With socio-economic development, patients’ demands for quality of life, and the availability of new materials, the number of patients undergoing total knee arthroplasty is getting younger. Younger and more active patients are inevitable for increased joint wear, but are there other potential problems? Background: Although aseptic mechanical failure early after total knee arthroplasty has been reported in younger patients, it is unclear whether revision due to periprosthetic infection is associated with this population. The purpose of this study was primarily to determine if there was a significant difference in the incidence of early periprosthetic infections requiring revision between those younger than 50 years of age and those older than 50 years of age. METHODS: Large sample study based on patients discharged from a California nonpublic hospital: Inclusion criteria were: patients who underwent unilateral primary total knee replacement from 2005-2009; and patients who underwent partial or total revision surgery for periprosthetic infections or aseptic mechanical failures within 1 year postoperatively. The multivariate study included risk correction for key demographic and clinical variables, and the effect of total knee arthroplasty on infection and aseptic mechanical failure was investigated using a stratified modeling approach. Results: At 1 year postoperatively, of 120,538 total knee arthroplasty patients, 983 (0.82%) had revision surgery for periprosthetic infection, whereas 1,385 (1.15%) had revision surgery for mechanical failure.The cumulative incidence of revision for periprosthetic infection in patients younger than 50 years of age was 1.36%, and that of revision for aseptic mechanical failure was 3.49%. In a risk-corrected model, the risk of periprosthetic infection was 1.8 times higher in patients younger than 50 years of age than in patients 65 years of age or older, and the risk of aseptic mechanical failure was 4.7 times higher than the risk in patients 65 years of age or older. CONCLUSIONS: Patients younger than 50 years of age 1 year after total knee arthroplasty have a significantly higher risk of revision due to periprosthetic infection or aseptic mechanical failure.