Post-operative Weight Gain After Total Knee Arthroplasty: Prevalence and Its Possible Attenuation Using Intraoperative Sensors

As the proportion of adults with obesity continues to climb, so too does the need for total knee arthroplasty. Unfortunately, total knee replacement patients often experience post-operative weight gain, despite improved joint function. The purposes of this study were: 1) To execute a literature meta-analysis in order quantify the changes in body mass that are typically observed following TKA, and 2) Evaluate data from a prospective, multicenter study to assess any trends towards weight loss in a group of “balanced”, sensor-assisted TKA patients. The literature review found that average proportion of patients who had weight gain after TKA is 47% to 66%. In literature, the average post-operative weight gain was 9.5 lbs. (1.6 kg/m2 BMI increase), up to 14 lbs. (2.3 kg/m2). In the multicenter study, only 30.4% of patients and 36.9% of patients exhibited weight gain at 6 months and 1 year, respectively. At the 1-year interval, this indicates an 11% decrease from reported averages (p=0.049), up to 29% as reported by the NIH (p<0.001). The average weight gain in the multicenter patient group was 4.3 lbs. (0.72 kg/m2 BMI increase) at 6 months, and 3.5 lbs. (0.58 kg/m2) at 1 year, both of which are non-clinically meaningful. The average weight loss of those in the non-gaining group was 7.8 lbs. (1.3 kg/m2) at 6 months and 9.6 lbs. (1.6 kg/m2) at 1 year. Both of these values are clinically meaningful. This evaluation demonstrates that weight gain after TKA is prevalent, but ensuring soft-tissue balance (via technologies such as intraoperative sensing) may help mitigate this expected increase in body mass.Keywords: total knee arthroplasty, increased BMI, intraoperative sensors, weight gain, obesity