What are the best markers for disease progression in osteoarthritis (OA)?

To be able to prevent progression of osteoarthritis, the knowledge of prognostic factors of this progression is important. If certain prognostic factors are modifiable, they may enhance our ability to reduce osteoarthritis progression. Even if these prognostic factors are not modifiable, they can still be used to identify high-risk groups, which may have implications for patient information and the perspective of medical treatment. Prognostic factors of progression are reviewed here, mainly for hip and knee osteoarthritis as most data available concern these localisations. Areas of further research are highlighted.