2008 Abstract : 7

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Authors: Ghanem E, Azzam K, Seeley M, Voshi A, Parvizi J

Title: Staged Revision for Knee Arthroplasty Infection: What is the Role of Serological Tests Prior to Reimplantation?

Institution: Rothman Institute, Philadelphia, PA

Purpose: The current study aims to determine the prognostic value of ESR and CRP performed prior to second stage reimplantation for the treatment of infected TKA.

Methods: Our cohort consisted of 108 patients who had undergone two-stage revision TKA for sepsis during the period of 1999 to 2006 at our institution. ESR and CRP testing was performed prior to resection and reimplantation. Receiver operating characteristic (ROC) curves were constructed to determine discriminatory value of ESR and CRP prior to reimplantation in predicting treatment outcome. Differences between serological values prior to resection and before reimplantation were also studied as possible outcome predictors of reinfection.

Results: A total of 25 patients required revision surgery for recurrence of PJI. Patients who were treated successfully with two-stage protocol had similar mean ESR (49 vs. 51) and CRP (2.04 vs. 2.62) values compared to patients with infection recurrence. The ROC areas under the curve revealed that ESR and CRP were poor predictors of reinfection after TKA reimplantation. Optimal cut-off values could not be obtained due to the high variance. Similar conclusions were ascertained regarding the change in ESR and CRP levels from time of resection.

Discussion and Conclusion: Although ESR and CRP are reflective of systemic changes in infection and pose an attractive, less invasive diagnostic test, the current study shows that there are no ideal cut-off values for ESR and CRP that would predict revision outcome in infected TKA patients. More accurate diagnostic tools are needed to support clinical judgment in monitoring infection progress and thus deciding whether or not to proceed with TKA reimplantation.