The Oxford Knee Score misses key concepts for patients with severe OA

This is a qualitative study testing the content validity of the Oxford Knee Score (OKS) through semi-structured group interviews with patients suffering from OA with or without TKA. 
The 12-item OKS does not possess adequate content validity. Apart from minor issues, the items of OKS are relevant and understandable. However, the patients did not feel that the OKS covered the whole spectrum of their condition regarding pain and function, thus key concepts are missing.

As a consequence, the constructs ”pain” and ”function” of OKS may not adequately reflect the patients’ actual pain and function, which brings uncertainty to what is truly measured with this questionnaire.