Abstract
Prosthetic joint infection continues to remain a diagnostic challenge for unhappy primary arthroplasty of hip and knees. There is increasing dependence upon alpha-defensin test to make key decisions like whether to revise or not & to decide between one-stage versus two-stage.
Aim
This study aims to assess diagnostic accuracy of alpha-defensin test in determining prosthetic hip & knee infection and to provide guidance for appropriate use of this novel but expensive investigation.
Methods
Retrospective review of all alpha-defensin investigated patients in an orthopaedic institute between February 2015 & March 2017 was performed. Clinical and radiological outcomes including re-infections, re-operations were analysed and alpha-defensin outcomes were compared with that of other available investigations.
Results
Of total 52 tests performed (17 hips & 35 knees), 3 were positive. On comparison with intra-operative culture (gold standard), sensitivity is 100%. All suspected prosthetic hip infections have good clinical outcomes following their decisions being made based upon alpha-defensin test. Among the negative knee test results, 6 patients developed signs of infection in the post-operative period, 4 of which have been revised with washout, poly exchange or full revision.
Conclusion
No single clinical investigation can accurately predict prosthetic joint infection in revision for suspected infection. Alpha-defensin test, however, is a useful adjunct to intra-operative surgeon's findings & pre-operative investigations to decide for crucial decisions like whether to revise or not & for deciding between single and two stage.
