PurposePeriprosthetic joint infection (PJI) continues to be a significant complication after total joint arthroplasty. Diagnosis of PJI can be challenging and elusive in the absence of a gold standard. This purpose of this article is to review the current evidence on the utility of serum and synovial fluid biomarkers to help aid in the diagnosis of PJI with focusing on synovial fluid alpha-defensin.