Weight and activity change in overweight and obese patients after primary total knee arthroplasty.

Few studies have examined the effect of primary total knee arthroplasty on the weight and physical activity of overweight and obese patients in the United States. We conducted a prospective study of changes in mean weight, body mass index (BMI), and physical activity over 2 years in 188 consecutive overweight or obese patients. Weight, BMI, and physical activity, evaluated using the Lower Extremity Activity Scale (LEAS), were assessed preoperatively and at 1 and 2 years. At 2 years, no significant weight change was found (P = .80), but BMI increased by 0.46 kg/m(2) (P = .049). The LEAS score increased from preoperatively to 2 years (P < .001). Preoperative LEAS score was not associated with weight or BMI at 2 years. This finding has implications for patient expectations and preoperative counseling.