Obese diabetic patients are at substantial risk for deep infection after primary TKA.

UNLABELLED: We conducted a prospective study of 1214 consecutive primary TKAs to compare the deep prosthetic infection rate between obese and nonobese patients during the first 12 months after surgery. We also sought to determine whether patient or surgical variables such as comorbidities, age, gender, blood transfusion, use of surgical drains, and antibiotic-impregnated cement were predictors of subsequent prosthetic infection after primary TKA. The overall prosthetic infection rate was 1.5% (n = 18). The odds for a deep prosthetic infection were greater in patients with morbid obesity (odds ratio [OR], 8.96; 95% confidence interval, 1.59-50.63) and diabetes (OR, 6.87; 95% confidence interval, 2.42-19.56). Men were more likely to have a prosthetic infection develop than women (OR, 5.93; 95% confidence interval, 1.95-18.04) and the prosthetic infection rate was lower (OR, 0.24; 95% confidence interval, 0.06-0.95) in patients when a surgical drain was used. There were no prosthetic infections in patients with diabetes who were not obese. This compares with 11 prosthetic infections in patients who were obese and diabetic and four prosthetic infections in patients who were obese but not diabetic. Morbid obesity and obesity combined with diabetes are risk factors for periprosthetic infection after TKA. LEVEL OF EVIDENCE: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.