Analysis of Serum and Synovial Inflammatory Markers in Periprosthetic Joint Infections: A Narrative Review

Periprosthetic joint infection (PJI) is considered a rare but devastating complication after total joint arthroplasty (TJA). The problem lies in the fact that there is a paucity of "gold standard" diagnostic tests that make the diagnosis of PJI extremely challenging. Recently, there have been increasing evidence-based guidelines that have been introduced to standardise the approach to a patient with a suspected PJI. Diagnosing a case of PJI traditionally involves initial screening for elevated serum inflammation markers C-reactive protein (CRP) (mg/dL) and erythrocyte sedimentation rate (ESR), and aspiration remains the sole confirmatory investigation. However, several factors would affect the values of the aforementioned markers, such as gender, age, and the presence of inflammatory circumstances. Serum D-dimer that detects fibrinolytic activities during infection has high sensitivity, but the specificity was not persuasive as it would elevate during other conditions, such as venous thromboembolism. Therefore, there is also a need for a simultaneous and secondary marker. There are also several synovial biomarkers, including ESR, CRP, alpha-defensin, and synovial fluid leukocyte count and differential for the detection of PJI. In this narrative review, we want to sum up the serum and inflammatory markers that have been introduced so far for detecting PJI.