Patients Less Likely to Lose Weight Following a Knee Replacement: Results From the Osteoarthritis Initiative.

BACKGROUND: Knee replacement typically results in reduced pain and improved function, but it is unclear if these improvements lead to weight loss. OBJECTIVE: The purpose of this study was to examine weight change patterns preoperatively and postoperatively among overweight/obese knee replacement patients. METHODS: The study evaluated 210 overweight/obese patients from the Osteoarthritis Initiative who underwent a knee replacement during an 8-year longitudinal study. Average annual weight changes during 1- to 2-year intervals prior to, including, and subsequent to knee replacement were categorized as loss (≥-2.5%), maintain (>-2.5% to <2.5%), and gain (≥2.5%). Weight changes across time intervals were compared using logistic regression with generalized estimating equations, adjusting for demographic, health, and knee factors. RESULTS: On average, patients lost -0.6 kg/y during the interval when the surgery was performed, but weight gain (0.9 kg/y) in the initial postoperative interval represented an overall net weight gain (0.3 kg/y) compared with presurgery. Continued weight gain (0.3 kg/y) was also seen among patients with additional follow-ups. Patients were significantly less likely to have a meaningful weight loss in the time interval immediately following the surgery compared with the interval in which the surgery took place (odds ratio, 0.37; 95% confidence interval, 0.18-0.79). CONCLUSIONS: Overweight and obese patients initially lost weight during the interval including knee replacement; however, they were less likely to lose more than 2.5% of their weight in the 1 to 2 years immediately after the surgery. Knee replacement patients may benefit from weight management interventions both preoperatively and postoperatively.