The knee society index of severity for failed total knee arthroplasty - Development and validation

Compared with primary knee replacement, total knee arthroplasty revision su rgery is a more complex procedure and accounts for greater expenditures of healthcare resources at each clinical stage. Overall, patients having revis ion procedures have poorer functional outcomes and higher complication rate s than patients having primary arthroplasty. Despite the expanded scope of revision problems and the rapidly emerging technology in revision surgery, the long-term success of any method remains in question. Because there is l ittle consensus on the timing of revision surgery, optimal surgical reconst ruction, and the type of prosthesis to be implanted, the Knee Society began development of an Index of Severity for Failed Total Knee Arthroplasty. Fi fty-four percent of Knee Society members completed an 82-item questionnaire that determined their clinical impression about potential risk factors for the outcomes of revision surgery for failed total knee replacements. Using these results, a consensus group developed the final version of the index. The result of the nominal group process was the Knee Society Index of Seve rity, which was based on eight distinct domains. Each domain was divided in to attributes and weights based on the questionnaire responses and consensu s meeting. Actual case scenarios from five institutions were used to test i nterrater reliability and validity. The interrater reliability of the avera ge score of all ratings was 0.95; the correlation of the criterion rating w ith the mean rating was 0.77. When three outliers were not included, the Pe arson product correlation increased to 0.92. These data support the applica tion of the Knee Society Index of Severity as a critical component of risk factor studies, effectiveness research, and cost-effectiveness analysis inv olving revisions of total knee replacements.