Introduction. In revision surgery, detection of periprosthetic joint infection is of prime importance. Valuable preoperative and intraoperative diagnostic tests and tools are necessary. The classical standard procedures are puncture and bacteriology examination, frozen section intraoperative and powerfield micro analysis. Since autumn 2014 a new device for detection of periprosthetic joint infection is available, named Synovasure. It is a fast test for the detection of Alpha defensing, which plays a major role in the antimicrobial defence and only occurs in inflammatory processes. „The alpha-defensin test is an immunoassay that measures the concentration of the alpha-defensin peptide in human synovialfluid. A-Defensin is an antimicrobial peptide that is secreted into the synovial fluid by human cells in response to pathogenic presence” (Deirmengian C et al., CORR 2014). Summarized, the evidence of Alpha defensin indicates infection. It is produced by CD Diagnostics (Wynnewood, PA, USA) and merchandised by Zimmer (Warsaw, IL, USA). We are using Synovasure in daily routine at our department since September 2014. The aim of this conducted study is to present our first clinical experience and to report our results of the first 54 cases. Material and Methods. At our department Synovasure is standardly used in hip and knee revision surgery. Additionally an intraoperative frozen section and a standard bacteriology were performed. The explanted endprosthesis were sent to examination by sonification in order to gain culture of the sonification fluid and were further examined by Multiplex PCR. A pathologist with more than 15 years of experience conducted the frozen section. The results of Synovasure were matched with all above examinations in order to describe specifity and sensitivity of it. Results. A negative Synovasure Test during surgery and a negative PCR were observed in 3 patients, however, the bacterial culture was positive (after 14 days of breeding) as well as the Multiplex PCR. One patient had a negative frozen section and a negative culture but a positive PCR. Another patient with a high CRP level, all clinical signs of infection and a positive Synovasure Test, had 6 negative cultures. This patient suffered from a Metallosis as well, due to a broken PE inlay of the TKA, which supports the previously stated that Metallosis may interfere this new tool. Unfortunately in this patient neither a frozen section nor a PCR are available. One patient, who had explanation due to infection, underwent reimplantation. During surgery the Synovasure Test and the frozen section were negative (Synovial Fluid), but postoperatively a positive culture and a positive histological report for infection were assessed. Furthermore, a total of 5 tests showed an application error and the test did not show any control line. Conclusion. In conclusion Synovasure helps to detect perprosthetic joint infection in an easy and fast manner. It is simple to integrate into daily routine, nevertheless all standardized examinations for infection need to be conducted

Introduction. The intra-operative diagnosis of Prosthetic Joint Infection (PJI) is a dilemma requiring intra-operative sampling of suspicious tissues for frozen section, deep tissue culture and histopathology to secure a diagnosis. Alfa defensin-1 testing has been introduced as a quick and reliable test for confirming or ruling out PJI. This study aims to assess its intra-operative reliability compared to the standard tests. Methods. Twenty patients who underwent revision hip and knee arthroplasty surgery were included. Patients joint aspirate was tested intra-operatively with the Synovasure kit, which takes approximately ten minutes for a result. Our standard protocol of collecting 5 deep tissue samples for culture and one sample for histopathology was followed. Results for Alfa defensin-1 test were then compared with final culture and histopathology results in all these patients. Results. Our results show an excellent correlation with the final deep tissue cultures and histopathology outcomes. Literature reports frozen section to have low (58–73%) sensitivity but high (96%) specificity. Conclusions. Alfa defensin-1 test is easy, quick and efficient; results were available immediately intra-operatively. Cryosection is time consuming with samples shipped to the reference laboratory at times resulting in intra-operative delays. In our practice Alfa defensin-1 test certainly will replace frozen section for intra-operative testing

Introduction

Periprosthetic joint infection (PJI) is considered one of the most feared causes of implant failure, due to the difficulty in formulating a proper and timely diagnosis. In the diagnostic workup are often used test with a low specificity, such as the dosage of ESR and CRP, or sensitivity, such as cultures or the leukocyte count of the synovial fluid. Radiological investigations are expensive and unreliable to play a direct role in the diagnosis of PJI. The alpha-defensin is an antimicrobial peptide released by neutrophils in response to pathogens and it is an ideal biomarker for the diagnosis of PJI. It is now possible to verify the presence of alpha-defensin in periprosthetic synovial fluid with an ELISA (Synovasure® PJI, Zimmer) that provides results in 10 minutes, with a sensitivity of 97% and a specificity of 96%, without being affected by systemic inflammatory diseases or by the assumption of antibiotics. The purpose of this study is to assess the applicability and reliability of Synovasure® PJI, correlating its results with microbiological analyzes, laboratory tests and imaging studies of the patient.

Frozen section is a recognised technique to assist in the diagnosis of infection and there are standards for reporting. Our aim of this review was to assess the value of frozen section in the diagnosis of infection, as well as other variables. We performed a retrospective review of all frozen sections for suspected infection in 2016. Patient demographics, histological and microbiological investigations, laboratory and bedside tests were recorded and analysed using statistical software. 46 patients had 55 frozen sections; the majority were for lower limb arthroplasty. No sections were reported as polymorphonuclear neutrophils per high-power field. Three sections showed signs of infection and one without evidence had positive cultures. One uncertain section did not grow organisms. 10 patients had two-stage procedures, four of these were intended to be determined by frozen section but only two had evidence of infection on analysis. Evidence of infection on frozen section does correlate with microbiological growth but does not relate to intention to stage procedures in half of patients. The effect of new tests such as Synovasure is highlighted by this review. Frozen section analysis is reported subjectively but is a good predictor of infection. Clinical assessment is accurate in diagnosing infection. Histological, microbiological and additional investigations should be considered in relation to their cost-effectiveness