Alternative models to support weight loss in chronic musculoskeletal conditions: effectiveness of a physiotherapist-delivered intensive diet programme for knee osteoarthritis, the POWER randomised controlled trial

Objectives To determine if physiotherapists can deliver a clinically effective very low energy diet (VLED) supplementary to exercise in people with knee osteoarthritis (OA) and overweight or obesity. Methods 88 participants with knee OA and body mass index (BMI) >27 kg/m 2 were randomised to either intervention (n=42: VLED including two daily meal replacement products supplementary to control) or control (n=46: exercise). Both interventions were delivered by unblinded physiotherapists via six videoconference sessions over 6 months. The primary outcome was the percentage change in body weight at 6 months, measured by a blinded assessor. Secondary outcomes included BMI, waist circumference, waist-to-hip ratio, self-reported measures of pain, function, satisfaction and perceived global change, and physical performance tests. Results The intervention group lost a mean (SD) of 8.1% (5.2) body weight compared with 1.0% (3.2) in the control group (mean (95% CI) between-group difference 7.2% (95% CI 5.1 to 9.3), p<0.001), with significantly lower BMI and waist circumference compared with control group at follow-up. 76% of participants in the intervention group achieved ≥5% body weight loss and 37% acheived ≥10%, compared with 12% and 0%, respectively, in the control group. More participants in the intervention group (27/38 (71.1%)) reported global knee improvement than in the control group (20/42 (47.6%)) (p=0.02). There were no between-group differences in any other secondary outcomes. No serious adverse events were reported. Conclusion A VLED delivered by physiotherapists achieved clinically relevant weight loss and was safe for people with knee OA who were overweight or obese. The results have potential implications for future service models of care for OA and obesity. Trial registration number NIH, US National Library of Medicine, Clinicaltrials.gov NCT04733053 (1 February 2021).