47). Laboratory-based alpha-defensin testing remains a promising tool for diagnosing PJI. The lateral flow cassette has a significantly lower performance and pooled results are comparable to the leucocyte esterase test. Further studies are required before the widespread adoption of the lateral flow cassette alpha-defensin test. Cite this article: Bone Joint J 2018;100-B:703-11.
Highlights
Infection was the cause for revision in 13,801 (11%) of the 130,195 revision hip or knee arthroplasties completed in the U.K. between 2003 and 20151
The protocol had a minor alteration with the inclusion of a sub-group analysis of the lateral flow cassette when it became evident that this was a source of heterogeneity within the published studies
Lateral flow cassettes can be an effective technique for evaluating synovial fluid, as demonstrated by Wouthuyzen-Bakker et al using synovial calprotectin with a sensitivity of 89% and specificity of 95% for periprosthetic joint infection[32]
Summary
Infection was the cause for revision in 13,801 (11%) of the 130,195 revision hip or knee arthroplasties completed in the U.K. between 2003 and 20151. It has been estimated that the mean cost from each revision for infection is over £20,0002. As the incidence of joint arthroplasty increases, this burden from infection will rise[3]. The diagnosis of periprosthetic joint infection is challenging. In the initial Musculoskeletal Infection Society (MSIS) consensus guidelines, infection could be diagnosed with either one positive major criterion or four positive minor criteria[4]. These guidelines were adapted and updated in 2013, with one positive major criterion or three minor criteria identifying periprosthetic infection[5] (Table 1)
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