Preoperative evaluations in revision total knee arthroplasty.

UNLABELLED: There are many causes of total knee arthroplasty failure, and an accurate preoperative diagnosis is essential to optimize the results of revision surgery. We discuss our standard pre-operative evaluation routine and we retrospectively reviewed the last 295 patients who underwent revision total knee arthroplasty to establish the clinical value of the most commonly performed investigations used to diagnose sepsis. Routinely performed preoperative investigations include erythrocyte sedimentation rate, C-reactive protein, microbiology, bacteriology cultures of preoperative knee aspirations, and intraoperative tissue bacteriology cultures. Each investigation was compared with the reason for revision (eg, septic or aseptic) to establish the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of each. 79 cases (26.8%) were revised for infection. Of the investigations, the ESR had a sensitivity of 0.63, a specificity of 0.55, a positive predictive value of 0.39, a negative predictive value of 0.77, and an accuracy of 0.57. The respective values for C-reactive protein were 0.6, 0.63, 0.45, 0.76, and 0.62, and 0.53, 0.94, 0.75, 0.85, and 0.83 for intraoperative tissue culture. There was no preoperative investigation accurate enough to be solely relied on for diagnosing infection. We believe that clinical findings and the routine use of simple tests such as C-reactive protein, ESR, and knee aspiration yield predictable results. LEVEL OF EVIDENCE: Prognostic study, level II-1 (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.