Predictive validity of the Knee Society Index of Severity: a prospective, multicenter cohort study

Compared with primary total knee arthroplasty, revision knee arthroplasties are more complex and account for greater expenditures of health care resources at all stages of the clinical process. The Knee Society Index of Severity (KSIS) was developed to stratify and quantify the severity of knee arthroplasties, and it has proved to be a reliable and valid measure. This article evaluates the ability of the preoperative KSIS to predict intraoperative findings. Thirty-one surgeons from 13 institutions used the KSIS to classify preoperative clinical parameters and radiographs. Preoperatvie KSIS information was compared with intraoperative KSIS findings (reference standard). Unweighed kappa statistics were used to assess correlation. Sixty-three patients (65 cases) met inclusion criteria and were prospectively studied. All feasible comparisons between the preoperative and the intraoperative KSIS revealed statistically significant association, P<.001. The preoperative KSIS accurately reflects intraoperative conditions, and KSIS can be used by orthopedic surgeons to plan revision arthroplasties.