When obese patients undergo total knee arthroplasty (TKA), many surgeons require or request preoperative weight loss. A group of researchers sought to determine the amount of weight loss needed in this patient population, to improve TKA operative time, length of stay, discharge to a rehab facility, and functional improvement after surgery. This is the first known study to look exclusively at obese patients to understand how preoperative weight loss might improve knee surgical outcomes after TKA.
Those considered morbidly obese have a body mass index (BMI) of 40 or higher. This study looked at 203 patients with a BMI of 40 or more. They were evaluated 90 days before their TKA, and again immediately preceding TKA, to assess weight loss. Of those who lost weight preoperatively, 41% had lost five or more pounds, 29% lost 10 or more pounds, and 14% lost 20 or more pounds.
Losing 10 or less pounds before surgery made no difference in operative time, length of stay, the need for discharge to a rehab facility, or post-operative functional improvement. However, the preoperative loss of 20 pounds or more showed benefits: It lowered the odds of discharge to a rehab facility, and was associated with a shortened length of stay. There were, however, no significant differences in surgery times or functional improvements for those who lost 20-plus pounds.
A longer stay in the hospital or discharge to a rehab facility is a driver of higher costs in primary total knee arthroplasty. Preoperative weight loss may reduce overall costs. The need for Discharge to a rehab facility is also correlated with an increased rate of post-operative infection. In the future, this study could help surgeons target a specific level of weight loss prior to TKA, for their patients to improve knee surgical outcomes.
If you’d like to discuss obesity or weight concerns prior to your total knee arthroplasty, or just want to learn more about the knee replacement procedure, please contact our office. We’ll help you return to your healthy, pain-free lifestyle.
Dr. Stickney, a Kirkland orthopedic surgeon, is an expert in total and partial knee arthroplasty, exercise and health, and more.