Effects of Behaviour Change Interventions Combined With Exercise on Device-Measured Physical Activity in People With Hip and Knee Osteoarthritis: A Systematic Review and Meta-Analysis.

Behaviour change techniques (BCTs) are recommended as core components of physical activity (PA) interventions for people with lower limb osteoarthritis (OA), and identifying effective BCTs is an emerging research priority. This systematic review aimed to evaluate the effects of combined behaviour change and exercise interventions on objectively measured total PA (primary outcome) and other device-measured activity behaviours, including moderate-to-vigorous physical activity (MVPA), steps and sedentary behaviour, in people with hip or knee OA (secondary outcomes). Five databases were searched from inception until September 2025. The titles of identified randomised controlled trials (n = 907) were screened by two reviewers, and 12 studies involving 1162 participants with OA were included. Study quality was assessed using the SIGN checklist, and certainty of evidence was evaluated using the GRADE approach. Most studies were rated as low quality, and the certainty of evidence was low to very low across all outcomes. Random-effects meta-analyses found little to no difference for the use of behaviour change and exercise interventions for our primary outcome of total PA postintervention (3 studies, n = 246; MD 21.25 min/day, 95% CI -26.11-68.61) or at 12-month follow-up (3 studies, n = 221; MD 30.52 min/day, 95% CI -25.42-86.45). A meta-analysis of four studies (n = 307) found a small increase in device-measured MVPA at short-term follow-up (MD 2.53 min/day, 95% CI 0.18 to 4.88; I 2 = 21%). No significant effects were observed for any of the other outcomes (long-term MVPA, steps or sedentary behaviour). The existing evidence is limited, and findings should be interpreted cautiously given the low to very low certainty of the evidence and the small number of studies available. This highlights the need for higher quality studies with clear BCT reporting and fidelity procedures to establish whether behaviour change combined with exercise improves PA behaviours.