An unsupervised online Tai Chi program for people with knee osteoarthritis ("My Joint Tai Chi"): Study protocol for the RETREAT randomised controlled trial.

Background: Knee osteoarthritis (OA) is a leading contributor to global disability, with exercise proven to be an effective treatment. Tai Chi is a recommended type of exercise, but it is primarily done in person which imposes an accessibility issue. This study aims to evaluate the effects of an online unsupervised program, when provided with online educational information and exercise adherence support, on changes in knee pain and physical function, when compared to online education control for people with knee OA.

Methods: A two-arm, superiority parallel-design, pragmatic randomised controlled trial will be conducted involving 178 people with a clinical diagnosis of knee OA. After completing baseline assessment, participants will be randomly assigned to either: i) "My Joint Education", an education control website containing OA information only; or ii) "My Joint Tai Chi", an intervention website containing the same information as the control, a 12-week unsupervised online Tai Chi program to be undertaken at home 3 times a week, and information about an exercise adherence support app. All participants will be reassessed at 12 weeks after randomisation. Primary outcomes are overall knee pain during walking and physical function using the Western Ontario and McMaster Universities Osteoarthritis Index subscale.

Discussion: This randomised controlled trial will provide evidence about the effectiveness of the "My Joint Tai Chi" website compared to "My Joint Education" website on self-reported knee pain and physical function for people with knee OA.

Trial Registration: Prospectively registered with the Australia New Zealand Clinical Trials Registry (ID: ACTRN12623000780651) on 18 July 2023.