Obesity has reached epidemic proportions and in the US, the age-adjusted obesity prevalence is 32% for men and 36% for women. The osteoarthritis risk is nearly four-fold for obese men and five-fold for obese women. The purpose of this study was to evaluate the US national obesity trends of TKA utilization. The Nationwide Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality (AHRQ) 2002–2009 datasets were merged to identify 753,268 TKAs. Over this period, obese patients represented 15% of all TKAs. Despite well documented concerns regarding perioperative complications associated with TKA in obese patients, TKA utilization doubled from 2002–2009. Additionally, 30% of obese patients had greater than 3 co-morbidities, compared to 7% in the non-obese group. With greater complication risks, the increasing TKA utilization in obese patients is concerning and warrants increased attention.