Diagnostic accuracy of the alpha-defensin lateral flow test in periprosthetic shoulder infection: a retrospective...

The aim of this study is to assess the diagnostic value of the alpha-defensin lateral flow (ADLF) test in a group of patients with suspected shoulder periprosthetic joint infections (PJIs) and its usefulness and correlation with other diagnostic tests in the decision-making process.

This retrospective single-center study was conducted between 2018 and 2023. Alpha-defensin was measured using an ADLF test kit. The final diagnosis of shoulder PJI was confirmed or ruled out based on the Musculoskeletal Infection Society criteria.

After selecting patients based on the exclusion criteria, the final study group comprised 22 patients. Of all patients, the test was positive in five cases. The ADLF test was false-positive in two patients and was false-negative in zero patients. The test was truly negative in 17 cases, resulting in a sensitivity of 100.00% (95% CI, 100.00%-100.00%) and a specificity of 89.47% (95% CI, 76.65%-102.30%). The positive predictive value was 60.00% (95% CI, 39.53%-80.47%) and the negative predictive value was 100.00% (95% CI, 100.00%-100.00%). The accuracy of the α-defensin test was found to be 90.9%.

Although this study has limitations such as small sample size and research design, the ADLF test has proven to be a useful diagnostic tool. It can serve as a supplement to traditional tests, providing additional support to orthopedic surgeons in both preoperative and intraoperative diagnosis, especially in its ability to exclude the possibility of a PJI. Level of evidence: III.