This trial asks a previously unaddressed and important clinical question about management of knee osteoarthritis (OA) patients.~Current recommendations of management of knee OA highlight weight loss as first choice and weight loss is a potential principal intervention against knee OA as a co-morbidity to obesity.~Knee arthroplasty (KA) is an effective treatment of knee OA in patients with pain that limits the patient's ability to perform their normal daily activities. KA is considered a successful orthopedic procedure to alleviate knee pain and disability in end stage knee OA. The demand for KA is large and growing worldwide; in Denmark alone approximately 10,000 KA procedures are performed annually, which pose a substantial economic burden to the health care system. KA carries relatively low risk both in terms of systemic complications and suboptimal outcomes for the joint itself. KA is one of the most effective surgical procedures available with very few contraindications. As a result, the demand from patients for these treatments continues to rise along with the confidence of surgeons to offer KA to a wider range of patients in terms of age, disability and co-morbidities.~However, the quality of evidence for KA efficacy is low as very few randomized controlled trials (RCTs) exist - particularly with respect to comparative effectiveness. To inform decision making for obese individuals with knee OA, it is important to evaluate the comparative effectiveness of a weight loss intervention against KA. The present trial has been designed to compare the effectiveness of weight loss and KA in individuals with obesity and knee OA.~This study addresses this question by comparing two recommended and potentially competing strategies in the management of obese knee OA patients:~Strategy A. A 3-months waiting list followed by a 12-week Intensive supervised diet intervention; Strategy B. A 3-months waiting list followed by surgical knee arthroplasty including standard post-operative rehabilitation.~Although a trial to address this question is needed, so far this study has not been carried out, presumably because trials in routine clinical practice are quite expensive and health care professionals (HCPs) responsible for delivery of either strategy have little incentive to compare KA to less expensive, non-surgical therapies. Moreover, the Danish Health and Medicines Authority have not required such comparisons. Since the Danish healthcare system already provides KA at public hospitals, it appears that such settings are ideally suited to address this question and, in the process, help clinicians around the world make better judgments for their patients with OA.~The sparse comparative effectiveness evidence that could inform clinical decision making, combined with existing evidence from RCTs and observational studies on knee surgery and weight loss provide a clear-cut ethical and scientific justification for the trial described in this protocol.
This study addresses this question by comparing two recommended and potentially competing strategies in the management of obese knee OA patients:~Strategy A. A 3-months waiting list followed by a 12-week Intensive supervised diet intervention; Strategy B. A 3-months waiting list followed by surgical knee arthroplasty including standard post-operative rehabilitation.~The primary outcome is taken at week 38 from inclusion (baseline) corresponding to 6 months after treatment start (either surgery or intensive diet program).~Outcomes are also taken at baseline, week 13 (before treatment start), week 26 (end of diet program), week 38 (primary endpoint), and week 64.