Despite many years of research, there is still considerable uncertainty on what causes placebo effects and how these are mediated. Saline is a pharmacologically inert agent frequently used as placebo comparator in clinical trials of intra-articular (IA) treatments for knee osteoarthritis (OA) and patients often experience a significant pain improvement from this treatment even when it is administered as an open label placebo treatment.~It has further been shown that beneficial effects can be induced merely by having a conversation with a health professional and several studies have found the alliance between therapist and patient to have a positive effect on treatment outcome in physical rehabilitation indicating that positive attention by itself leads to beneficial treatment outcomes. Still it is unclear wether the effect of an open label placebo treatment can be influenced by a conversation and if the extent of this infleuence depends on the focus of the conversation.~The aim of this study is to determine whether a conversation about the individual's illness perception related to knee OA affects the response to a placebo treatment (saline injection) in individuals with knee OA.
Saline intra-articular injections used as placebo treatments have been shown to provide pain relief in knee osteoarthritis (OA) It has further been shown that beneficial effects can be induced merely by having a conversation with a health professional.~The aim of this study is to determine whether an individual conversation based on the individual's illness perception related to knee OA affects the response to an intra-articular treatment with saline in individuals with knee OA.