ABSTRACT
Periprosthetic infection remains one of the most challenging complications of total joint arthroplasty. Despite the substantial reduction in the prevalence of this complication over the last two decades, periprosthetic infection is the second most common complication of joint arthroplasty, after loosening1,2. Infection has been reported to occur in association with 1% to 4% of primary total knee arthroplasties3,4 and about 1% of primary total hip arthroplasties5,6. The prevalence of periprosthetic infection after revision arthroplasty is much higher, reported to be 3.2% for hips and 5.6% for knees7. It is believed that the prevalence of periprosthetic infection is on the rise once again8. The treatment of periprosthetic infection differs vastly from the treatment of aseptic loosening. Hence, it is paramount to distinguish between septic and aseptic joint failures preoperatively. The diagnosis of infection after total joint arthroplasty continues to pose a challenge, particularly when it presents as a subacute or low-grade infection. Currently, there is no universally accepted diagnostic test or modality that is absolutely accurate or reliable for the determination of infection. The diagnosis of periprosthetic infection relies on clinical suspicion and a combined armamentarium of serological and imaging modalities9, with isolation of organisms from the intraoperative culture samples constituting the “gold standard” for ultimate diagnosis10,11. Serological tests, including the erythrocyte sedimentation rate and the C-reactive protein level, are frequently used to screen for septic and aseptic failure of total joint arthroplasty and have a relatively high sensitivity and specificity when combined12. However, their specificity and sensitivity vary depending on the cutoff values chosen10. The role of analysis of synovial fluid for determination of the leukocyte count and neutrophil percentage, although frequently employed, remains unclear.