Leukocyte esterase reagent strips for the rapid diagnosis of periprosthetic joint infection

A total of 223 consecutive total hip or total knee arthroplasties were evaluated for periprosthetic joint infection (PJI) using leukocyte esterase reagent (LER) strips. Fifty-two LER strips were read as positive (23.3%), 106 were read as negative (47.5%), and 65 strips (29.2%) were unable to be read secondary to debris or blood in the aspiration. Using a synovial fluid white blood cell count of greater than 3000 white blood cell per microliter as an indicator of PJI, the sensitivity and specificity were 92.9% and 88.8%, respectively. When using positive cultures for diagnosis of PJI, sensitivity and specificity were 93.3% and 77.0% and 100% and 86.8% for the cases where a reoperation was performed and a combination of factors were used to define PJI. Leukocyte esterase reagent strips represent a rapid, inexpensive, and sensitive tool for the diagnosis of PJI. Their utility is limited, however, by blood or debris in the synovial fluid rendering them unreadable in one-third of cases.