Surgical weight-loss to improve functional status trajectories following total knee arthroplasty: SWIFT trial: Rationale, design, and methods

Total Knee Arthroplasty (TKA, also known as total knee replacement) is a highly effective surgical intervention for the restoration of physical function and improving quality of life in patients with disabling knee osteoarthritis. Recent data suggest that obesity is a major risk factor in the pathogenesis and progression of knee osteoarthritis, with increases in body mass index (BMI, kg/m2) directly correlating with the prevalence of knee osteoarthritis. However, recent data also suggest that there are increased risks associated with TKAs when performed in patients with morbid obesity (BMI > 40 kg/m2). Patients with morbid obesity are routinely referred for weight management prior to surgery. Many of these patients fail to meet the recommended weight loss goals prior to TKA, potentially making them ineligible for surgery or placing them at increased risk for sub-optimal outcomes. Thus, the purpose of this study is to examine the potential therapeutic impact and long-term outcomes of surgically induced weight loss on TKA outcomes. Specifically, these outcomes will include measures of physical function, mobility, and indices of joint function at 1 and 2 years post-TKA compared between extremely obese patients who undergo TKA (Control group, n = 150) and those with TKA performed ~1 year after bariatric surgery (Test group, n = 150). An additional primary endpoint will be the percent of bariatric patients that negate or delay the need for TKA. Secondary endpoints include perioperative outcomes after TKA.