This study compared the functional results of an articulating antibiotic spacer for 2-stage revision knee arthroplasty for infection, to the functional results of aseptic revision. One hundred twenty-five patients who underwent revision of total knee arthroplasty for infection and aseptic loosening were identified. All of the patients with infection were treated with the PROSTALAC system (DePuy). At a minimum 2-year follow-up, WOMAC, Oxford-12, SF-12, patient satisfaction data, Harris Hip Score knee scores, and range of motion were assessed. The 2 cohorts (4 deaths in total, leaving 54 septic, 57 aseptic) were equivalent for age, gender, and comorbidity scores. At a mean of 41 months, none of the outcomes were significantly worse for the septic group, which had 2 recurrences of infection (4%). The satisfactory functional results of the PROSTALAC system may be related to the design features.