Intraoperative Diagnosis of Periprosthetic Joint Infection Using a Novel Alpha-Defensin Lateral Flow Assay

Background The present study investigates the novel Synovasure periprosthetic joint infection (PJI) lateral flow test device for detection of alpha-defensin and attempts to determine its diagnostic accuracy for the intraoperative diagnosis of PJI and compares it to frozen section. Methods Forty consecutive patients, who underwent revision surgery, between September 2014 and September 2015 were included. The patients underwent 29 revision total knee arthroplasties and 11 revision total hip arthroplasties. Twelve patients had a confirmed PJI based on Musculoskeletal Infection Society criteria, and 28 patients were considered aseptic. Results The overall accuracy to detect PJI using the lateral flow assay was 85% (95% CI 70%-93%). The device has a positive predictive value of 80% (95% CI 44%-96%) and a negative predictive value of 87% (95% CI 68%-96%) and showed a sensitivity of 67% (95% CI 35%-89%) and specificity of 93% (95% CI 75%-99%). Frozen section had a lower sensitivity (58% [95% CI 29%-84%]) but a higher specificity (96% [95% CI 80%-100%]). Receiver operator curve analysis demonstrates an area under the curve of the Synovasure PJI Lateral Flow Test Kit and frozen section of 0.80 and 0.77, respectively. Conclusion The present study suggests that the intraoperative lateral flow test is at least equivalent to intraoperative frozen section and is a useful tool to confirm the absence of PJI. Although the clinical results are promising, they are not as good as previous studies using alpha-defensin levels measured in a laboratory.