TOPLINE

In patients with obesity and severe knee osteoarthritis (OA) who were eligible for knee arthroplasty, a supervised intensive dietary weight-loss program was clinically inferior to knee arthroplasty for patient-reported pain and function outcomes and quality of life at 6 months despite resulting in greater weight loss.

METHODOLOGY

• Researchers conducted a pragmatic, randomized, noninferiority clinical trial comparing the effectiveness of a supervised intensive diet intervention with that of knee arthroplasty in adults with obesity and knee OA who were eligible for knee arthroplasty.
• They included 92 adult participants (mean age, 67.5 years; 62% women) with obesity (BMI ≥ 30) and tibiofemoral OA (with or without patellofemoral involvement) from outpatient clinics in Denmark, who were randomly assigned to receive an intensive diet (n = 45) or knee arthroplasty (n = 47) initiated 12 weeks after randomization.
• The intensive diet group underwent a 12-week supervised weight-loss program, starting with an 8-week complete meal replacement (810 kcal/d), followed by a 4-week fixed energy diet (1200 kcal/d), along with cognitive-behavioral therapy and dietary counseling, whereas participants assigned to surgery underwent knee arthroplasty.
• The primary outcome was the patient’s perspective on pain and physical function assessed using the Oxford Knee Score (score range, 0-48; higher scores indicated better outcomes) at 6 months after treatment initiation, with a prespecified noninferiority margin of 4 points and an SD of 8 points on the score.
• Secondary outcomes included improvement in patient-reported health-related quality of life, change in metabolic syndrome factors, treatment failure, and adverse events.

TAKEAWAY

• At 6 months, an increase in the Oxford Knee Score was observed in the intensive diet and knee arthroplasty groups (least-squares mean, 28.2 and 36.5 points, respectively), with an estimated between-group difference of -8.2 points (95% CI, -11.5 to -5.0; P < .0001), which favored knee arthroplasty; the estimated 95% CI for the group difference did not include the predefined noninferiority margin of 4 score points.
• At 6 months, patients who received the intensive diet lost more weight than those who underwent knee arthroplasty (mean between-group difference, -9.7 kg; 95% CI, -11.8 to -7.6), with 10.3% and 1.2% body weight loss, respectively.
• At 6 months, the knee arthroplasty group demonstrated greater improvements in quality of life, physical function, and treatment satisfaction (P < .05 for all), whereas treatment failure was more common in the intensive diet group.
• The rate of serious adverse events was similar between the intensive diet and knee arthroplasty groups (12% vs 10%), with gastrointestinal disorders and cardiac symptoms being the most common events; the overall rate of adverse events was also similar (67% vs 74%).

IN PRACTICE

“This trial focused on a reduced-calorie diet and instructional intervention for weight loss, but clinical attention has shifted to pharmacological means to aid weight loss, and future research is needed to inform whether weight loss in general, including pharmaceutical means, multicomponent combinations of nonsurgical approaches may produce different results,” the authors of the study wrote.

SOURCE

The study was led by Marius Henriksen, PT, PhD, The Parker Institute, Copenhagen University Hospital Bispebjerg Frederiksberg, Copenhagen, Denmark. It was published online on July 10, 2026, in Osteoarthritis and Cartilage.

LIMITATIONS

The trial did not reach its planned enrollment target. Enrollment bias may have limited generalizability to patients with more severe symptoms. Knee arthroplasty procedures were performed at the discretion of the participating surgeons, which may have introduced heterogeneity in the arthroplasty group.

DISCLOSURES

The study received funding from the Novo Nordisk Foundation; the institute was supported by a grant from the Oak Foundation. Several authors reported having financial relationships with various companies and organizations, including Zimmer Biomet, Contura International, Ascendis Pharma, and others outside the submitted work.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.