Keele Research Repository

Symptoms of osteoarthritis (OA) evolve over years with variable rate and course. While studies have focused on understanding long-term trajectories of OA [e.g., 1 ], how these relate to shorter-term fluctuations in symptoms is not well-understood. Yet for many people, the lived experience of OA is recurrent fluctuations in episodic pain of varying frequency, intensity and duration; it is these episodes of increased pain and associated disability that often drive primary healthcare consultation. Historically, the term ‘exacerbation’ and ‘flare-up’ have been used interchangeably to describe sudden-onset episodes of increased pain; the term ‘flare-up’ has been adopted herein 2 . Patients describe flare-ups as being unpredictable and distressing, particularly in advanced stages 3 . Because of the recognized importance of flare-ups to the patient experience, there have been efforts to develop diagnostic criteria and consensus definition for OA flare-ups 4 , 5 , though a specific definition has not yet been widely accepted or validated. It is also important to differentiate between flare-ups and ‘complications’ that may result in symptoms (e.g., subchondral insufficiency micro-fracture), as treatment strategies will differ.