We are presenting a paper at the 75th annual meeting of the American Academy of Orthopaedic Surgeons, outlining risk factors associated with infection after total knee arthroplasty. A review of over 5800 total knees, done at seven centers across the United States, revealed that patients who are obese (Body Mass Index greater than 30) have a significantly increased risk of infection after total knee arthroplasty. Furthermore, patients with a Body Mass Index greater than or equal to 35, classified as highly obese, had an even greater risk of infection following total knee replacement. Obesity increases the risk of surgical complications as a result of more difficult exposure, longer operative time, prolonged wound drainage, due to the thick layer of adipose tissue which is present between the skin and the deeper tissue, leading to the higher risk of wound complications and infection. It is important that individuals who are overweight work to try and maximize their health prior to surgery and strategize on how to keep their weight as reasonable as possible. There is strong evidence that obesity leads to an increased risk of developing arthritis in the knee and in fact, in our study 55% of the patients were in fact obese at the time of surgery.