Total knee arthroplasty (TKA) is considered to be a successful and cost-effective intervention for treatment of advanced symptomatic OA [1]. However, despite improvement in knee pain and disability, 15–20% of the patients report being dissatisfied with their prosthetic knee owing to insufficient pain relief, loss of function and limitations in physical functioning [2–5]. To improve the dissatisfaction rate, a clear and valid definition of what a poor outcome after TKA entails is needed.
