JBJS, August 1, 2007, Volume 89, Issue 8

Use of Erythrocyte Sedimentation Rate and C-Reactive Protein Level to Diagnose Infection Before Revision Total Knee Arthroplasty

Nelson V. Greidanus, MD, MPH, FRCSC Bassam A. Masri, MD, FRCSC Donald S. Garbuz, MD, MHSc, FRCSC S. Darrin Wilson, MBBCh, MD, FRCS M. Gavan McAlinden, MBBCh, MPH, MD, FRCS Min Xu, MSc Clive P. Duncan, MD, MSc, FRCSC

Knee

Background: Despite the widespread use of several diagnostic tests, there is still no perfect test for the diagnosis of infection at the site of a total knee arthroplasty. The purpose of this study was to evaluate the diagnostic test characteristics of the erythrocyte sedimentation rate and C-reactive protein level for the assessment of infection in patients presenting for revision total knee arthroplasty.

Methods: One hundred and fifty-one knees in 145 patients presenting for revision total knee arthroplasty were evaluated prospectively for the presence of infection with measurement of the erythrocyte sedimentation rate and the C-reactive protein level. The characteristics of these tests were assessed with use of two different techniques: first, receiver-operating-characteristic curve analysis was performed to determine the optimal positivity criterion for the diagnostic test, and, second, previously accepted criteria for establishing positivity of the tests were used.

Results: A diagnosis of infection was established for forty-five of the 151 knees that underwent revision total knee arthroplasty. The receiver-operating-characteristic curves indicated that the optimal positivity criterion was 22.5 mm/hr for the erythrocyte sedimentation rate and 13.5 mg/L for the C-reactive protein level. Both the erythrocyte sedimentation rate (sensitivity, 0.93; specificity, 0.83; positive likelihood ratio, 5.81; accuracy, 0.86) and the C-reactive protein level (sensitivity, 0.91; specificity, 0.86; positive likelihood ratio, 6.89; accuracy, 0.88) have excellent diagnostic test performance.

Conclusions: The erythrocyte sedimentation rate and the C-reactive protein level provide excellent diagnostic test information for establishing the presence or absence of infection prior to surgical intervention in patients with pain at the site of a knee arthroplasty.

Level of Evidence: Diagnostic Level I. See Instructions to Authors for a complete description of levels of evidence.

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