According to the ROC analysis, the abundance of CD82+ EVs above 2.0 × 106 objects/ml were significantly associated with PJI with a total misclassification rate of 13.3% and a false negative rate of 16.6% or a false positive rate of 10%, respectively (sensitivity: 83.3%, specificity: 90.0%, AUC: 0.886, 95%CI of AUC: 0.764; 1.000; P = 0.0001). The gene discussed is CD82; the disease is juvenile polyposis syndrome.