390 patients with chondral knee defects and previously failed surgery were randomized to undergo either autologous chondrocyte implantation (ACI) or an alternative standard repair procedure (ie. microfracture, autologous matrix-induced chrondrogenesis, mosaicplasty, debridement), with the choice of standard treatment left to the patient and surgeon. The purpose of this study was to determine if ACI conferred a significant functional benefit when compared to standard chondral repair procedures over the long-term. Primary outcomes were Lysolm score and loss of benefit, with secondary measures included patient-report outcome measures (Cincinnati, IKDC, and EQ5D) and patient satisfaction. Results at 5 years were reported. Both groups displayed a high rate of reoperation (247 additional procedures between the two groups), with no significant difference in Lysholm score or Cincinnati score. The ACI group demonstrated significantly higher IKDC scores at 5 years, as well as higher patient satisfaction (59% vs. 43%). Patients will continue to be followed-up for an additional 5 years.