We determined outcomes for patients classified as appropriate, inconclusive, or inappropriate for total knee arthroplasty (TKA) using a modified version of a validated appropriateness algorithm. Outcome measurement was conceptualized as short-term postoperative change attributable primarily to surgery and rehabilitation (2 months) and as longer-term postoperative change and recovery (1 and 2 years).
Preoperative and yearly postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function, Knee Injury and Osteoarthritis Outcome Score (KOOS) symptoms and KOOS pain scores were examined for persons undergoing primary TKA in the Osteoarthritis Initiative. Multigroup, 2-piece latent growth curve modeling was used to determine differences in outcome variable changes for each group from presurgery to 2-months postsurgery, as well as over a 2-year postoperative period.
Data from 167 persons with primary TKA were examined. Prevalence rates of appropriate, inconclusive, and inappropriate judgments were 47.9%, 20.8%, and 31.3%, respectively. The inappropriate group showed no change at 2 months following surgery, while appropriate and inconclusive groups had substantial improvement in all outcomes. One-year and 2-year postoperative recovery outcomes were not significantly different among the 3 groups.
The inappropriate group was unchanged 2 months after surgery and on average improved by 2.3 WOMAC function points from presurgery to 1 year following surgery based on our models. Appropriate and inconclusive groups improved by an average of 19.8 WOMAC function points at 1-year postsurgery. These data provide a compelling case for consensus-building efforts to define eligibility criteria for TKA with the goals of reducing variation in patient selection and optimizing both change over time and final outcomes.