Progressive resistance training compared to neuromuscular exercise in patients with hip osteoarthritis and the additive effect of exercise booster sessions: protocol for a multicentre cluster randomised controlled trial (The Hip Booster Trial)

INTRODUCTION: The primary aim of this randomised controlled trial is to investigate the effectiveness of 3 months of progressive resistance training (PRT) compared to neuromuscular exercise (NEMEX) on functional performance in patients with hip osteoarthritis (OA). Secondary aims are to investigate the effectiveness of exercise booster sessions (EBS) in prolonging the effects of the initial exercise interventions as well as to investigate the cost-effectiveness of PRT, NEMEX and EBS at 12-month follow-up. METHODS AND ANALYSIS: This multicentre cluster randomised controlled trial will be conducted at hospitals and physiotherapy clinics across Denmark. A total of 160 participants with clinically diagnosed hip OA will be recruited. Participants will be cluster randomised to a 3-month intervention of either PRT or NEMEX and to receive EBS or not, resulting in four treatment arms. The primary outcome is change in functional performance, measured by the 30 s chair stand test at 3 months for the primary comparison and at 12 months for the EBS comparisons. Secondary outcomes include changes in 40 m fast-paced walk test, 9-step timed stair climb test, leg extensor muscle power and maximal strength, Hip disability and Osteoarthritis Outcome Score subscales, EuroQol Group 5-dimension, global perceived effect, physical activity and pain. Outcomes are measured at baseline, after the initial 3 months of intervention, and at 6-month, 9-month and 12-month follow-up. An intention-to-treat approach will be used for analysing changes in the primary and secondary outcome measures. ETHICS AND DISSEMINATION: The trial has been approved by the Central Denmark Region Committee on Biomedical Research Ethics (Journal No 1-10-72-267-20) and registered at the Danish Data Protection Agency (Journal No 1-16-02-11-21). Results will be published in international peer-reviewed scientific journals. TRIAL REGISTRATION NUMBER: NCT04714047.