German and Dutch versions of the original English language OAKS (one for hip osteoarthritis (OA) [HOAKS] and one for knee OA [KOAKS]) have recently been established by the researchers involved in this project. This process followed the 2010 Consensus-based Standards for the Selection of Health Status Measurement Instruments (COSMIN) recommendations to ensure equivalence between the original questionnaire and the target version. The psychometric properties (validity and reliability) of the German and Dutch versions shall now be determined in accordance with the COSMIN checklist, enabling their application as valid and reliable instruments for assessing OA knowledge among German-speaking and Dutch-speaking individuals with hip and/or knee osteoarthritis, respectively. Data will be collected through web-based surveys in both countries.