Abstract
BACKGROUND: With the advent of recent point of care testing to evaluate for prosthetic joint infection (PJI) such as alpha-defensin and calprotectin, the diagnosis of PJI has reached a new paramount. The most widely accepted diagnostic criteria in the literature at this time is the international consensus meeting (ICM) score by Parvizi et al in 2018. One of the proposed limitations of the ICM criteria is determining if fluid analysis can be trusted for bloody joint aspirations. A proposed formula to correct red blood cells in aspirations was described in 2008 but has not been explored since then. AIM: To determine if the "true leukocytosis" formula for prosthetic joint aspirations is useful in determining PJIs. METHODS: Of 158 cases with International Classification of Diseases, 10(th) revision diagnoses of total knee arthroplasty PJIs from 2020-2021 from a single health system were reviewed and preoperative ICM scores were calculated. Inclusion criteria involved preoperative scores indicating infection, first time diagnoses, and culture positive infections. Culture positivity remained our gold standard for infection confirmation. We compared sensitivity, specificity, positive predictive value, negative predictive value, and area under the curve for preoperative ICM score and corrected preoperative ICM score. RESULTS: Of 81 cases met the inclusion criteria and had preoperative ICM scores calculated. Of the 81 cases that met inclusion criteria, no cases were found to have different preoperative ICM scores after applying the correction formula for "true leukocytosis" proposed by Ghanem et al in 2008. CONCLUSION: Given the lack of variance in ICM score following the proposed correction formula, it appears that the proposed "true leukocytosis" formula is not a useful adjuvant in treatment decision making.